Putting the life back in science fiction


Younger Dryas Impact Hypothesis and Alt-History

Just a quick note for those who, like me, need to fiddle for a few hours while the world burns.  Oh wait, that’s not quite what I meant, but anyway, if you want a distraction, here’s one: the Younger Dryas Impact Hypothesis.

The basic idea, as noted in the Wikipedia link above, is that around 12,800 years ago, a bolide either fragmented above the Earth in sort of a super-Tunguska, or an asteroid hit (possibly under the Hiawatha glacier in Greenland, near where the Cape York meteorite was found.  And yes, possibly the Cape York fragments are part of it).  I’m personally partial to an asteroid strike because one of the (to me) more solid lines of evidence is a spike in platinum around the world dating from around 12,800 BP, found most recently in Africa, but basically on every continent except Antarctica.

This hypothesis is controversial of course–it should be, given the way normal science works.  But I think it does clear up some mysteries.  For example, it may explain why the megafaunal extinction happened around then in America and norther Eurasia, and not thousands of years earlier.

Anatomically modern humans were around for at least 300,000 years, and we evidently tried agriculture around 22,000 years ago near what’s now the Dead Sea.  While people like to hypothesize that ancient humans were more primitive than moderns, and that’s why they stayed few in number and simple in lifestyle, but I disagree.  I personally think that the reason that humans didn’t take over the Earth hundreds of thousands of years ago was that the climate in the ice age fluctuated too radically to allow the rise of civilization.    There’s little point in depending on crops if they fail most years.

Anyway, during those 300,000 years, humans lived alongside big animals (megafauna), except in the Americans (settled 10,000-20,000 years ago), in Australia (settled 65,000 years ago) and New Zealand and the Pacific (settled less than 3,000 years ago–we’ll ignore this for now).  My personal hypothesis before I started thinking about the Younger Dryas Impact Hypothesis was that megafaunal extinctions were due to human predation and habitat change.  While that’s unambiguously true in the Polynesian Islands and Madagascar (which I hate saying), it’s not clear what happened in Australia and the Americas.  In Australia, the aboriginal population first settled around 65,000 years BP, but the megafaunal die off happened “rapidly thereafter”(per the biologists)  starting around 46,000 years BP.  This is a classic example of why biologists need to do more math.  19,000 years of coexistence is NOT rapid.  Similarly in the Americas, humans lived alongside the megafauna for at least 2,000 years, if not 8,000 years, before the megafaunal extinction started “rapidly” happening.  We don’t blame Europeans or Asians for wiping out their mammoths and other megafauna (do you ever hear the Chinese criticized for wiping out the elephants and rhinos around Beijing 3,000 years ago?  That was considerably more rapid.).  That’s why I agree with the Native Americans and Aboriginals who say that accusations of ancient ecocide are just veiled neo-colonial attempts to justify taking their land.  They’re right: thousands of years of coexistence is not a short time.

And that leaves the Younger Dryas Impact. If it happened,  it presumably did not play a role in the Australian megafaunal extinction (it’s around 33,000 years too late), but it could have played a major role in the megafaunal extinctions in the northern hemisphere, and possibly into South America.  All that platinum had to come from somewhere.

One criticism leveled against the impact hypothesis is questioning why the proposed impact only killed big animals, not little ones.  That’s easily answered, at least if you believe Anthony Martin, author of The Evolution Underground: Burrows, Bunkers, and the Marvelous Subterranean World Beneath our Feet (BigMuddy Link, in case you want to read this really fun book).  He makes a point that during extinction events, mass or otherwise, animals that can shelter underground survive disproportionately well.  So if a smallish asteroid struck, especially during northern winter, it would harm everything living above the surface (e.g. the megafauna) but animals hunkered down in burrows, especially under the snow, would be proportionally less affected.    That’s not quite what we see, as things like bison and moose survived the possible impact, but it’s a reasonable hypothesis that can be tested.

Anyway, you can want to dive down the rabbit hole for shelter, you can waste  happy hours on something other than obsessing about national meltdowns in the US or UK.  That’s  one reason I’m posting this.

The other reason to post is that I don’t know of much, well any, alt-history SF that explores worlds where the impact didn’t happen and the megafauna of the Americas and Eurasia didn’t go extinct 12,800 years ago.  As an alt-history, the changes are rather subtle, more about setting than plot, in a No Younger Dryas (NYD) world. But they could be fun.

