Chapter 9, Lesson 2

What evidence supports evolution?

Fossils, patterns of early development, similar body structures, and similarities in DNA and protein structures all provide evidence that organisms have changed over time

By examining fossils, we can tell that organisms that lived in the past are very different from those alive today

The millions of fossils that scientists have collected are called the fossil record​

Similarities in Early Development

• When organisms begin their development, they may have many similar features to help show that they have a common ancestor

• The organisms pictured each have a tail in the early stages​

Similarities in Body Structure

• Body structure is an organism's basic body plan - how bones are arranged

• Homologous Structures - structures that are similar in different species and that have been inherited from a common ancestor

• Fossils sometimes show homologous structures with living species - whale fossils had legs and walked on land

Similarities in DNA and Protein Structure

• Scientists infer that the species inherited many of the same genes from a common ancestor

• The more similar the DNA sequences, the more closely related the species are​