UNIT

5The origin of life and evolution

Biology and Geology 4. Secondary Education

HOMOLOGOUS, ANALOGOUS AND VESTIGIAL ORGANS

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3

Biology and Geology 4. Secondary Education

UNIT

5Homologous, 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:

Click on each organ to find out more.

Homologous organs

Analogous organs

Vestigial organs

UNIT

3

Biology and Geology 4. Secondary Education

UNIT

5Homologous, analogous and vestigial organs

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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.

Basic structure present in a common ancestor

Dolphin

Dog

Bat wing HumanHorse

UNIT

3

Biology and Geology 4. Secondary Education

UNIT

5Homologous, 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

Insect wingGo back to the Start menu

UNIT

3

Biology and Geology 4. Secondary Education

UNIT

5Homologous, 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.

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Coccyx