Researchers collected DNA from more than a million-year-old fossil, shedding light on the woolly mammoth and Columbian mammoth roots.
Scientists have recovered DNA from more than a million-year-old mammoth fossil discovered in Siberian permafrost. This DNA, the oldest genetic evidence found to date, sheds light on the evolutionary origins of woolly and Columbian mammoths. It also increases the possibility of retrieving DNA from other ancient species, such as extinct human relatives. Researchers have been attempting to retrieve ever more significant quantities of DNA from ever older remains since the discovery of two short DNA sequences from a recently extinct zebra distinct species known as the ” quagga ” in 1984. DNA extraction and sequencing methods finally discovered cave bears and Neandertals’ genomes.
“Our vision back into the human experience is sadly still restricted since the early humans who have been uncovered so far were not discovered under such perfect conditions.”
Researchers revealed in 2013 that they had extracted DNA from a 700,000-year-old horse fossil, making it the world’s oldest genomic evidence. However, as ancient as the genetic material was, it wasn’t the only thing that was old. Some scientists estimated that sequenceable DNA would persist in snowy conditions for more than a million years. The recent results, which were reported in Nature today, back up the prediction.
Tom van der Valk and Love Dalén of the Center for Paleogenetics in Stockholm and their teammates extracted the DNA from the molar teeth of three mammoths from various periods. The dental features of mammoth specimens can be used to differentiate them. One tooth found in 700,000-year-old deposits looked like it belonged to an early woolly mammoth, Mammuthus primigenius. The other two teeth matched molars of the steppe mammoth ( Mammuthus trogontherii ) and were aged to about one million years ago and 1.2 million years later or more.
The genetic material derived from the teeth had weakened significantly over millennia, fragmenting into several small fragments.
The researchers used the genomes of modern-day elephants ( mammoth ) as guides to reassemble the pieces and help flush out any DNA from bacteria or other toxins, similar to how anyone completing a jigsaw puzzle would respond to the picture on the package.
In all, billions of DNA base pairs were recovered from the youngest fossil (the woolly mammoth), accounting for 70 to 80 percent of the genome.
They obtained hundreds of millions of base pairs, making up between 25% to 30% of the world’s second-oldest mammoth genome. Even though the oldest fossil yielded minor DNA, the team could sequence about 60 million base pairs from it, which enabled them to learn more about mammoth evolution.
According to the fossil record, mammoths originated about five million years ago in Africa and dispersed throughout most of the globe, developing into a variety of animals and surviving for millions of years until becoming extinct just a few thousand years ago.
The new genomic evidence was compared to the genomes of younger mammoths. The researchers verified their hypothesis that the woolly mammoth descended from the steppe mammoth, and they demonstrated that it adapted rapidly to withstand the harsh cold of ice age Siberia.
The findings have uncovered some surprising facts about another mammoth family branch.
The team discovered that the oldest mammoth they sampled belonged to a previously extinct lineage descended from the mammoths that colonized North America 1.5 million years ago during the early Pleistocene period and gave birth to the Columbian mammoth that lived in temperate climates of North and Central America. According to the researchers, the Columbian mammoth resulted from the interbreeding among woolly mammoths and members of the lineage to which the researchers’ oldest fossil specimen related.
Ancient DNA reveals that the steppe mammoth was the woolly mammoth’s ancestor.
According to outside scholars, the study is a significant step forward in ancient DNA analysis. Eske Willerslev of the University of Copenhagen, whose team retrieved the 700,000-year-old horse genome in 2013, says, “It’s an interesting analysis showing DNA survival above what anyone in the field may have expected as the upper limit only a decade ago.” He and his colleagues were among the scientists who determined that DNA dating back over a million years could persist in permafrost conditions. He says, “Now this has been confirmed.”
“This is an interesting research because the DNA that the team collected from these very ancient mammoths gives valuable insights into early mammoth populations and the history of later mammoths both in Europe and the Americas,” says Janet Kelso of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Mammoths aren’t the only prehistoric animals worth studying.
Many modern-day mammal and bird species found their way in the Early and Middle Pleistocene, according to Dalén, van der Valk, and their colleagues. Dalén said the team is launching projects to look at some of these animals ( including goats, musk ox, and other mice ) during a press teleconference on February 16. Is it possible that scientists would be able to retrieve DNA from identical ancient human ancestors? The oldest specific dinosaurs date back seven million years. The earliest human DNA has been discovered in 430,000-year-old bones. “We recognize that environmental factors play a significant role in DNA preservation.
The fact that these mammoth fossils have been kept on ice is possibly the reason for their exceptional longevity —cooled in Northern Siberia after the mammoths died,” Kelso, who has analyzed a host of ancient human genomes, says. “Our vision back into the human experience is sadly still restricted since the early humans who have been uncovered so far were not discovered under such perfect conditions.” So it’s not just doom and gloom.
” Every year, new approaches emerge, ” Dalén said during the press teleconference. ” Perhaps in a few years, approaches will be available to retrieve DNA from human non permafrost collections that are approaching a million years old. ” ” It is very likely that anyone would discover human remains buried in permafrost in the future, ” he said.
