New Human Relative Shakes Family Tree
March 22 , 2001
By Jennifer Viegas, Discovery News
Scientists working in northern Kenya have unearthed a battered, but almost complete, skull for a new breed of early human ancestor that could change human evolutionary history.
The 3.5-million-year old remains, damaged by minerals growing in cracks throughout the bone, have been assigned the scientific name Kenyanthropus platyops, or the Flat-Faced Man from Kenya.
Prior to this discovery, 3.2-million-year-old "Lucy" (Australopithecus afarensis) widely was believed to be the great ancestor of modern humans. But now, researchers must decide which hominid lies on the human family tree, and which doesn't.
"We've always assumed Lucy was our ancestor and now we need to re-evaluate that idea," Frank Brown, dean of the College of Mines and Earth Sciences at the University of Utah and a contributing author of the report, told the university news service.
A team of scientists led by Meave Leakey, a paleoanthropologist at the National Museums of Kenya, assigned K. platyops to a new genus and species because of differences that distinguish it from Lucy and other early hominids. In addition to his flat face, K. platyops had a relatively small brain — about the size of a chimpanzee's — flat nostrils, small ear holes, high cheekbones, no depression behind the brow ridge and small molar teeth.
According to the team's report, published in this week's journal Nature, variations in face shape and tooth size among early humans suggest each breed had a different diet and could have existed side by side due to lack of competition for food sources.
Brown indicated the Flat-Faced Man probably lived in a fertile region near what is now the Lomekwi River.
"There is good evidence for a mosaic of habitats in the vicinity of the fossil finds, including open grassland, and also more wooded habitats, possibly with forests fringing ancient stream courses," said Brown. "The creatures may have lived in any one of these habitats, or have used resources from all of them."
In addition to the skull, three dozen teeth, jaw fragments and other fossils, as yet unclassified, were unearthed at the Lomekwi site.
Despite the puzzle surrounding humans' murky evolutionary past, Daniel Lieberman, an anthropologist at The George Washington University and author of a Nature commentary on the recent finds, thinks "the creation of the new genus was a sensible idea."
"But," he added, "until we can figure out reliably the evolutionary relationships between this species and other fossil human species, the new genus will remain controversial and open to debate. I think we are far from knowing how most fossil human ancestors were related to each other."
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