[Note: This is the eighteenth sample from my rough draft of a far from finished new book, Wild, Free, & Happy. I don’t plan on reviewing more books for a while. My blog is home to reviews of 201 books, and you are very welcome to explore them. The Search field on the right side will find words in the full contents of all rants and reviews, if you are interested in specific authors, titles, or subjects.]
Every continent has regions of grasslands — savannahs, steppes, prairies, and so on. Grasslands provide the nutritious greenery that can nourish herds of large herbivores. Forest or desert ecosystems are far less ideal for grazing animals. Meat provides nutrients that are essential for good health — nutrients much harder to acquire from wild grassland vegetation. Hunters prefer to kill a large animal, rather than numerous rodents, grubs, worms, and so on.
Naturally, the existence of large herbivores needs to be kept in balance by the existence of hungry carnivores. Too many grass eaters can turn grasslands into barren wastelands. Large herbivores and large carnivores are both megafauna. Megafauna are animals weighing more than 100 pounds (45 kg). (Outside of America, more than 50 kg.)
Many families of megafauna species have expanded across five continents: Africa, Europe, Asia, North America, and South America. During glacial cycles, some regions currently separated by water became connected by dry land, as sea levels dropped. Land bridges allowed megafauna on both sides to cross over into new habitats. Australia has mostly been isolated from the other five continents. It has its own unique story of herbivores, carnivores, and megafauna extinction spasms.
Buried under downtown London, construction crews have discovered the remains of hippos, elephants, Irish elk, aurochs, and lions. North America was the original homeland for the ancestors of horses, bears, rhinos, camels, and others. Horses and bears spread across the five continents. Camels expanded into Asia and Africa. Rhinos vanished from America five million years ago.
Mother Africa was the homeland for the saber-tooth cat group, which later expanded across Eurasia, and then to North America and South America. Africa was also where the elephant-like family began, which eventually colonized the five continents, diversifying into many forms over millions of years, including mammoths and mastodons. Until 13,000 years ago, mammoth country ranged from Western Europe, across Siberia, and down into Mexico. In the Americas, before hunters from Siberia arrived, there were seven elephant-like species.
On nutrient rich grasslands, a major trend in evolution was to encourage herbivores to gradually expand to jumbo-sized proportions, a trait that increased their odds for survival. Bigger was better — thicker hide, stronger, and more dangerous. Size mattered. For example:
Giant beavers could grow to 7.6 feet (2.3 m) long, and weigh up to 276 pounds (125 kg) — about the size of a black bear.
Giant ground sloths could grow as large as elephants. They could stand erect up to 20 feet (6 m) tall, and weigh 2,204 pounds (1,000 kg).
Giant armadillos were mammals that had an armor of bony plates. Some weighed more than 1,000 pounds (454 kg).
Short-faced bears were among the largest land dwelling mammalian carnivores. They could weigh over 1,500 pounds (680 kg).
Irish elk were giant deer that could weigh more than 2,500 pounds (1,133 kg). Their enormous antlers weighed more than the animal’s skeleton. They could spread up to 13 feet (4 m) across.
Of course, the rise of jumbo herbivores encouraged evolution to also select for larger carnivores. Grasslands were home to a continuous evolutionary arms race, the ancient sacred dance of eaters and eaten.
Later, when skilled teams of hominin hunters became prominent, jumbo size eventually became a huge liability. (Jumbo herbivores became as vulnerable as whales did when primates began harpooning them from boats.) Jumbo herbivores were easy to see, and they did not excel at high speed getaways. To hungry hunters, they were slow moving giant meatballs.
In 1961, Colin Turnbull noted that a Mbuti pygmy hunter could singlehandedly kill an elephant with a short handled spear. This deadly spear technology was available to African hunters two million years ago.
Paul Martin stimulated much controversy in the study of megafauna extinctions. In the 1960s, he was surprised to discover that in Africa, about 1.4 million years ago, a cluster of megafauna species went extinct. The number of elephant-like species dropped from twelve to eight. Three species of sabertooth cats, adapted for preying on large animals like the elephant family, also vanished from Africa. These cats had two long upper teeth that were useful for stabbing through the very thick hides of elephants. When the elephants declined, the huge incisors became a fatal handicap.
Baz Edmeades notes that this time period corresponds to when hominin hunters developed the larger and more complex Acheulean class of tools. Apparently, hominins were getting better at competing against the sabertooths for jumbo-sized prey. As the prey populations declined, so did the cats that ate them. Hominins can survive on a far wider variety of foods. When elephants are scarce, they can feast on eggs, grubs, or lizards.
The notion of hominin-caused extinctions 1.4 million years ago did not sit well with those who proposed the Great Leap Forward theory. While Jared Diamond accepted the notion of the more recent overkill in North America 13,000 years ago, the far earlier date clashed with his belief that humans were essentially cute chimp-class primates until 40,000 years ago, when the miracle of turbocharged cognitive abilities arrived. (This date also corresponds to the start of the human migration into snow country.)
