Friday, 1 November 2013

Chapter 9: Australopithecus

The customer reviews of The Greatest Hoax on Earth on Amazon are an occasionally useful place to obtain information on the issues raised in the book:
Interestingly (and bizarrely), Sarfati himself appears to comment on some of the reviews:
Copied below is a good example of a useful comment by Christine Janis, Professor of Biology at Brown University.  Her comment addresses Sarfati's discussion of Australopithecus afarensis on pages 156-158 of The Greatest Hoax on Earth.
First a little preamble. As many reviewers have noted here, the Sarfati book might look convincing on areas in which they have no specialized knowledge, but on areas in which they do have knowledge the distortion and manipulation of the data is enough to make you want to pull your hair out. Sarfati is the master of the "opposition soundbite": rather than actually present the evidence from evolutionary (or, at least non-creationist) scientists that support the claims, he presents the issue as a given (perhaps he expects all to be reading along with a copy of Dawkins book); then he cherry picks some data from the science literature that appears to combat the claim in one way or another (usually he has set up a strawman marginally relevant to the issue to be attacked), and ends up appearing to the naïve reader as if he (Sarfati) is the one with the specialized scientific knowledge while Dawkins comes off as speaking nonsense. Nobody can deny that Sarfati is a clever man.

Let's turn to the issue of Lucy, the iconographic specimen of Australopithecus afarensis. Sarfati provides absolutely no evidence to show why scientists might consider her to have been bipedal - nothing about the truly intermediate condition (between human and a chimp-like ape) of her pelvis, femur, foot, etc., so we're left thinking that this is just some vague proposition that scientists had about her skeleton. But what he does do is set up a strawman: that is, if Lucy can be shown to be not completely bipedal like a modern human, then there is no evidence for her being any kind of "intermediate" form.

Think about this for a minute: if Lucy has intermediate morphology for bipedality, then would anyone expect her to walk in the precise manner of modern humans? No: nobody does, or ever has. Not to mention that it's always been known that australopiths had longer fingers and toes than humans, indicative of retaining more climbing ability.

First Sarfati cites Oxnard "earlier multivariate analyses" to show that australopiths weren't human-like bipeds. The footnote here is #28, which just provides Oxnard's identity, not a citation for this paper. Could this be because the original paper is from 1975, before Lucy was described in the scientific literature? His original study was on some fragmentary bones of robust australopithecines, and even in later works (as cited by Sarfati) he doesn't claim that they weren't bipedal, just that they weren't 100% human-like, a conclusion with which all scientists would concur. (See talk origins for a more complete coverage of how Oxnard is miscited by creationists

However, more importantly, Oxnard never concluded from any of his work that australopithecines were unrelated to humans, as Sarfati claims insinuates. For example, page 158, third paragraph: "As we saw above, Charles Oxnard is one of several experts who do not believe that any of the australopithecines were on the human line". This is again playing on the ignorance of the public who still think that scientists search for "missing links", the direct ancestors. Oxnard certainly does think that australopithecines were more closely related to humans than to chimps, even if Lucy and the robust forms are on a bit of a side branch not leading directly to Homo (now the current view). This (i.e. Sarfati's claim) is like saying that your cousin isn't your relative.

Sarfati then goes on to cite the work of Fred Spoor on the semi-circular canals in australopiths inner ears, assuring us that Spoor, as the editor for "Journal of Human Evolution", must know his stuff. What Spoor et al. did was to show that the australopith semi-circular canals are more ape-like than human-like, confirming what everyone had been saying all along, that the australopiths were likely less committed bipeds than humans, and retained some arboreal habits. This was not evidence for them being quadrupedal, as Sarfati implies.

So, rather than this article by Spoor being some fatal blow to the evolutionary story, it backs up the details of the story as determined by the bones. Talk origins also covers this issue: (By the way, as a practicing scientist I can attest that Talk Origins is usually excellent: I rarely find even minor mistakes in their postings on areas in which I have expert knowledge, and I'm very picky).

Then Sarfati brings in the work of Eric Stokstad to show that Lucy had "wrist-locking abilities 'classical for knuckle walkers', which is hardly consistent with Dawkins' claim that Lucy walked upright like we do." It is true that the popular press made a deal of this meaning that early humans did knuckle-walking, but this is not what the paper claims.

The paper is actually about the issue of whether or not knuckle-walking is primitive for the grouping of gorilla, chimp and human, or whether it evolved independently in gorilla and chimp (which would be implied by the current evidence, as humans don't knuckle-walk but molecular evidence shows that chimps are more closely related to humans than gorillas are). So, with this relationship, either knuckle-walking evolved twice (which seems rather unlikely), or it evolved once in the common ancestor, and was then lost in the hominid lineage, for which we had no evidence UNTIL THIS PAPER.

Basically the earliest australopithecines show the remnants of the bony signature for knuckle-walking in their wrists, lost later in both Homo and more derived australopithecines. Again, nothing in this paper was saying anything about australopithecines not being upright walkers, just about knuckle-walking being a basal feature of the gorilla/chimp/human lineage (and Stokstad's argument is far from universally accepted in primate evolutionary studies).

In conclusion, Sarfati is citing "expert scientists" to support his strawman claim that, if Lucy wasn't human-like in her bipedality, then she can't be a transitional form. As I have shown, none of these sources actually support the notion that australopiths were not bipedal – if you read what the papers actually say, not what you might mistakenly infer from the titles of the papers. If I had a spare lifetime I could do this analysis with many other issues raised by Sarfati in this book (in fact, every single issue on which I have the knowledge, relating to vertebrate evolution).

No comments:

Post a Comment