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Tuesday, November 28, 2023
Dr. Brown: What happened to the mammoths, just a few thousand years ago?

Beginning in Africa several million years ago, mammoths reached much of Eurasia, and eventually 20,000 years ago, the Americas.

Some mammoths developed a rich covering of fur to protect them against the cold in northern climes.

Most were enormous creatures, larger than modern-day Indian elephants and possessed a foreshortened tallish bulbous skull and in both sexes, gigantic tusks that originated from the base of the skull, and curved down and out before twisting up and back toward the top of the skull in adults.

Like elephants, mammoth societies were matriarchal. Females stayed together in their natal society, but with the coming of puberty, young males were nudged out to become loners or possibly join loose groups of other males.

Inexperience and perhaps impetuousness, sometimes trapped young males into deep sucking swamps from which they were unable to escape, or they drowned trying to cross ice fields unable to support their weight. Those fates were far less common among females.

Mammoths and other mega-fauna such as sabre-toothed lions, cave bears, giant rhinoceroses, and early versions of what would later become cattle and horses, were often portrayed in the cave art of western Europe beginning roughly 40,000 years ago to as late as 15,000 years ago.

However, by the 10,000-year mark, woolly and other mammoths were gone on all continents, except for two remote islands, which in lower seas had been part of the land bridge between Siberia and Alaska.

On St. Paul island, the last woolly mammoth died 5,000 years ago in the face of rising sea levels that shrank the available food and fresh water, without which their fate was sealed.

On Wrangel, the other island, genetic studies of the last mammoths revealed that too many mutant protein-encoding genes affecting key functions such as taste, smell and probably fertility, had accumulated for natural selection to weed out.

And so, the last of the mammoths died 3,400 years ago, the product of genetic collapse when there were too few members of a species left to maintain the health of their genome.

What caused the extinction of mammoths elsewhere? Here the culprits were probably humans and neanderthals.

Mammoths were like a grocery and hardware store combined for archaic and early humans. They offered an enormous supply of rich protein and fat in their flesh and bone marrow, much of which could be stored in cold temperatures, fat for lamps, enormous bones and tusks for framing shelters and large skins as covers and clothing.

On every continent from Eurasia to the Americas and Australia, within a few thousand years of the arrival of modern humans, megafauna of all sorts began to disappear. It’s hard to argue with the notion that our species played a major role in the extinction of mammoths and other megafauna.

The most interesting part of this story for me was a recent study that traced the meanderings of one male woolly mammoth, throughout Alaska, named Kik by the scientists.

Footprints fascinate me, especially those that chronicled the bipedal, human-like steps of Australopithecus afarensis (Lucy’s species) 3.44 million years ago in east Africa, the footprints of a family of neanderthal children and adults wandering a beach in southern Spain 100,000 years ago, and those of a young mother carrying her child on her hip in New Mexico 8,000 years ago.

Footprints trigger our imagination. Who were they? What were they thinking and feeling? Where were they going? And what happened to them? 

So also, with young Kik, except that instead of footprints, Kik’s tusk provided the master timepiece, whose strontium levels reflected the strontium levels in the grass he munched each day and thus the strontium levels in the rocks on which the grass grew.

Tusks grow from the base, the oldest part of which is the tip of the tusk. By cutting the tusk into fine slices and measuring the levels of strontium isotopes in successive slices, it was possible to match those levels with known strontium levels in rock formations throughout Alaska – and hence trace his wanderings throughout much of his lifetime until he died 17,000 years ago at the age of 27, half the age of most mammoths at death.

The record revealed that when he was young, he travelled widely but as he aged, he travelled less far and less often. Sound familiar?

Here was brilliant detective work that mapped the travels of a young mammoth thousands of years ago. For me, who previously thought of mammoths in the plural, this was a one mammoth with a late-bequeathed name, and a story to tell through his tusk. Fascinating.

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the InfoHealth series at the Niagara-on-the-Lake Public Library.  

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