Combination of humans, climate change hampered post-ice age survival: study

Many, but not all, ice-age mammals went extinct due to climate change and human influences. (FILE PHOTO)

BRADLEY BOUZANE
Postmedia News

A new U.S. study that explains the demise of some mammals at the end of the last ice age might not bode well for vulnerable Canadian species that currently face increased risks with a warming climate.

Researchers from Penn State University noted that species such as the polar bear and Peary caribou — found in the High Arctic islands — which are dealing with diminished numbers, may face even more difficult hurdles because of the relatively quick rate at which the Earth’s climate is warming.

“Animals are really good at adapting to change as long as the climate change happens slowly,” said Beth Shapiro, an associate professor of biology at Penn State who led the study.

“One thing we have to fear about climate change today is that global warming is so much faster than it has been in any of the previous cycles, that there’s no time for the vegetation or the animals to adapt to whatever changes are happening.

“With polar bears, in particular, their habitat is completely disappearing because they rely entirely on sea ice,” she said Wednesday.

The researchers looked at six large herbivores — the woolly mammoth, woolly rhinoceros, wild horse, bison, reindeer and muskox — which all faced challenges at the end of the last ice age, about 14,000 years ago. This despite their continued presence throughout the Pleistocene Epoch, a period of time that lasted about two million years and saw many climate fluctuations.

The study found that in addition to a warming climate presenting difficulties for species more adapted to cold weather, the increasing human population also got in the way as the ice age drew to a close.

“When it was cold, the warm-adapted species were able to find [refuge] in places where it was still reasonable for them to survive and vice versa, when it was warm, the cold-adapted animals could [find livable space],” Shapiro said. “Where humans come into this is that during this last cycle [the end of the ice age], we have an extinction event and we never had those events before.

“One of the biggest differences between the cycles is people. Probably what we did was not over hunt them . . . but just blocked off their ability to move back and forth between [livable regions], so their population sizes became smaller, [they] weren’t able to find mates and eventually became extinct.”

Shapiro, who was on her way to a conference in Hamilton, Ont., said the Canadian Arctic provides a nearly ideal setting for the research.

“We’re trying to understand why species go extinct while others don’t, and the best place for us to work is in the Arctic,” she said. “First of all, we have this mass extinction that happened over the last 10,000 years or so, so it’s very accessible using DNA… because it’s cold up there, the bones are preserved really well.”