UNIT 5 The origin of life and evolution

UNIT 5 The origin of life and evolution HOMOLOGOUS, ANALOGOUS AND VESTIGIAL ORGANS Biology and Geology 4. Secondary Education

UNIT 5 3 Homologous, analogous and vestigial organs • 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 Click on each organ to find out more. Biology and Geology 4. Secondary Education Vestigial organs

UNIT 5 3 Homologous, analogous and vestigial organs 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 Bat wing Human Horse Go back to the Start menu Biology and Geology 4. Secondary Education Basic structure present in a common ancestor

UNIT 5 3 Homologous, analogous and vestigial organs 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. Bird wing Bat wing Go back to the Start menu Biology and Geology 4. Secondary Education Insect wing

UNIT 5 3 Homologous, analogous and vestigial organs 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 Biology and Geology 4. Secondary Education