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Toba Catastrophe Theory

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49 pointsbenbreen17 comments

My understanding is that most of the modern research has generally advised against the idea that Toba caused a population bottleneck. I'm not sure there's any archaeological evidence of any hominid settlements that were abandoned as a result of the eruption--and there are several sites that demonstrate continuity through the eruption. Furthermore, better constraints on the date of the Toba eruption appear to put it after the onset of the glacial period.

So the theory that it caused a severe bottleneck is something that I'd consider 'discredited' rather than 'disputed' or even 'controversial.'

If not Toba, it still seems likely that there was a severe population bottleneck at some point. How else can we explain why human genetic diversity is substantially lower than so many other species, including our nearest extant evolutionary relative, the chimpanzee?

Might a serial founder effect during the peopling of Eurasia result in low genetic diversity and the fact that diversity increases the closer you get to Africa? Is there a way to distinguish low diversity due to a serial founder effect and a bottleneck cause by a natural catastrophe?

Given an average 25 years per generation what blows my mind is this all occurred maybe 2500-3000 generations so.

If correct, that's a lot of diversity in so few generations. Image what could have been.

> According to the genetic bottleneck theory, between 50,000 and 100,000 years ago, human populations sharply decreased to 3,000–10,000 surviving individuals.

This is one of the reasons I believe that any concept of humans living in “harmony with nature” is deeply flawed. Nature is scary and does what it will do.

Humans have to look at things through the lens of controlling and managing nature for our benefit and put any sentimentality about “balance” and “harmony” aside.

To some extent that's true, but you're missing a fundamental aspect of humanity's relationship with nature: we're completely dependent on it, but it's not dependent on us.

Humans, for example, could change the biosphere to the extent that human life would be difficult, and billions of us would die off. Nature, however, wouldn't "care" at all, as life tends to find a way.

The looming background risk of nature the most distressing part of the constant and ongoing petty human squabbling.

The coronavirus is really nothing compared to the scale of disaster that is expected over a 100 year period. And yet people persist in running down all their buffers and living lives assuming that nothing will go wrong. Their really should be an expectation that every household has at least a years supply of tinned food.

> Their really should be an expectation that every household has at least a years supply of tinned food.

What scenario do you have in mind there, where the ability to get basic supplies is disrupted so badly and widely that we don't have the resources to send in help, but also things are mostly resolved after a year?

My feeling is that if you exclude the 1-5% of people in the most extreme areas, then everyone else can get through almost all reasonably recoverable disasters with 2-4 weeks of emergency food and water. And if it's not reasonably recoverable then extra canned food is of pretty limited use.

More supplies means more time to find new food sources. If you have two weeks supply then you start acting on desperation after the first week. If you know you have a year’s supply you are less likely to take unnecessary risks.

In an area so big that no help is coming any time soon (because if it was, just wait a week), what new food sources? Spreading everyone out over the land and trying to set up subsistence farms is already a nightmare scenario and a year of canned food isn't enough resources to get there either. Other than that, what's going to feed everyone? And why couldn't we have gotten it set up within the first couple weeks?

It doesn’t need to be a big area. In war, a single town can be cut off from supplies for months or years.

> months or years

Where, again, for most durations in that range it doesn't matter if you have 3 weeks of food or 60 weeks of food, you're going to run out. And it's not a good situation to start setting up tons of farms either.

You'd need evacuation preparedness, not more cans. Other emergency supplies would be better, and if you already have enough supplies just keeping the money around for an emergency is more likely to have a bigger impact on your life.

> Humans have to look at things through the lens of controlling and managing nature for our benefit and put any sentimentality about “balance” and “harmony” aside.

Why? This seems like a religious statement ("man was created in the image of god" and therefore needs to be the apex of creation). What makes us more important than the rest of nature? What makes us think that we're somehow separate from nature?

There's an implicit "if we want to keep living with nature, or indeed at all".

That's the why. If you don't agree, oh well. Most people think that's a key motivation though.

It doesn't necessarily make us more important or separate.

This event comes up in the Atlantis Gene book series, which is one of my favorite. It’s Indiana Jones meets Star Trek, and instantly drew me in.

As a Brazilian, any Toba catastrophes terrify me.

I had no idea there was such a severe bottleneck in the recent past. Only 3-10k living humans! It really inspires a sense of how overwhelming geological timescales are, and what a new phenomenon the Anthropocene is.

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