Evidence for Evolution

Evidence of evolution can be found in many fields of science. For example, advances in molecular biology and genetics help scientists determine the relatedness of living and extinct species by comparing their DNA. Similar structures resulting from common ancestry include morphological homologous structures, similarities in DNA sequences, and similarities in embryonic development. Let’s look at the three major ideas behind evolutionary theory and some of the major supporting evidence.

You REALLY need to learn the vocabulary and examples scattered in the videos below. Make yourself a chart like this example:

the image lists some of the major pieces of evidence for evolution

Species Change Over Time

Watch the Evidence video below, and think about how species have changed over time.

Selection is What Causes the Change in Species

Watch the Evidence for Evolution video below, and think about how species have changed over time.

Remember that both natural and artificial selection serve as evidence and can change populations over time.

How does species interaction encourage or slow changes in species?

The interaction between humans and other organisms has led to quick evolutionary changes through artificial selection. The farmer or animal breeder determines fitness and decides which traits to pass on, instead of nature. In natural selection, the current conditions of the environment determine fitness and survival, not a breeder or genetic engineer in a lab.

Common Ancestry

Watch the Evidence for Evolution video below, and think about how species have changed over time.

Common ancestry in eukaryotes can be seen in structural evidence. Animals with similar structures often have evolved from a common ancestor. These similar structures, called homologous structures, are shared by related species. All vertebrates, or animals with backbones, have the same basic bone structure in their limbs. These bones are examples of homologous structures.

The image shows the bone structure of a human hand, dog leg, bird wing, and whale flipper.

Through millions of years, these limbs have become modified to fit different purposes in different species. This includes flying, crawling, or swimming. The similarities and differences between the homologous structures of two species determine how recently they shared a common ancestor. For example, the front limbs of birds are more similar to those of reptiles than those of mammals. This similarity, as well as other structural similarities, indicates that birds and reptiles share a common ancestor more recent than the common ancestor of birds and mammals.

Practice your evidence knowledge below by sorting the items in the Evidence Sort activity.

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