Lake Turkana itself is a geologically recent phenomenon, but what is now the Lake Turkana basin has an archaeological record that stretches back 2.5 million years and a paleontological record that extends back to the Cretaceous Period. Vertebrate fossils were first discovered in the lower Omo Valley at the beginning of the twentieth century, but the first multidisciplinary international expedition to investigate the region was that of the International Omo Research Expedition in 1967. The National Museums of Kenya participated in the first IORE but thereafter mounted their own multinational and multidisciplinary expeditions to the Kenyan part of the Lake Turkana basin. The Koobi Fora sand spit on the east side of the lake served as the National Museums' field headquarters for the Koobi Fora Research Project on that side of the lake, the subsequent West Turkana Project, more recent fieldwork at Lothagam and Kanapoi, and ongoing field research today. The fossils and artifacts recovered from the Lake Turkana basin have contributed much to our current understanding of early human origins.