title: Michelle Wie West

text: Wie was born on October 11, 1989 in Honolulu, Hawaii. She is the only child of immigrant parents from South Korea who came to the United States in the 1980s. Her father, Byung-wook Wie, is a former professor of travel industry management at the University of Hawaii. Her mother, Bo, was South Korea's women's amateur golf champion in 1985, and competed in a Miss Korea beauty pageant. Her paternal grandfather, Sang-Kyu Wie, a resident of Jangheung, Jeollanam-do, was an emeritus professor at Seoul National University. When she was born, Wie was a dual citizen of South Korea (by "jus sanguinis") and the United States (by "jus soli"). She renounced her South Korean citizenship in February 2013.


title: Michelle Wie West

text: Wie graduated from Punahou School in Honolulu in June 2007. On December 19, 2006, she announced that she would be attending Stanford University, where there are family ties. Her paternal grandfather was a visiting professor, and an aunt and uncle are both graduates. She enrolled in September 2007 as a freshman, but as a professional golfer, Wie was not eligible under NCAA rules to play for Stanford's golf team. During her first three years at Stanford, she attended only during the fall and winter quarters, running from late September through mid-March each year. She took leaves of absence during the rest of the year to play professional golf. Wie completed her studies at Stanford in March 2012 with a major in communications. She participated in the university's graduation ceremony in June 2012.


title: Michelle Wie West

text: Wie began playing golf at the age of four. In 2000, at the age of ten, she became the youngest player ever to qualify for the U.S. Women's Amateur Public Links Championship. Eight years later, Wie's mark was surpassed by fellow Hawaiian Allisen Corpuz, who qualified when she was five months younger than Wie had been when she set the record. Wie remained the youngest player to advance to match play in this tournament, until 2014 when Lucy Li surpassed her by one week. In 2001, at the age of 11, she won both the Hawaii State Women's Stroke Play Championship and the Jennie K. Wilson Women's Invitational. The Jennie K. Wilson Women's Invitations is the oldest and most prestigious women's amateur tournament in Hawaii. She also advanced into match play at the Women's U.S. Amateur Public Links Championship.


title: Michelle Wie West

text: In 2002, she won the Hawaii State Open Women's Division by thirteen shots. She also became the youngest player to qualify for an LPGA event, the Takefuji Classic held in Wie's home state of Hawaii. While she went on to miss the cut, her record stood for five more years until it was broken in 2007 by 11-year-old Ariya Jutanugarn.


title: Michelle Wie West

text: At the 2003 Kraft Nabisco Championship, Wie became the youngest player to make an LPGA cut. She carded a 66 in the third round, tying the amateur record for a women's major championship and qualifying her to play in the final group of the championship. In June 2003, Wie won the Women's Amateur Public Links tournament, becoming the youngest person ever, male or female, to win a USGA adult event. Later that summer, she made the cut at the US Women's Open when she was still just 13, the youngest player ever to do so.


title: Michelle Wie West

text: Wie was given a sponsor's exemption to the 2004 Sony Open in Hawaii, becoming the fourth, and youngest, female to play a PGA Tour event. Her second round score of 68 was the lowest ever by a woman in a PGA Tour event, though she went on to miss the cut in the tournament. While missing the cut by 1 stroke she bettered the 36 hole score of 47 men including 4 major winners and matched the scores of 15 more men including 3 more major winners. This in itself was an utterly incredible achievement by a 14 year-old girl. At age 16, 2 years later she shot another round of 68 in the men's tour Sony open and bettered the 36 hole score of 18 men including 2 major winners and matched the score of 9 others including 1 major winner. She again played in the LPGA Kraft Nabisco Championship, finishing fourth. As part of the victorious U.S. team, she became the youngest woman ever to play in the Curtis Cup tournament. Wie started her 2005 season by accepting another sponsor's invitation to play on the PGA Tour at the Sony Open in Hawaii, where she again missed the cut. She played five more LPGA Tour events that year as well as a PGA Tour event, the John Deere Classic. It was her third outing at a PGA Tour event; she missed the cut by two strokes. She entered qualifying for the U.S. Amateur Public Links and became the first female golfer to qualify for a USGA national men's tournament, tying for first place in a 36-hole qualifier for the U.S. Amateur Public Links. Wie made the top 64 in the stroke play rounds to qualify for match play. She lost in the quarterfinals to eventual champion Clay Ogden.


title: Michelle Wie West

text: On October 5, 2005, a week before her 16th birthday, Wie announced that she was turning professional. She signed sponsorship contracts with Nike and Sony reportedly worth more than $10 million per year.


title: Michelle Wie West

text: When Wie turned professional, she was not a member of any professional tour. LPGA Tour membership age requirements require a golfer to be 18, although some players such as Morgan Pressel and Aree Song have successfully petitioned for an exemption to join at age 17. Wie chose not to request an exemption and was thus only allowed to participate in a limited number of LPGA Tour events when given a sponsor's exemption from 2005 until 2008.


title: Michelle Wie West

text: Wie played her first professional event in the 2005 LPGA Samsung World Championship, where she was disqualified from a fourth-place finish for signing an incorrect scorecard. A journalist, Michael Bamberger, reported a day after Wie had completed her round that she had illegally dropped the ball closer to the hole than its original lie. Wie would later go on to tally four top-5 finishes on the LPGA tour, including a second at the Evian Masters, a tie for third at the Kraft Nabisco Championship, and a tie for 5th at the LPGA Championship. In the initial Rolex World Golf Rankings in February, 2006, Wie was placed third, behind Annika Sörenstam and Paula Creamer, but eventually dropped to 7th, partially due to a limited schedule.


title: Michelle Wie West

text: 2006 also involved several competitions against male competitors, starting with the PGA Tour Sony Open, where she again missed the cut, this time by four strokes. In May she became the first female medalist in a local qualifier for the men's U.S. Open, but did not advance past the New Jersey final stage qualifier. At the PGA John Deere Classic, after a 6-over-par first round, and 10 strokes off the projected cut, midway through round two, she withdrew from the tournament, citing heat exhaustion and tiredness.


title: Michelle Wie West

text: Wie also played on both the European and Asian tours. At the SK Telecom Open, a men's tournament in South Korea, she became the second woman (after Se Ri Pak) to make the cut on the Asian Tour, and in addition, reportedly received appearance fees exceeding the event's total prize money. However, Wie finished the season with several disappointing performances in both male and female tournaments, including the Omega European Masters, PGA 84 Lumber Classic, LPGA Tour Samsung World Championship and the Casio World Open. At this point, Wie had played 14 consecutive rounds of tournament golf without breaking par and had missed the cut in 11 out of 12 tries against men and remained winless against the women.


title: Michelle Wie West

text: In 2007, Wie's slump continued, including a four-month hiatus, due to injuries to both wrists, a disqualification, and several missed cuts and withdrawals. At the LPGA Ginn Tribute Hosted by Annika, she was 14 over par through 16 holes in the first round before withdrawing, citing the injury. The withdrawal was controversial owing to the LPGA Rule of 88, which states that a non-LPGA member shooting a score of 88 or more is forced to withdraw and banned from LPGA co-sponsored events for the rest of the year. Later that year, after finishing one stroke off the lead during the second round of the State Farm Classic, she was disqualified for walking outside of the official tournament area before returning to sign her scorecard. Despite the lack of victories, Wie was ranked #4 in the 2007 Forbes Top 20 Earners Under 25, with an annual earnings of $19 million .


title: Michelle Wie West

text: Wie finally became eligible to play full-time on the LPGA Tour in 2009, when she tied for 7th place at the LPGA qualifying tournament in Daytona Beach.


title: Michelle Wie West

text: After passing LPGA Qualifying School in December 2008, Wie declared that she still planned to play in tournaments against men. However, for the second consecutive year, she did not receive a sponsor exemption to play in the Sony Open in Hawaii where she had played four years in a row from 2004 through 2007. Her first tournament as an LPGA member was the season-opening SBS Open at Turtle Bay where she shot 66, 70 to move into a tie with Angela Stanford going into the final round of the tournament. Wie held a three-stroke lead with eight holes remaining, but ended up losing to Stanford by three strokes.


title: Michelle Wie West

text: It was reported in early March, 2009, that Wie had left the William Morris Agency, the Hollywood talent agency that had represented her since she turned pro in 2005, and would be signing with sports agency IMG.


title: Michelle Wie West

text: At the second major of the year, the LPGA Championship, she finished tied for 23rd, her best finish in a major since 2006. During this tournament she also scored her first recorded hole-in-one as a professional. However, the day after her final round of the LPGA Championship, she failed to qualify for the U.S. Women's Open due to a mediocre performance at a sectional qualifying tournament.


title: Michelle Wie West

text: In August, at Rich Harvest Farms golf course in Sugar Grove, Illinois, Wie was a captain's pick for the United States team in Solheim Cup competition, where she led the American squad to victory with a 3-0-1 performance, the best record on the American team.


title: Michelle Wie West

text: On November 15, 2009, Wie won her first professional individual tournament, the Lorena Ochoa Invitational in Guadalajara, Mexico, an event on the LPGA Tour limited to the top 36 female golfers in the world as determined by the LPGA money list and Rolex women's world golf rankings, posting a score of thirteen under par 275 for a two-stroke margin over fellow American Paula Creamer, and beating Jiyai Shin, Cristie Kerr and Morgan Pressel by two strokes. She then finished second in the Ladies European Tour season-ending Dubai Ladies Masters tournament on December 9–12, 2009, shooting a 15-under-par 273, which put her three shots behind winner In-Kyung Kim.


title: Michelle Wie West

text: On August 29, 2010, she posted a three-shot win over a full field at the CN Canadian Women's Open, held at St. Charles Country Club in Winnipeg, Manitoba, for her second career professional victory. In her next LPGA event two weeks later, she finished second in the 54-hole P&G NW Arkansas Championship shooting 201 (−12) and losing to Yani Tseng by one stroke after giving up an overnight three-stroke lead.


title: Michelle Wie West

text: On April 19, 2014, Wie won her third LPGA Tour event – and her first in the United States – the LPGA Lotte Championship. She was four strokes behind Angela Stanford after 54 holes but shot a 67 to Stanford's 73 to win by two strokes.


