Question

Give an example of characteristics being used to determine how close two species are in evolutionary terms.

Answer 1

To determine how close species are in evolutionary terms we can take the example of humans and apes:

1. Humans, as well as apes, have more or less a similar body design and both of them have quite a similar pattern of body hair growth along with the presence of mammary glands. On this basis, we can say that these two are closely related to each other in evolutionary terms.
2. To prove the above point true we can compare humans with fish, both of them have got vertebral columns, a brain box, and jaws still the fish and man look entirely different from each other. This point proves that humans and fishes are not very closely related in evolutionary terms rather they are related very distantly.
3. The evolutionary relationship can be found with the help of homologous and analogous organs.

• Homologous organs: These are the organs that have a similar origin and basic structure but they perform very different functions in different organisms, i.e. they show divergent evolution. For example, the forelimb of man, bat, and cheetah are structurally alike but they perform different functions in each of them.
• Analogous organs: these organs are very different in their basic structure but they perform a similar function in different organisms, i.e. they show convergent evolution. For example, the eyes of an octopus and humans have different structures but they perform a similar function of vision.