A Copper Jaw

Copper (Cu), in an amount that is normally toxic to organisms, is present in the jaws of bloodworms as a biomineral [Science (2002) 298, 389–392]. Helga C. Lichtenegger and coworkers from the University of California, Santa Barbara, the Austrian Academy of Sciences, and University of Leoben, Austria, have imaged the structural organization of the biomineral and show that the bloodworm’s jaws have a remarkable abrasion resistance. Understanding this structure-property relationship could lead to the design of new biomimetic materials. "The marriage of protein with Cu mineral… may also serve as a design prototype for new materials that need to be hard, lightweight, and durable," say the authors.

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Bull Mastodons in Deadly Combat; Sound and Fury from Silent Bones

The American mastodon (a relative to the elephants that went extinct 10,000 years ago) had enormous tusks, and skeletal evidence suggests these tusks were used as weapons in mastodon combat. Examination of tusk sockets suggests that unusually large ligaments held the tusks in place, and could have served as effective shock absorbers during dynamic tusk duels, where tusk tips were used in a sweeping motion to gore opponents.

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The Primate Bite: Brawn Versus Brain?

A change in a single muscle protein may have been a key step in the evolution of modern humans, according to a new theory. A mutation in a myosin gene (MYH16) 2.4 million years ago made the protein less effective. Because of this change, primates' massive jaw muscles shrank, proposes Hansell Stedman, a gastrointestinal surgeon at the University of Pennsylvania, making possible a threefold expansion of the brain.
"The big surprise is that this deletion was common in all the human DNA that we tested," says Stedman. In contrast, the researchers found that in macaques, chimpanzees, gorillas, and five other nonhuman primates, the gene reliably runs its course to make the complete protein.
By using genetic comparisons among species, the team calculated that the mutation appeared about 2.4 million years ago, just before human evolution took off. The protein proved to be a key component only in some jaw muscles. And in humans, it builds just a "sliver" of a jaw muscle compared to the same muscle in nonhuman primates, says Stedman. "We're not suggesting that this mutation alone [buys] you Homo sapiens," he says, "but it could make possible brain growth."

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Shark Flexes Its Teeth for Tough Meals

Sharks typically use their rows of sharp teeth for gripping and slicing prey, but at least one variety has the ability to temporarily flatten its spiky rows of teeth. By doing so, the sharks may be able to create a flat surface for cracking crab shells to get inside. Sharks seem to accomplish this feat through a trick of anatomy: with rows of teeth are imbedded in a broad and unusually flexible ligament, and when pressed on a hard surface, the rows of teeth have been shown to bend backward, overlapping with neighboring rows and providing a flat surface suitable for applying great pressure without cracking the teeth.

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Hookworm Mouth

This photograph shows the front section of the hookworm, and the mouth parts which it uses to feed. The cutting plates, used to attach to the lining of the intestine where they suck blood for nourishment, are visible. Three species of hookworm cause infection in the United States, including this species, Necator americanus. (Image courtesy of the Centers for Disease Control and Prevention.)