The Importance of Being Human

In the summer of 1965, my paleontological colleague, Bryan Patterson, was in charge of a Harvard expedition working near the shore of Lake Turkana in northern Kenya. At a locality called Kanapoi, while he was searching in deposits believed to be of the early Pleistocene the last geological epoch before the present, he picked up an important fossil. The broken lower end of a left humerus the upper arm, it was easily recognized as hominoid; that is, it came from a creature of the group that includes humans and their closest living relatives, the apes, but not from a monkey. What was the special importance of the fossil? From shape and size it could be seen at once not to belong to a gorilla, an orangutan, or a gibbon and the last two have never been present in Africa anyhow. It was extraordinarily similar to the same piece in modern humans; in fact, it was indistinguishable. But the date of the deposit was certainly before the existence of anything like modern humans, and after the field season was over, volcanic basalt from a bed lying