title: Michelle Wie West

text: On June 22, 2014, Wie won her fourth LPGA Tour event and first major championship, the U.S. Women's Open. She was tied for the lead with Amy Yang after 54 holes at two-under-par. She double-bogeyed the 16th hole to fall within one shot of Stacy Lewis, but birdied the next hole and parred the last hole for a final round par-70 to win by two strokes over Lewis. The win, coupled with her second-place finish in the 2014 Kraft Nabisco Championship, resulted in her winning the inaugural Rolex Annika Major Award. In 2014, she was also named one of ESPNW's Impact 25.


title: Michelle Wie West

text: In May 2022, Wie West announced that she would be stepping away from the game following the 2022 U.S. Women's Open.


title: Michelle Wie West

text: From the beginning of her public career, Michelle Wie was the subject of controversy expressed by fans, media, peers, and other observers.


title: Michelle Wie West

text: Despite the publicity her appearances garnered, Wie made only one cut in a men's tournament: at the rain-shortened 2006 SK Telecom Open on the Asian Tour. She made no cuts on the PGA Tour. After she missed the cut at the 2007 Sony Open by 14 shots, many sports critics began to doubt whether she ever would.


title: Michelle Wie West

text: Wie's last appearance in a men's professional event was at the 2008 Legends Reno-Tahoe Open, an alternate event on the PGA Tour. Wie shot rounds of 73 and 80, missing the cut by nine strokes.


title: Michelle Wie West

text: Professional golfers, fans, and media critics remarked that allowing Wie to compete in PGA events took away opportunities from more deserving golfers. By late 2007, the criticism over the use of exemptions had extended to Wie's participation in women's events on the LPGA Tour as well. Wie declined to enter LPGA Tour qualifying school after turning 18 and therefore would have to depend on sponsor exemptions to play in future LPGA tournaments. This decision drew criticism from golf fans and commentators. Such criticism ended after Wie qualified for the LPGA Tour through the 2008 qualifying tournament.


title: Michelle Wie West

text: Early in her career, Wie employed many different caddies after her father stopped being her caddie in 2004. She created controversy when, after finishing tied for 26th at the 2006 British Open, her caddie Greg Johnston was fired over the phone by Wie's then-agent Ross Berlin. Johnston said he was "surprised and disappointed" at the firing and at the fact that "no one named Wie gave me the news." Wie employed several other professional caddies after Johnston, and also returned to using her father for the remainder of the 2007 season, parting ways with caddie David Clarke after she missed the cut at that year's British Open. For much of 2009, Wie used on-loan caddie Patrick Tarrant, who worked for then-injured PGA pro Brett Wetterich; however, at the end of that year but prior to her first LPGA victory, Tarrant recommended that she work with his friend Brendan Woolley, who continued as her exclusive caddie through the 2010 season. Woolley and Wie parted ways in December 2012 after finishing 64th on the LPGA Money List and earning just $158,546 that season. In January 2013, Wie employed Mark Wallington, who caddied for another LPGA professional and European Solheim Cup player, Sophie Gustafson, for three tournaments. Wie then began working with Duncan French, who has continued caddying for her exclusively since.


title: Michelle Wie West

text: In the first week of February 2007, it was reported that Wie hurt her left wrist in a fall while running. However, little information was provided to the public due to concerns about her privacy. Initially, her public relations staff reported that she would be away from golf for 4 to 6 weeks but the injury lasted until the end of May.


title: Michelle Wie West

text: In response to the lack of information and prolonged absence, Brittany Lincicome questioned whether Wie and her parents had fabricated the injury in order to give her a reason to take a break from golf. At the Ginn Tribute Hosted by Annika in May 2007, Wie's playing partner, Alena Sharp, questioned Wie's withdrawal from the tournament due to wrist injury. However, Wie's other playing partner, Janice Moodie, stated that she heard Wie say "Ouch!" after hitting her tee shot, and confirmed "She didn't swing as hard from that point on."


title: Michelle Wie West

text: In April 2008, she announced that she had three broken bones in her wrist, despite her agent's March 2007 announcement that the wrist was not broken. A 2009 article about Wie's injury stated that the original misinformation resulted from Wie and her family failing to "understand or accept the severity of the injury," and that during the entire 2007 season, Wie played under a great deal of pain, taking four to five pain killers a day.


title: Michelle Wie West

text: In March 2019, Wie announced that she was engaged to be married to Jonnie West, who is Director of Basketball Operations for the Golden State Warriors and is the son of NBA legend Jerry West. They married on August 10, 2019, at a private home in Beverly Hills, California. In January 2020, she announced she was pregnant with a daughter, and has expressed interest in eventually returning to competitive golf. On June 19, 2020, she gave birth to her daughter, Makenna Kamalei Yoona West.


title: Michelle Wie West

text: Wie played her first professional event while still an amateur in February 2002. Prior to her first win in a professional tournament, on November 15, 2009, she played in a total of 80 professional events as either an amateur or a professional:


title: Cohen's kappa

text: Cohen's kappa coefficient (κ, lowercase Greek kappa) is a statistic that is used to measure inter-rater reliability (and also intra-rater reliability) for qualitative (categorical) items. It is generally thought to be a more robust measure than simple percent agreement calculation, as "κ" takes into account the possibility of the agreement occurring by chance. There is controversy surrounding Cohen's kappa due to the difficulty in interpreting indices of agreement. Some researchers have suggested that it is conceptually simpler to evaluate disagreement between items.


title: Cohen's kappa

text: The seminal paper introducing kappa as a new technique was published by Jacob Cohen in the journal "Educational and Psychological Measurement" in 1960.


title: Cohen's kappa

text: Cohen's kappa measures the agreement between two raters who each classify "N" items into "C" mutually exclusive categories. The definition of formula_1 is


title: Cohen's kappa

text: where is the relative observed agreement among raters, and is the hypothetical probability of chance agreement, using the observed data to calculate the probabilities of each observer randomly seeing each category. If the raters are in complete agreement then formula_3. If there is no agreement among the raters other than what would be expected by chance (as given by ), formula_4. It is possible for the statistic to be negative, which can occur by chance if there is no relationship between the ratings of the two raters, or it may reflect a real tendency of the raters to give differing ratings.


title: Cohen's kappa

text: For categories, observations to categorize and formula_5 the number of times rater predicted category :


title: Cohen's kappa

text: Where formula_8 is the estimated probability that both rater 1 and rater 2 will classify the same item as k, while formula_9 is the estimated probability that rater 1 will classify an item as k (and similarly for rater 2).


title: Cohen's kappa

text: The relation formula_10 is based on using the assumption that the rating of the two raters are independent. The term formula_9 is estimated by using the number of items classified as k by rater 1 (formula_12) divided by the total items to classify (formula_13): formula_14 (and similarly for rater 2).


title: Cohen's kappa

text: In the traditional 2 × 2 confusion matrix employed in machine learning and statistics to evaluate binary classifications, the Cohen's Kappa formula can be written as:


title: Cohen's kappa

text: where TP are the true positives, FP are the false positives, TN are the true negatives, and FN are the false negatives. In this case, Cohen's Kappa is equivalent to the "Heidke skill score" known in Meteorology. The measure was first introduced by Myrick Haskell Doolittle in 1888.


title: Cohen's kappa

text: Suppose that you were analyzing data related to a group of 50 people applying for a grant. Each grant proposal was read by two readers and each reader either said "Yes" or "No" to the proposal. Suppose the disagreement count data were as follows, where A and B are readers, data on the main diagonal of the matrix (a and d) count the number of agreements and off-diagonal data (b and c) count the number of disagreements:


title: Cohen's kappa

text: A case sometimes considered to be a problem with Cohen's Kappa occurs when comparing the Kappa calculated for two pairs of raters with the two raters in each pair having the same percentage agreement but one pair give a similar number of ratings in each class while the other pair give a very different number of ratings in each class. (In the cases below, notice B has 70 yeses and 30 nos, in the first case, but those numbers are reversed in the second.) For instance, in the following two cases there is equal agreement between A and B (60 out of 100 in both cases) in terms of agreement in each class, so we would expect the relative values of Cohen's Kappa to reflect this. However, calculating Cohen's Kappa for each:


title: Cohen's kappa

text: we find that it shows greater similarity between A and B in the second case, compared to the first. This is because while the percentage agreement is the same, the percentage agreement that would occur 'by chance' is significantly higher in the first case (0.54 compared to 0.46).


title: Cohen's kappa

text: P-value for kappa is rarely reported, probably because even relatively low values of kappa can nonetheless be significantly different from zero but not of sufficient magnitude to satisfy investigators.


title: Cohen's kappa

text: Confidence intervals for Kappa may be constructed, for the expected Kappa values if we had infinite number of items checked, using the following formula:


title: Cohen's kappa

text: This is calculated by ignoring that is estimated from the data, and by treating as an estimated probability of a binomial distribution while using asymptotic normality (i.e.: assuming that the number of items is large and that is not close to either 0 or 1). formula_27 (and the CI in general) may also be estimated using bootstrap methods.


title: Cohen's kappa

text: If statistical significance is not a useful guide, what magnitude of kappa reflects adequate agreement? Guidelines would be helpful, but factors other than agreement can influence its magnitude, which makes interpretation of a given magnitude problematic. As Sim and Wright noted, two important factors are prevalence (are the codes equiprobable or do their probabilities vary) and bias (are the marginal probabilities for the two observers similar or different). Other things being equal, kappas are higher when codes are equiprobable. On the other hand, Kappas are higher when codes are distributed asymmetrically by the two observers. In contrast to probability variations, the effect of bias is greater when Kappa is small than when it is large.


title: Cohen's kappa

text: Another factor is the number of codes. As number of codes increases, kappas become higher. Based on a simulation study, Bakeman and colleagues concluded that for fallible observers, values for kappa were lower when codes were fewer. And, in agreement with Sim & Wrights's statement concerning prevalence, kappas were higher when codes were roughly equiprobable. Thus Bakeman et al. concluded that "no one value of kappa can be regarded as universally acceptable." They also provide a computer program that lets users compute values for kappa specifying number of codes, their probability, and observer accuracy. For example, given equiprobable codes and observers who are 85% accurate, value of kappa are 0.49, 0.60, 0.66, and 0.69 when number of codes is 2, 3, 5, and 10, respectively.


