Dr. Hill and his collaborators will continue their research in the Tugen Hills region of Kenya and conduct an additional three seasons of fieldwork. Within this area fossiliferous sediments, in five major formations, range from older than 14 million years to less than 2.4 million years ago. In addition to a wide range of mammalian species, these sediments have yielded two important primate remains: a Proconsul (early ape) specimen dated to approximately 12 million years ago and a hominid (human) with an age of ca. 5 million years. This is the oldest known hominid specimen. The group will continue their systematic examination of the Tugen Hills and in particular focus on sediments which have the potential to yield significant primate fossils. The stratigraphic sequence will be refined and absolute ages determined by K/Ar and paleomagnetic dating techniques. This region is particularly important because it fills an important gap in the human paleontological record. From areas in both Africa and other parts of the world, good samples of higher primates and associated fauna are available for the period from 32 to 14 million years ago and also for a subsequent period from 3.6 million years to the present. However, information concerning the intervening time, from 14 to 4 million years is lacking. The best available relevant section in Africa is provided by the Tugen Hills, and thus, research there is important. In a broader perspective this project is significant because it helps to trace the development of the human species. To understand ourselves as we are today, it is necessary to trace our long-term history and to elucidate the processes which are reflected therein.