Humans get a bad rap, and many times justifiably so, but apparently, we did not cause the extinction of the woolly mammoth; it was climate change that brought about the end of the gigantic mammals after having lived on the Earth for five million years.
Naturally, the climate has changed in all parts of the world many times over the history of the earth. At one point, Antarctica was a tropical jungle, for example. Many animals, as well as humans, have had to quickly adapt to the warming or cooling of their local environment.
But the speed at which the last Ice Age ended and the rise of the wetlands and trees that resulted from it was too precipitate for the great land animals to be able to cope with, as their endless grasslands eventually became forests and lakes.
The last woolly mammoths strode the Earth approximately 4,000 years ago on Wrangel Island in Russia off the northwest coast of Alaska. Now, scientists have finally been able to pinpoint how their species became extinct.
It is true that both ancient and more modern peoples who lived fairly recently coexisted with the giants, sometimes taking them down with weapons using their bones and tusks for a range of things including shelters, harpoons, and even musical instruments.
A flute carved out of a mammoth bone approximately 30,000 years ago was recently found by archaeologists. Artistic representations of woolly mammoths have been found on cave walls, as well. Clearly, humans and mammoths go way back.
Woolly mammoths evolved from the species Mammuthus subplanifrons in the early Pliocene era about 5.333 to 2.58 million years ago. Its closest relative that still exists is the Asian elephant.
As the species thrived, populations expanded throughout the northern hemisphere of the earth from Eastern Canada all the way through the continent to Western Europe via the land bridge in what is now the Bering Strait.
Naturally, over these vast expanses of Earth and over this stretch of time, there were multiple changes in climate—even almost complete reversals of it—with which the mammoths had to contend. However, somehow they managed to survive and adapt to the changing world around them.
Herds of not only mammoths but reindeer and woolly rhinoceroses also thrived in the cold snows of the North during those times.
Nevertheless, during the summers as snows receded, small shrubs, flowers and vast plains of grass were plentiful fodder for the gigantic animals. Scientists even speculate that they used their oversized tusks to shovel snow away from their food sources and may have even been able to use them to uproot the toughest grasses during the long winters, as reported in Science Daily.
Indeed, the animals may have grown as large as they did (the size of double decker buses) because they needed huge stomachs to digest the enormous quantities of grass that they ate to survive.
Marginalization of food sources led to shrinking habitat, genetic diversity
Finally, we now know just what it took to bring down the giants of the north. By analyzing environmental DNA from the animals and the soils in which they perished, scientists say in a paper published in the journal Nature Today that the melting of the glaciers at the end of the last Ice Age about 12,000 years ago led to such an alteration of the environment that they couldn’t adapt fast enough to the changes.
With the runoff from the glaciers that once covered the northern reaches of the entire Northern Hemisphere during the last Ice Age, vast forests and wetlands were formed— neither of which features the grass that woolly mammoths needed to survive.
Taking over a decade, the research project on their extinction was led by Professor Eske Willerslev, a Fellow of St. John’s College at the University of Cambridge and director of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen.
Using DNA shotgun sequencing from plant and animal remains collected over a time period of twenty years in the Arctic, scientists gleaned that the animals could not adapt quickly enough after their typical foods became harder to find.
Professor Willerslev states “Scientists have argued for 100 years about why mammoths went extinct. Humans have been blamed because the animals had survived for millions of years without climate change killing them off before, but when they lived alongside humans they didn’t last long and we were accused of hunting them to death.”
Willerslev adds that: “We have finally been able to prove that it was not just the climate changing that was the problem, but the speed of it that was the final nail in the coffin—they were not able to adapt quickly enough when the landscape dramatically transformed and their food became scarce.”
“As the climate warmed up, trees and wetland plants took over and replaced the mammoth’s grassland habitats,” he adds. “And we should remember that there were a lot of animals around that were easier to hunt than a giant woolly mammoth…they could grow to the height of a double decker bus!”
Mammoths once ranged on all continents except Australia, South America, Africa
In 1965, a Ukrainian farmer dug up the lower jawbone of a mammoth while in the process of expanding his cellar. Further excavations revealed the presence of four huts, made up of a total of 149 mammoth bones.
These dwellings, dating back some 15,000 years, were determined to have been some of the oldest shelters known to have been constructed by pre-historic man, usually attributed to Cro-Magnon. Also found on the site was a map inscribed onto a bone, presumably showing the area around the settlement; the remains of a “drum” made of a mammoth skull painted with a pattern of red ochre dots and lines; and amber ornaments and fossil shells.
Mammoths were indeed hunted for these uses, but they still had enormous herds and were everywhere in the world except Australia, South America, and Africa during the time they lived alongside humans. They could even travel an astonishing distance during their lifetime equivalent to two trips around the world.
As part of the research into their disappearance, Willerslev and his team additionally sequenced the DNA of a total of 1,500 Arctic plants for the very first time in history.
Dr. Yucheng Wang, the primary author of the scientific paper and a Research Associate at the Department of Zoology at the University of Cambridge, stated “The most recent Ice Age—called the Pleistocene—ended 12,000 years ago when the glaciers began to melt and the roaming range of the herds of mammoths decreased.”
“It was thought that mammoths began to go extinct then,’ Wang added, “but we also found they actually survived beyond the Ice Age all in different regions of the Arctic and into the Holocene, the time that we are currently living in—far longer than scientists realized.”
Formation of our lakes, rivers, marshes tolled death knell for woolly mammoths
“We zoomed into the intricate detail of the environmental DNA and mapped out the population spread of these mammals [to] show how it becomes smaller and smaller and their genetic diversity gets smaller and smaller too, which made it even harder for them to survive,” Wang explained.
Wang further adds that: “When the climate got wetter and…ice began to melt it led to the formation of lakes, rivers, and marshes. The ecosystem changed and the biomass of the vegetation reduced and would not have been able to sustain the herds of mammoths.”
According to Wang, it was shown that “climate change, specifically precipitation, directly drives the change in the vegetation [and] humans had no impact on them at all based on our models.”
The extinction of the woolly mammoth is something that has not only posed a scientific conundrum but has been gnawing at the conscience of some people for many decades, as it had been theorized that humans exterminated the species through their own lack of foresight.
However, it now seems clear that much more powerful forces were at work, namely ones that we still grapple with today as the climate of the Earth is always changing.
Willerslev declares “This is a stark lesson from history and shows how unpredictable climate change is [as] once something is lost, there is no going back.”
“Precipitation was the cause of the extinction of woolly mammoths” according to Willerslev, “through the changes to plants. The change happened so quickly that they could not adapt and evolve to survive.”
According to Willerslev, when it comes to the forces of nature and dramatic climatic changes, early humans would have been confronted with a world entirely beyond recognition, something that could once again come to fruition. It cannot be guaranteed that modern humans will be around to witness such drastic changes, but one thing that remains certain is that any changes will most definitely be monumental in the repercussions it will have on the planet.