World's oldest DNA sequenced from molar of million-year-old mammoth
Scientists have taken a significant step toward understanding mammoths by sequencing the world's oldest DNA. The DNA was sequenced from molars of three different mammoths. The youngest tooth is nearly 500,000-800,000 years old and the remaining are 1 million-1.2 million years old. Until now, the oldest DNA sequenced by scientists belonged to a horse, believed to have lived 560,000-780,000 years ago. Here's more.
The molars had been unearthed in Siberia in the early 1970s by Russian paleontologist Andrei Sher, reports National Geographic. The researchers of this new study, reportedly, drilled out tiny samples from each molar for isolating DNA. "The more puzzle pieces you have, the harder it is to reconstruct the whole puzzle," said Tom van der Valk, the co-author of the study.
Work on this project began in 2017 when the Russian Academy of Sciences handed a sample over to the Centre for Palaeogenetics. van der Valk and his team ensured that they focused only on DNA snippets, which were actually old, and belonged to mammoths. Contamination was more than obvious considering the teeth had been buried for centuries and had been handled by numerous scientists since the discovery.
The research pointed out that the youngest mammoth is actually one of the oldest known woolly mammoths. These Ice Age creatures ruled the Northern Hemisphere for thousands of years, before going extinct about 10,500 years ago due to warmer temperatures. However, a smaller population of these mammoths survived later, dying out only about 4,000 years ago. The second mammoth was a steppe mammoth.
The third specimen belongs to the Krestovka lineage of mammoths. The researchers believe the Krestovka mammoth arrived in North America nearly 1.5 million years ago before hybridizing with woolly mammoths. The study also suggested that mammoths were hairy long before the woolly mammoths even emerged.
Some scientists had earlier doubted whether a DNA as old as one million years can even be sequenced. Putting this doubt to rest, co-author Beth Shapiro said, "These [specimens] push back pretty substantially what we'd come to think of as the oldest possible ancient DNA." van der Valk and another co-author Love Dalén claimed DNA as old as 2.6 million years can be sequenced.