Woolly mammoths’ small ears helped keep them toasty on minus 50C Siberian steppes as they developed mutations to reduce heat loss, scientists have discovered. Researchers say it adds to evidence they were wiped out by global warming, rather than hunting.
They believe the giant beasts starved to death when the end of the Ice Age made it too wet for the plants they fed on to thrive.
The creatures, which used their 15ft tusks to dig under snow for shrubs and grasses, were covered in two layers of fur. The shaggy outer one was 20in long. Woolly mammoths also had a lump on their back similar to a camel’s hump to store fat when food was scarce.
Dr David Diez-del-Molino, of the Centre for Palaeogenetics in Stockholm, Sweden, said: “We wanted to know what makes a mammoth a woolly mammoth.
“Woolly mammoths have some very characteristic morphological features, like their thick fur and small ears, that you obviously expect based on what frozen specimens look like.
“But there are also many other adaptations like fat metabolism and cold perception that are not so evident because they are at the molecular level.”
The Swedish research team compared genomes – including remains belonging to the oldest known woolly mammoth, seven million-year-old Chukochya – with modern-day Asian and African elephants to find out what made them unique.
They discovered trademark features became more defined as the species roamed the Earth.
Chukochya shared about 92 per cent of its mutations with its more modern relatives.
Thick fur, fat metabolism and cold-perception skills were already present during evolvement from the steppe mammoth. But the traits developed further in Chukochya’s descendants.
Prof Love Dalen said: “The very earliest woolly mammoths weren’t fully evolved. They possibly had larger ears, and their wool was different, perhaps less insulating and fluffy compared to later woolly mammoths. We can say these specific mutations are unique to woolly mammoths and they didn’t exist in its ancestors.”
The study identifying genes common to all woolly mammoths rather than individuals, which was published in the journal Current Biology, is the largest of its kind.
All the mammoths whose genomes were included in the research were collected in Siberia. Scientists now hope to compare the North American woolly variety.
