Possible human ancestor in Australopithecus sediba

The hominid’s unusual build may place it in humankind’s lineage

A surprising mix of apelike and humanlike features from head to toe supports a controversial contention that a 2-million-year-old member of the human evolutionary family gave rise to the genus Homo, an international team of researchers reports in six papers published April 12 in Science.

BONES OF CONTENTION A reconstruction of the curious-looking hominid Australopithecus sediba shows an unusual mosaic of body characteristics that may make it a direct human ancestor. L. Berger, Univ. of Witwatersrand

Anthropologist Lee Berger of the University of the Witwatersrand in Johannesburg, South Africa, and his colleagues assigned two partial skeletons and other fossils found in a South African cave in 2008 to a species they named Australopithecus sediba. Among the group’s new findings: A. sediba’s teeth suggest that this hominid evolved into a Homo species but had no links to earlier East African hominids often regarded as Homo ancestors. Those hominids include 3.2-million-year-old Australopithecus afarensis, best known for Lucy’s partial skeleton. A. sediba’s relatively long arms were suited to hanging out in trees, consistent with its narrow, apelike upper rib cage. But these hominids also had narrow, humanlike lower rib cages and lower backs that were longer and more flexible than those of people today. A. sediba probably walked awkwardly with its feet rolling inward and slightly pigeon-toed.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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