A 3.5 million year-old skull unearthed in a small 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 Kenyanthropus platyops which means 鈥渇lat-faced human from Kenya鈥�. Since 1974, only one hominid species, Australopithecus afarensis, had been found in the fossil record from three to four million years ago.
That made A. afarensis 鈥� and its most famous member, the fossil Lucy 鈥� the sole candidate for the ancestors of modern humans.
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Now she has competition, says Frank Brown, a geologist at the University of Utah in Salt Lake City who helped date the Kenyan remains. 鈥淚t seemed as if our lineage had to run through Lucy,鈥� he says. 鈥淏ut that was before this very nice skull.鈥�
Little teeth
Several features of K. platyops distinguish it from Lucy鈥檚 people. As the name suggests the new species has less of a protruding jaw and more pronounced cheek bones, making the face less ape-like and more like hominid fossils 1.5 million years younger.
But given its facial features, K. platyops also has surprisingly small teeth. The distinctness of the two contemporary species suggests they probably had different diets and lifestyles.
Since few scientists have had a chance to examine the bones, there is bound to be heated debate over whether the flat faced man warrants the creation of a new genus and species.
Distinct lineage
But Bill Kimbel, an Australopithecus expert 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.
Despite the more modern appearance of K. platyops, the researchers say it is impossible to tell whether it is more closely related to modern humans than Lucy and her kin. There are simply too many intervening pieces missing in the fossil record.
Indeed, the discovery makes sorting out the origin of humans more challenging, says Meave Leakey, a palaeontologist at the National Museums of Kenya in Nairobi, whose team unearthed the new fossils. 鈥淭he early stages of human evolution are more complex than we previously thought,鈥� she says.
More at: Nature (vol 410, p. 433)