Luskin On Neanderthals And A Johanson Redux

I received my copy of Science & Human Origins today and will have a more in depth review of the paleoanthropological content once I have had a chance to read it.

In the meantime, the picture above gives one of Luskin’s arguments. I have also discovered another instance of Luskin playing fast and loose with the facts. Here is Luskin:

Donald Johanson suggests that were erectus alive today, it could mate successfully with modern humans to produce fertile offspring.¹²² In other words, were it not for our separation by time, we might be considered biologically as interbreeding members of the same species.¹²³

Both footnotes reference Johanson and Edey 1981 Lucy: The Beginnings of Humankind page 144. Does Johanson really say this? Well, kind of:

Isolation in a single population is also achieved through time. Here the separation is not so much horizontal as vertical. We are concerned with descending lineages, and the changes that take place over many generations within groups, not between them. Homo erectus did not produce several types that now, a million years later, confront each other as biological strangers. Humans the world over can and do interbreed today. What Homo erectus did was sire descendants who might not recognize him as a sexual partner. It would be interesting to know if a modern man and a million-year-old Homo erectus woman could together produce a fertile child. The strong hunch is that they could; such evolution as has taken place is probably not of the kind that would prevent a successful mating. But that does not flaw the validity of the species definition given above, because the two cannot mate. They are reproductively isolated by time. Therefore, somewhere along the evolutionary path that leads from one to the other a species line may be drawn if, in the opinion of anatomists, the differences between them are significant.

So, yes, he kind of did but it doesn’t mean, when placed in context, what Luskin wants it to mean. Luskin, and I will have more to say on this later, wants to argue that there is a large gap between the australopithicines and Homo. He also seems to want to argue that there is not that much difference within australopithecines and within Homo – the former are all apes and the later are all humans – except Homo habilis which is an ape too. In light of that I can’t resist continuing with next paragraph from Johanson:

Since the word “significant” means different things to different people, there will always be disagreement about where – or whether – to draw species lines in extinct lineages. Loring Brace concedes measurable differences between africanus and habilis, but he does not regard them as important enough to justify pasting another label on the later. He would prefer waiting until evidence of evolution has progressed a little further, until still a larger brain, greater differences in skull proportion, a shorter face and a more humanlike set of teeth show up – as they do in Homo erectus. Brace has no trouble drawing a species line there; the earlier types are all australopithecines; the later ones are all humans. Most others disagree. They would insert ,em>habilis. On the evidence of 1470, that appears to be an appropriate insertion.

More to come later.