Is This Why the Woolly Mammoth Went Extinct?

Woolly mammoth
A file picture shows a man touching a giant bronze sculpture of a woolly mammoth in the Siberian city of Khanty-Mansiysk, March 7, 2011. A new study highlights the overlooked role water may have played in the extinction of the animal. Natalia Kolesnikova/Getty

Lack of fresh water probably killed off one of the last populations of woolly mammoths living on a remote Alaskan island, new research suggests.

The mammoths of St Paul Island became extinct around 5,600 years ago at about the same time Minoan culture was developing in Crete, Greece.

Scientists discovered that they survived some 5,000 years longer than isolated populations on the mainland.

The mammoths were trapped on the island when rising sea levels submerged the Bering Sea land bridge connecting Siberia and the north American continent.

A study of mammoth bones and teeth, and the fossilised remains of ancient aquatic insects in lake sediments, enabled the researchers to build up a picture of what happened to the animals, The Guardian reported.

They believe fresh water became increasingly scarce as conditions became drier. At the same time, rising sea levels meant there was less land available where the mammoths could look for new water supplies.

Pollen from the lake sediments showed the mammoths had cleared the area around the lake of vegetation, which the researchers suggested came from mammoths congregating around the remaining fresh water supply as elephants do. As sea levels rose and the island shrank, the mammoths were concentrated in a smaller area with less access to fresh water.

"It paints a dire picture of the situation for these mammoths," said Dr Matthew Wooller, from the University of Alaska Fairbanks, who co-led the research.

"Freshwater resources look like the smoking gun for what pushed them into this untenable situation."

The study, published in the journal Proceedings of the National Academy of Sciences, provides one of the most accurate dates for a prehistoric extinction.

"It's amazing that everything turned out so precisely with dating of extinction at 5,600 plus or minus 100 years," said co-author Professor Russell Graham, from Pennsylvania State University in the US.

Previous research had dated the remains of five mammoths from St Paul Island to about 6,480 years ago.

The study highlights the overlooked role water availability may play in extinctions, according to scientists.