Aug 222016
 

I always assumed that modern humans, living in industrial societies, did most of the animal extermination in the world. After all, there are billions of us, covering a good portion of the planet. Everyone knows that Europeans wiped out the dodo in the 16th century, and the passenger pigeon (which had been perhaps the world’s most common bird) in the 19th. We see photos of poachers shooting elephants and rhinoceroses. Clearly we are a destructive species. It’s not like long ago, when we lived as simple hunter-gatherers,  in harmony with the planet.

I was surprised to learn that hunter-gatherers didn’t live in harmony with nature at all. Our ancestors ate their way across the planet, causing one of the biggest extinctions the world has ever seen. The extinction of the dinosaurs? It’s nothing compared to this.

The trouble is, it’s very difficult for a hunter-gatherer to live sustainably. Of course, you can go into the forest and shoot a deer, but, whether you’re using a rifle or a spear, if you keep this behaviour up for long, the deer in the area will soon be gone. To live sustainably, the hunter gatherer needs a very large area of land, so the animals can reproduce and make up their lost numbers. In good conditions (lots of water and plant life), it’s estimated that one hunter-gatherer can survive well on about 150 hectares. That’s about 370 acres and a lot of walking.

In an industrial society, one person eating an extravagant Western diet, with cereals, vegetables and plenty of mean is supported by 0.5 hectares per person. The land supporting one hunter gatherer will support about 740 fat Americans.

Most people in the world are supported by much smaller amounts of land. According to the UN Food and Agriculture Organization, the minimum land to support a person, with careful farming and a vegetarian diet is about 0.07 hectares (0.17 acres). So the land that will support one hunter-gatherer can support over two thousand subsistence farmers.

The problem is that, in real life, hunter-gatherers didn’t live sustainably. They didn’t try. They moved around the planet. As they moved into new areas they would eat every animal they could kill, then move on when the animal population was exhausted. That’s why people wandered the globe. They weren’t sightseeing – they were following the food, sometimes backtracking to sweep back over areas that had recovered from the previous pass.

It’s thought that early humans used persistence hunting to kill animals. It involves chasing animals at our slow, steady pace, and forcing them to gallop until they collapse from exhaustion. Even large animals could be hunted this way, and we seem to have evolved to become slow, long distance runners.

In some parts of the world, like Africa, the animals had a chance to adapt to this dangerous upright ape, and they evolved strategies to deal with humans. In other parts of the world, where animals had never seen humans before, the hunting was as easy as it was thorough, and the devastation increased as humans became better hunters.

Humans arrived in North America around 13,000 years ago. Once they’d passed the ice sheets, they found a huge area, teeming with wildlife.

In the space of a thousand years, people had worked their way from Alaska to the southern tip of South America, eating and producing more humans as they went, and wiping out virtually every large species on the continent.

That included every wild horse. (All North American horses are descended from European imports.) Every tapir. Various elephants (mammoths and mastodons). Most of the big cats, like lions and cheetahs.

Giant ground sloths.

This is a glyptodon. It’s a giant armadillo the size of a car. All eaten. People used the shells for houses.

Humans hunting Glyptodon

There were nine-foot salmon known as “sabertooth salmon” (really!). Delicious. All gone.

We wiped out most of the camels. That’s right. Camels are originally from North America. The ones in Egypt, and the shaggy ones from Asia are descended from North American camels that migrated west.

One of the few survivors was the pronghorn, or North American “antelope”. It’s one of the fastest animals on earth, nearly as fast as a cheetah, and able to run much, much further. Hard for a human hunter to catch, and not a good target for persistence hunting.

This disappearance of most of the world’s large animals is known as the Quaternary extinction event. Some scientists think it was caused by climate change, but if it was, it was an usually selective climate change, wiping out large animals but leaving the most of the small animals and birds. And when humans arrived in Australia and New Zealand, the animals there disappeared in just the same way. Humans didn’t arrive in Madagascar until 2000 years ago, long after the ice ages were over, but all the large animals there had disappeared within a few centuries.

The idea of living off the land, in harmony with nature, is mostly a myth. In fact, a modern human has less impact on the environment than any human in history, and much less than humans in pre-history. With the right technology we could reduce that impact still further, allowing billions of humans to coexist with wildlife in a way that was impossible for our ancestors.

 Posted by at 6:04 pm

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