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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...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
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...
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Who Killed the Elephants?
11 April 2005 (All day)
Hungry prehistoric hunters, not climate change, drove elephants and wooly mammoths to extinction during the Pleistocene era, new research suggests.
At least 12 kinds of elephants and mammoths used to roam the African, Eurasian, and American continents. Today, only two species of elephants are left in South Asia and sub-Saharan Africa. One theory for this dramatic demise holds that rapid climate shifts at the end of the most recent major ice age, some 10,000 years ago, altered vegetation and broke up habitats, causing the death of those unable to adapt to the new conditions. Another hypothesis blames prehistoric humans, whose improved weapons and hunting techniques allowed them to wipe out whole herds of elephants and mammoths (Science, 8 June 2001, p. 1888).
To help resolve the debate, archaeologist Todd Surovell of the University of Wyoming, Laramie, and colleagues tested two assumptions. If humans caused the elephant and mammoth extinctions, Surovell reasoned, the timing of the die-offs in specific regions should match human expansion into those regions. On the contrary, if the extinction of these mammals were due to climate change, elephants and mammoths should remain in regions already colonized by humans and would only begin to die off once climate change occurred.
The team tested both theories by analyzing where and when elephants and mammoths were killed. In all, the study included 41 archaeological sites on five continents. The researchers found that, as humans migrated out of Africa, they left a trail of dead elephants and mammoths in their wake. The creatures disappear from the fossil record of a region once it became colonized by humans. Modern elephants survived in refuges uninviting to humans, such as tropical forests, says Surovell, whose team reports its findings online this week in the Proceedings of the National Academy of Sciences.
Biologist R. Dale Guthrie of the University of Alaska in Fairbanks largely agrees with the findings, but he says more work is needed to explain why some mammoths seem to have survived in regions colonized by humans and why many modern elephants live in areas easily accessible to humans, such as the African savannah.
More on Guthrie's research