title: Cohen's kappa

text: Nonetheless, magnitude guidelines have appeared in the literature. Perhaps the first was Landis and Koch,


title: Cohen's kappa

text: who characterized values < 0 as indicating no agreement and 0–0.20 as slight, 0.21–0.40 as fair, 0.41–0.60 as moderate, 0.61–0.80 as substantial, and 0.81–1 as almost perfect agreement. This set of guidelines is however by no means universally accepted; Landis and Koch supplied no evidence to support it, basing it instead on personal opinion. It has been noted that these guidelines may be more harmful than helpful. Fleiss's equally arbitrary guidelines characterize kappas over 0.75 as excellent, 0.40 to 0.75 as fair to good, and below 0.40 as poor.


title: Cohen's kappa

text: Kappa assumes its theoretical maximum value of 1 only when both observers distribute codes the same, that is, when corresponding row and column sums are identical. Anything less is less than perfect agreement. Still, the maximum value kappa could achieve given unequal distributions helps interpret the value of kappa actually obtained. The equation for "κ" maximum is:


title: Cohen's kappa

text: "k" = number of codes, formula_31 are the row probabilities, and formula_32 are the column probabilities.


title: Cohen's kappa

text: Kappa is an index that considers observed agreement with respect to a baseline agreement. However, investigators must consider carefully whether Kappa's baseline agreement is relevant for the particular research question. Kappa's baseline is frequently described as the agreement due to chance, which is only partially correct. Kappa's baseline agreement is the agreement that would be expected due to random allocation, given the quantities specified by the marginal totals of square contingency table. Thus, κ = 0 when the observed allocation is apparently random, regardless of the quantity disagreement as constrained by the marginal totals. However, for many applications, investigators should be more interested in the quantity disagreement in the marginal totals than in the allocation disagreement as described by the additional information on the diagonal of the square contingency table. Thus for many applications, Kappa's baseline is more distracting than enlightening. Consider the following example:


title: Cohen's kappa

text: The disagreement proportion is 14/16 or 0.875. The disagreement is due to quantity because allocation is optimal. κ is 0.01.


title: Cohen's kappa

text: The disagreement proportion is 2/16 or 0.125. The disagreement is due to allocation because quantities are identical. Kappa is −0.07.


title: Cohen's kappa

text: Here, reporting quantity and allocation disagreement is informative while Kappa obscures information. Furthermore, Kappa introduces some challenges in calculation and interpretation because Kappa is a ratio. It is possible for Kappa's ratio to return an undefined value due to zero in the denominator. Furthermore, a ratio does not reveal its numerator nor its denominator. It is more informative for researchers to report disagreement in two components, quantity and allocation. These two components describe the relationship between the categories more clearly than a single summary statistic. When predictive accuracy is the goal, researchers can more easily begin to think about ways to improve a prediction by using two components of quantity and allocation, rather than one ratio of Kappa.Some researchers have expressed concern over κ's tendency to take the observed categories' frequencies as givens, which can make it unreliable for measuring agreement in situations such as the diagnosis of rare diseases. In these situations, κ tends to underestimate the agreement on the rare category. For this reason, κ is considered an overly conservative measure of agreement. Others contest the assertion that kappa "takes into account" chance agreement. To do this effectively would require an explicit model of how chance affects rater decisions. The so-called chance adjustment of kappa statistics supposes that, when not completely certain, raters simply guess—a very unrealistic scenario. Moreover, some works have shown how kappa statistics can lead to a wrong conclusion for unbalanced data.


title: Cohen's kappa

text: A similar statistic, called pi, was proposed by Scott (1955). Cohen's kappa and Scott's pi differ in terms of how is calculated.


title: Cohen's kappa

text: Note that Cohen's kappa measures agreement between two raters only. For a similar measure of agreement (Fleiss' kappa) used when there are more than two raters, see Fleiss (1971). The Fleiss kappa, however, is a multi-rater generalization of Scott's pi statistic, not Cohen's kappa. Kappa is also used to compare performance in machine learning, but the directional version known as Informedness or Youden's J statistic is argued to be more appropriate for supervised learning.


title: Cohen's kappa

text: The weighted kappa allows disagreements to be weighted differently and is especially useful when codes are ordered. Three matrices are involved, the matrix of observed scores, the matrix of expected scores based on chance agreement, and the weight matrix. Weight matrix cells located on the diagonal (upper-left to bottom-right) represent agreement and thus contain zeros. Off-diagonal cells contain weights indicating the seriousness of that disagreement. Often, cells one off the diagonal are weighted 1, those two off 2, etc.


title: Cohen's kappa

text: where "k"=number of codes and formula_34, formula_35, and formula_36 are elements in the weight, observed, and expected matrices, respectively. When diagonal cells contain weights of 0 and all off-diagonal cells weights of 1, this formula produces the same value of kappa as the calculation given above.


title: 3D projection

text: A 3D projection (or graphical projection) is a design technique used to display a three-dimensional (3D) object on a two-dimensional (2D) surface. These projections rely on visual perspective and aspect analysis to project a complex object for viewing capability on a simpler plane.


title: 3D projection

text: 3D projections use the primary qualities of an object's basic shape to create a map of points, that are then connected to one another to create a visual element. The result is a graphic that contains conceptual properties to interpret that the figure or image as not actually flat (2D), but rather, as a solid object (3D) being viewed on a 2D display.


title: 3D projection

text: 3D objects are largely displayed on two-dimensional mediums (i.e. paper and computer monitors). As such, graphical projections are a commonly used design element; notably, in engineering drawing, drafting, and computer graphics. Projections can be calculated through employment of mathematical analysis and formulae, or by using various geometric and optical techniques.


title: 3D projection

text: Projection is achieved by the use of imaginary "projectors"; the projected, mental image becomes the technician's vision of the desired, finished picture. Methods provide a uniform imaging procedure among people trained in technical graphics (mechanical drawing, computer aided design, etc.). By following a method, the technician may produce the envisioned picture on a planar surface such as drawing paper.


title: 3D projection

text: In parallel projection, the lines of sight from the object to the projection plane are parallel to each other. Thus, lines that are parallel in three-dimensional space remain parallel in the two-dimensional projected image. Parallel projection also corresponds to a perspective projection with an infinite focal length (the distance from a camera's lens and focal point), or "zoom".


title: 3D projection

text: Images drawn in parallel projection rely upon the technique of axonometry ("to measure along axes"), as described in Pohlke's theorem. In general, the resulting image is "oblique" (the rays are not perpendicular to the image plane); but in special cases the result is "orthographic" (the rays are perpendicular to the image plane). "Axonometry" should not be confused with "axonometric projection", as in English literature the latter usually refers only to a specific class of pictorials (see below).


title: 3D projection

text: The orthographic projection is derived from the principles of descriptive geometry and is a two-dimensional representation of a three-dimensional object. It is a parallel projection (the lines of projection are parallel both in reality and in the projection plane). It is the projection type of choice for working drawings.


title: 3D projection

text: If the normal of the viewing plane (the camera direction) is parallel to one of the primary axes (which is the "x", "y", or "z" axis), the mathematical transformation is as follows;


title: 3D projection

text: To project the 3D point formula_1, formula_2, formula_3 onto the 2D point formula_4, formula_5 using an orthographic projection parallel to the y axis (where positive "y" represents forward direction - profile view), the following equations can be used:


title: 3D projection

text: where the vector s is an arbitrary scale factor, and c is an arbitrary offset. These constants are optional, and can be used to properly align the viewport. Using matrix multiplication, the equations become:


title: 3D projection

text: While orthographically projected images represent the three dimensional nature of the object projected, they do not represent the object as it would be recorded photographically or perceived by a viewer observing it directly. In particular, parallel lengths at all points in an orthographically projected image are of the same scale regardless of whether they are far away or near to the virtual viewer. As a result, lengths are not foreshortened as they would be in a perspective projection.


title: 3D projection

text: With "multiview projections", up to six pictures (called "primary views") of an object are produced, with each projection plane parallel to one of the coordinate axes of the object. The views are positioned relative to each other according to either of two schemes: "first-angle" or "third-angle" projection. In each, the appearances of views may be thought of as being "projected" onto planes that form a 6-sided box around the object. Although six different sides can be drawn, "usually" three views of a drawing give enough information to make a 3D object. These views are known as "front view", "top view", and "end view". The terms "elevation", "plan" and "section" are also used.


title: 3D projection

text: In "oblique projections" the parallel projection rays are not perpendicular to the viewing plane as with orthographic projection, but strike the projection plane at an angle other than ninety degrees. In both orthographic and oblique projection, parallel lines in space appear parallel on the projected image. Because of its simplicity, oblique projection is used exclusively for pictorial purposes rather than for formal, working drawings. In an oblique pictorial "drawing", the displayed angles among the axes as well as the foreshortening factors (scale) are arbitrary. The distortion created thereby is usually attenuated by aligning one plane of the imaged object to be parallel with the plane of projection thereby creating a true shape, full-size image of the chosen plane. Special types of oblique projections are:


title: 3D projection

text: In cavalier projection (sometimes cavalier perspective or high view point) a point of the object is represented by three coordinates, "x", "y" and "z". On the drawing, it is represented by only two coordinates, "x″" and "y″". On the flat drawing, two axes, "x" and "z" on the figure, are perpendicular and the length on these axes are drawn with a 1:1 scale; it is thus similar to the dimetric projections, although it is not an axonometric projection, as the third axis, here "y", is drawn in diagonal, making an arbitrary angle with the "x″" axis, usually 30 or 45°. The length of the third axis is not scaled.


title: 3D projection

text: The term cabinet projection (sometimes cabinet perspective) stems from its use in illustrations by the furniture industry. Like cavalier perspective, one face of the projected object is parallel to the viewing plane, and the third axis is projected as going off in an angle (typically 30° or 45° or arctan(2) = 63.4°). Unlike cavalier projection, where the third axis keeps its length, with cabinet projection the length of the receding lines is cut in half.


