Literature

This is a case study of Paranthropus boisei, an ape-like animal that is regarded by evolutionists as a member of the human family tree. It is "known popularly as the "Nutcracker Man" because it has the biggest, flattest cheek teeth and the thickest enamel of any known hominin." Inevitably, these teeth have stimulated discussion about the animal's diet.

"Since the first specimen was reported by Mary and Louis Leakey in 1959, scientists have believed that P. boisei fed on nuts and seeds or roots and tubers found on the savannas throughout eastern Africa because the teeth, cranium and mandible appear to be built for chewing and crunching hard objects."

Paranthropus boisei (Source)

The research has involved a microwear texture analysis of the molars of seven specimens of P. boisei. This utilised sophisticated microscopy techniques to map patterns of pits and scratches on the surface of the teeth.

"The researchers looked at complexity and directionality of wear textures in the teeth they examined. Since food interacts with teeth, it leaves behind telltale signs that can be measured. Hard, brittle foods like nuts and seeds tend to lead to more complex tooth profiles, while tough foods like leaves lead to more parallel scratches, which corresponds with directionality.
They compared the dental microwear profiles of P. boisei to the microwear profiles of modern-day primates that eat different types of diets - grey-cheeked mangabeys and brown capuchins, which eat mostly soft items but fall back on hard nuts or palm fronds, and the mantled howling monkey and silvered leaf monkey, which eat mostly leaves and other tough foods."

The results were surprising.

"The P. boisei teeth had light wear, suggesting that none of the individuals ate extremely hard or tough foods in the days leading up to death. It's a pattern more consistent with modern-day fruit-eating animals than with most modern-day primates. "It looks more like they were eating Jell-o," Ungar said."

So, teeth that look as though they are an adaptation to eating hard foods show a microwear texture that suggests they bit into soft fruit. This is a paradox that can be illustrated today by the gorilla - and there are some important implications.

"If you give a gorilla a choice of eating a sugary fruit or a leaf, it will take the fruit every time," Ungar said. "But if you look at a gorilla's skull, its sharp teeth are adapted to consuming tough leaves. They don't eat the leaves unless they have to."
This finding represents a fundamental shift in the way researchers look at the diets of these hominins. "This challenges the fundamental assumptions of why such specializations occur in nature," Ungar said. "It shows that animals can develop an extreme degree of specialization without the specialized object becoming a preferred resource."

These findings provide another nail in the coffin of adaptationism. There is a tendency in the evolutionary literature to provide a "Just-So" story for every trait. Even though Darwinists know this approach lacks rigour, they show total commitment to finding plausible accounts for the origins of every feature they see. However, it is now becoming apparent that some specialisations are vestigial and have lost touch with their roots. This gives even more of a free hand to adaptationist storytelling/speculation.

Furthermore, the implications are even more significant for Darwinists. If the mechanisms of variation and natural selection forged the original adaptation, why are these mechanisms apparently powerless to bring about further transformation with continuing environmental change? Why was P. boisei left with over-engineered dentition when the animal ate the equivalent of Jell-o? Why do gorillas have teeth that are out of character with their diet? The "adaptive landscape" concept invokes morphological continuity for adaptive change, but these findings suggest that adaptation may not always be a reversible or multi-way process. Some trajectories of adaptation may lead an organism into a cul-de-sac from which it cannot retreat. This leads to a model of genetic impoverishment by specialisation and speciation that explains a significant body of data. It is a useful model to explain some aspects of extinction. But it is not a model that Darwinists have embraced, because it does not fit comfortably with their adaptive landscape model, nor with their extrapolation of microevolutionary change to macroevolution.

Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei
Peter S. Ungar, Frederick E. Grine, Mark F. Teaford.
PLoS ONE 3(4) 30 April 2008: e2044 | doi:10.1371/journal.pone.0002044

Abstract: The Plio-Pleistocene hominin Paranthropus boisei had enormous, flat, thickly enameled cheek teeth, a robust cranium and mandible, and inferred massive, powerful chewing muscles. This specialized morphology, which earned P. boisei the nickname "Nutcracker Man", suggests that this hominin could have consumed very mechanically challenging foods. It has been recently argued, however, that specialized hominin morphology may indicate adaptations for the consumption of occasional fallback foods rather than preferred resources. Dental microwear offers a potential means by which to test this hypothesis in that it reflects actual use rather than genetic adaptation. High microwear surface texture complexity and anisotropy in extant primates can be associated with the consumption of exceptionally hard and tough foods respectively. Here we present the first quantitative analysis of dental microwear for P. boisei. Seven specimens examined preserved unobscured antemortem molar microwear. These all show relatively low complexity and anisotropy values. This suggests that none of the individuals consumed especially hard or tough foods in the days before they died. The apparent discrepancy between microwear and functional anatomy is consistent with the idea that P. boisei presents a hominin example of Liem's Paradox, wherein a highly derived morphology need not reflect a specialized diet.

See also:

New Findings Challenge Conventional Ideas On Evolution Of Human Diet, Natural Selection, ScienceDaily (Apr. 30, 2008)