Climate killed off mammoths, not humans: scientist

LONDON (Reuters) – Climate shifts were probably responsible
for the extinction of the mammoth and other species more than
10,000 years ago, not over-hunting by humans, according to new
research published on Wednesday.

Radiocarbon dating of 600 bones of bison, moose and humans
that survived the mass extinction and remains of the mammoth
and wild horse which did not, suggests humans were not
responsible.

“That is what this new data points out,” said Dr Dale
Guthrie of the University of Alaska in Fairbanks.

“It is not that people weren’t hunting these creatures. But
climate would have reduced the numbers considerably,” he added
in an interview.

Various theories have been put forward to explain the
disappearance of the mammoth and the wild horse, Equus ferus,
which coincided with the arrival of humans from central Asia in
North America more than 12,000 years ago.

One hypothesis suggested a virulent disease was responsible
for the extinctions. Another theory was that by killing grazing
animals, humans triggered changes in vegetation that resulted
in the mass deaths.

The Blitzkrieg, or overkill theory, said human hunters
devastated most large mammal species and drove some to
extinction.

“But contrary to that theory, my dates show numbers of
bison and wapiti (elk) were expanding both before and during
human colonization,” Guthrie explained.

His radiocarbon research, reported in the journal Nature,
shows there was a 1,000-year different between the demise of
the wild horse and the woolly mammoth which Guthrie said is
inconsistent with other theories.

Instead, he suggests climate shifts transformed the dry,
arid and cold region. The wetter, warmer summers led to changes
in vegetation to which mammoths and wild horses could not
adapt.

“The new patterns of dates indicate a radical ecological
sorting during a uniquely forage-rich transitional period,
affecting all large mammals, including humans,” Guthrie added.