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A 3.5-million-year-old skull unearthed in a gully in Kenya may force
scientists to re-examine the evolution of modern humans.

The skull, and additional pieces of jaws and teeth, have been classified as
part of a previously unknown hominid species dubbed 鈥渇lat-faced human from
Kenya鈥�, Kenyanthropus platyops. Only one other hominid species, Australopithecus
afarensis, dates from a similar age鈥� 3 to 4 million years ago.

That discovery made A. afarensis鈥攁nd its most famous member, the fossil
Lucy鈥攖he sole candidate as ancestors of modern humans. 鈥淚t seemed as if
our lineage had to run through Lucy,鈥� says Frank Brown, a geologist at the
University of Utah in Salt Lake City who dated the Kenyan remains. 鈥淏ut that was
before this very nice skull.鈥�

Several features of K. platyops distinguish it from Lucy and her kin. It has
a less protruding jaw and more pronounced cheekbones, making the face less
ape-like and more like hominids 1.5 million years younger. Given its facial
features, K. platyops has surprisingly small teeth. Because the two species are
so different, they probably had different diets and lifestyles.

Few scientists have had a chance to examine the bones, and there is bound to
be heated debate over whether the flat-faced human deserves to be in a new genus
and species of its own. But Bill Kimbel, an Australopithecus expert at the
Institute of Human Origins at Arizona State University in Tempe, has looked at
casts of the skull and believes there is no doubt it represents a distinct
lineage. 鈥淭he evidence is as strong as one could hope for,鈥� he says.

Meave Leakey, a palaeontologist at the National Museums of Kenya in Nairobi
whose team unearthed the new fossil, says it is impossible to tell whether we
are more closely related to Lucy or K. platyops. There is simply too much
missing from the fossil record since then. In fact, she says, the discovery
makes sorting out the origin of humans more challenging.