The Little Rock Zoo

.The Little Rock Zoo needs to step up and care for the animals better! Please read the several artciles here with deaths, sickness and a bald chimp!

Monday, August 17, 2009

Chimpanzees, Creation VS Evolution

Creationist Arguments: Australopithecines
In 1950, Wilfred Le Gros Clark published a paper which definitively settled the question of whether the australopithecines were apes or not. He performed a morphological study (based on the shape and function) of teeth and jaws, since these formed most of the fossil evidence. By studying human and modern ape fossils, Le Gros Clark came up with a list of eleven consistent differences between humans and apes. Looking at A. africanus and robustus (the only australopithecine species then known), he found that they were humanlike rather than apelike in every characteristic. Judged by the same criteria, A. afarensis falls somewhere between humans and apes, and possibly closer to the apes (Johanson and Edey 1981). White et al. (1994) did not judge A. ramidus by these criteria, but it is clear that ramidus is even more chimpanzee-like than afarensis. The ramidus arm bones also display a mixture of hominid and ape characteristics.
Solly Zuckerman attempted to prove with biometrical studies (based on measurements) that the australopithecines were apes. Zuckerman lost this debate in the 1950’s, and his position was abandoned by everyone else (Johanson and Edey 1981). Creationists like to quote his opinions as if they were still a scientifically acceptable viewpoint.

Charles Oxnard (1975), in a paper that is widely cited by creationists, claimed, based on his multivariate analyses, that australopithecines are no more closely related, or more similar, to humans than modern apes are. Howell et al.(1978) criticized this conclusion on a number of grounds. Oxnard’s results were based on measurements of a few skeletal bones which were usually fragmentary and often poorly preserved. The measurements did not describe the complex shape of some bones, and did not distinguish between aspects which are important for understanding locomotion from those which were not. Finally, there is "an overwhelming body of evidence", based on the work of nearly 30 scientists, which contradicts Oxnard’s work. These studies used a variety of techniques, including those used by Oxnard, and were based on many different body parts and joint complexes. They overwhelmingly indicate that australopithecines resemble humans more closely than the living apes.

Creationists often cite Oxnard’s qualifications, and use of computers to perform his calculations, with approval. This is special pleading; many other scientists are equally qualified, and also use computers. Gish (1993) states that "[a] computer doesn’t lie, [a] computer doesn’t have a bias". True enough, but the results that come out of a computer are only as good as the data and assumptions that go in. In this case, the primary assumption would seem to be that Oxnard’s methods are the best method of determining relationships. This seems doubtful, given some of the other unusual results of Oxnard’s study (1987). For example, he places Ramapithecus as the ape closest to humans, and Sivapithecus as closely related to orang-utans, even though the two are so similar that they are now considered to be the same species of Sivapithecus.

Less controversially, Oxnard also claims that, while probably bipedal, australopithecines did not walk identically to modern humans. Creationists sometimes quote this conclusion in a highly misleading manner, saying Oxnard proved that australopithecines did not walk upright, and then adding, as an afterthought (or in Willis’ (1987) case, not at all) "at least, not in the human manner".

Creationists are generally reluctant to accept that australopithecines, including Lucy, were bipedal. A statement by Weaver (1985) that "Australopithecus afarensis … demonstrates virtually complete adaptation to upright walking" is dismissed by Willis (1987) as "a preposterous claim". Willis adds: "Many competent anthropologists have carefully examined these and other "Australopithicine" [sic] remains and concluded that Lucy could not walk upright."

Willis’ evidence for this consists of a statement by Solly Zuckerman made in 1970; a 1971 statement from Richard Leakey that australopithecines "may have been knuckle-walkers", and a quote from Charles Oxnard about the relationship between humans, australopithecines and the apes. In fact, none of these quotes refer to Lucy. Two of them were made before Lucy, and A. afarensis, was even discovered (and the third was made very soon afterwards, before Lucy had been studied).

Even in 1970, Zuckerman’s views had long since been largely abandoned. In what is obviously a fabrication, Willis says that Leakey "referred to Lucy as an ape who did not walk upright", three years before Lucy was discovered. Leakey was merely making a suggestion (about robust australopithecines) which he soon retracted, not stating a firm opinion, and he has since stated (1994) that Lucy "undoubtedly was a biped". Oxnard (1975; 1987) has some unorthodox opinions about the australopithecines, but the Oxnard quote supplied by Willis discusses neither bipedality nor A. afarensis. Elsewhere in the same paper that Willis refers to, Oxnard (1975) repeatedly mentions that australopithecines may have been bipedal, and he has since stated (1987) that the australopithecines, including Lucy, were bipedal.