title: 3D projection

text: A variant of oblique projection is called "military projection". In this case, the horizontal sections are isometrically drawn so that the floor plans are not distorted and the verticals are drawn at an angle. The military projection is given by rotation in the "xy"-plane and a vertical translation an amount "z".


title: 3D projection

text: "Axonometric projections" show an image of an object as viewed from a skew direction in order to reveal all three directions (axes) of space in one picture. Axonometric projections may be either "orthographic" or "oblique". Axonometric instrument drawings are often used to approximate graphical perspective projections, but there is attendant distortion in the approximation. Because pictorial projections innately contain this distortion, in instrument drawings of pictorials great liberties may then be taken for economy of effort and best effect.


title: 3D projection

text: "Axonometric projection" is further subdivided into three categories: "isometric projection", "dimetric projection", and "trimetric projection", depending on the exact angle at which the view deviates from the orthogonal. A typical characteristic of orthographic pictorials is that one axis of space is usually displayed as vertical.


title: 3D projection

text: "Axonometric projections" are also sometimes known as "auxiliary views", as opposed to the "primary views" of "multiview projections".


title: 3D projection

text: In isometric pictorials (for methods, see Isometric projection), the direction of viewing is such that the three axes of space appear equally foreshortened, and there is a common angle of 120° between them. The distortion caused by foreshortening is uniform, therefore the proportionality of all sides and lengths are preserved, and the axes share a common scale. This enables measurements to be read or taken directly from the drawing.


title: 3D projection

text: In dimetric pictorials (for methods, see Dimetric projection), the direction of viewing is such that two of the three axes of space appear equally foreshortened, of which the attendant scale and angles of presentation are determined according to the angle of viewing; the scale of the third direction (vertical) is determined separately. Approximations are common in dimetric drawings.


title: 3D projection

text: In trimetric pictorials (for methods, see Trimetric projection), the direction of viewing is such that all of the three axes of space appear unequally foreshortened. The scale along each of the three axes and the angles among them are determined separately as dictated by the angle of viewing. Approximations in Trimetric drawings are common.


title: 3D projection

text: Objects drawn with parallel projection do not appear larger or smaller as they extend closer to or away from the viewer. While advantageous for architectural drawings, where measurements must be taken directly from the image, the result is a perceived distortion, since unlike perspective projection, this is not how our eyes or photography normally work. It also can easily result in situations where depth and altitude are difficult to gauge, as is shown in the illustration to the right.


title: 3D projection

text: In this isometric drawing, the blue sphere is two units higher than the red one. However, this difference in elevation is not apparent if one covers the right half of the picture, as the boxes (which serve as clues suggesting height) are then obscured.


title: 3D projection

text: This visual ambiguity has been exploited in op art, as well as "impossible object" drawings. M. C. Escher's "Waterfall" (1961), while not strictly utilizing parallel projection, is a well-known example, in which a channel of water seems to travel unaided along a downward path, only to then paradoxically fall once again as it returns to its source. The water thus appears to disobey the law of conservation of energy. An extreme example is depicted in the film "Inception", where by a forced perspective trick an immobile stairway changes its connectivity. The video game "Fez" uses tricks of perspective to determine where a player can and cannot move in a puzzle-like fashion.


title: 3D projection

text: Perspective projection or perspective transformation is a linear projection where three dimensional objects are projected on a "picture plane". This has the effect that distant objects appear smaller than nearer objects.


title: 3D projection

text: It also means that lines which are parallel in nature (that is, meet at the point at infinity) appear to intersect in the projected image. For example, if railways are pictured with perspective projection, they appear to converge towards a single point, called the vanishing point. Photographic lenses and the human eye work in the same way, therefore perspective projection looks most realistic. Perspective projection is usually categorized into "one-point", "two-point" and "three-point perspective", depending on the orientation of the projection plane towards the axes of the depicted object.


title: 3D projection

text: Graphical projection methods rely on the duality between lines and points, whereby two straight lines determine a point while two points determine a straight line. The orthogonal projection of the eye point onto the picture plane is called the "principal vanishing point" (P.P. in the scheme on the left, from the Italian term "punto principale", coined during the renaissance).


title: 3D projection

text: The principal vanishing point is the vanishing point of all horizontal lines perpendicular to the picture plane. The vanishing points of all horizontal lines lie on the horizon line. If, as is often the case, the picture plane is vertical, all vertical lines are drawn vertically, and have no finite vanishing point on the picture plane. Various graphical methods can be easily envisaged for projecting geometrical scenes. For example, lines traced from the eye point at 45° to the picture plane intersect the latter along a circle whose radius is the distance of the eye point from the plane, thus tracing that circle aids the construction of all the vanishing points of 45° lines; in particular, the intersection of that circle with the horizon line consists of two "distance points". They are useful for drawing chessboard floors which, in turn, serve for locating the base of objects on the scene. In the perspective of a geometric solid on the right, after choosing the principal vanishing point —which determines the horizon line— the 45° vanishing point on the left side of the drawing completes the characterization of the (equally distant) point of view. Two lines are drawn from the orthogonal projection of each vertex, one at 45° and one at 90° to the picture plane. After intersecting the ground line, those lines go toward the distance point (for 45°) or the principal point (for 90°). Their new intersection locates the projection of the map. Natural heights are measured above the ground line and then projected in the same way until they meet the vertical from the map.


title: 3D projection

text: While orthographic projection ignores perspective to allow accurate measurements, perspective projection shows distant objects as smaller to provide additional realism.


title: 3D projection

text: The perspective projection requires a more involved definition as compared to orthographic projections. A conceptual aid to understanding the mechanics of this projection is to imagine the 2D projection as though the object(s) are being viewed through a camera viewfinder. The camera's position, orientation, and field of view control the behavior of the projection transformation. The following variables are defined to describe this transformation:


title: 3D projection

text: Most conventions use positive z values (the plane being in front of the pinhole), however negative z values are physically more correct, but the image will be inverted both horizontally and vertically.


title: 3D projection

text: Otherwise, to compute formula_13 we first define a vector formula_20 as the position of point "A" with respect to a coordinate system defined by the camera, with origin in "C" and rotated by formula_21 with respect to the initial coordinate system. This is achieved by subtracting formula_22 from formula_23 and then applying a rotation by formula_24 to the result. This transformation is often called a , and can be expressed as follows, expressing the rotation in terms of rotations about the "x," "y," and "z" axes (these calculations assume that the axes are ordered as a left-handed system of axes):


title: 3D projection

text: This representation corresponds to rotating by three Euler angles (more properly, Tait–Bryan angles), using the "xyz" convention, which can be interpreted either as "rotate about the "extrinsic" axes (axes of the "scene") in the order "z", "y", "x" (reading right-to-left)" or "rotate about the "intrinsic" axes (axes of the "camera") in the order "x, y, z" (reading left-to-right)". Note that if the camera is not rotated (formula_26), then the matrices drop out (as identities), and this reduces to simply a shift: formula_27


title: 3D projection

text: Alternatively, without using matrices (let us replace formula_28 with formula_29 and so on, and abbreviate formula_30 to formula_31 and formula_32 to formula_33):


title: 3D projection

text: This transformed point can then be projected onto the 2D plane using the formula (here, "x"/"y" is used as the projection plane; literature also may use "x"/"z"):


title: 3D projection

text: in conjunction with an argument using similar triangles, leads to division by the homogeneous coordinate, giving


title: 3D projection

text: The distance of the viewer from the display surface, formula_38, directly relates to the field of view, where formula_39 is the viewed angle. (Note: This assumes that you map the points (-1,-1) and (1,1) to the corners of your viewing surface)


title: 3D projection

text: In which formula_41 is the display size, formula_42 is the recording surface size (CCD or film), formula_43 is the distance from the recording surface to the entrance pupil (camera center), and formula_44 is the distance, from the 3D point being projected, to the entrance pupil.


title: 3D projection

text: Subsequent clipping and scaling operations may be necessary to map the 2D plane onto any particular display media.


title: 3D projection

text: A "weak" perspective projection uses the same principles of an orthographic projection, but requires the scaling factor to be specified, thus ensuring that closer objects appear bigger in the projection, and vice versa. It can be seen as a hybrid between an orthographic and a perspective projection, and described either as a perspective projection with individual point depths formula_45 replaced by an average constant depth formula_46, or simply as an orthographic projection plus a scaling.


title: 3D projection

text: The weak-perspective model thus approximates perspective projection while using a simpler model, similar to the pure (unscaled) orthographic perspective.


title: 3D projection

text: It is a reasonable approximation when the depth of the object along the line of sight is small compared to the distance from the camera, and the field of view is small. With these conditions, it can be assumed that all points on a 3D object are at the same distance formula_46 from the camera without significant errors in the projection (compared to the full perspective model).


title: 3D projection

text: To determine which screen "x"-coordinate corresponds to a point at formula_50 multiply the point coordinates by:


title: 3D projection

text: Because the camera is in 3D, the same works for the screen "y"-coordinate, substituting "y" for "x" in the above diagram and equation.


title: 3D projection

text: You can use that to do clipping techniques, replacing the variables with values of the point that's are out of the FOV-angle and the point inside Camera Matrix.


title: 3D projection

text: This technique, also known as "Inverse Camera", is a Perspective Projection Calculus with known values to calculate the last point on visible angle, projecting from the invisible point, after all needed transformations finished.


title: Homo ergaster

text: Homo ergaster is an extinct species or subspecies of archaic humans who lived in Africa in the Early Pleistocene. Whether "H. ergaster" constitutes a species of its own or should be subsumed into "H. erectus" is an ongoing and unresolved dispute within palaeoanthropology. Proponents of synonymisation typically designate "H. ergaster" as "African "Homo erectus" or "Homo erectus ergaster"". The name "Homo ergaster" roughly translates to "working man", a reference to the more advanced tools used by the species in comparison to those of their ancestors. The fossil range of "H. ergaster" mainly covers the period of 1.7 to 1.4 million years ago, though a broader time range is possible. Though fossils are known from across East and Southern Africa, most "H. ergaster" fossils have been found along the shores of Lake Turkana in Kenya. There are later African fossils, some younger than 1 million years ago, that indicate long-term anatomical continuity, though it is unclear if they can be formally regarded as "H. ergaster" specimens. As a chronospecies, "H. ergaster" may have persisted to as late as 600,000 years ago, when new lineages of "Homo" arose in Africa.


