16 July 2004

Many of you have read news stories or seen television shows about the animals of Kenya. Lions, hyenas, elephants, zebra, antelope, baboons, and ostriches define Africa to many people around the world. When you think of human ancestors walking across the landscape here, you may imagine they were eating antelope and scaring off lions. But how realistic a view is this? You know from our earlier dispatches that a different species of hominin lived here 900 thousand years ago or so. There were also different species of animals that lived here that long ago.

Theropithecus oswaldi cast
Theropithecus oswaldi
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Part of our purpose in uncovering fossil bones is to identify which species of animal they came from. Many of the bones we see are from species that are now extinct, just like the hominin skull we found. (Even though we're not sure exactly which species it was, we know that the partial skull was significantly different from our species, Homo sapiens). We have identified many different extinct species - everything from a form of baboon called Theropithecus oswaldi to an elephant called Elephas recki.

Elephas recki excavation
Elephas recki
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What's interesting is that we know from their fossils here at Olorgesailie and elsewhere in Africa that these extinct species lived in different environments and ate different things from what their living relatives eat. Theropithecus, for example, was a baboon that had very big molars and strong jaws, and the microscopic scratches on their teeth (based on a study by my good friend Dr. Mark Teaford of Johns Hopkins University) tell us that this baboon at lots of grass. Modern baboons have smaller molars and jaws, and eat a wide variety of plants and even animals on rare occasions. Elephas recki was also bigger than its living elephant counterpart, and its jaws and skull also show that it was a grass-eating specialist, while modern African elephants (Loxodonta africana) mainly browse on leaves. By comparing the fossil assemblages through time, we can get a clearer picture of the types of food that were available and how the environment changed. The fossil data, in fact, tell us that the environment at Olorgesailie changed dramatically through time. That's a story we'll get into on another day.

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