Gish (1985) has a long discussion of the debate about Lucy’s locomotion. He quotes extensively from Stern and Susman (1983), who list many apelike features of A. afarensis and argue that it spent a significant amount of time in the trees. As Gish admits, none of the scientists he mentions deny that Lucy was bipedal, but he goes on to suggest, with no evidence or support, that A. afarensis may have been no more bipedal than living apes, which are well adapted to quadrupedality and only walk on two legs for short distances. By contrast, the feet, knees, legs and pelvises of australopithecines are strongly adapted to bipedality. Gish’s conclusion is strongly rejected by Stern and Susman, and, apparently, everyone else:

"That bipedality was a more fundamental part of australopithecine behavior than in any other living or extinct nonhuman primate is not in serious dispute."
"… we must emphasize that in no way do we dispute the claim that terrestrial bipedality was a far more significant component of the behavior of A. afarensis than in any living nonhuman primate." (Stern, Jr. and Susman 1983)

"The most significant features for bipedalism include shortened iliac blades, lumbar curve, knees approaching midline, distal articular surface of tiba nearly perpendicular to the shaft, robust metatarsal I with expanded head, convergent hallux (big toe), and proximal foot phalanges with dorsally oriented proximal articular surfaces. (McHenry 1994)

Gish writes as if showing that A. afarensis did not "walk upright in the human manner" is all that is needed to disqualify it as a human ancestor. But there is no reason that bipedality, when it first arose, had to be identical to human bipedality; that final step could have occurred later. As Stern and Susman (1983) state:

"In our opinion A. afarensis is very close to what can be called a "missing link". It possesses a combination of traits entirely appropriate for an animal that had traveled well down the road toward full-time bipedality …"
Creationist John Morris writes:

"From the neck down, certain clues suggested to Johanson that Lucy walked a little more erect than today’s chimps. This conclusion, based on his interpretation of the partial hip bone and a knee bone, has been hotly contested by many paleoanthropologists." (Morris 1994)
Almost everything in this quote is a distortion (Johanson’s and Lucy’s names are about the only exceptions). "Certain clues suggested" doesn’t mention that the whole find screamed "bipedality" to every qualified scientist who looked at it. "a little more erect", when everyone believes that Lucy was fully erect. "the partial hip bone and a knee bone", when Lucy included almost a complete pelvis and leg (taking mirror imaging into account, and excluding the foot). "has been hotly contested", when no reputable paleoanthropologist denies that Lucy was bipedal. The debates are about whether she was also arboreal, and about how similar the biomechanics of her locomotion was to that of humans. Given that we have most of Lucy’s leg and pelvis, one has to wonder what sort of fossil evidence it would take to convince creationists of australopithecine bipedality.
To support the idea that australopithecines are just apes, Parker says:

"In their critique of the Leakeys, Johanson and White (1980) noted: ‘Modern chimpanzees, by this definition [Richard Leakey's] would be classified as A. africanus.’ Apes after all?" (Morris and Parker 1982)
When the paper by Johanson and White is examined, it is apparent that Parker has taken their quote out of context in a way that almost reverses its meaning. Leakey did not call A. africanus a chimp, nor did Johanson and White accuse him of doing so. They criticized Leakey’s definition because it was imprecise enough to also include chimps. Of course, such a criticism only makes sense if A. africanus is not a chimp.
In 1987, creationist Tom Willis accused Donald Johanson of fraud, claiming that the skeleton known as "Lucy" consisted of bones that had been found at two sites about 2.5 km (1.5 miles) apart. Willis had actually confused two separate finds which belong to the same species. (This was in spite of the fact that a best-selling book (Johanson and Edey 1981) has photos of both fossils: AL 129-1 is a right knee, while Lucy has a right femur and a left tibia.) This was a spectacular error which could hardly have been made by anyone who had done the most elementary research, but that didn’t stop many other creationists from picking up the claim and repeating it. For a full history of this claim, read the knee-joint FAQ file (Lippard 1997).

Creationists rarely address the issue of why australopithecines have a foramen magnum at the bottom of the skull. Gish (1985) criticizes Dart’s reasoning that the Taung baby walked upright, based on the position of its foramen magnum. Gish correctly states that the position of the foramen magnum is closer in juvenile apes and humans than it is in adults (in apes, it moves backwards during growth), and concludes that Dart was unjustified in analyzing this feature on a juvenile skull. This is the same criticism that Dart originally faced from scientists, but Gish fails to mention that later evidence proved Dart’s analysis correct and silenced his critics.

Creationists also rarely mention australopithecine teeth. Gish says that "[Dart] pointed out the many ape-like features of the skull, but believed that some features of the skull, and particularly of the teeth, were man-like". (Note the misleading implication that the apelike features really exist, while the humanlike ones are a figment of Dart’s imagination.) Gish disputes this, pointing out that the molar teeth of africanus are extremely large. What Gish does not tell readers is that this is one of the few differences between them and human teeth. When the teeth of the Taung child could be properly examined, Dart’s claim was strongly confirmed, and is now generally accepted:

"In fact, though the molars were larger than is now normal, most of the teeth [of the Taung child] could have belonged to a child of today." (Campbell 1988)

You continue to make excellent points. Bravo.

Yes, I have heard of Australopithecines. And most Creationists don’t do their share of research.


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