Wednesday, October 14, 2009

Carl Weiland of CMI on Ardipithecus

Creation Ministries International's Carl Wieland, a long time member of the old guard of creationists, has an article on the site about Ardipithecus. He writes this:
Our writings in this ministry have already pointed out for years, referring to the detailed work of evolutionist anatomists such as Charles Oxnard, that there is a broad group of fossil creatures, now extinct, that is more dissimilar to both modern apes and modern humans than these are to each other. Oxnard’s conclusion was that australopithecines (the main constituents of this group) were not in the human line. We agree with him, not surprisingly. Ardipithecus appears to belong to this group as well; in fact, when the highly fragmented specimen was first discovered in the mid 1990s, it was originally put into that same genus, and called Australopithecus ramidus. Tim White, director of the Human Evolution Research Center at the University of California, Berkeley, says that Ardipithecus is not the common ancestor of apes and humans. But, he says, “it’s the closest we have ever been able to come”.
What is not being said here is that Mr. Wieland is still quoting the out-of-date Charles Oxnard paper about australopithecines, which was written before A. afarensis was described. Oxnard said, at the time (1975!) that although australopithecines were likely bipedal, they resembled apes more than humans. This paper was roundly criticized by many in the palaeoanthropological world because it relied on a very small set of measurements. Mr. Wieland is putting forth this evidence as if the last thirty-four years of palaeoanthropological research do not exist.

Tim White is perfectly correct about this. Ardipithecus shows us a creature that is closer to the split between humans and apes but, based on its morphology, is likely not at the split. Wieland continues to show his misunderstanding of evolution by continuing to rely on the outmoded unilineal, top-to-bottom ancestor tree idea that was abandoned by evolutionary biologists decades ago. He writes:

Did Ardi possess features which indicate a more upright stance than modern apes? Quite possibly, even likely. But then, so did the australopithecines/habilines. And both groups also possessed features making them suited for life in the trees as well. And CT scans of australopithecine skulls show that the organs of balance (the ‘semi-circular canals”) were positioned in ways quite different from that required for a creature that walks habitually upright.

In short, the significance of Ardi can be interpreted within either an evolutionary or creationist framework, and the latest analyses of these recycled bones and claims would appear to add no weight at all to the claims of either side. As cited elsewhere, a 1995 Nature article stated that it was “possible that Australopithecus [now Ardipithecus] ramidus is neither an ancestor of humanity, nor of chimpanzees … ”.1 And indications are that nothing has really changed since then.

First off, let's be clear: Homo habilis had absolutely no specializations for living in the trees. In fact, by the time you get to Australopithecus africanus and A. robustus, those specializations are long gone. So, Wieland is completely wrong about this. He does, however, quote Henry Gee correctly. It is entirely possible that Ardipithecus ramidus was not a direct ancestor to the hominid forms that came later. This does not mean she is not transitional, nor does it mean she is unrelated to the hominids that came later. Once again, this goes to the heart of the difference between direct ancestry and collateral ancestry. One only needs to look at the diversity of australopithecines to see evidence of that. It is clear, based on the fossil record, that A. boisei became extinct somewhere around 1.2-1.5 gigayears ago. That doesn't mean that one of the other branches of australopithecines did not give rise to later hominids. It is clear that the hominids of Ardipithecus ramidus' time (be they only one species or many) were on a track to bipedality.

Ardipithecus shows us a window into an anthropological past before that of Lucy, where bipedalism has taken hold in at least one hominid species but was not fully developed. At one point, Wieland notes that this find is nothing new because the bones were discovered in 1994. What he does not say is that it took over ten years to painstakingly remove the bones from the surrounding matrix and reconstruct them. This is common for palaeoanthropological discoveries. What Wieland is calling ho-hum, is, in fact, a very exciting discovery.

1Gee, H., Uprooting the human family tree, Nature 373(6509):15, 5 January 1995
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1 comment:

  1. Ayn Rand challenges a creationist who thinks Ardipithecus disproves evolution.