July 3, 2009

18 Million Years Later, an Expedition to East Africa

Professor of Paleoanthropology at Lehman College and Research Associate in Paleontology at the American Museum of Natural History

RUSINGA ISLAND, Kenya | Searching for our fossil ancestors is an esoteric business, but it also elicits a disproportionately wide degree of attention in the popular press. Maybe this is because knowing where we came from (and how we got here!) is one of those fundamental questions people like to ask. Quiz the average person on the street, and many will have heard of Lucy, the famous three-million-year-old fossil hominin who walked upright. Or perhaps they will recollect the heavy-set Neanderthals or their more “refined” cousins, the Cro Magnons.

These species, however, occupy only the most recent course of human evolution. Based on current estimates, the last common ancestor between us and chimpanzees (our genetically closest living relatives) lived between six and seven million years ago. Many researchers are currently looking for the remains of such creatures. A lot fewer are out there looking for the ape-like creatures that lived before them. Between 20 and 7 million years ago, a multitude of different ape lineages emerged across Africa, Asia and Europe. Most of these lineages died out, but a number evolved into the different apes we have today–including us.

Investigating the evolution of these first apes is what has drawn me to Africa this year to look for fossils. I’m fascinated by the factors and conditions that led to the emergence of these creatures, and why they then proliferated into so many different lineages. As it turns out, the first apes emerged exclusively in Africa, and their remains are particularly well preserved today in the countries that make up East Africa.

Our field area is in the very west of Kenya, and constitutes two small islands in Lake Victoria, Africa’s largest body of water and the source of the Nile. The islands are called Rusinga and Mfangano. Rusinga has been particularly famous in paleontological circles since the 1930s and 1940s, when a very well-known genus of fossil ape called Proconsul was discovered here.

The wonderful thing about these islands today is that they are still packed with fossils. And not just fossil apes. We have fossil plants and seeds, miniature insects, the remains of giant lumbering mammals, birds, reptiles, bats – you name it. Apart from collecting fossils, we will also conduct a complex series of geological analyses of the islands’ sediments. In combining the geological work with excavation of new fossils, our hope is to be able to accurately reproduce both the evolutionary events and the environmental and ecological conditions on the island some 18 millions years ago and therefore investigate how subtle ecological changes may have influenced the emergence of Proconsul and its cousins.

We have an exciting team of experts joining us this year. I co-direct the site with Dr. Holly Dunsworth, from Northeastern Illinois University, and Dr. Kieran McNulty, an ex-CUNY graduate student now at the University of Minnesota. Both are experts on early fossil apes. In addition we have three geologists, three experts on fossil mammals, an expert in fossil plants and a number of graduate students, three of them from CUNY. They’ll contribute occasional posts to this blog–if I can tear them away from the fossil apes for a few minutes!