Today we will be discussing mammoths and other large Ice Age creatures like woolly rhinos died out remains a mystery.
According to DNA evidence, woolly mammoths survived in north-central Siberia for thousands of years longer than could be established from fossil finds. A new study argues that long-lasting preservation of remains in frigid environments can skew the results by thousands of years.
Some ancient DNA may be leading paleontologists astray in attempts to date when woolly mammoths and woolly rhinos went extinct.
In 2021, an analysis of plant and animal DNA from sediment samples from the Arctic, spanning about the last 50,000 years, suggested that mammoths survived in north-central Siberia as late as about 3,900 years ago. That’s much later than when the youngest mammoth fossil found in continental Eurasia suggests the animals died out; it dates to about 10,700 years ago. Only on Wrangle Island off the coast of Siberia and the Pribilof Islands in the Bering Sea were mammoths known to have survived later.
The finding was one of several in recent years using ancient DNA found in sediment and other environmental material to suggest new insights into animal extinctions. Genetic evidence from woolly rhinos in Eurasia and horses in Alaska have also indicated that these animals remained thousands of years longer in some areas than was thought.
But thousands of years is also how long the animals’ large bones can linger on the ground in the frigid north, slowly weathering and shedding tiny bits of DNA, two researchers write November 30 in Nature. Mammoths survived in north-central Siberia as late as about 3,900 years ago.
That means that the youngest ancient DNA in sediment samples may have come from such bones, not living mammoths, woolly rhinos and other megafauna. Studies that rely on this genetic evidence could skew estimates of when these animals went exciton by thousands of years toward the present, say paleontologists Joshua Miller of the University of Cincinnati and Carl Simpson of the University of Colorado Boulder.
When, and why, mammoths and some other Ice Age creatures died out is a lingering mystery. Dating when these animals went extinct could help reveal what drove them to their Elise— humans, a warming climate, some combination of the two, or something else entirely.
But getting a good sense of when a species disappeared from its range, or from the planet, is not straightforward. For long-gone animals, fossils can help, but it would be a huge coincidence if the youngest fossil ever found of an extinct species was also the last individual to live.
Where fossils give out, DNA has started to take over. For the last two decades, environmental DNA, or E-DNA, has become a go-to technique to find out what organisms are living, or used to live, in a certain place.
Paleontologists generally focus on a variant of E-DNA that glooms onto minerals and other material and gets buried over time. That “sedimentary ancient DNA,” or Sedna, is what evolutionary geneticist Yucheng Wang of the University of Cambridge and his colleagues analyzed. This is my final conclusion for this article.
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