A million years since the production of DNA surprises the mammoth

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Woolly mammoths are famous people of the Ice Age. These massive, shaggy beasts traversed most of the Northern Hemisphere between 700,000 and 10,000 years ago, and thrived during cold times when glaciers widened and vast, cold grasslands spread. But, according to a study published in 2021 in Nature, the traits that allowed woolly mammoths to withstand the cold were not unique to these furry elephants alone. Woolly mammoths have inherited many of their cold-adapted traits from older mammoth species, according to a new discovery by million-year-old DNA.

(credit: Tricia Daniel/Shutterstock)

The analysis, led by Tom van der Valk, a bioinformatician at the Swedish Science for Life Laboratory, and colleagues was based on ancient DNA taken from three massive molars found in northeastern Siberia during the 1970s. Each of the fossils has a pseudonym – the oldest, called Krestovka mamoth, is more than 1.2 million years old, while the Adycha mamoth dates back about 1 million years, and the Chukochya mamoth lived between 800,000 and 500,000 years ago. By analyzing such ancient mammoths, researchers hoped to find genetic clues about when woolly mammoths evolved their shaggy coats and physiological adaptations to their frigid environments.

However, the DNA evidence differed from the expectations of paleontology. Older mammoths who lived before the time of rockwool had genetic signs of traits that adapted to the cold. This means that characteristics previously thought to be unique to the woolly mammoth evolved earlier, and were actually found in its proposed ancestor, the steppe mammoth.

“Palaeobiology shows us how limited our evolutionary imagination was when we were limited to morphological data,” says Chris Widga, a paleontologist at the Gray Fossil site and museum, who was not involved in the new study. For more than a century, nearly everything we know about mammoths came from bones, footprints, and the occasional carrion. Wadja notes that the relatively new tools for studying ancient DNA — not just in mammoths, but in other Pleistocene species — are quickly overturning what experts have long believed.

The genetic material caused another shock: the researchers found that the Krestovka mammoth represents a new, previously unknown breed of mammoth. These probably interbred with early woolly mammoths to produce a large North American form known as the Columbian mammoth. In other words, rather than appearing due to adaptation, the Columbian mammoth was most likely a hybrid. It’s the first such event to be documented in ancient DNA, allowing paleontologists to see these majestic beasts in a whole new light.

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