title: Homo ergaster

text: Those who believe "H. ergaster" should be subsumed into "H. erectus" consider there to be too little difference between the two to separate them into distinct species. Proponents of keeping the two species as distinct cite morphological differences between the African fossils and "H. erectus" fossils from Asia, as well as early "Homo" evolution being more complex than what is implied by subsuming species such as "H. ergaster" into "H. erectus". Additionally, morphological differences between the specimens commonly seen as constituting "H. ergaster" might suggest that "H. ergaster" itself does not represent a cohesive species. Regardless of their most correct classification, "H. ergaster" exhibit primitive versions of traits later expressed in "H. erectus" and are thus likely the direct ancestors of later "H. erectus" populations in Asia. Additionally, "H. ergaster" is likely ancestral to later hominins in Europe and Africa, such as modern humans and Neanderthals.


title: Homo ergaster

text: Several features distinguish "H. ergaster" from australopithecines as well as earlier and more basal species of "Homo", such as "H. habilis". Among these features are their larger body mass, relatively long legs, obligate bipedalism, relatively small jaws and teeth (indicating a major change in diet) as well as body proportions and inferred lifestyles more similar to modern humans than to earlier and contemporary hominins. With these features in mind, some researchers view "H. ergaster" as being the earliest true representative of the genus "Homo".


title: Homo ergaster

text: "H. ergaster" lived on the savannah in Africa, a unique environment with challenges that would have resulted in the need for many new and distinct behaviours. Earlier "Homo" probably used counter-attack tactics, like modern primates, to keep predators away. By the time of "H. ergaster", this behaviour had probably resulted in the development of true hunter-gatherer behaviour, a first among primates. "H. ergaster" was an apex predator. Further behaviours that might first have arisen in "H. ergaster" include male-female divisions of foraging and true monogamous pair bonds. "H. ergaster" also marks the appearance of more advanced tools of the Acheulean industry, including the earliest known hand axes. Though undisputed evidence is missing, "H. ergaster" might also have been the earliest hominin to master control of fire.


title: Homo ergaster

text: The systematics and taxonomy of "Homo" in the Early to Middle Pleistocene is one of the most disputed areas of palaeoanthropology. In early palaeoanthropology and well into the twentieth century, it was generally assumed that "Homo sapiens" was the end result of gradual modifications within a single lineage of hominin evolution. As the perceived transitional form between early hominins and modern humans, "H. erectus", originally assigned to contain archaic human fossils in Asia, came to encompass a wide range of fossils covering a large span of time (almost the entire temporal range of "Homo"). Since the late twentieth century, the diversity within "H. erectus" has led some to question what exactly defines the species and what it should encompass. Some researchers, such as palaeoanthropologist Ian Tattersall in 2013, have questioned "H. erectus" since it contains an "unwieldly" number of fossils with "substantially differing morphologies".


title: Homo ergaster

text: In the 1970s, palaeoanthropologists Richard Leakey and Alan Walker described a series of hominin fossils from Kenyan fossil localities on the eastern shore of Lake Turkana. The most notable finds were two partial skulls; KNM ER 3733 and KNM ER 3883, found at Koobi Fora. Leakey and Walker assigned these skulls to "H. erectus", noting that their brain volumes (848 and 803 cc respectively) compared well to the far younger type specimen of "H. erectus" (950 cc). Another significant fossil was a fossil mandible recovered at Ileret and described by Leakey with the designation KNM ER 992 in 1972 as ""Homo" of indeterminate species".


title: Homo ergaster

text: In 1975, palaeoanthropologists Colin Groves and Vratislav Mazák designated KNM ER 992 as the holotype specimen of a distinct species, which they dubbed "Homo ergaster". The name ("ergaster" being derived from the Ancient Greek ἐργαστήρ, "ergastḗr", 'workman') roughly translates to "working man" or "workman". Groves and Mazák also included many of the Koobi Fora fossils, such as KNM ER 803 (a partial skeleton and some isolated teeth) in their designation of the species, but did not provide any comparison with the Asian fossil record of "H. erectus" in their diagnosis, inadvertently causing some of the later taxonomic confusion in regards to the species.


title: Homo ergaster

text: A nearly complete fossil, interpreted as a young male (though the sex is actually undetermined), was discovered at the western shore of Lake Turkana in 1984 by Kenyan archaeologist Kamoya Kimeu. The fossils were described by Leakey and Walker, alongside paleanthropologists Frank Brown and John Harris, in 1985 as KNM-WT 15000 (nicknamed "Turkana Boy"). They interpreted the fossil, consisting of a nearly complete skeleton, as representing "H. erectus". Turkana Boy was the first discovered comprehensively preserved specimen of "H. ergaster"/"erectus" found and constitutes an important fossil in establishing the differences and similarities between early "Homo" and modern humans. Turkana Boy was placed in "H. ergaster" by paleanthropologist Bernard Wood in 1992, and is today, alongside other fossils in Africa previously designated as "H. erectus", commonly seen as a representative of "H. ergaster" by those who support "H. ergaster" as a distinct species.


title: Homo ergaster

text: "H. ergaster" is easily distinguished from earlier and more basal species of "Homo", notably "H. habilis" and "H. rudolfensis", by a number of features that align them, and their inferred lifestyle, more closely to modern humans than to earlier and contemporary hominins. As compared to their relatives, "H. ergaster" had body proportions more similar to later members of the genus "Homo", notably relatively long legs which would have made them obligately bipedal. The teeth and jaws of "H. ergaster" are also relatively smaller than those of "H. habilis" and "H. rudolfensis", indicating a major change in diet. In 1999, palaeoanthropologists Bernard Wood and Mark Collard argued that the conventional criteria for assigning species to the genus "Homo" were flawed and that early and basal species, such as "H. habilis" and "H. rudolfensis", might appropriately be reclassified as ancestral australopithecines. In their view, the true earliest representative of "Homo" was "H. ergaster".


title: Homo ergaster

text: Since its description as a separate species in 1975, the classification of the fossils referred to "H. ergaster" has been in dispute. "H. ergaster" was immediately dismissed by Leakey and Walker and many influential researchers, such as palaeoanthropologist G. Philip Rightmire, who wrote an extensive treatise on "H. erectus" in 1990, continued to prefer a more inclusive and comprehensive "H. erectus". Overall, there is no doubt that the group of fossils composing "H. erectus" and "H. ergaster" represent the fossils of a more or less cohesive subset of closely related archaic humans. The question is instead whether these fossils represent a radiation of different species or the radiation of a single, highly variable and diverse, species over the course of almost two million years. This long-running debate remains unresolved, with researchers typically using the terms "H. erectus" s.s. ("sensu stricto") to refer to "H. erectus" fossils in Asia and the term "H. erectus" s.l. ("sensu lato") to refer to fossils of other species that may or may not be included in "H. erectus", such as "H. ergaster", "H. antecessor" and "H. heidelbergensis".


title: Homo ergaster

text: For obvious reasons, "H. ergaster" shares many features with "H. erectus", such as large forward-projecting jaws, large brow ridges and a receding forehead. Many of the features of "H. ergaster" are clearly more primitive versions of features later expressed in "H. erectus", which somewhat obscures the differences between the two. There are subtle, potentially significant, differences between the East African and East Asian fossils. Among these are the somewhat higher-domed and thinner-walled skulls of "H. ergaster", and the even more massive brow ridges and faces of Asian "H. erectus".


title: Homo ergaster

text: The question is made more difficult since it regards how much intraspecific variation can be exhibited in a single species before it needs to be split into more, a question that in and of itself does not have a clear-cut answer. A 2008 analysis by anthropologist Karen L. Baab, examining fossils of various "H. erectus" subspecies, and including fossils attributed to "H. ergaster", found that the intraspecific variation within "H. erectus" was greater than expected for a single species when compared to modern humans and chimpanzees, but fell well within the variation expected for a species when compared to gorillas, and even well within the range expected for a single subspecies when compared to orangutans (though this is partly due to the great sexual dimorphism exhibited in gorillas and orangutans). Baab concluded that "H. erectus" s.l. was either a single but variable species, several subspecies divided by time and geography or several geographically dispersed but closely related species. In 2015, paleanthropologists David Strait, Frederick Grine and John Fleagle listed "H. ergaster" as one of the seven "widely recognized" species of "Homo", alongside "H. habilis", "H. rudolfensis", "H. erectus", "H. heidelbergensis", "H. neanderthalensis" and "H. sapiens", noting that other species, such as "H. floresiensis" and "H. antecessor", were less widely recognised or more poorly known.


title: Homo ergaster

text: Comparing various African fossils attributed to "H. erectus" or "H. ergaster" to Asian fossils, notably the type specimen of "H. erectus", in 2013, Ian Tattersall concluded that referring to the African material as "H. ergaster" rather than "African "H. erectus"" was a "considerable improvement" as there were many autapomorphies distinguishing the material of the two continents from one another. Tattersall believes it to be appropriate to use the designation "H. erectus" only for eastern Asian fossils, disregarding its previous use as the name for an adaptive grade of human fossils from throughout Africa and Eurasia. Though Tattersall concluded that the "H. ergaster" material represents the fossils of a single clade of "Homo", he also found there to be considerable diversity within this clade; the KNM ER 992 mandible accorded well with other fossil mandibles from the region, such as OH 22 from Olduvai and KNM ER 3724 from Koobi Fora, but did not necessarily match with cranial material, such as KNM ER 3733 and KNM ER 3883 (since neither preserves the jaw), nor with the mandible preserved in Turkana Boy, which has markedly different dentition.


