# Wikijunior:Biology/Science and theory of evolution



## Science and theory of evolution

The aim of science is to understand the world better (knowledge) and to
produce new technology (innovation). Scientists develop mental models
(theories) and functional models (such as an engine). Then they test
these models through thought and experimentation. Appropriate models are
presented to the public. Scientists change these models and test them
again. *For scientists, models are not the truth.* They are therefore
always looking for improvements. Good theories are understandable and
thoroughly tested.

<File:Cucurbita_maxima_02_-_Orange.jpg%7CCucurbita> maxima
<File:Cucurbita_pepo_accidental_hybrid_Acchini.jpg%7CCucurbita> pepo
Acchini <File:2006-10-18Cucurbita_pepo02.jpg%7CCucurbita> pepo
File:Cucurbita_pepo\_\'Ufo\'\_-\_scallop_group_Weißer_Kürbis\_\"Ufo\".jpg\|Cucurbita
pepo \'Ufo\' <File:Assorted> Cucurbita pepo and maxima
gourds.jpg\|thumb\|Assorted Cucurbita pepo <File:Cucurbita> in Bayern -
Kürbis - Sortenvielfalt.jpg\|thumb\|Cucurbita from Bayern

## Development of the theory of evolution

For centuries, scientists have repeatedly suspected that today\'s
creatures had common ancestors. They knew that breeders of crops and
livestock can change the characteristics of living beings. So, the
pumpkin growers used only the seeds of the best pumpkins for the next
seed. In some regions, growers propagated red gourds, in other regions
green ones. This is how different shapes came about. However, the
scientists could not explain how breeding without a breeder could work.
!Charles Darwin **Charles
natural selection is possible without a breeder. For example, if the
food is encased in a thick shell, a bird must be able to crack it to
survive. A thick beak makes this possible. The problems in the habitat
of living beings determines the goals. A narrow-pointed beak helps to
capture insects. He realized this through observations on a trip to the
Galapagos Islands.

<File:Evolution_sm.png> <File:Darwin's_finches.png%7CDarwin's> finches
<File:Darwin's_Finches,_Denver_Museum_of_Nature_and_Science.jpg>

## Evolution as natural selection

!DNA double helix
horizontal
The genes are located in the cells of living beings. The genes contain
the building and operating instructions of the living being. These are
made up of DNA.

-   **Mutation**\
    DNA can be altered by naturally occurring radioactive radiation.
    This leads to changes in the offspring. As a result, children, such
    as Darwin finch chicks, have different characteristics. They are
    called variations.

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-   **Selection**\
    Some chicks die, others survive. Creatures that are better adapted
    to the environment have a better chance of surviving. Chicks with a
    feeding beak are more likely to survive.

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-   **Propagation**\
    The survivors can have children.

## Evolution as a scientific process

!Chick before the first
flight
Evolution and scientific work are based on a comparable process:

-   **Mutation**\
    Science: Scientists modify existing models.\
    Evolution: Radiation changes DNA.

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-   **Selection**\
    Science: Scientists test the models in experiments.\
    Evolution: The realities of nature are a severe test for all living
    beings.

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-   **Propagation**\
    Science: Through a publication, other scientists learn about the
    model.\
    Evolution: Living beings have children.

The theory of evolution describes a scientific knowledge and innovation

## Direction and destination

A breeder strives for goals, the evolutionary process of nature does
not. But the mechanism of evolution has one direction: best possible
adaptation to the environment in order to survive. For example, being
able to fly is very useful. Many innovations were needed before the
physical and mental abilities were available for birds to fly and find
their way back home after a migration.

## Science and truth

In philosophy, there have been arguments about truth for centuries.
Since each side was convinced that they had the (absolute) truth at
their disposal, an agreement was impossible. Science has solved the
problem: on the one hand, science dispenses with absolute statements.
All statements are preliminary and can always be improved. On the other
hand, scientists have developed methods to check the quality of models.
Scientific statements are not true or untrue, but of high or low
quality. That doesn\'t mean scientists aren\'t confident in their
theories. However, good scientists are generally willing to revise their

## Is the theory of evolution a good theory?

-   The theory of evolution is understandable. It is clear that
    well-adapted creatures are more likely to survive.

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-   The theory of evolution is logical. It is based on the laws of
    mathematics (statistics).

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-   The theory of evolution is often tested. It has been verified by
    computer simulations, experiments and observations in nature.

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-   The theory of evolution is helpful. It explains many properties of
    living things and processes in nature that would otherwise be
    incomprehensible.

The theory of evolution is a high-quality theory.

In particular, questions of speciation, the Cambrian Explosion and the
origin of life are currently under discussion.




## References



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