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 — once Antarctica was a tropical jungle — and many animals as well as humans have had to adapt, and quickly, 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 — and now, scientists have finally been able to pinpoint how their species became extinct.
Yes, it is true that ancient peoples and not-so-ancient 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 30,000 years ago was found recently by archaeologists. Artistic representations of woolly mammoths have been found on cave walls as well. Clearly, humans and mammoths go way back together.
Woolly mammoths evolved from the species Mammuthus subplanifrons in the early Pliocene era, from 5.333 million years ago to 2.58 million years ago. Its closest relative that still exists is the Asian elephant.
As the species thrived, populations expanded over all 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. But somehow they managed to survive and adapt to the world that was changing around them.
Herds of not only mammoths, but reindeer and woolly rhinoceroses, also thrived in the cold snows of the North during those times.
But during the Summers, as the 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 their powerful tusks 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 now 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 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 20 years in the Arctic, the 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.
“We have finally been able to prove was 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. 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 of the equivalent of going two times around the world during their lifetimes.
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, 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 and 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 explains “When the climate got wetter and the 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. We have shown that climate change, specifically precipitation, directly drives the change in the vegetation — 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, it 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.
But now it seems clear that much more powerful forces were at work, 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 — once something is lost, there is no going back.
“Precipitation was the cause of the extinction of woolly mammoths through the changes to plants. The change happened so quickly that they could not adapt and evolve to survive.
“It shows nothing is guaranteed when it comes to the impact of dramatic changes in the weather. The early humans would have seen the world change beyond all recognition — that could easily happen again and we cannot take for granted that we will even be around to witness it. The only thing we can predict with any certainty is that the change will be massive.”