The skeleton of the immature male to the right is quite possibly one of the most important finds in the field of paleoanthropology. The skeleton is over 90% complete when bilateral symmetry is taken into account (the missing left humerus -- upper arm bone -- can be reconstructed as the mirror image of the right). The find has told us much about the anatomy of the early human species Homo ergaster.

Earlier humans had roughly the same body size as modern chimpanzee. Yet this immature male had already surpassed a height of five feet at the time of his death, and probably would have attained a height of 6 feet and a weight of roughly 150 lbs., assuming Homo ergaster underwent an adolescent growthspurt as modern teenagers do. The hips were more slender and adapted to walking and running over long distances. The proportions of his arm and leg bones were like those of modern humans, as opposed to the shorter legs and longer arms (more ape-like proportions) of Homo habilis and A. afarensis. The cranial capacity of WT 15000 is measured at 880cc. Using the same extrapolations that were used for height, it is estimated that he would have attained an adult cranial capacity of 909cc. His body was long and slender, probably adapted to a tropical environment, given that most tropical populations of modern humans are also tall and slender.

The gender of the skeleton can be determined with certainty by the prominence of the browridges and the shape of the pelvis. An age of 9 to 12 years at time of death has been assigned to the boy, based on the eruption of the second molars (see bottom photograph below) and the pattern of long bone growth.