Woolly mammoths roamed the globe for five million years until they perished for good around 4,000 years ago, and scientists have now discovered why.
Their carcasses were used to build shelters, harpoons were fashioned from their gigantic tusks, artwork depicting them is daubed on cave walls, and the earliest known musical instrument, a flute, was created out of a mammoth bone 30,000 years ago.
Geneticists analyzed historic environmental DNA to determine that as the icebergs melted, it became far too moist for the gigantic creatures to live since their food supply - flora - was virtually wiped out.
Studying the Mammoth's Extinction
Professor Eske Willerslev, a Fellow of St John's College, University of Cambridge, and head of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen, led the 10-year research effort published in Nature.
The researchers utilized DNA shotgun sequencing to examine ambient plant and animal remnants from soil samples meticulously gathered over 20 years from areas in the Arctic where mammoth remains were discovered, including urine, feces, and skin cells. Thanks to improved new technologies, scientists no longer need to rely on DNA samples from bones or teeth to acquire enough genetic material to reproduce an ancient DNA profile. During the pandemic, the same technology was utilized to identify, track, and analyze Covid-19 in the sewage of human populations.
Living with Prehistoric Humans
"Scientists have disputed for 100 years about why mammoths became extinct," Professor Willerslev remarked. People were blamed since the creatures had previously lasted for millions of years without being wiped out by climate change, but when they coexisted with humans, they didn't endure long, and we were accused of hunting them to extinction.
"What we've now been able to show is that it wasn't simply climate change that was the issue; it was the speed with which it happened that was the last nail in the coffin - they weren't able to adapt quickly enough when the landscape significantly changed, and food became scarce."
"As the temperature warmed, forests and wetlands supplanted the mammoth's grassland habitats." And we should keep in mind that there were many of species nearby that were simpler to hunt than a big woolly mammoth, which might grow to be as tall as a double-decker bus!"
Roaming the Earth
The woolly mammoth and its relatives inhabited the Earth for five million years, evolving and surviving successive Ice Ages. Mammoths, reindeer, and woolly rhinoceroses flourished in the cold and snowy circumstances at this time.
Grass, flowers, plants, and tiny bushes would have all been consumed by the vegetarian mammoths who presumably used their tusks to sweep the snow away and their trunks to uproot difficult grasses despite the cold. They were so large because the grass required large stomachs to digest.
According to fossil records, mammoths could travel the equivalent of twice around the world in their lifetime, and they existed on every continent except Australia and South America. Although populations were known to have survived the end of the last Ice Age in small pockets off the coasts of Siberia and Alaska - on Wrangel Island and St Paul Island, respectively - the research found that they lived longer elsewhere as well and that the mammoth breeds on both islands were closely related despite being separated geographically. To make these internationally relevant findings, the researchers sequenced the DNA of 1,500 Arctic plants for the first time as part of the experiment.
Blaming Climate Change
"The most recent Ice Age - termed the Pleistocene - ended 12,000 years ago when the glaciers began to thaw and the traveling area of mammoth herds diminished," said Dr. Yucheng Wang, first author of the work and a Research Associate at the University of Cambridge's Department of Zoology. Mammoths were assumed to have gone extinct at that time, but we discovered that they lasted past the Ice Age in various parts of the Arctic and into the Holocene - the period we are currently living in - considerably longer than experts expected.
"We zeroed in on the fine details of environmental DNA to map out the population distribution of these creatures and illustrate how it is shrinking, and their genetic variety is shrinking as well, making it even more difficult for them to survive."
"Lakes, rivers, and marshes were formed as the environment became wetter and the ice began to melt. As a result, the environment altered, and the biomass of the plants decreased, making it impossible for mammoth herds to survive. We've demonstrated that climate change, especially precipitation, promotes changes in vegetation - and that people have no influence on them at all, according to our models."
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