I’ve long been interested in the megafauna extinctions of Pleistocene North America. A number of books endorse Paul Martin’s “Pleistocene Overkill Hypothesis,” which asserts that the early humans on the continent were “super predators” who launched a blitzkrieg of overhunting. Hunting began in northwest Canada, and spread south and east like a wild fire. Within 2,000 years, at least 33 genera (50 species) of large mammals went extinct — many more than in the preceding three million years. At first contact, large animals who had never before seen odd-looking humans, did not sense danger.
In other locations, when humans first arrived, extinctions followed — for example, Australia, New Zealand, Madagascar, and Caribbean islands. Hunting, and hunting alone, was the cause, said Martin. His ideas really pissed off Native Americans, like Vine Deloria, because overkill implied that Indians were as foolish as Euro Americans.
Deloria blasted the hypothesis, pointing to the fantastic number of bones found in northern Siberia — mammoths, mastodons, rhinos, horses, bison. Chinese have been hauling away mammoth tusks since medieval times, and this ivory is still being mined today; a high-quality tusk can fetch over $40,000. The white keys on grandma’s piano might be mammoth ivory.
These bones were not the result of a blitzkrieg. Mastodons had been living in Siberia for 400,000 years, and woolly mammoths for 250,000 years. The frigid climate helped to preserve their remains. In central Russia, more than 70 mammoth bone huts have been found. One hut had 385 bones, and weighed 20 tons.
I just read The Call of Distant Mammoths by paleontologist Peter Ward, and learned a lot about extinction and evolution. I’ve often wondered how hairy lads, on foot, with wooden spears, were able to exterminate every horse in all of North America within 2,000 years. Bison were also residents of the open plains, able to sprint up to 35 miles per hour, and they did not go extinct — and horses could run even faster.
Ward introduces us to the climate change hypothesis. During the two million year Ice Age (the Pleistocene), there were at least 18 glaciation cycles. Until the last cycle, the megafauna had mostly survived. The last one began 18,000 years ago, and it was the most intense of all. It ended 12,000 years ago. The ice pack melted, forest advanced, and habitats rapidly changed. The mammoth tundra fragmented and shrank, which split the herbivore population into isolated groups.
Ward also studied the extinction of dinosaurs. They roamed the Earth for 160 million years, and then disappeared. Ward was an early advocate of the notion that the dinosaur mass extinction was sudden, caused by an asteroid strike near Chicxulub, Mexico. Some say it resulted in a decade of near-freezing temperatures on a planet that was largely tropical.
Throughout the dinosaur era, small mammals also existed — insect eating night creatures. The extinction of dinosaurs eliminated large animals, and made the age of mammals possible. If not for the asteroid, humans and elephants would have never evolved. Mammoth country once ranged from France to Siberia to New York.
Our primate ancestors evolved in the trees. Their tropical homeland was eventually chilled by an era of glaciation. It thinned the rainforest, and expanded savannahs, which encouraged the evolution of large mammals, including our hominid ancestors. Thus, you and I are the children of climate change and asteroids.
Evolution is a process that creates and deletes species. New species can only emerge when a group becomes isolated, evolves unique traits, and eventually becomes unable to interbreed with their old kin. Homo sapiens come in many sizes, shapes, and colors, but all belong to the same species, because we can all interbreed. Ward expects white skinned people to disappear in a few thousand years, because of their increasing vulnerability to skin cancer.
Our cultural myths tell us that humans are continuously getting smarter. Ward believes that the brains of modern humans are essentially the same as the first Homo sapiens in Africa, 125,000 to 200,000 years ago (but we’ve learned lots of stuff since then). Once a new species emerges, it changes little thereafter. Humans are the last species of the hominids, and this has risks. A gene pool has better odds for long-term survival when it diversifies into multiple species, as the ants have.
Another way for critters to avoid extinction is to become generalists, like humans, rats, and cockroaches, who have adapted to many different ecosystems around the world. Today, humans live everywhere. There is no place a group could remain isolated for millennia. So, there is little chance for a new hominid species to emerge.
Evolution is random, like tossing dice. The process is influenced by ongoing environmental change, natural selection, and genetic drift (chance genetic changes). Evolution has no foresight; it can’t anticipate coming changes. It’s not always progressive. Greenland ice core data tells us that there have been times when global temperature changed up to 18°F in a few decades. Many gene pools that work well in one set of conditions will fail to adapt to sudden shifts.
The golden rule of evolution is adapt or die. Ward doesn’t discuss cultural evolution, which is a million times faster than genetic evolution, and has catapulted humankind onto extremely thin ice, by overloading our tropical primate brains with way too many half-smart ideas. We are, by far, the world champion resource parasites. We are hurling countless species into the abyss in our insane impossible quest for perpetual economic growth.
In an extremely quirky twist, Ward celebrates human supremacy at causing mass extinction. “We are the comet now. And not only have we won the game of evolution; we control the rules of the game,” he wrote. “And to this winner, in my view, goes an even greater prize: species immortality. It is my opinion that no matter where on the board we humans land and no matter what card we draw, we cannot be knocked into extinction.” Who could disagree?
The book was written 20 years ago, when resource limits and climate change were still dumb ideas among the lunatic fringe — rational people. Ward is employed in academia, which remains a militant hotbed of radicalized human supremacists.
OK, back to the megafauna. Doubts are growing about the overkill hypothesis. Martin claimed a sudden 2,000-year rampage wiped out the megafauna, but this was based on data generated by obsolete dating technology. Improved dating does not confirm sudden extinction. Martin claimed the extinctions fanned out in a wave, beginning in Alberta — so kill sites far from there should be more recent. They aren’t. We have only discovered a dozen sites where human artifacts are found with mammoth remains.
Dan Fisher has studied of mammoth tusks in Michigan and Ohio. Tusks have annual rings inside, like tree trunks. Rings are thin in hungry years. In female tusks, rings mark each pregnancy, providing a birth rate. If climate change had killed the mammoths, the rings would indicate malnutrition, but Fisher found that the last mammoths were “fat, fit, and well fed.”
Ward suspects that the mammoths were not the victims of a blitzkrieg. Unlike bunnies, mammoths were slow to mature, and had low reproduction rates. If hunters had regularly taken just two percent of the animals each year, the extinction process would have taken 400 years — too slow for each generation of hunters to notice. Hunting alone could have wiped them out. Ward thinks that if there had been no hunting, mammoths would probably have survived the warming climate.
In the 1990s, editors adamantly insisted that manuscripts like Ward’s include brilliant solutions and happy endings, because bummer books didn’t sell. So, his mammoth book ends with a happy visit to the year 3001. Population was well below its peak of 11 billion. The U.S. grain belt was a desert. African survivors were healthy vegetarians with solar panels and pedal-powered transport. The rainforest was long gone, replaced with endless fields of GMO crops. Wildlife and livestock had been eliminated by starving hordes. Happily, the human species survived — hooray!
Compulsory happy endings meant that vital knowledge was deliberately withheld from an entire generation, who are now teachers, reporters, and leaders. Even today, a “don’t frighten the children” strategy remains common among educators, and young minds are still being infected with a carcinogenic worldview. Bummer!
Ward, Peter D., The Call of Distant Mammoths, Copernicus, New York, 1997.