Woolly Mammoths Had Humps Like Camels, and Genes Made For Cold

What makes a mammoth different from an elephant? The Asian elephant is the closest living relative of the prehistoric woolly mammoth, but mammoths lived under vastly different circumstances from their cousins—in the freezing tundra versus the tropics.

In a new study in the journal Cell Reports, geneticists and anthropologists from the University of Chicago and Penn State University sequenced the genomes of three Asian elephants and two woolly mammoths to discover what genetic changes would have allowed mammoths to live in such different climates from their modern relatives. 

In order to live in climates where average winter temperatures ranged from -22 degrees Fahrenheit to -58 degrees Fahrenheit, mammoths had small ears and tails and large sebaceous glands, which secrete oil to waterproof and insulate mammals. They also had thick layers of fat to protect them from the elements, including a hump of fat much like those seen in modern-day camels. This hump would have helped them store energy during long Arctic winters without sunlight.

And they had a genetically coded preference for the cold. An amino acid change specific to woolly mammoth DNA played a major role in the animals' sensitivity to temperature, according to the study. The TRPV3 gene is involved in exterior temperature sensation, cellular differentiation, and hair growth, and mice without it are more sensitive to heat, and prefer colder temperatures. In the lab, the researchers found that the woolly mammoth's genetic tweak turned down the activity of the protein produced by TRPV3.

The mammoth DNA in the study came from individuals that died 20,000 to 60,000 years ago. Some came from mammoth fur bought on eBay for a mere $100, the researchers told NPR.