By the time Jennifer, Jessica, and I reached camp this afternoon, Kampi Safi was certainly more than a piece of barren land. It was a "tent city", as some of my visiting colleagues have called it in previous years. We received a warm greeting from our crew and from our Maasai friends. Olorgesailie is in the midst of Maasai land, where the local people wrapped in red shukas (robes) herd their cattle, goats, and sheep, and collect containers of water from local sources, which are then strapped to the sides of donkeys that plod back to the Maasai homesteads, or manyattas.

The late afternoon sunlight on the rift valley walls and gullies today was awe-inspiring. To enter the rift from Nairobi, you drive to the southwest and climb up the Ngong Hills (an area made famous by the author Karen Blixen in her book Out of Africa). Approaching the eastern edge of the rift, you sense that you're coming to the edge of the world. You turn a bend in the road and there it is - a marvelous vista of land and sky made by the inexorable pulling apart of Earth's crust and by earthquakes that have caused the land to drop down along geologic faults. There you see this tremendous expanse, the Great Rift Valley, which runs north-south and is interrupted by eroded volcanic hills and ridges. Mount Olorgesailie sits on the floor of the rift, about 2000 meters below.

xAlthough nothing seems to be happening, the slow drama of Africa's Great Rift has created a sight to behold - a complex beauty that is fitting for the tale of survival, extinction, and evolutionary change that it contains. In fact, the rift valley is known as the "cradle of mankind." It's called that because of the preservation of early stone tools and fossilized early human bones here. Although southern Africa and parts of west-central and northern Africa also give important clues of early human life and evolution, the rift valley is a huge natural catchment of sediment. In the past this catchment included lakes and rivers where the bones and artifacts of early humans were naturally buried. Due to earthquakes and faulting, some of these ancient sediment traps have been uplifted and eroded - and that's why there are so many interesting finds about human origins in the rift valley.

The water sources and lake margins were attractive to early humans, and allowed natural burial. The dynamics of the region provided a great challenge to survival and a stimulus to evolutionary change. And then earth movements exposed the ancient layers of sediment to erosion. Finally, scientists and excavators have come along to discover the fragmentary evidence of early humans and their surroundings as it tumbles out of the layers. I've always thought that's pretty amazing - the whole cycle from ancient times to the present. In fact, in all the years I've visited the Great Rift, I've never lost that feeling of a deep connection between our lives in the present and something mysterious - I guess I'd call it the roots of being human. I'll talk more about it all as our studies proceed. Tomorrow, our research at Olorgesailie begins.