Wednesday , March 3 2021

The oldest DNA in the world in a sequence from a mammoth that lived more than a million years ago



A mammoth tooth that roamed the Siberian prairie more than a million years ago yielded the oldest DNA sequence in the world.

This is the first time that recovered DNA from animals has remained more than a million years old.

In the past, the oldest DNA sample was from a horse that lived 560,000 to 780,000 years ago.

The oldest DNA in the world in a sequence from a mammoth that lived more than a million years ago
The figure represents a reconstruction of the prairie mammoths that preceded the woolly mammoth, based on new genetic knowledge. (Zeiken House / Palaeogenetics Center)

The information returned from this Ice Age grant reveals how mammoths evolved and adapted to life in cold climates.

It may also show a species of mammoth that was not previously known.

“This DNA is remarkably old. The specimens are a thousand times older than the remnants of the Viking and even prolong the existence of humans and Neanderthals in advance, “said Love Dalen, a professor of evolutionary genetics at the Center for Paleogenetics in Stockholm.

An international team of researchers was able to isolate DNA from moles from three separate mammoths collected from the Siberian permafrost in the 1970s.

They will date the teeth using geological data and DNA analysis.

The study was published in the journal nature Yesterday.

The oldest mammoth tooth occurred 1.2 million to 1.65 million years ago.

The younger estimate comes from a method known as bio-stratigraphy, in which scientists estimate the presence of small rodents found in the sediment layers – a species that only existed for certain periods of time.

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They also measured the so-called palaeomagnetism of rocks and sediments at the site.

This method uses the direction of the Earth’s magnetic field, which has changed over time and leaves traces of magnetic minerals in the rock, to determine ages for fossils and rocks.

The older assessment stems from the genome that the researchers recovered.

“There could be several reasons why these estimates differ from each other. For example, perhaps Krastovka’s specimen originally came from an older stratum but at some point eroded and then was repositioned in a younger stratum,” said Professor Dalan.

“Alternatively, and in our opinion it is more likely that our estimated molecular clock rate has dropped slightly,” he said, suggesting that setting the date is not an exact science.

“Anyway, these two types of dating analysis show an age of more than a million years.”

The study is named after the Krastovka Mammoth after the place where it was found, and showed that this type of mammoth is different from other Siberian mammoths more than two million years ago.

The oldest DNA in the world in a sequence from a mammoth that lived more than a million years ago
Examples of mammoth teeth, two of which have been found to be more than a million years old. (Pavel Nikolsky)

“This completely surprised us. All previous studies have shown that in Siberia at that time there was only one type of mammoth, called the prairie mammoth,” wrote research author Tom van der Volk, a postdoctoral researcher at the Swedish Museum of Natural History.

According to him, their DNA analysis showed that there are two different genetic lineages and they may represent different species.

They also believe that the mammoths belonging to this previously unknown lineage settled in North America about 1.5 million years ago.

The second mammoth in the oldest lived 1.34 million years ago and belonged to a population that were the ancestors of the woolly mammoth, the last mammoth to become extinct about 5,000 years ago.

They compared his genome to a woolly mammoth that lived about 700,000 years ago and some that lived not long before it disappeared.

The oldest DNA in the world in a sequence from a mammoth that lived more than a million years ago
The trunk of the frozen juvenile mammoth named Yuka, discovered in 2014 in Yakutia, Siberia. (Love Dalen)

Their analysis showed that traits associated with life in the Arctic – hair growth, fat deposits and cold tolerance – already existed more than a million years ago and would develop slowly and gradually over time.

The youngest specimen they found and a floor was a tooth of an early form of a woolly mammoth that lived more than 680,000 years ago.

The researchers said that permafrost helped preserve DNA, but was still very challenging to extract from the samples.

The DNA disintegrated into very small fragments that researchers compared to a puzzle with more than a billion pieces.

To inform about the process, they used a detailed genome of a live African elephant, which acted a bit like the lid of a jigsaw puzzle.

“It usually helps to have a box cover to sneak into at the peak of direction and so we use the elephant’s reference genome,” said Professor Dalan.

The ability to extract and analyze a million-year-old DNA can allow scientists to track the origins and evolution of many different species, including our own potentials.

In theory, the researchers said DNA could be extracted from samples 2.6 million years old.

This is the earliest era of permfrost – soil that stays frozen all year round and helps prevent DNA degradation.

It is unlikely that ancient DNA can be preserved so much outside of perforated regions, they say.

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Permfrost is covered with a layer of soil that compromises in the summer – sometimes revealing a well-preserved mammoth and other ancient remains of ice-age creatures like cave bears and a rhinoceros – sometimes with tactile soft tissue.

In recent decades, this “thaw season” has lengthened as a result of climate change, Professor Dalan said, as the region warms twice as much as the rest of the globe.

This led to an increase in the number of early finds.


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