Scientists managed to sequence DNA from the teeth of mammoths found in Siberia in the 1970s.
Teeth from mammoths buried deep within the thick Siberian permafrost for over a million years resulted in the oldest DNA sequence of all time, according to a study that was recently published, shining some light into the ancient times.
Researchers stated that the three specimens, one approximately 800,000 years old and two over a million years old, provide crucial insights regarding the giant Ice Age mammals, including the woolly mammoth’s genome.
The formerly oldest sequenced DNA dates from between 780,000 and 560,000 years ago, and it originates from a horse.
Love Dalen, a professor of evolutionary genetics of the Centre for Palaeogenetics in Stockholm and the senior study author, wrote in the journal Nature:
“This DNA is incredibly old. The samples are a thousand times older than Viking remains and even predate the existence of humans and Neanderthals.”
The mammoths were first discovered in the 1970s in Siberia and were stored in the Russian Academy of Sciences in Moscow.
Researchers first dated the specimens according to geology, regarding other species like little rodents, known to be specific to particular periods and present in similar sedimentary layers.
That showed that two of the mammals were ancient steppe mammoths over a million years old!
Researchers also took genetic data from minuscule samples of powder from each mammoth tooth, “essentially like a pinch of salt you would put on your dinner plate,” according to Dalen.
Though it degraded into minuscule fragments, scientists managed to sequence tens of millions of chemical base pairs, which form the DNA strands and conduct age estimates out of the genetic data.
It turned out that the oldest mammoth, called Krestovka, is even older! The new analysis showed that Krestovka is 1.65 million years old, while Adycha, the second, is approximately 1.34 million years old. Chukochya, the youngest of the trio, is 870,000 years old.
According to Dalen, the discrepancy for the oldest mammoth may be the result of an underestimation in the DNA dating process, which means that the creature was likely approximately 1.2 million years old, as geological evidence showed.
However, he added that it is possible that the specimen was indeed older and had thawed out of the permafrost for some time and then got wedged in between new layers of sediments.
The DNA fragments were a lot like puzzles with millions of small bits.
Tom van der Valk, a lead author, member of the Science for Life Laboratory from the Uppsala University, said that those small pieces are “way, way, way smaller than you would get from modern, high-quality DNA.”
Genetic data from an African elephant, a modern descendant of the mammoth, as somewhat of a blueprint for their algorithm, the researchers managed to reconstruct parts of the mammoth genomes.
The analysis showed that the older Krestovka mammoth features a formerly unknown genetic lineage, which researchers think is a trait inherited from other mammoths approximately two million years old and is an ancestral trait of the behemoths of North America.
The study also analyzed the lineage from the million-year-old Adycha steppe mammoth to Chukochya and other “younger” woolly mammoths.
They discovered gene variants relevant to life in the Arctic – hairiness, fat deposits, thermoregulation, and cold tolerance in the older specimen. That means that mammoths likely were already hairy long before the woolly mammoth was born.