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Extinction of large animals due to humans, climate change?

india Updated: Mar 06, 2012 16:32 IST

Modern humans and climate change are both responsible for the extinction of many of the world’s big animals over the last 100,000 years, scientists have revealed.

By examining extinctions during the late Quaternary period (from 700,000 year ago until present day), but primarily focusing on the last 100,000 years, researchers from the University of Cambridge have been able to assess the relative importance of different factors in causing the extinctions of many of the world’s terrestrial megafauna, animals 44 kg or larger.

These extinctions included mammoths in North America and Eurasia as well as mastodons and giant sloths in the Americas, the woolly rhino in Europe, giant kangaroos and wombats in Australia, and the moas (giant flightless birds) in New Zealand.

The researchers used data from an Antarctic ice core, which gives one of the longest running records of changes in the earth''s climate, covering the last several hundred thousand years.

They also compiled information on the arrival of modern humans from Africa on five different landmasses (North America, South America, most of Eurasia, Australia and New Zealand).

By conducting a statistical analysis using both the climatic information and the timing of arrival of modern humans, they were able to determine whether the pattern of extinctions across landmasses was best explained by climate change, the arrival of modern humans, or both.

They concluded that it was a combination of both the arrival of man (probably through hunting or habitat alteration) as well as climate change, which caused the extinctions.

The researchers believe that the research provides insights into the consequences of pressures on megafauna living today, including tigers, polar bears, elephants and rhinos.

Graham Prescott, currently a PhD student at the University of Cambridge and co-author on the paper, highlighted how their research may inform us about the current plight facing large animals.

“Our research suggests that a combination of human pressure and climate change was able to cause the extinctions of many large animals in the past,” said Prescott.

“Many large, charismatic animals today are threatened by both hunting pressure and changes in climate; if we do not take action to address these issues we may see further extinctions. And in contrast to the people who first encountered these megafauna, people today are fully aware of the consequences of our actions; this gives us hope that we can prevent future extinctions, but will make it all the worse if we do not,” he added.

Their findings were recently reported in the journal PNAS.