Bird taxonomy is a difficult field because of the severe anatomical constraints imposed by flight. There are only so many ways to design a bird capable, say, of catching insects in mid-air, with the result that birds of similar habitats tend to have very similar anatomies, whatever their ancestry. For example, American vultures look and behave much like Old World vultures, but biologists have come to realize that the former are related to storks, the latter to hawks, and that their resemblances result from their common lifestyle.
Ahead of me lies the familiar litany: weakening of the heart, hardening of the arteries, increasing brittleness of bones, decreases in kidney filtration rates, lower resistance of the immune system, and loss of memory. The list could be extended almost indefinitely. Evolution seems indeed to have arranged things so that all our systems deteriorate, and that we invest in repair only as much as we are worth.
History followed different courses for different peoples because of differences among peoples' environments, not because of biological differences among peoples themselves
Today Charles Darwin is best known for establishing the fact of evolution and for recognizing the major role of natural selection in driving it.
Recent discoveries about apes suggest, however, that a gorilla or common chimp stands at least as good a chance being murdered as the average human.
Biology is the science. Evolution is the concept that makes biology unique.
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