Later, Martin grated even more nerves when he presented his research on the megafauna extinctions in North America. He framed them as a rapid thousand year “blitzkrieg” (lightning war) of overkill. Following World War II, there was a golden age of anthropology, when scholars visited many lands, and learned that most wild folks were not stupid, fiendish, bloody savages. In fact, they had many admirable traits. In fact, in many ways their lives were far healthier and saner than those of the anxious stressed out consumers of industrial civilization.
It became trendy to issue shining halos to wild people, because they were clearly not relentless maniacal planet thrashers. Indeed, compared to modern consumers, their eco-impacts can seem close to insignificant. But, as centuries pass, even modest impacts can gradually snowball into embarrassing blunders that hurl numerous species off the stage.
In hindsight, it’s easy to see that most or all techno-innovations have unintended consequences (even fire drills and wooden spears). These consequences can often outweigh the benefits. Also, the combined consequences of numerous innovations can swirl into bad juju hurricanes that can sharply impact the stability of entire ecosystems, even the planet’s atmosphere and climate systems.
It’s important to put these impacts into proper perspective. Compared to modern consumers, whose whirlwind lives have staggering eco-impact, the lives of those Pleistocene ancestors were much closer to ecologically sustainable. Walter Youngquist reported that in just the last few hundred years, highly educated civilized people have dug up and burned 500 million years of safely sequestered carbon, most of it during the lifetime of the baby boomer generation — me and my peers. Look, it took 1,400,000 years to finally drive all sabertooth cats extinct on five continents. It took just 40 years for greed-crazed American yahoos, with their rifles and railroads, to exterminate something like 60 million buffalo, and waste most of their meat. Technology matters.
At the same time, paying careful attention to reality leads to far less cognitive dissonance than indulging in magical thinking. Dan Flores prodded the romantics. If the Paleolithic was such a long wonderful era of harmony, why did our ancestors abandon it? Why, in the last 50,000 years, did they fan out across the world? Why does the pattern of megafauna extinction spasms correspond to the geographical pattern of human expansion?
It’s always embarrassing to compare the human saga to our ancestral baseline. Chimps and bonobos have continued to live sustainably, in the same way, in the same place, for several million years, without swerving off to dangerous experiments in technological innovation. We seem to be the one and only living species that has wandered off the traditional path. Many cultures have foolishly succeeded at monopolizing the exploitation of resources in their territories — a perfectly insane joyride of ecological self-destruction that will not have a happy ending.
Now, I must confess that I find it a bit difficult to effortlessly believe the overkill theory without a doubt. I mean, how could a modest population of hunters, travelling on foot, armed with spears, exterminate all of the horses in all of North America, over the course of a dozen centuries or so, while the bison and others survived? Many readers who have hunted wild horses with spears will find this idea hard to swallow. To get a deeper understanding of this extinction tragedy, it’s time to pull on our waders, slog down bloody Megafauna Lane, and take a bunch of selfies.
Trail of Tears
Hominins have been around for maybe 2.8 million years. During our visit on Earth, there have been several spasms of megafauna extinctions. The spasms during the hominin era began in Africa about two million years ago, when the hominin predecessors of Homo sapiens were romping around on the savannah.
Our species emerged maybe 300,000 years ago, and eventually expanded eastward, across tropical Asia. Around 50,000 years ago, folks arrived in Australasia, setting off a wave of large animal extinctions. Over the course of several thousand years, 17 out of 18 genera of megafauna blinked out.
What’s a genera? It’s the plural of genus. A genus is a category of closely related species. For example, the Homo genus includes the species Homo sapiens, Homo neanderthalensis, Homo erectus, and so on.
Around 40,000 years ago, humans wandered into Europe, where the extinctions were less extreme because the local megafauna had already been living with dangerous armed primates (Neanderthals and others) for maybe 500,000 years. The megafauna had learned the hard way that primates were not their good little buddies. In the European spasm, 21 of 37 genera vanished.
Eventually folks expanded across northern Asia (Siberia), and crossed into the Americas, where the extinction spasm was rapid and intense. Asia lost 24 of 46 genera, North America lost 45 of 61, and South America got hammered hard, with 58 of 71.
Finally, on many isolated islands, extinctions happened much later, when humans arrived. For example, 4,700 years ago in Cuba, 1,500 years ago in Madagascar, 500 years ago in New Zealand, and so on.
Attentive readers will perceive that this series of extinction spasms clearly corresponds to the expansion of humans into new regions. [Martin’s chart] It is also absolutely clear that the pattern of extinctions does not correspond to patterns in climate history. Most or all of the genera that blinked out had been in existence for at least several million years, and had survived numerous glacial cycles.
Fernando Fernandez summed up the extinctions more broadly. Between 50,000 years ago, and A.D. 1500, about two thirds of the world’s megafauna species went extinct. In this process, of the 150 genera of large mammals, at least 97 went extinct. This statistic does not include the extinctions in Africa prior to 50,000 years ago. When we take a moment to reverently sniff reality’s butt, it’s easy to see that, in the long run, innovation is not a good little buddy of the family of life. Our magnificent standard of living has mindlessly created a global gas chamber.