For years the team has been recreating the environment around that time in a 62-square-mile paddock in Siberia they call "Pleistocene Park." They've introduced a variety of animals that used to live alongside mammoths, including reindeer, musk oxen, and moose. They found the large mammals carve out a grassy landscape from what would otherwise be tundra. Their trampling hooves kill mosses and scrub brush, but allow room for hearty, nutritious grasses to grow. The researchers believe that as long as mammoths and other creatures existed in abundance, they were able to maintain grasslands, even in the face of climate change. Something other than temperature must have gone haywire. Enter humans. Though armed only with spears, and in too few numbers to kill off mammoths entirely, they could have reduced the population enough to allow tundra plants to creep back into the ecosystem. "First the animals died, then the pastures vanished," Nikita Zimov said. There is evidence, too, of an asteroid or comet several miles wide impacting Earth 12,900 years ago, a fact the Russian team acknowledges. They argue that the changing climate, human hunting, and the asteroid all contributed to the mammoths' extinction. "This whole business of man causing the demise of these animals is way overstated," Richard Firestone of Lawrence Berkeley National Laboratory in California said. "Man co-existed with these animals for 100,000 years before the Younger Dryas." Related Links: Get More NewsMouse Cloned From Long-Frozen CellResearchers create a mouse from a long-frozen cell. Will the mammoth be next?'Bubble' Could Protect AstronautsScientists say a "bubble" around a Mars-bound spaceship could protect astronauts.Big Reduction of Snowmobiles in Yellowstone ProposedA new plan would cut snowmobile use by 40 percent in Yellowstone.Microbes: Fuel of the Future?A reddish South American microbe is literally breathing fuel, say scientists.DNA Links Remains to Steve FossetDNA tests on two bones found in California confirm they are those of Steve Fossett.Women Carry More Bacteria Than MenSome bacteria prefer women, suggests a new study. But why?Ancient 'Water Monster' Facing ExtinctionA foot-long salamander that was a key part of Aztec legend is threatened by extinction.Grand Canyon's Youth ConfirmedThe Grand Canyon is millions of years younger than previously thought, argue geologists.My Take: E-Voting Not User FriendlyOpinion: Electronic voting machines don't always capture the intent of voters.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.At 40, Brain and Body SlowThe part of the brain in charge of motion starts a gradual slide in middle age.Spiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates. |
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