biology question #520
Jen, a 15 year old female from Orland Park asks on January 7, 2002,Q:
If you find a bone in an archeological dig how can u tell what kind of animal it was?
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An animal's bones are usually distinctive because they have evolved to fit that animal to a behavioral lifeway. For example, the common ancestor of horses and cows had five digits. A differentiation of lifeways occurred many millions of years ago such that some animals (horses and their kin) became adapted to fast running while others (cattle and their kin) became adapted to a slower gait. As these animals evolved the numbers of digits declined to one for horses and two for cattle. Pigs still have four but the rear two don't touch the ground. These adaptations can be very specific such that one species' bones are clearly different from another. Sometimes, as in sheep and goats, it is difficult to tell leg bones apart but skulls are quite distinct. Human locomotion called bipedality (walking on two feet) is so specialized that almost any bone from our bodies, or even fragments, can be distinguished from any other animal. We can also use biochemistry and remnant DNA to differentiate bones from archaeological species. Usually, however, bone specialists employ comparative anatomy techniques to tell what kind of animal it came from. In other words, they take a lot of courses at university to understand the subtle differences between the bones of different animals.