Daily MOS: The Toba Catastrophe That Wasn’t

Humans are delicate little carbon flesh sacks. If you’re alive today, it means you’re the result of an unbroken chain of DNA that’s been passed down since the beginning of life on Earth, surviving famines, diseases, and whatever the fuck passed for fifth century food safety protocols.

Then of course, there’s been the occasional extinction level event. A few of us survived, and nature’s been working to rectify that ever since.

Today’s Moment of Science… The Toba Bottleneck that probably never happened.

A genetic bottleneck occurs when a small subset of a population survives a mass die-off. Sometimes it’s because of a genetic quirk that helps you survive, sometimes it’s by virtue of being far enough away from the earth shattering kaboom. Whatever the cause, the drastically reduced species size, if built back up, gets a new and different genetic fingerprint. Some ethnic groups individually have been through genetic bottlenecks after genocides, and the human population as a whole has likely been shaped by our deaths as much as our births.

So when evidence of the Toba supervolcano’s eruption approximately 70,000 years ago came to light, it was pretty natural to think, “someone not named Rudy Giuliani banged their cousin to save the species.”

There are only a few things that can fuck up life on this planet quickly and for all of us. Large scale nuclear disasters, a huge asteroid, Dane Cook’s comedy career, and giant fucking volcanoes. The Toba explosion was orders of magnitude more powerful than any volcanic explosion in modern history. It ejected 2,800 cubic kilometers of gasses, ash, and magma into the air.

For comparison’s sake, the eruption of Mt. St. Helens in 1980 was pretty devastating and it unleashed a mere one cubic kilometer of bullshit on Washington state.

It was hypothesized that there was a volcanic winter for several years and the temperature of the planet dropped for a millenium. Greenland ice cores show increased dust deposits and a change in oxygen isotopes. Seeing the global scale of it, scientists tossed around a hypothesis that we’d had a population bottleneck. It made for splendid headlines. My favorite was that the human race had gotten down to as few as 40 breeding pairs.

But, as with many great fantastical stories, this one is looking more and more like a fairy tale, possibly one with a sinister motive.

The popularizer of the story was one Henry Harpending, professor of anthropology at the University of Utah. The bottleneck caused a “genetic break” between Africans and Europeans, he argued, and subsequently human evolution sped up outside of Africa the last 10,000 years. He believed there were major differences in races that have been fundamental in explaining societal differences, and the bottleneck theory fed into his explanation that something helped differentiate us other than geography. So it must be their inferior genes, and here’s this convenient volcano that upended the planet to blame.

Now, it’s true that humans started moving out of Africa around the same time the volcano had its little tantrum, give or take a few tens of thousands of years. But, the theory was that they left Africa seeking a more hospitable climate after the eruption is nonsense. Newer studies indicate that the climate of Africa was barely touched. Furthermore, new studies show humans were seemingly living in India by that time. Though they’ve found Toba’s ash in the fossil record, it also seems that human tools were found before and after the ash, suggesting humans survived.

Some still hold fast to the hypothesis that Toba caused a mass die-off, but it’s not a widely accepted theory anymore.

Professor Harpending died a few years ago. He denied that any of his motivation for his ideas were because he’s a racist, but he denied that when giving a speech at H.L. Mencken, an organization run by Richard Spencer and other noted nazis, so.

Toba likely killed a lot of people and fucked up life on the planet for a good long time. Population bottlenecks have happened to other species and likely will happen to us come hell or high asteroid. But as has happened to so many other hypotheses in science, what is corrupted by motivated reasoning can be corrected by evidence.

This has been your daily Moment of Science, and a lesson that you have to change on the fly with science. Because I was planning to write about the Toba bottleneck event that I was sure was a thing. Awkward.

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