2. The theory of evolution is based on evidence from different fields, among which is comparative anatomy. • Comparative anatomy involves studying and comparing the structure of different organs. Two organisms are related if their organs have a similar internal structure, even if they are shaped differently. • There are: Homologous organs Analogous organs Vestigial organs Click on each organ to find out more.

3. Homologous organs • Homologous organs are similar in structure and share a common origin but may be adapted to perform different functions. • One example of homology is the case of the limbs of mammals. Dog Dolphin Horse Basic structure present in a common ancestor Human Bat wing Go back to the Start menu

4. Analogous organs • Analogous organs are those that have evolved separately but look alike because they are adapted to perform the same function. • One example of analogous organs is the case of the wings of insects and birds. Birdwing Bat wing Insectwing Go back to the Start menu

5. Vestigial organs • Vestigial organs are those organs, found in some living things, that do not perform any functions. They simply show an evolutionary relationship with other living things. • One example of a vestigial organ is the coccyx, or tailbone, in humans. The coccyx is the remnant of a lost tail. Coccyx Go back to the Start menu