Researchers just retrieved the oldest DNA ever found, going back more than one million years. The success represents a landmark in DNA science. It reveals that scientists already have the resources to probe further in history, much deeper than once considered feasible.
DNA sequencing is very recent, but some of the samples studied by scientists have been around for a very long time. Up to now, the earliest DNA sample to be recovered and sequenced for its genome was from a horse that lived 700,000 years ago. It was back in 2013.
Mammoth's Oldest DNA: How Old Is It?
A team headed by scientists at the Centre for Palaeogenetics at the University of Stockholm has looked at mammoth bones up to 1.2 million years away. Love Dalén, Professor of Evolutionary Genetics at the Centre and senior author of the latest research, announced that the samples are thousands of times older than Viking remains, humans' existence, and the Neanderthals.
The genomes of the oldest surviving mammoths were examined from DNA derived from teeth recovered preserved in the Siberian permafrost. They were from the time of the steppe mammoth who lasted roughly early and middle Pleistocene, between 1.7 million-200,000 years ago, predating wooly and Colombian mammoths, each yet to grow. The males had spiral tusks that could reach up to 16 feet in length, known to have risen to about 13 feet to the shoulders.
The mammoths Krestovka, Adycha and Chukochya are based on the sample sites in permafrost and discovered in the 1970s, CBS News wrote. Krestovka is about 1.65 million years old, while Adycha is around 1.34 million years old. Chukochya is thought to be one of the oldest recognized woolly mammoths, at approximately 0.87 million years old, scientists said.
What Makes It Surprising?
The oldest of the three specimens unleashed a surprise. Unlike the others, it originated from a separate, distinct genetic lineage; the Krestovka mammoth has now been named for the tooth's area. It diverged from other Siberian mammoths over two million years ago, according to genome research.
"This came as a complete surprise to us," says study lead author Tom van der Valk. Both prior findings have shown that at that point of time, there was only one mammoth population in Siberia, called the steppe mammoth. But our DNA research now reveals that there are two distinct genetic lineages, the Adycha mammoth, and the Krestovka mammoth, which we refer to here. We can't tell for sure yet, but we believe two separate animals might be described by these.
While a modern, endangered species is fascinating enough, what keeps the Krestovka mammoth unique is how it allows to explain the animals' occupation of North America. The latest hypothesis is that not only did Krestovka lineage mammoths arrive in North America nearly 1.5 million years ago. But half of the genome later discovered in the Colombian mammoth has contributed. It has previously been assumed the Ice Age animals descended exclusively from the woolly mammoth.
How The Discovery Would Help Understand Mammoth's Way Of Living
While the scientists told USA Today they faced different challenges in extracting the DNA from the samples, the recent discovery helps explain exactly how in the harsh cold weather the Columbian mammoth endured. From older mammoth lineages, survival variables such as hair development, thermoregulation, fat deposits, cold resistance, and some circadian cycles were handed down. That meant scientists had previously looked at the rapid evolutionary explanation to understand that mammoth cold adaptations may not necessarily need to be required.
While the recently sequenced genome sets a new record, scientists are also optimistic that even deeper trawls via historic DNA are feasible while only up to a degree.
Anders Götherström, a professor of molecular archaeology and joint study head at the Centre for Palaeogenetics, said they would be facing the question of how far they could go back in time.
"We still haven't hit the cap. An intelligent estimate will be that we might restore, and potentially go as far back as 2.6 million, DNA that is two million years ago. There was no permafrost previous to that, where ancient DNA may have been stored.
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