Description
Comparative anatomy has long served as evidence for evolution, it indicates that various organisms share a common ancestor. Also, it assists scientists in classifying organisms based on similar characteristics of their anatomical structures. Comparative anatomy supports Darwin's theory of descent with modification, also known as evolution. A common example of comparative anatomy is the similar bone structures in forelimbs of cats, whales, bats, and humans. All of these appendages consist of the same basic parts; yet, they serve completely different functions. The skeletal parts which form a structure used for swimming, such as a fin, would not be ideal to form a wing, which is better-suited for flight. One explanation for the forelimbs' similar composition is descent with modification. Through random mutations and natural selection anatomical structures gradually became better-adapted to the every organism's respective habitat. Two major concepts of comparative anatomy are:
- Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales.
- Analogous structures - structures similar in different organisms because they evolved in a similar environment, rather than were inherited from a recent common ancestor. They usually serve the same or similar purposes. An example is the streamlined torpedo body shape of porpoises and sharks. So even though they evolved from different ancestors, porpoises and sharks developed analogous structures as a result of their evolution in the same aquatic environment.
The rules for development of special characteristics which differ significantly from general homology were listed by Karl Ernst von Baer (the Baer laws).
Read more about this topic: Comparative Anatomy
Famous quotes containing the word description:
“Do not require a description of the countries towards which you sail. The description does not describe them to you, and to- morrow you arrive there, and know them by inhabiting them.”
—Ralph Waldo Emerson (1803–1882)
“He hath achieved a maid
That paragons description and wild fame;
One that excels the quirks of blazoning pens.”
—William Shakespeare (1564–1616)
“I fancy it must be the quantity of animal food eaten by the English which renders their character insusceptible of civilisation. I suspect it is in their kitchens and not in their churches that their reformation must be worked, and that Missionaries of that description from [France] would avail more than those who should endeavor to tame them by precepts of religion or philosophy.”
—Thomas Jefferson (1743–1826)