Ancient 'Nutcracker Man' challenges ideas on evolution of ...(ll-O Ungar said. This finding while...)

This finding, while contradictory to previous speculation on the diet of P. boisei, is in line with a paradox documented in fish. Liem's Paradox states that animals may actively avoid eating the very foods they have developed adaptations for when they can find other food sources.

It appears the paradox may hold true for P. boisei and for some modern-day primates as well.

"If you give a gorilla a choice of eating fruit or a leaf, it will take the fruit every time," Ungar says. "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."

Accordingly, the finding represents a fundamental shift in the way researchers look at the diets of early human ancestors.

"For many years, the perspective has been that the very large teeth and thick dental enamel of P. boisei were adaptations to consuming very hard food types year-round," says Lambert. "Such specialization has historically been viewed as a potential cause for this fossil species' extinction. The research team demonstrated that such generalizations require careful re-thinking, and that P. boisei was a more flexible feeder than has classically been viewed."

"This challenges the fundamental assumptions of why such specializations occur in nature," Ungar says. "It shows that animals can develop an extreme degree of specialization without the specialized object becoming a preferred resource."

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