Question

Explain with suitable examples the importance of anatomical evolution.

Answer 1

Hint: Anatomical evidence is one of the strongest forms of evidence for evolution. The structural similarities between organisms are compared to determine their evolutionary relationships.

Complete answer:
- Organisms with similar anatomical features are assumed to be relatively closely related evolutionarily, and they are assumed to share a common ancestor. However, some such organisms may differ a lot in their functions. These are called homologous structures. Such similar structures may indicate an evolutionary relationship and a common ancestor of the species that possess them. For example, the forelimbs of mammals. The forelimbs of humans, whales, dogs, and bats all are very similar in structure.

- Each possesses the same number of bones, arranged in almost the same way. However, they have different external features and their function is also different, the embryological development and anatomical similarities in form are similar. By comparing the anatomy of these organisms, scientists have determined that they share a common evolutionary ancestor and in an evolutionary sense, they are relatively closely related.

- There are organisms with anatomical structures that function in very similar ways, however, morphologically and developmentally these structures are very different. These are called analogous structures. These organisms do not indicate an evolutionary relationship nor do they share a common ancestor. For example, the wings of a bird and dragonfly both have the same function, helping the organism to fly.

- However, when comparing the anatomy of these wings, they are very different. The bird wing has bones inside and is covered with feathers, while the dragonfly wing is missing both of these structures. Analogous structures are evidence that these organisms evolved along separate lines.

- Vestigial structures are anatomical features that are still present in an organism, often reduced in size, even though they no longer serve a function. The presence of vestigial structure also indicates that the organisms share a common evolutionary ancestor and that they are relatively closely related. Whales, which evolved from land mammals, have vestigial hind leg bones in their bodies. While they no longer use these bones in their marine habitat, they do indicate that whales share an evolutionary relationship with land mammals. Humans possess more than 100 vestigial structures in their bodies.

Note: Anatomical evidence sheds light on the process of evolution. It allows us to examine homologous, analogous, and vestigial structures, and how each type of anatomical structure plays a valued role in the collection of evidence for evolutionary change amongst organisms.