title: Homo ergaster

text: The most "iconic" fossil of "H. ergaster" is the KNM ER 3733 skull, which is sharply distinguished from Asian "H. erectus" by a number of characteristics, including that the brow ridges project forward as well as upward and arc separately over each orbit and the braincase being quite tall compared to its width, with its side walls curving. KNM ER 3733 can be distinguished from KNM ER 3883 by a number of features as well, notably in that the margins of KNM ER 3883's brow ridges are very thickened and protrude outwards but slightly downwards rather than upwards. Both skulls can be distinguished from the skull of Turkana Boy, which possesses only slightly substantial thickenings of the superior orbital margins, lacking the more vertical thickening of KNM ER 3883 and the aggressive protrusion of KNM ER 3733. In addition to this, the facial structure of Turkana Boy is narrower and longer than that of the other skulls, with a higher nasal aperture and likely a flatter profile of the upper face. It is possible that these differences can be accounted for through Turkana Boy being a subadult, 7 to 12 years old. Furthermore, KNM ER 3733 is presumed to have been the skull of a female (whereas Turkana Boy is traditionally interpreted as male), which means that sexual dimorphism may account for some of the differences.


title: Homo ergaster

text: The differences between Turkana Boy's skull and KNM ER 3733 and KNM ER 3883, as well as the differences in dentition between Turkana Boy and KNM ER 992 have been interpreted by some, such as paleoanthropologist Jeffrey H. Schwartz, as suggesting that Turkana Boy and the rest of the "H. ergaster" material does not represent the same taxon. Schwartz also noted none of the fossils seemed to represent "H. erectus" either, which he believed was in need of significant revision. In 2000, French palaeoanthropologist Valéry Zeitoun suggested that KNM ER 3733 and KNM ER 3883 should be referred to two separate species, which she dubbed "H. kenyaensis" (type specimen KNM ER 3733) and "H. okotensis" (type specimen KNM ER 3883), but these designations have found little acceptance.


title: Homo ergaster

text: Although frequently assumed to have originated in East Africa, the origins of "H. ergaster" are obscured by the fact that the species marks a radical departure from earlier species of "Homo" and "Australopithecus" in its long limbs, height and modern body proportions. Though a large number of Pleistocene tools have been found in East Africa, it can not be fully ascertained that "H. ergaster" originated there without further fossil discoveries. It is assumed that "H. ergaster" evolved from earlier species of "Homo", probably "H. habilis". Though populations of "H. ergaster" outside of Africa have been inferred based on the geographical distribution of their descendants and tools matching those in East Africa, fossils of the species are mainly from East Africa in the time range of 1.8 to 1.7 million years ago. Most fossils have been recovered from around the shores of Lake Turkana in Kenya.


title: Homo ergaster

text: The oldest known specimen of "H. erectus" s.l. in Africa (i.e. "H. ergaster") is DNH 134, a skull recovered in the Drimolen Palaeocave System in South Africa, dated to 2.04 to 1.95 million years ago. The skull is also the oldest known "H. erectus" s.l. specimen overall, showing clear similarities to KNM ER 3733, and demonstrates that early "H. ergaster" coexisted with other hominins such as "Paranthropus robustus" and "Australopithecus sediba".


title: Homo ergaster

text: There are also younger specimens of "H. ergaster"; notably, Turkana Boy is dated to about 1.56 million years ago. A handful of even younger African skulls make the case for long-term anatomical continuity, though it is unclear if they can appropriately be formally regarded as "H. ergaster" specimens; the "Olduvai Hominid 9" skull from Olduvai Gorge is dated to about 1.2 to 1.1 million years ago and there are also skulls from Buia (near the coast of Eritrea, dated to ~1 million years old), the Bouri Formation in Ethiopia (dated to between 1 million and 780,000 years old) and a fragmentary skull from Olorgesailie in Kenya (dated to between 970,000 and 900,000 years ago). The Olduvai skull is similar to Asian "H. erectus" in its massive brow ridge, but the others only show minor differences to earlier "H. ergaster" skulls.


title: Homo ergaster

text: The "H. erectus" in Asia, as well as later hominins in Europe (i. e. "H. heidelbergensis" and "H. neanderthalensis") and Africa ("H. sapiens") are all probably lineages descended from "H. ergaster." Because "H. ergaster" is thought to have been ancestral to these later "Homo", it might have persisted in Africa until around 600,000 years ago, when brain size increased rapidly and "H. heidelbergensis" emerged.


title: Homo ergaster

text: Traditionally, "H. erectus" was seen as the hominin that first left Africa to colonise Europe and Asia. If "H. ergaster" is distinct from "H. erectus", this role would apply to "H. ergaster" instead. Very little concrete information is known on when and which "Homo" first appeared in Europe and Asia, since Early Pleistocene fossil hominins are scarce on both continents, and that it would have been "H. ergaster" (or "early "H. erectus"") that expanded, as well as the particular manner in which they did, remains conjecture. The presence of "H. erectus" fossils in East Asia means that a human species, most likely "H. ergaster", had left Africa before 1 million years ago, the assumption historically having been that they first migrated out of Africa around 1.9 to 1.7 million years ago. Discoveries in Georgia and China push the latest possible date further back, before 2 million years ago, also casting doubt on the idea that "H. ergaster" was the first hominin to leave Africa.


title: Homo ergaster

text: The main reason for leaving Africa is likely to have been an increasing population periodically outgrowing their resource base, with splintering groups moving to establishing themselves in neighboring, empty territories over time. The physiology and improved technology of "H. ergaster" might have allowed them to travel to and colonise territories that no one had ever occupied before. It is unclear if "H. ergaster" was truly uniquely capable of expanding outside Africa; australopithecines had likely colonised savannah grasslands throughout Africa by 3 million years ago and there are no clear reasons as to why they would not have been able to expand into the grasslands of Asia before "H. ergaster".


title: Homo ergaster

text: The general assumption is that hominins migrated out of the continent either across the southern end of the Red Sea or along the Nile Valley, but there are no fossil hominins known from either region in the Early Pleistocene. The earliest "Homo" fossils outside Africa are the Dmanisi skulls from Georgia (dated to 1.77–1.85 million years old, representing either early "H. ergaster" or a new taxon, "H. georgicus"), three incisors from Ubeidiya in Israel (about 1.4 to 1 million years old) and the fossils of Java Man ("H. erectus erectus", more than five thousand miles away). The dating of key Asian "H. erectus" specimens (including Java Man) is not entirely certain, but they are all likely to be 1.5 million years old or younger. Ubeidiya is also the oldest firmly confirmed site of Acheulean tools (one of the tool industries associated with "H. ergaster") outside Africa, the tools recovered there closely resembling older tools discovered in East Africa.


title: Homo ergaster

text: The earliest fossil evidence of "Homo" in Asia are the aforementioned Dmanisi skulls, which share many traits with "H. ergaster" in Africa, suggesting that "H. ergaster" might have expanded out of Africa as early as 1.7–1.9 million years ago. In addition to "H. ergaster"-like traits, the Dmanisi skulls possess a wide assortment of other traits, some of which are similar to traits in earlier hominins such as "H. habilis", and the site notably lacks preserved hand axes (otherwise characteristic of "H. ergaster"), which means that hominins might have spread out of Africa even earlier than "H. ergaster". The skull D2700 (Dmanisi skull 3) in particular resembles "H. habilis" in the small volume of its braincase (600 cc), the form of the middle and upper face and the lack of an external nose. The mixture of skulls at Dmanisi suggests that the definition of "H. ergaster" (or "H. erectus") might most appropriately be expanded to contain fossils that would otherwise be assigned to "H. habilis" or that two separate species of archaic humans left Africa early on. In addition to the Dmanisi fossils, stone tools manufactured by hominins have been discovered on the Loess Plateau in China and dated to 2.12 million years old, meaning that hominins must have left Africa before that time.


title: Homo ergaster

text: An alternative hypothesis historically has been that "Homo" evolved in Asia from earlier ancestors that had migrated there from Africa, and then expanded back into Europe, where it gave rise to "H. sapiens". This view was notably held by Eugène Dubois, who first described "H. erectus" fossils in the 19th century and considered the fossils of Java Man, at the time undeniably the earliest known hominin fossils, as proof of the hypothesis. Though the discovery of australopithecines and earlier "Homo" in Africa meant that "Homo" itself did not originate in Asia, the idea that "H. erectus" (or "H. ergaster") in particular did, and then expanded back into Africa, has occasionally resurfaced. Various fossil discoveries have been used to support it through the years, perhaps most famously a massive set of jaws from Indonesia which were perceived to be similar to those of australopithecines and dubbed "Meganthropus" (now believed to be an unrelated hominid ape). The discovery of "H. floresiensis" in 2003, which preserved primitive foot and wrist anatomy reminiscent of that of "H. habilis" and "Australopithecus" again led to suggestions of pre-"erectus" hominins in Asia, though there are no known comparable foot or wrist bones from "H. erectus" which makes comparisons impossible. The idea that "H. ergaster"/"H. erectus" first evolved in Asia before expanding back into Africa was substantially weakened by the dating of the DNH 134 skull as approximately 2 million years old, predating all other known "H. ergaster"/"H. erectus" fossils.


title: Homo ergaster

text: The only well-preserved post-cranial remains of "H. ergaster" come from the Turkana Boy fossil. Unlike the australopithecines, Turkana Boy's arms were not longer relative to their legs than the arms of living people and the cone-shaped torso of their ancestors had evolved into a more barrel-shaped chest over narrow hips, another similarity to modern humans. The tibia (shin bone) of Turkana Boy is relatively longer than the same bone in modern humans, potentially meaning that there was more bend in the knee when walking. The slim and long build of Turkana Boy may be explained by "H. ergaster" living in hot and arid, seasonal environments. Through thinning of the body, body volume decreases faster than skin area and greater skin area means more effective heat dissipation.


title: Homo ergaster

text: "H. ergaster" individuals were significantly taller than their ancestors. Whereas Lucy, a famous "Australopithecus" fossil, would only have been about tall at her death, Turkana Boy was about tall and would probably have reached or more if he had survived to adulthood. Adult "H. ergaster" are believed to have ranged in size from about tall.


title: Homo ergaster

text: Because of being adapted to a hot and arid climate, "H. ergaster" might also have been the earliest human species to have nearly hairless and naked skin. If instead "H. ergaster" had an ape-like covering of body hair, sweating (the primary means through which modern humans prevent their brains and bodies from overheating) would not have been as efficient. Though sweating is the generally accepted explanation for hairlessness, other proposed explanations include a reduction of parasite load and sexual selection. It is doubtful if australopithecines and earlier "Homo" were sufficiently mobile to make hair loss an advantageous trait, whereas "H. ergaster" was clearly adapted for long-distance travel and noted for inhabiting lower altitudes (and open, hot savannah environments) than their ancestors. Australopithecines typically inhabited colder and higher altitudes 1,000–1,600 m (3,300–5,200 ft), where nighttime temperatures would have gotten significantly colder and insulating body hair may have been required.


