It's important to plan the last week of our excavations with great care. I've also begun to take stock of what we've uncovered so far this season, and how it compares to what we thought we might find. I remember thinking when we started this year's work at Site 15 that we might find another butchery site. The bones and stones that were visible in the wall of the excavation seemed to suggest that a zebra was cut up for meat here by early humans.

What we actually found through the season did not paint so clear a picture. We did find many flakes and stone tools, which would have been used in a butchery site. We also found a good number of teeth of a very large zebra, which represent the extinct species known as Equus oldowayensis. You can compare the fossil tooth, which is black, with the modern zebra tooth, which is white. These extinct horses had huge teeth! Despite the large numbers of teeth and the stone tools, we found only a few zebra bones, and only one bone of the appropriate size had an obvious butchery mark. This was a joint surface where early humans had apparently succeeded in separating the shoulder joint. We usually like to see more evidence than this to call the site a butchery site, where an entire zebra had died and been cut up for meat. But what we found is a clue that a zebra had died pretty close to where we dug. There's still much work to do in the laboratory in Nairobi, where I'll be able to study the stone tools and fossil bones more carefully than we had time for during the excavation.

At Site 15, we also exposed several small channels, two of which are pretty clearly game trails containing hippopotamus footprints. At the bottom of one of the channels, we found many bone fragments and stones that had been kicked around and stepped on by the animals that had made the trail. We also got a clearer idea of the local environment. The footprints, some small patches of diatomite, and many vertical root marks that are typical of reeds, indicate that this was a low-lying, swampy area, with at least seasonal water. This would have been a good place for animals to find water to drink, but also for carnivores to stalk and kill their prey. In the lab, I'll look for evidence (gnaw marks) of carnivore activity at this site. But one thing's for sure: the early humans were around, left lots of sharp and used stone tools around, and probably ate their share of meat.