Dr. Osbjorn Pearson of UNM's Department of Anthropology was part of an international team of researchers who analyzed a partial skeleton of Homo habilis from Inert in northern Kenya. Their article, New partial skeleton  of Homo habilis  from the upper Burgi Member, Koobi Fora Formation, Ileret, Kenya has been published by Wiley in The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology, the journal of the American Association of Anatomy, which publishes new discoveries in the morphological aspects of evolutionary, molecular, cellular, and systems biology. The discovery stands as the most complete set of postcranial, or below-the-head, bones ever attributed to Homo habilis. The skeleton dates to between 2.02 and 2.06 million years ago, placing it firmly within the early chapter of the genus Homo.

Homo habilis is a species of fossil human (a hominin) that existed between ~2.5 to 1.4 million years ago and was probably ancestral to Homo erectus. In  Africa, fossils of Homo erectus date between 2.0 and ~0.6  million year ago -- the end point is still debated -- and was almost certainly ancestral to modern humans (Homo sapiens). Some major adaptive changes happened between earlier hominids and the appearance of Homo erectus. Homo habilis is key to understanding the nature and timing of these changes.

Most fossils of Homo habilis are known from Kenya, Tanzania, and South Africa.  The  species is mostly known from teeth, jaws, and skulls.  Associated skeletons and teeth are rare. The find, KNM-ER 64061, is a partial skeleton consisting of upper limb bones, clavicles, a scapula, and a small portion of the pelvis. It is likely associated with a complete set of lower teeth (KNM-ER 64060) that were recovered 10-25 meters upslope from the bones of KNM-ER 64061. It is likely that both sets of fossils came from a single individual. The teeth  of KNM-ER 64060 closely resemble those of fossils of Homo habilis.

In  2012, Dr. Deming Yang (Department of Anatomy, Midwestern University and Division of Anthropology, American Museum of Natural History) found the fossils of KNM-ER 64061. Dr. Yang was part of a team led by Dr. Louise Leakey and Dr. Meave Leakey (both of the Turkana Basin Institute of Stony Brook University). Arbollo Aike, a Kenyan member of the team, discovered KNM-ER 64060, which led to Dr. Yang's discovery as the team scoured the area for additional fragments. Dr. Louise Leakey  and Dr. Meave Leakey invited other scientists, including Dr. Frederick Grine and Dr. William Jungers (both of Stony Brook University) to assist  with the analyses of the fossils. Dr. Grine subsequently recruited Dr. Pearson to help with a portion of it.

The analysis showed that many details of the anatomy of the limb bones resemble those of Homo erectus and later species of Homo, but also that KNM-ER 64061 was shorter, less heavy, and had  proportionally longer and stronger arms relative to its size than  Homo erectus. The extra arm strength resembles the more ancient pattern present in species of Australopithecus.

Dr. Pearson is Professor and Regents' Lecturer in the Department of Anthropology at UNM. He joined UNM's faculty in fall, 1999.

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