title: Homo ergaster

text: Alternatively and despite this, the loss of body hair could have occurred significantly earlier than "H. ergaster". Though skin impressions are unknown in any extinct hominin, it is possible that human ancestors were already losing their body hair around 3 million years ago. Human ancestors acquired pubic lice from gorillas about 3 million years ago, and speciation of human from gorilla pubic lice was potentially only possible because human ancestors had lost most of their body hair by this early date. It is also possible that the loss of body hair occurred at a significantly later date. Genetic analysis suggests that high activity in the melanocortin 1 receptor, which produces dark skin, dates back to about 1.2 million years ago. This could indicate the evolution of hairlessness around this time, as a lack of body hair would have left the skin exposed to harmful UV radiation.


title: Homo ergaster

text: Differences to modern humans would have been readily apparent in the face and skull of "H. ergaster". Turkana Boy's brain was almost fully grown at the time of his death, but its volume (at 880 cc) was only about 130 cc greater than the maximum found in "H. habilis", about 500 cc below the average of modern humans. The 130 cc increase from "H. habilis" becomes much less significant than what could be presumed when the larger body size of Turkana Boy and "H. ergaster" is considered. With all "H. ergaster" skulls considered, the brain volume of the species mostly varied between 600 and 910 cc, with some small examples only having a volume of 508–580 cc. Since their brain was smaller than that of modern humans, the skull of "H. ergaster" immediately narrowed behind the eye sockets (post-orbital constriction).


title: Homo ergaster

text: The brain case was long and low, and Turkana Boy's forehead was flat and receding, merging at an angle with the brow ridge above their eyes. A noticeable difference between Turkana Boy and the australopithecines and "H. habilis" would have been their nose, which would have been similar to that of modern humans in projecting forwards and having nostrils oriented downwards. This external nose may have also been an adaptation towards a warmer climate, since the noses of modern humans are usually cooler than their central bodies, condensing moisture that would otherwise have been exhaled and lost during periods of increased activity. The face of Turkana Boy would have been longer from top to bottom than that of modern humans, with the jaws projecting farther outwards (prognathism). Though the jaws and teeth were smaller than those of the average australopithecine and "H. habilis", they were still significantly larger than those of modern humans. Since the jaw slanted sharply backwards, it is probable that they were chinless.


title: Homo ergaster

text: The overall structure of Turkana Boy's skull and face is also reflected in other "H. ergaster" skulls, which combine large and outwardly projecting faces with brow ridges, receding foreheads, large teeth and projecting nasal bones. Though Turkana Boy would have been no more than 12 years old when he died, their stature is more similar to that of a modern 15-year-old and the brain is comparable to that of a modern 1-year-old. By modern standards, "H. ergaster" would thus have been cognitively limited, though the invention of new tools prove that they were more intelligent than their predecessors.


title: Homo ergaster

text: "H. ergaster" possessed a significantly larger body mass in comparison to earlier hominins such as early "Homo", "Australopithecus" and "Paranthropus". Whereas australopithecines typically ranged in weight from 29–48 kg (64–106 lbs), "H. ergaster" typically ranged in weight from 52–63 kg (115–139 lbs). It is possible that the increased body size was the result of life in an open savannah environment, where increased size gives the ability to exploit broader diets in larger foraging areas, increases mobility and also gives the ability to hunt larger prey. The increased body mass also means that parents would have been able to carry their children to an older age and larger mass.


title: Homo ergaster

text: Though reduced sexual dimorphism has often been cited historically as one of the radical differences between "H. ergaster" and earlier "Homo" and australopithecines, it is unclear whether australopithecines were significantly more sexually diamorphic than "H. ergaster" or modern humans. Skeletal evidence suggests that sexes in "H. ergaster" differed no more in size than sexes in modern humans do, but a 2003 study by palaeoanthropologists Philip L. Reno, Richard S. Meindl, Melanie A. McCollum and C. Owen Lovejoy suggested that the same was also true for the significantly earlier "Australopithecus afarensis". Sexual dimorphism is difficult to measure in extinct species since the sex of fossils is usually not determinable. Historically, scientists have typically measured differences between the extreme ends (in terms of size and morphology) of the fossil material attributed to a species and assumed that the resulting ratio applies to the mean difference between male and female individuals.


title: Homo ergaster

text: The dimensions of a 1.8 million years old adult female "H. ergaster" pelvis from Gona, Ethiopia suggests that "H. ergaster" would have been capable of birthing children with a maximum prenatal (pre-birth) brain size of 315 cc, about 30–50 % of adult brain size. This value falls intermediately between that of chimpanzees (~40 %) and modern humans (28%). Further conclusions about the growth and development in early "Homo" can be drawn from the Mojokerto child, a ~1.4–1.5 million year old ~1-year old Asian "H. erectus", which had a brain at about 72–84% the size of an adult "H. erectus" brain, which suggests a brain growth trajectory more similar to that of other great apes than of modern humans. Both the Gona pelvis and the Mojokerto child suggest that the prenatal growth of "H. ergaster" was similar to that of modern humans but that the postnatal (post-birth) growth and development was intermediate between that of chimpanzees and modern humans. The faster development rate suggests that altriciality (an extended childhood and a long period of dependency on your parents) evolved at a later stage in human evolution, possibly in the last common ancestor of Neanderthals and modern humans. The faster development rate might also indicate that the expected lifespan of "H. ergaster" and "H. erectus" was lower than that of later and modern humans.


title: Homo ergaster

text: It is frequently assumed that the larger body and brain size of "H. ergaster", compared to its ancestors, would have brought with it increased dietary and energy needs. In 2002, palaeoanthropologists Leslie C. Aiello and Jonathan C. K. Wells stated that the average resting metabolic requirements of "H. ergaster" would have been 39% higher than those of "Australopithecus afarensis", 30% higher in males and 54% higher in females. However, the torso proportions of "H. ergaster" implies a relatively small gut, which means that energy needs might not necessarily have been higher in "H. ergaster" than in earlier hominins. This is because the earlier ape (and australopithecine) gut was large and energy-expensive since it needed to synthesize fat through fermenting plant matter, whereas "H. ergaster" likely ate significantly more animal fat than their predecessors. This would have allowed more energy to be diverted to brain growth, increasing brain size while maintaining the energy requirements of earlier species.


title: Homo ergaster

text: If they had increased energy requirements, "H. ergaster" would have needed to eat either vastly more food than australopithecines, or would have needed to eat food of superior quality. If they ate the same type of foods as the australopithecines, feeding time would then have had to be dramatically increased in proportion to the extra calories required, reducing the time "H. ergaster" could use for resting, socialising and travelling. Though this would have been possible, it is considered unlikely, especially since the jaws and teeth of "H. ergaster" are reduced in size compared to those of the australopithecines, suggesting a shift in diet away from fibrous and difficult-to-chew foods. Regardless of energy needs, the small gut of "H. ergaster" also suggests a more easily digested diet composed of food of higher quality.


title: Homo ergaster

text: It is likely that "H. ergaster" consumed meat in higher proportions than the earlier australopithecines. Meat was probably acquired through a combination of ambushes, active hunting and confrontational scavenging. "H. ergaster" must not only have possessed the ability of endurance running, but must also have been able to defend themselves and the carcasses of their prey from the variety of contemporary African predators. It is possible that a drop in African carnivoran species variety around 1.5 million years ago can be ascribed to competition with opportunistic and carnivorous hominins.


title: Homo ergaster

text: On its own, meat might not have been able to fully sustain "H. ergaster". Modern humans can not sufficiently metabolize protein to meet more than 50% of their energy needs and modern humans who heavily rely on animal-based products in their diet mostly rely on fat to sustain the rest of their energy requirements. Multiple reasons make a fully meat-based diet in "H. ergaster" unlikely, the most prominent being that African ungulates (the primary prey available) are relatively low in fat and that high meat diets demand increased intake of water, which would have been difficult in an open and hot environment. Modern African hunter-gatherers who rely heavily on meat, such as the Hadza and San peoples, also use cultural means to recover the maximum amount of fat from the carcasses of their prey, a method that would not have been available to "H. ergaster".


title: Homo ergaster

text: "H. ergaster" would thus likely have consumed large quantities of meat, vastly more than their ancestors, but would also have had to make use of a variety of other food sources, such as seeds, honey, nuts, invertebrates, nutritious tubers, bulbs and other underground plant storage organs. The relatively small chewing capacity of "H. ergaster", in comparison to its larger-jawed ancestors, means that the meat and high quality plant food consumed would likely have required the use of tools to process before eating.


title: Homo ergaster

text: "H. ergaster" lived on the African savannah, which during the Pleistocene was home to a considerably more formidable community of carnivorans than the present savannah. Hominins could probably only have adapted to life on the savannah if effective anti-predator defense behaviours had already evolved. Defense against predators would likely have come through "H. ergaster" living in large groups, possessing stone (and presumably wooden) tools and effective counter-attack behaviour having been established. In modern primates that spend significant amounts of time on the savannah, such as chimpanzees and savannah baboons, individuals form large, multi-male, groups wherein multiple males can effectively work together to fend off and counter-attack predators, occasionally with the use of stones or sticks, and protect the rest of the group. It is possible that similar behaviour was exhibited in early "Homo". Based on the male-bonded systems within bonobos and chimpanzees, and the tendency towards male bonding in modern foragers, groups of early "Homo" might have been male-bonded as well. Because of the scarcity of fossil material, group size in early "Homo" cannot be determined with any certainty. Groups were probably large, it is possible groups were above the upper range of known group sizes among chimpanzees and baboons ( 100 individuals or more). In 1993, palaeoanthropologists Leslie C. Aiello and R. I. M. Dunbar estimated that the group size of "H. habilis" and "H. rudolfensis", based on neocortex size (as there is a known relationship between neocortex size and group size in modern non-human primates), would have ranged from about 70–85 individuals. With the additional factor of bipedalism, which is energetically cheaper than quadrupedalism, the maximum ecologically tolerable group size may have been even larger. Aiello's and Dunbar's group size estimate in regards to "H. ergaster" was 91–116 individuals.


