In 2021, ancient DNA was recovered from a 1.2-million-year-old mammoth tooth — the oldest DNA ever found at the time. This incredible achievement not only pushed the boundaries of scientific methods, but the project also revealed a new lineage in the mammoth family.
Genetic material was obtained from the teeth of three mammoths buried in Siberian permafrost in the 1970s. Two of these specimens are over 1 million years old and predate the existence of the woolly mammoth, while the third is approximately 700,000 years old and represents one of the earliest known woolly mammoths.
“This is – by a wide margin – the oldest DNA ever recovered,” study author Professor Love Dalen of the Center for Paleogenetics in Stockholm told a press conference at the time. However, 2-million-year-old DNA found in northern Greenland trumped that.
The second oldest specimen is from an ancient steppe mammoth (Mammuthus trogontheri), a direct ancestor of the woolly mammoth (Mammuthus primigenius), but the oldest specimen belongs to a previously unknown genetic lineage of mammoth, now called the Krestovka mammoth. It now looks like the iconic Colombian mammoth (Mammuthus columbi) that lived in North America during the last ice age was a hybrid between this Krestovka genus and the woolly mammoth.
The researchers conservatively estimated the oldest known mammoth to be 1.2 million years old, as this is the age of the geological section in which it was found. However, mitochondrial genome data suggest that this specimen may actually be 1.65 million years old, while the second mammoth may be 1.34 million years old. Whatever you count, it’s much older than the previous record holder for oldest known DNA, which came from a horse preserved in Canadian permafrost, 780,000-560,000 years ago.
The genome of these ancient mammals has seen much better days and has degraded drastically over the millennia. Instead of a nice long strip of flawless genetic material, researchers were faced with billions of tiny odd DNA fragments, which they had to work hard on.
“A good analogy is to think of a puzzle. We have many small puzzle pieces and we are trying to reconstruct the puzzle. The smaller the piece you have, the more difficult it is to reconstruct the whole puzzle,” said lead study author Dr. Tom van der Valk explained.
To make matters even harder, many of the puzzle pieces they saw weren’t even mammoths, but bacteria or fungi that had contaminated the sample. Fortunately, they had some helpful clues to piece together the puzzle. Like looking at the front cover of the puzzle box for clues, the researchers had high-quality genomes of woolly mammoths and today’s elephant relatives to use for reference.
Stay tuned for that.
Now that this research has demonstrated what can be achieved, the team believes it is theoretically possible to recover DNA older than mammoths. Professor Dalen noted that the Northern Hemisphere does not contain any permafrost older than 2.5 million years, so recovering DNA beyond this time would be very difficult, if not impossible. However, a wealth of natural history can be mined from this broad time frame, not just a few defining chapters in our own human story.
“In the future, it is possible that there will be methods to recover DNA from human non-permafrost specimens that are close to 1 million years old,” speculates Professor Dalen.
“Another alternative is to find A Homo erectus In the permafrost. No such finds have been made to date, but it is possible that someone will find human remains in the permafrost of this age. If so, obtaining genetic DNA from these (hominin specimens) would be almost as easy as obtaining DNA from mammoths.
The study is published in Nature.
An earlier version of this article was published February 2021.