Climatic change put an end to bison existence

An international research team claims that it was major climate change, not hunting that led to major bison extinction.

Moving in huge herds, more than 20 million bison roamed the American West before white men arrived. For centuries, the Indians hunted them with bows, arrows and spears for food, clothing and shelter, reports San Francisco Chronicle.

According to Bloomberg, about 37,000 years ago, the genetic diversity of &to=http://english.pravda.ru/world/2000/10/12/198.html' target=_blank>bison living in what's now Alaska, Canada and Siberia decreased significantly, according to a review of DNA from bison fossils. Archaeological evidence shoes humans didn't inhabit those regions until more than 15,000 years later.

Oxford University researchers, who wrote the study, said the decline in bison genetic lines correlates with a deep freeze that probably decimated the &to=http://english.pravda.ru/fun/2002/10/16/38267.html' target=_blank>animals. They say their study shows that the two subspecies of bison living in North America today are descendents of a single population that traveled south before the freeze set in.

Scientists previously theorized that modern bison descended from animals that migrated throughout North America after the freeze. A loss of habitat and extensive hunting by humans were blamed for the dwindling population, not cold weather.

Cold "and arid conditions increasingly dominated, and some component of these ecological changes may have been sufficient to stress bison populations across Beringia," the study's authors wrote in Friday's issue of the journal Science.

Brown bears and a type of horse went extinct in Alaska at about the same time.