They ran out of groceries
It was probably humans who killed off the megafauna.
For a long time, these extinctions were thought to be linked to natural changes in the environment – until 1966, when palaeontologist Paul S Martin put forward his controversial “overkill hypothesis” that humans were responsible for the extinctions of megafauna, destroying the romantic vision of early humans living in harmony with nature.
Well, it was harmony from the early humans’ point of view.
Prof Mark Maslin, from University College London (UCL), suggests that the unsustainable hunting of megafauna may have been one of the driving forces that led humans to domesticate plants and animals. People started farming in at least 14 different places, independently of each other, from about 10,500 years ago. “Weirdly enough, I think the first biodiversity crisis was at the end of the last ice age, when early humans had slaughtered the megafauna and therefore they’d sort of run out of food, and that precipitated, in many places, a switch to agriculture,” he says.
Although the debate is far from settled, it appears ancient humans took thousands of years to wipe out species in a way modern humans would do in decades. Fast forward to today and we are not just killing megafauna but destroying whole landscapes, often in just a few years. Farming is the primary driver of destruction and, of all mammals on Earth, 96% are either livestock or humans. The UN estimates as many as one million plant and animal species are at risk of extinction.
And that’s on top of what we’ve already driven to extinction.
“Farming is the primary driver of destruction”
Here are a couple of articles about a proposed way to reduce that problem.
There are more on that website.
https://www.replanet.ngo/post/entire-world-s-protein-can-be-produced-on-an-area-of-land-smaller-than-london
https://www.replanet.ngo/post/towards-a-farm-free-future-everything-you-need-to-know-about-fermenting
With each passing year, it’s becoming clearer that world oil production peaked in 2018.
https://crudeoilpeak.info/will-the-world-ever-reach-peak-crude-production-of-november-2018-again-part-1
What will the downside be like? Talk about pulling the rug out underneath ourselves…
Even if humans didn’t kill each and every animal, it wouldn’t take a lot of hunting to drive any slow to reproduce species to extinction. If the animals in question were “naive,” unacustomed to recently arrived humans as predators (unlike African megafauna, which had had millions of years of experience evolving alongside hominins), then it’s possible that the “hunts” were a lot easier than we might expect. Certainly the wave of island extinctions which coincided with human arrival once we became a seafaring species looks like more of the same.
I used to think that early human cultures, which might have had a more supernaturally tinged understanding of prey animal population dynamics rather than a biological one, might be excused because of their comparative ignorance. Unfortunately, our allegedly knowing “better” doesn’t seem to have made a big difference to our overall behaviour. Certainly there are small victories, but if there’s a buck to be made, whate species, ecosystem or biome is going to be allowed to stand in the way? Rather than the gods and goddesses of the hunt, our sacrifices (and those we inflict on and extract from other beings) are made to the almighty dollar, a god that can never be satisfied.
Agriculture has historically been the driver of extinctions, but now it appears to be urbanization (which also is wiping out farmland – nearly every WalMart I ever see is sitting on former farmland, just as the house I live in is sitting on former prairie).
We ran out of groceries, found a way to provide more by wiping out other organisms. Then we ran out of space, and found ways to provide more by wiping out other organisms.
Either way, it is lose-lose in the long term.