Remains of Homo erectus from Bouri, Middle Awash, Ethiopia

Summary of article appearing in Nature, Volume 416, 21 March 2002, pages 317-320.

Article by Berhance Asfaw, W. Henry Gilbert, Yonas Beyene, William K. Hart, Paul R. Renne, Giday WoldeGabriel, Elisabeth S. Vrba, and Tim D. White

A one-million-year-old calvarium found in the Daka Member of Ethiopia's Middle Awash may shed new light on the diversity of Homo erectus. This fossil has features characteristic of Asian Homo erectus and calls into question the division of Homo erectus fossils into two different species, one African and the other Asian.

The calvarium has an intact base and is only slightly distorted. Its cranial capacity is approximately 995 cm³. The postcranial elements include three isolated femora and a proximal tibia. Although these are not complete specimens, they have characteristics, such as a thick outer layer of bone at the midshaft, that are typical of Homo erectus. The Pleistocene sediments also contained Acheulean artifacts, such as handaxes and cleavers. The vertebrate fossils found in the Daka Member included many bovid species thought to indicate open grasslands. Other fossils, such as hippos, indicate that some of these habitats may have been near water.

The species Homo erectus has been recognized since the late nineteenth century. It is debated whether Homo erectus was a strictly Asian form, represented by fossils from the island of Java, Indonesia (at the sites of Trinil, Sangiran, and Ngandong) and China (such as at the site of Zhoukoudian), or whether Homo erectus also includes African specimens. Measurements of the Daka fossil show that they overlap with the measurement of fossils from both Asia and Africa. The authors thus conclude that the African and Asian fossils are populations of the single widespread species, Homo erectus.

Another debate about Homo erectus comes from early fossils from Turkana (Kenya) and Dmanisi (Republic of Georgia), which some researchers assign to the species Homo ergaster, a species closely related to Homo erectus. By arranging African fossils in anatomical and chronological series and including the new find, the authors of this paper believe that they see a single evolving African lineage. Therefore, they do not believe that the early forms should be labeled as a separate species, Homo ergaster. Rather, the authors believe it significant that by one million years ago, a single species Homo erectus occurred in such distant places as East Asia and Africa, having apparently colonized the Old World without separating into different species.

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