“Million-Year-Old DNA Rewrites the Mammoth Family Tree: Genomic Data—The Oldest Ever Recovered from a Fossil—Reveals the Origin and Evolution of the Columbian Mammoth”, 2021-02-27 (; similar):
When it comes to the mammoth family tree, it has long been believed that the Columbian mammoth evolved earlier than the smaller, shaggier woolly mammoth. But now, using DNA that is more than a million years old—the oldest ever recovered from a fossil—researchers have turned that assumption on its head: They found that the Columbian mammoth is in fact a hybrid of the woolly mammoth and a previously unrecognized mammoth lineage.
…Fossilized remains of mammoths, particularly those preserved in exquisite detail, can shed light on how these animals lived and died. But analyzing an ancient creature’s genetic code—by recovering its DNA and reassembling it into a genome—opens up vast new research possibilities, said David Díez-del-Molino, another paleogeneticist at the Centre for Palaeogenetics. “You can track the origin of species.”
A team of researchers, including Dr. Dalen and Dr. Díez-del-Molino, recently set out to do just that using three mammoth molars unearthed in northeastern Siberia. These teeth are old—about 700,000 years, 1.1 million years and 1.2 million years—and they’re also impressive to look at, Dr. Dalen said. “They’re the size of a carton of milk.”…After removing the non-mammoth DNA, the team was left with between 49 million and 3.7 billion base pairs in each of their three samples. (The mammoth genome is roughly 3.2 billion base pairs, which is slightly larger than the human genome.) The researchers compared their data with African elephant DNA a second time, which allowed them to put all their DNA fragments in the correct order.
This mammoth DNA smashes the record for the oldest DNA ever sequenced, which was previously held by a roughly 700,000-year-old horse specimen, said Morten E. Allentoft, an evolutionary biologist at Curtin University in Perth, Australia, who was not involved in the research. “It’s the oldest DNA that’s ever been authentically identified”, he said.
When the researchers looked at the three genomes they reconstructed, the oldest stood out. “The genome looked weird”, Dr. Dalen said. “I think it’s likely this is a different species.” That was a shock: Researchers have long believed that there was only a single lineage of mammoths in Siberia that gave rise to woolly and Columbian mammoths. This discovery suggests that a previously undiscovered mammoth lineage existed as well.