Sure, he looks good. But how about his sperm? 
 
 That might not be such a ridiculous-sounding question, now that a new study has identified a link between men's facial attractiveness and the quality of their semen--with handsome, masculine-looking guys having slightly lower-quality semen than other men. 
 
 "To [the] best of our knowledge, this is the first demonstration of the phenomenon," study co-author Dr. Jukka Kekalainen, adjunct lecturer in the Centre for Evolutionary Biology at the University of Australia in Crawley, told The Huffington Post in an email. 
 
 The researchers have no ready explanation for their finding, although previous research has shown that high testosterone levels can harm sperm production, the New York Daily News reported. And the finding seems to be at odds with the so-called phenotype-linked fertility hypothesis, which holds that females prefer handsome males because their offspring may enjoy hereditary benefits, such as better health and higher intelligence. 
 
 For the new study, which was published in the September 2014 issue of the Journal of Evolutionary Biology, a team of researchers from Spain, Australia, and Colombia performed semen analyses on 50 Caucasian students recruited from the University of Valencia. Next, photos of the men's faces were shown to heterosexual men and women in their twenties, including Caucasians and blacks. 
 
 The women evaluators were asked to rate the men as if they were looking for a long-term mate. The men evaluators were asked to rate the men as they thought women would rate them. 
 
 The researchers also performed an "anthropometric analysis" of the facial characteristics of all 50 men, measuring the size of their eyes, the width of their cheekbones and nostrils, and other markers that previous research identified as masculine features. And finally the researchers compared the men's facial features with the motility (movement), morphology (structure), and concentration of the men's sperm cells. 
 
 In addition to looking for the link between masculine-looking faces and sperm quality, the researchers wanted to know if men's sperm quality was related to their handsomeness. 
 
 "And we found that in fact it is," Kekalainen said in the email. 
 
 But does that mean women eager to find a mate capable of fathering children should be wary of handsome men? Maybe not--at least not until more research corroborates the finding. As Kekalainen said in the email, "we would need more studies to demonstrate the causation and mechanism behind this finding...before giving any mating tips to the females." ||||| Guys with classically masculine facial features, such as square jawlines and pronounced cheekbones, may produce sperm of a lower quality than men who don’t share the same features, a new study finds. 
 
 The findings rely on an oft-studied phenomenon in the animal kingdom known as the phenotype-linked fertility hypothesis. It states the greater presence of male sexual ornaments signals a stronger vitality for reproduction. These ornaments are typically anatomical in nature, such as the set of feathers on one species of bird or the song of another. 
 
 But in humans the hypothesis hasn’t gotten much attention. So researchers recruited a group of 62 college students, from both Colombia and Spain, to rate the physical attractiveness of select pictures of men who had donated their sperm earlier in the experiment. Researchers censored all but the subjects’ faces, including hairstyle, to minimize external influences. 
 
 ketrin1407, CC BY 2.0 
 
 They compared levels of attractiveness, masculinity, and sperm health to determine which features, if any, correlated with one another. The results were decidedly lukewarm. While they did find a significant negative relationship between masculine features and sperm motility, the significance vanished when the team controled for outright unhealthy sperm. It was the outliers, in other words, that were doing the heavy lifting. 
 
 So, the hypothesis didn’t seem to ring as true as they might have expected. But they did find a relationship between how males perceived males versus how females perceived males. The subjects most likely to rate the faces as attractive were other men, and particularly among the Spanish students. 
 
 “This suggests that male facial cues may provide culture- and sex-independent information about male fertility,” they wrote. However, it also indicates humans may be poor judges of attractiveness when it comes to people who are culturally near to them. And males, on average, are worse judges than females. 
 
 What does the study say about the phenotype-linked fertility hypothesis as it relates to humans? Unfortunately, not much. A large camp of evolutionary biology likes to believe the animalistic traits we possessed as ancient hominids have changed to accommodate modern-day mating rituals. All women want tall, protective men in good social standing, they are apt to say. Beneath our material, hi-tech infatuations are primal desires that prove even if we’re a population of smart animals, we’re still animals. 
 
 Science is increasingly finding these theories don’t hold much water. Tall men, with their far-reaching gaze, may have the advantage over short men when it comes to scanning the plains for enemies, or dinner, but if a woman’s goal is to keep a tidy house and send her kids to college, short men — the biological underdogs — tend to prevail. 
 
 Prior research has upheld the link between elevated testosterone levels and poor sperm. In their study, masculine men were thought to have low sperm counts in part because they don’t need as much, being the sexual dynamos they are. However, since the researchers were also measuring attractiveness, it’s worth mentioning the attractive men (who weren’t necessarily masculine) had better sperm. Chalk this one up to round jaws and low cheekbones. 
 
 Source: Soler C, Kekäläinen J, Núñez M, et al. Male facial attractiveness and masculinity may provide sex- and culture-independent cues to semen quality. Journal of Evolutionary Biology. 2014. ||||| Women may drool over George Clooney and Brad Pitt, but their lust may be more for these macho guys' immune systems than their pretty faces and chiseled abs, new research suggests. 
 
 Men with high levels of the sex hormone testosterone are seen as more hunky — and these same men have stronger immune responses, researchers report Tuesday (Feb. 21) in the journal Nature Communications. The findings suggest that women may be attracted to manly facial types because the macho look signals good health. 
 
 Researchers led by Fhionna Moore of Abertay University in the United Kingdom recruited 74 Latvian men in their early 20s to give blood samples right before and one month after their first dose of the Hepatitis B vaccine. The vaccine triggers the immune system to create antibodies against the virus. The researchers measured these levels of antibodies as well as testosterone levels and levels of the stress hormone cortisol. 
 
 Next, 94 Latvian women, also in their early 20s, rated photographs of each man on a 10-point scale of attractiveness. The researchers then looked for links between the immune response as measured by Hepatitis B antibodies, hormone levels and attractiveness. 
 
 They found that high testosterone correlated with both sexy faces and a strong immune response. Men with the strongest immune responses were rated as better looking than those with weak immune responses. The link between testosterone and hotness was strongest in men with low levels of the stress hormone cortisol, suggesting that stress might take a toll on the immune system, and thus women's ratings of attractiveness. 
 
 While much research has hinted at a relationship between testosterone and the immune system, this study is the first to directly link women's opinions of a man's looks with the strength of his immune system. Researchers next hope to tease out whether the results hold across cultures and across different age ranges. 
 
 You can follow LiveScience senior writer Stephanie Pappas on Twitter @sipappas. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.
– Macho guys may attract more women, but the quality of their sperm might not be of he-man standards, a new study suggests. Oddly, the sperm of good-looking guys—but not necessarily macho ones with square jaws and distinct cheekbones—is just fine, reports Medical Daily. The link was found when researchers analyzed the semen of 62 Caucasian men, then compared its motility and structure to facial measurements of masculine traits and ratings of their attractiveness, the Huffington Post explains. Scientists theorize that the macho man trades virility for a gravely voice and ripped arms, and high testosterone hinders sperm production. Meanwhile, the study casts doubt on the belief the "phenotype-linked fertility hypothesis" (read: fancy feathers and pretty songs attract more ladies) applies to humans. A study that claimed short guys are preferred by women over tall ones, long believed to have the evolutionary upper hand, has also poked holes in that theory. But don't revamp your mating habits just yet, girls—researchers say their findings need further study. (Short guys are also less likely to divorce you.)