Rudolfensis and the Red-Nosed Paleoanthropologist

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 Possibly Discovered.”   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.  Not only that, the other Homo fossils are still in disarray: H. habilis, H. erectus, H. ergaster, H. heidelbergensis, H. neanderthalensis – the whole gang.  Are they ancestors, extinct lineages, or all variations on the same human species?

Wood believes there are “at least two” Homo species in the data, but he made statements that could make a creationist say “Aha!” (considering that they will deny the evolutionary dates assigned to these bones anyway).  For instance, he admitted that back in the 1970s there were questions whether the fossils from Koobi Fora represented different species or just males and females of the same species (he chose the former interpretation).  He also assumed back then that a particularly robust jaw went with the face of H. rudolfensis.  That has been refuted by the new finds, he said, leaving him to conclude that two or three separate lines of Homo coexisted.  His last paragraph, though, leaves enough gap to drive a truck through:

So where do we go from here? More work needs to be done using the faces and lower jaws of modern humans and great apes to check how different the shapes of the palate and lower jaw can be among individuals in living species. We also need to find a way to formally estimate the likelihood that the OH 7 lower jaw came from the same species as either KNM-ER 60000 or KNM-ER 1802. If the latter can be accommodated within H. habilis, then all well and good, but if not (which I think is more likely), then could KNM-ER 1802 and its ilk represent a third species? Finally, some researchers have suggested that evidence from the face and jaws of H. habilis and H. rudolfensis, plus what little fossil evidence we have of these species’ other body regions, stretches the definition of the genus Homo too far. Perhaps these two taxa belonged to a different lineage from that from which H. sapiens arose? My prediction is that by 2064, 100 years after Leakey and colleagues’ description of H. habilis, researchers will view our current hypotheses about this phase of human evolution as remarkably simplistic.

Did the news media include these confessions?  Only New Scientist mentioned Wood’s statement about stretching the definition of Homo too far.  Live Science and PhysOrg, decorating their articles with photos of the team looking very scientific with their tools, treated the statements of the discoverers as fact, saying they confirm the notion that there were three separate lineages of Homo living at the same time.  Pallab Ghosh at the BBC News was the most reckless, stating as a fact that a new species of Homo has been discovered by the Leakey team.  “With the discovery of the three new fossils researchers can say with more certainty that H.rudolfensis really was a separate type of human that existed around two million years ago alongside other species of humans,” he said, completely ignoring Wood’s remark about “our current hypotheses … as remarkably simplistic.” Ghosh captioned the press-release skull reconstruction positively: “A new species of human: One of several co-existing in Africa two million years ago.”

Ghosh even included the old “march of progress” icon of apes evolving into humans, with the caption, “The March of Progress had many dead ends” (presumably exempting his own top end).  To nail it for Darwin, Ghosh quoted Meave Leakey (hardly a disinterested party), saying, “evolution really does work…. It leads to amazing adaptions and amazing species and we are one of them.”  She did not explain whether the truthfulness of her propositions could be derived from random mutations.

For those of us who already know that their current hypotheses about human evolution are remarkably simplistic, ignore the latest self-serving Darwin Party infomercial and go back to work doing what good humans do: thinking rationally.

For more on Homo rudolfensis, see 3/27/2007, and especially 5/27/2009.  For more on Homo habilis, see 8/09/2007,  7/13/2009, and 9/21/2009.  For entertainment, follow the “Early Man” category over time.

*On “The Five” on Fox News today, Greg Gutfeld urged people to drop the phrase “shed light.”  The expression, he claimed, is a dodge.  When you have facts and numbers, you present them; when you don’t, you say your guesswork “sheds light” on whatever.  We agree: evolutionists, drop this worn-out, tired, useless expression!  (Actually, it does give us opportunities to show off Brett Miller’s great cartoon.)