Good point. I don't know much about anthropology, but it does seem that whenever they find a human fossil, they assume the find is typical of the culture at the time. What if, by the laws of random chance, the two people alive today whose fossils get preserved are Shaquille O' Neil and Robert Reich?
In one million years, the textbooks might be saying "In the primitive globalization era, humans consisted of two tribes: giants and pygmies. We suspect they were at war most of the time."
> it does seem that whenever they find a human fossil, they assume the find is typical of the culture at the time.
Statistically valid, and generally supported by further evidence. When you find a fossil *anything*, the greatest likelyhood is that it is a more or less average example of whatever it is.
Heck, doesn't even need to be a fossill... just pick a human (or cow, or cat, whatever) at random, and chances are pretty good that it'll be pretty representative.