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At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
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Homo Erectus a Bit Like a Chimp?
16 July 2004 (All day)
Homo erectus, the big-brained hominid thought to have made humankind's first exodus out of Africa, is accepted as one of the many intermediate stages between a chimplike ancestor and modern H. sapiens. But a study in chimp tooth growth suggests that growth patterns of H. erectus may have been closer to chimp than human.
Dental development among primates, including humans, correlates tightly with other important traits including life span, age at reproduction, and brain growth. In this respect H. erectus has been assumed to be intermediate between chimps and humans, with the emergence of the first molar (M1) at about 4.5 years of age, according to work on fossils by Christopher Dean of University College London and colleagues.
But most such cross-species comparisons have been made using captive chimps, says anthropologist Adrienne Zihlman of the University of California, Santa Cruz. Now she and colleagues have done a comparison with wild chimps. They found that in 18 wild African chimps, M1 emerges at about 4 years of age--almost a year later than in captive chimps and in the same league as H. erectus. That leaves slow-growing H. sapiens--whose first molars appear around age 6--an exception.
"Because brain size in Homo erectus is intermediate between that of chimps and modern humans, we have assumed that the timing of dental development was intermediate also," says Zihlman, whose study appears in the 20 July Proceedings of the National Academy of Sciences. So "the data came as a surprise to us." Anthropologist Barry Bogin of the University of Michigan, Dearborn, calls the study "very persuasive." Before this, he says, the only aspect of development known about wild chimps was their reproductive activity.
More about molars and other teeth