Friday, September 29, 2006

More on Casey Luskin and the Dikika Hominid

Afarensis has already dealt a blow to Casey Luskin’s disingenuous discussion of the new australopithecine fossil from Dikika in Ethiopia. I don’t wish to re-invent the wheel here, but in reading both discussions, several additional issues crossed my mind and made their way to my pen (well, computer key-board). Luskin, being the good ID advocate he is, needs a “big bang” of hominid (human family, including australopithecines) evolution to rival the Cambrian “explosion” that he, Wells, Dembski and others cite ad nauseum (which means, of course, they also need a paleontological discovery rich in quotations that can be expertly and selectively mined to present a much different argument than any the original authorities intended). Luskin would lead the uninitiated to believe he has found just such a hominid big bang:

These rapid, unique, and genetically significant changes are termed "a genetic revolution" where "no australopithecine species is obviously transitional." One commentator proposed this evidence implies a "big bang theory" of human evolution. Now that “Homo” habilis is best recognized as an australopithecine due to its ape-like skeletal structure (see "The Human Genus," Science, 284:65-71), it is no wonder an article in Nature last year recognized the lack of an clear-cut immediate ancestor for our genus Homo...

Of course, Luskin implies that the reporting of the Dikika australopithecine by the news media is purposely covering up the bigger story: australopithecines are just apes and the Homo lineage seemingly sprang from no where, a la Intelligent Design. (I have to give Luskin credit here: his manipulation is so precise that he gets a shot in for Intelligent Design as an alternative explanation, suggests that paleoanthropologists agree with this, twists gaps of knowledge into support for ID, synthesizes thousands of legitimate research into the written equivalent of a 30 second sound bite, AND slams the “liberal” news media for covering it up, all in a few sentences!).

Anyone familiar with the paleontological record (as it currently stands) of any species knows that the only way to get a clean, sudden appearance of any group of organisms is to ignore the volumes of data that don't fit. In citing the Hawks, et al. 2000 paper in the Journal of Molecular Biology and Evolution, Luskin is clearly suggesting that the authors themselves have established the “sudden appearance” of Homo as something quite distinct from australopithecines and again, implies that we have a clear case for Intelligent Design moving the inept humans along a specified path to greatness. First, setting aside for the moment the sneaking suspicion I have that there’s far more to the Hawks et al. paper than Luskin is willing to lay out (or readers of Evolution News and Views are willing to pursue – and Afarensis has delved into some of this already), there are a number of issues glossed over by the Discovery Institute minions.

First, Hawks et al. were discussing Homo ergaster and Homo erectus in the passage he cites. Luskin dismisses the habilines (Homo habilis, Homo rudolfensis) as nothing more than australopithecines with a single reference, making the gulf between australopithecines and Homo much wider. Pretty convenient. However, while there have been discussions about whether Homo habilis should actually be Australopithecus habilis, my understanding is that this taxonomic change has not garnered wide support. In fact, new dating of the East African early Homo shows that there are now no early small brained habilines (likely candidates for inclusion with the Australopithecus genus) and that rather, that in the habilines we actually now have potential great ancestors to the larger bodied Homo:

Now the situation has changed. The small Turkana habiline, KNM-ER 1813, is now contemporary with the Olduvai sample. There are no longer any small-skulled early Turkana habilines. KNM-ER 1805 makes sense as a male of the later, small-skulled sample because it is relatively small-brained but robustly built (e.g., with a sagittal crest). That leaves KNM-ER 1470, KNM-ER 1590, KNM-ER 3732, and KNM-ER 3735 as plausible habilines before 1.85 Ma.

This seems like a nice sample as a possible ancestor for both later large-bodied Homo and later habilines. Heck, Wood (1991) even wrote this in his description of KNM-ER 3735:

Some features (e.g. vault thickness) ally it with a Homo erectus-like hominid, but in other areas (e.g. the frontal) it is more like crania such as KNM-ER 1813, a conclusion endorsed by Walker (1987) and by Leakey et al. (1989). Tobias (1989) includes KNM-ER 3735 within H. habilis (Wood 1991:134-135).

What more could you ask of a common ancestor?

The only people who seem to think we can readily dismiss early Homo as nothing more than australopithecines are creationists (and I thought Intelligent Design wasn't creationism...silly me!).

Second, even discounting the early Homo fossils, the ID folks still have a problem with a hominid “big bang”. Human history is still best described as mosaic when you look at the data. Bipedalism started in australopithecines, not Homo (how would the ID folks explain bipedalism in Australopithecus versus early Homo – derived separately in both lineages by a designer?; do they not share an evolutionary relationship?); larger brain sizes begin in early Homo, but do not “explode” but rather show slow increases (even if we discount the habilines and start with ergaster as the ID crowd would prefer we do – so the Designer can’t jump up a couple of hundred cc’s right from the start, but has to develop it slowly?). Technology sure doesn’t explode on to the scene (this is another reason why early Homo just can’t be discounted comfortably – there’s no one else around likely to have created the Oldowan). And what of the Acheulean? Seems to be in use for more than a million years, followed by clearly gradual changes in technology…again, why not in one instance? What is the ID hypothesis that accounts for technological innovation beginning with the Oldowan? Nothing about modern humans appears to have come about in quick, consistent, well-designed fashion. Development of specified physical features as well as technology seems to derive far more from contingency than purposeful design.

Finally, the nature of human paleontology is so complex and changes so rapidly that it is hardly surprising Luskin and the Discovery Institute can hide the nuances of the discipline, skip the real questions and data, and portray a quick and easy final solution to those minds ready to swallow it and not venture forward with the hard work of science. I am reminded of another classic takedown by Keith Olbermann where he gets to the heart of what is deceptive about people (in this case he was discussing Ann Coulter) who depend on ignorance to get their point across regarding regarding science:

Yes, it's long, complex, boring [referencing a brief paragraph on the evidence for evolution]. You got to speed it up, that's the point, that's why some people still believe in creationism, because it's hard to grasp the complexities of evolution -- like why we humans have Adam's apples.

And the complexity is why fake authors with fake ideas can still peddle their crap by crafting their talking points so that honest rebuttals are by necessity, long, complex, and boring, which is why it's important that somebody check out the footnotes.

Don't suppose this refers to the Discovery Institute too?


afarensis said...

Yes, in addition to Wood and Collards' paper, cited by Luskin, the only others I know who have suggested sinking Homo habilis into the australopithecines are Wolpoff (in the second ed. of Paleoanthropology) and the Hawks et al paper. Conroy mentioned it in passing in Reconstructing Human Origins, but seems to be against it. The upshot is, very few people call it Australopithecus habilis - even Wood in later articles refers to Homo habilis.
Hawks et al was clearly written from a puntuated equilibria standpoint and as such is part and parcel of modern evolutionary theory. Even if they are correct it doesn't really undermine the fact that there are still traits (related to developing bipedality) that link australopithicines with modern humans. Australopithicines having traits that are also found in modern humans does not mean they are part of the genus Homo - a distinction Luskin fails to understand. For Luskin if it is not part of the genus Homo then it is an ape and can't share traits with anything in Homo.

Christopher O'Brien said...

Thanks for clarifying that Tim! Great points as usual! I knew there was some discussion about placing habilis in the Australopithecus genus, but it never seemed to have gone anywhere and in any event was taken more seriously by creationists than the paleoanthropologists (Wolpoff and Wood have always seemed to operate a bit out of the conventional box anyway)...

Health News said...

This is a wonderful site. The things mentioned are unanimous and needs to be appreciated by everyone.