Add Leakey to Homo skulls and what do you get?  Headlines! — with fine print that undermines the celebration.

The news media were full of headlines this week about our latest ape-like ancestors.  New Scientist announced, “Fossils confirm three early humans roamed Africa.”  Pallab Ghosh spoke for the BBC News, “New human species identified from Kenya fossils.”  PhysOrg trotted out the ever-ready cliche, “New Kenyan fossils shed light* on early human evolution.”  Live Science was slightly more tentative with “New Flat-Faced Human Species PossiblyDiscovered.”   They were reporting latest finds by Meave Leackey, Louis N. Leakey, Fred Spoor and team, announced forthrightly in Nature, “New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo” (Nature488, 09 August 2012, pp. 201–204, doi:10.1038/nature11322).  Trouble is, seasoned bone analyst Bernard Wood let most of the gas out of the bag in his analysis in the same issue of Nature (“Palaeoanthropology: Facing up to complexity,” Nature 488, 09 August 2012, pp. 162–163, doi:10.1038/488162a).

It’s not that Bernard Wood doubts human evolution from apes.  He made that clear: “There must have been a ladder-like sequence of species connecting us with that common ancestor,” he said, speaking of “the ancestral species we share exclusively with chimpanzees and bonobos.”  Then he added, “but it is unclear whether our section of the ‘tree of life’ is restricted to this ancestor–descendant sequence, or whether it includes other, now extinct, lineages.”

The gist of the find is that some new skull and jaw fragments found in Kenya by the Leakey-Spoor team seem to reinforce the idea the Homo rudolfensis, a.k.a. Skull 1470 that made a splash back in 1972, was an odd man out that might have represented an extinct lineage of Homo.  The problem, as Bernard Wood explains it, is that the data (as usual) are too fragmentary to confirm any one of several hypotheses.  There’s so much wiggle room in the data, he’s not sure what these new fossils mean….

Continue Reading on