title: Homo ergaster

text: Social and counter-attack behaviour of earlier "Homo" probably carried over into "H. ergaster", where they are likely to have developed even further. "H. ergaster" was probably the first primate to move into the niche of social carnivore (i. e. hunter-gatherer). Such behaviour would probably have been the result of counter-attacks in the context of competition over nutritious food with other carnivores and would probably have evolved from something akin to the opportunistic hunting sometimes exhibited by chimpanzees. The switch to predation in groups might have triggered a cascade of evolutionary changes which changed the course of human evolution. Cooperative behaviours such as opportunistic hunting in groups, predator defense and confrontational scavenging would have been critical for survival which means that a fundamental transition in psychology gradually transpired. With the typical "competitive cooperation" behaviour exhibited by most primates no longer being favored through natural selection and social tendencies taking its place, hunting, and other activities, would have become true collaborative efforts. Because counter-attack behaviour is typically exhibited in males of modern primates, social hunting in archaic humans is believed to have been a primarily male activity. Females likely conducted other types of foraging, gathering food which did not require hunting (i.e. fruits, nuts, eggs etc.).


title: Homo ergaster

text: With hunting being a social activity, individuals probably shared the meat with one another, which would have strengthened the bonds both between the hunters themselves and between the hunters and the rest of the "H. ergaster" group. Females likely shared what they had foraged with the rest of the group as well. This development could have led to the development of male-female friendships into opportunistic monogamous pair bonds. Since sexual selection from females probably favored males that could hunt, the emerging social behaviour resulting from these new behaviours would have been carried over and amplified through the generations.


title: Homo ergaster

text: The only direct evidence of "H. ergaster" group composition comes from a series of sites outside of Ileret in Kenya, where 97 footprints made around 1.5 million years ago by a group of at least 20 individuals have been preserved. Based on the size of the footprints, one of the trackways appears to have been a group entirely composed of males, possibly a specialised task group, such as a border patrol or a hunting or foraging party. If this assessment is correct, this would further suggest a male-female division of responsibilities. In modern hunter-gatherer societies who target large prey items, male parties are typically dispatched to bring down these high-risk animals, and, due to the low success rate, female parties tend to focus on more predictable foods.


title: Homo ergaster

text: Early "H. ergaster" inherited the Oldowan culture of tools from australopithecines and earlier "Homo", though quickly learnt to strike much larger stone flakes than their predecessors and contemporaries. By 1.65 million years ago, "H. ergaster" had created the extensively flaked artefacts and early hand axes that mark the Acheulean culture, and by 1.6–1.4 million years ago, the new tool industry was widely established in East Africa. Acheulean tools differ from Oldowan tools in that the core forms of the tools were clearly deliberate. Whereas the shape of the core forms in Oldowan tools, which were probably used mostly as hammers to crack bones for marrow, appears to not have mattered much, the hand axes of the Acheulean culture demonstrate an intent to produce narrow and sharp objects, typically in teardrop, oval or triangular shapes. Once in place, the Acheulean industry remained unchanged throughout "H. ergaster"'s existence and later times, with tools produced near its end about 250,000 years ago not being significantly different from tools produced 1.65 million years ago.


title: Homo ergaster

text: The oldest Acheulean assemblages also preserve core forms similar to those in Oldowan tools, but there are no known true intermediate forms between the two, suggesting that the appearance of Acheulean tools was an abrupt and sudden development. The most significant development that led to the Acheulean tools was likely early hominins learning the ability to strike large flakes, up to 30 cm (1 ft) or more in length, from larger boulders, from which they could manufacture new tools such as hand axes. Though "hand axe" implies that all hand axes were used for chopping and were hand-held, they came in a variety of different shapes and size and probably served several different functions. Carefully shaped and symmetric examples may have been hurled at prey akin to modern discuses, more casually made examples may simply have served as portable sources for sharp flakes and some could have been used for scraping or chopping wood. Additionally, hand axes are effective butchering tools and were possibly also used for dismembering carcasses of large animals.


title: Homo ergaster

text: There are preserved hand axes that are too unwieldy and large to be used for any apparent practical purpose. The use of these larger hand axes, and for some discovered collections of hundreds of hand axes without obvious signs of use, is speculative and conjectural. An idea that has been popular in the popular press, and frequently cited in academia, is that large and impressive hand axes might have been emblems used for attracting mates, with makers of large axes showing strength, coordination and determination, qualities that may have been regarded as attractive. Palaeoanthropologists April Nowell and Melanie Lee Chang noted in 2009 that though this theory is "both intriguing and emotionally appealing", there is little evidence for it and it is untestable. They considered it more probable that variations in hand axe morphology over the course of hundreds of thousands of years was the result of various different factors rather than a single, overarching factor in sexual selection.


title: Homo ergaster

text: As "Homo" migrated into open savannah environments, encounters with natural fires must have become more frequent and significant. It is possible that "H. ergaster" were the earliest humans to master the control of fire, which they may have used for cooking purposes. Cooking renders both meat and plant foods more digestible, which might have been important since the guts of "H. ergaster" were reduced in size compared to those of their ancestors. Though "H. ergaster"/"H. erectus" is frequently assumed to have been the earliest "Homo" to control fire, concrete evidence is somewhat lacking in the fossil record, perhaps partly due to the difficulty for actual evidence of fire usage to be preserved. Two of the earliest sites commonly claimed to preserve evidence of fire usage are FxJj20 at Koobi Fora and GnJi 1/6E near Lake Baringo, both in Kenya and both dated as up to 1.5 million years old. The evidence at FxJj20 consists of burned sediments and heat-altered stone tools, whereas GnJi 1/6E preserves large clasts of baked clay, associated with stone tools and faunal remains. Though it is difficult to exclude a natural origin for the fire residue evidenced, the sites remain strong candidates for early fire use.


title: Homo ergaster

text: Several sites, preserving more widely accepted evidence of fire usage, have been dated to 1 million years ago or younger, postdating the emergence and last generally accepted record of "H. ergaster". These sites include cave sites, such as Wonderwerk and Swartkrans in South Africa, and open sites, such as Kalambo Falls in Zambia. The site Gesher Benot Ya’aqov in Israel, dated to about 700,000 years ago, preserves widely accepted evidence of fire usage through burnt materials and burnt flint microartefacts being preserved at numerous levels. From around 400,000 years ago and onwards, traces of fire become even more numerous in sites across Africa, Europe and Asia.


title: Homo ergaster

text: The spinal cord of Turkana Boy would have been narrower than that of modern humans, which means that the nervous system of "H. ergaster", and their respiratory muscles, may not have been developed enough to produce or control speech. In 2001, anthropologists Bruce Latimer and James Ohman concluded that Turkana Boy was afflicted by skeletal dysplasia and scoliosis, and thus would not have been representative of the rest of his species in this respect. In 2006, when anthropologist Marc Meyer and colleagues described a "H. erectus" s.l. specimen from Dmanisi, Georgia, dated to 1.78 million years old. The fossil preserves the oldest known "Homo" vertebrae and the spine found falls within the range of modern human spines, suggesting that the individual would have been capable of speech. Meyer and colleagues concluded that speech was probably possible within "Homo" very early on and that Turkana Boy probably suffered from some congenital defect, possibly spinal stenosis.


title: Homo ergaster

text: In 2013 and 2014, anthropologist Regula Schiess and colleagues concluded that there was no evidence of any congenital defects in Turkana Boy, and, in contrast to the 2001 and 2006 studies, considered the specimen to be representative of the species.


title: Ovipositor

text: The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typically its form is adapted to functions such as preparing a place for the egg, transmitting the egg, and then placing it properly. For most insects, the organ is used merely to attach the egg to some surface, but for many parasitic species (primarily in wasps and other Hymenoptera), it is a piercing organ as well.


title: Ovipositor

text: Some ovipositors only retract partly when not in use, and the basal part that sticks out is known as the scape, or more specifically oviscape, the word "scape" deriving from the Latin word "scāpus", meaning "stalk" or "shaft".


title: Ovipositor

text: Grasshoppers use their ovipositors to force a burrow into the earth to receive the eggs. Cicadas pierce the wood of twigs with their ovipositors to insert the eggs. Sawflies slit the tissues of plants by means of the ovipositor and so do some species of long-horned grasshoppers. In the ichneumon wasp genus "Megarhyssa", the females have a slender ovipositor (terebra) several inches long that is used to drill into the wood of tree trunks. These species are parasitic in the larval stage on the larvae of horntail wasps, hence the egg must be deposited directly into the host's body as it is feeding. The ovipositors of "Megarhyssa" are among the longest egg-laying organs (relative to body size) known.


title: Ovipositor

text: The stingers of the Aculeata (wasps, hornets, bees, and ants) are ovipositors, highly modified and with associated venom glands. They are used to paralyze prey, or as defensive weapons. The penetrating sting plus venom allows the wasp to lay eggs with less risk of injury from the host. In some cases, the injection also introduces virus particles that suppress the host's immune system and prevent it from destroying the eggs. However, in virtually all stinging Hymenoptera, the ovipositor is no longer used for egg-laying. An exception is the family Chrysididae, members of the Hymenoptera, in which species such as "Chrysis ignita" have reduced stinging apparatus and a functional ovipositor.


title: Ovipositor

text: Fig wasp ovipositors have specialized serrated teeth to penetrate fruits, but gall wasps have either uniform teeth or no teeth on their ovipositors, meaning the morphology of the organ is related to the life history.


title: Ovipositor

text: Members of the Dipteran (fly) families Tephritidae and Pyrgotidae have well-developed ovipositors that are partly retracted when not in use, with the part that sticks out being the oviscape. Oestridae, another family within Diptera, often have short hairy ovipositors, the species "Cuterebra fontinella" has one of the shortest within the family.


title: Ovipositor

text: Ovipositors exist not only in winged insects, but also in Apterygota, where the ovipositor has an additional function in gathering the spermatophore during mating. Little is known about the egg-laying habits of these insects in the wild.