A publication of the Archaeological Institute of America
A 3.5-million-year-old skull found near northern Kenya's Lomekwi River is prompting a major rethink in our understanding of the human family tree. Discovered by Kenyan fossil hunter Justus Erus and Meave Leakey of the National Museums of Kenya during the 1998 and 1999 field seasons, the new found skull, named Kenyanthropus platyops, is strikingly different in appearance from that of its contemporary neighbor Australopithecus afarensis, the species to which the famous 3.2-million-year-old Lucy belongs. Kenyanthropus platyops means "Flatfaced Man of Kenya."
Though 40 percent of Lucy's skeleton had been recovered in 1974, most of her skull, aside from a lower jaw and a few cranial fragments, was missing, leaving may unanswered questions as to her dentition, facial architecture, and brain size. These questions were answered with the 1992 discovery at Hadar, Ethiopia, of a nearly complete 3.0-million-year-old male A. afarensis specimen, which exhibited a small braincase (ca. 500 cc.), thick molars and large canines, and a heavy, protruding brow ridge.
While the newly found K. platyops is similar in brain size, it differs significantly in facial appearance, having a flat face and small teeth, features, argues Leakey, that appear in a more fully developed form in Homo rudolfensis, a species that thrived in East Africa 2.4 to 1.8 million years ago, and which many view as the beginning of the Homo line.
"Based on the teeth alone," Leakey told ARCHAEOLOGY, "we believe that K. platyops exploited a different ecological niche, most likely subsisting on softer foods such as fruits and insects." A. afarensis, she believes ate a harsher diet, one of roots and grasses.
Until now, paleoanthropologists have thought that there was only one ancient ancestor that gave rise to what would become the human line three to four million years ago. Clearly, the picture of this critical time in human evolution is far more complicated. Leakey and her team published their findings in the March 22, 2001, edition of the publication Nature.