Teeth from Siberian mammoths yield oldest DNA ever
WASHINGTON: Scientists have recovered the oldest DNA on record, extracting it from the molars of mammoths that roamed northeastern Siberia up to 1.2 million years ago in research that broadens the horizons for understanding extinct species.
The researchers said on Wednesday they had recovered and sequenced DNA from the remains of three individual mammoths - elephant cousins that were among the large mammals that dominated Ice Age landscapes - entombed in permafrost conditions conducive to preservation of ancient genetic material.
While the remains were discovered starting in the 1970s, new scientific methods were needed to extract the DNA.
The oldest of the three, discovered near the Krestovka river, was approximately 1.2 million years old. Another, from near the Adycha river, was approximately 1 to 1.2 million years old. The third, from near the Chukochya river, was roughly 700,000 years old.
“This is by a wide margin the oldest DNA ever recovered,” said evolutionary geneticist Love Dalén of the Centre for Palaeogenetics in Sweden, who led the research published in the journal Nature. Until now, the oldest DNA came from a horse that lived in Canada’s Yukon territory about 700,000 years ago. By way of comparison, our species, Homo sapiens, first appeared roughly 300,000 years ago.
DNA is the self-replicating material that carries genetic information in living organisms - sort of a blueprint of life. “This DNA was extremely degraded into very small pieces, and so we had to sequence many billions of ultra-short DNA sequences in order to puzzle these genomes together,” Dalén said.
Most knowledge about prehistoric creatures comes from studying skeletal fossils, but there is a limit to what these can tell about an organism, particularly relating to genetic relationships and traits.
Ancient DNA can help fill in the blanks but is highly perishable. Sophisticated new research techniques are enabling scientists to recover ever-older DNA.
“It would be a wild guess, but a maximum of two to three million years should be doable,” Dalén said.