I’m pretty sure that agriculture and civilization would have arisen in NYD as they did in our timeline, although possibly 1,000 years or more earlier  (the Younger Dryas lasted around 1,200 years).  There are multiple reasons for this confidence:

  • Agriculture arose in West Africa, Ethiopia, China, India, and possibly Southeast Asia in places where there were lots of megafauna (elephants, rhinos, lions, tigers, etc.), so having big herbivores around does not preclude people inventing agriculture.
  • Someone tried agriculture back during the preceding ice age at least once that we know of, and that was with a full panoply of biggish critters around.  They most likely failed due to climate change, not rampaging mammoths.

What would be different in a NYD world is that mammoths, rhinos, cave lions, sabertooths, and all that ilk would either be present in modern times or recently extinct in civilized lands.  This would be particularly true in the Americas, if only because the classical Mediterranean civilizations, the Medieval Europeans, and the Chinese were all pretty darn good at getting rid of their megafauna.  Colonizing the New World would have been a bit more like attempts to colonize Africa than what actually happened, with the Hudson’s Bay Company equivalent trading as much in mammoth or mastodon ivory as in beaver furs, and livestock kept at night in kraals of, perhaps, spiny osage orange branches or similar, to keep the lions away.*

Anyway, it’s something for creatives to play with, if they want to distract themselves from the current chaos.  Heck, you could combine NYD with the Alt-Chinese colonizing (or attempting to colonize) the west coast of North America and introducing iron-working, first generation firearms, and a full complement of Old World diseases to the peoples of the Pacific Coast.  That would make things much, much weirder, especially if the Europeans colonized the east coast of the Americas centuries later in timeline, so that both the diseases and the technologies had their chance to rampage around the continent.

Have fun!

*Actually, there’s a whole post I could write about beavers as ecological engineers and about how their loss from the US just prior to European settlement has given us a really distorted idea of how this continent is supposed to work.  Maybe later.

 

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6 Comments so far
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I think the major possibility of a NYD world would be the presence of a wider range of animals that could potentially be domesticated than was the case. One of Jared Diamond’s major theses was that North American civilizations did not develop their technology or populations as rapidly as did European one’s for a number of reasons connected to geography, one of which was the lack of species that could be easily domesticated. Some of the criteria that Diamond lists as necessary for domestication are behavioral, which does not leave fossils and therefore we cant know for certain, but a sufficiently clever world-builder could probably make a plausible case for some of the fauna that went extinct. Which ones would make good candidates I have no idea, but I do note that horses were native to NA at that time. If they had not gone extinct, I expect that this would have had a significant impact on the development of culture and society.

Comment by Demarquis

I do tend to agree with Diamond that Australia is out, though, because the limited agriculture seems to have been pushing the limits of the possible. It’s just too variable here. And there’s never been a domesticated marsupial, although quolls would be worth the attempt IMO (bias: I want a pet quoll).

I’d like to read an explanation of the beaver issue, and ideally some exploration of (AFAIK) the odd prevalence of trees that produce edible items in NA after the loss of the human population. “they didn’t farm but they planted fruit trees everywhere” is a bit like the Australian view that aboriginies didn’t farm because their burning and seed-spreading doesn’t meet British standards (and vice versa, completely fucking the place in 10 generations doesn’t count as farming, at best it’s a form of mining)

Comment by Moz of Yarramulla

Some references for you, Moz, two of which you might have to buy:

The simple problem that Europeans have a limited idea of what agriculture looks like (grain, basically). There was something very much like agriculture in California, in the Pacific Northwest, in the Amazon, and in Australia. The trouble was, it was trees and/or fields of flowering bulbs rather than fields of grain, and it supported a lower population density than a true civilization requires, so it got dismissed as hunting and gathering.

You’re probably familiar with the Amazonian example of terra preta and food forests, from 1491. The best reference for California is Kat Anderson’s Tending the Wild. For Australia, it’s Dark Emu. For the Indians of Vancouver island, you can get a bit of it in this article from Hakai. I recommend Hakai just for having a lot of really good articles, although it focuses on Pacific Northwest coastal issues.

The beaver thing is really cool. You can read all about them in Ben Goldfarb’s Eager: The Surprising, Secret Life of Beavers and Why They Matter. The overly short version is that they used to be ubiquitous in North America and Europe. The dams they made radically shaped most watersheds, slowing water down, recharging aquifers, sequestering carbon in pond sediments, and providing habitat for a wide variety of aquatic organisms. Since the dams were mostly ephemeral (over the course of several years), they also meant that beaver-filled streams were constantly changing, and the constant flux of ponds changing back to streams and vice versa meant even more habitat richness as old dams broke down and new dams were built.

The fur trade wiped most beavers out of North America ahead of the colonial expansion (another one of the British Empires crimes against the world, degrading a continent for the sake of men’s fashion…), so the settlers encountered a landscape with denuded creeks cutting down into valleys that were becoming increasingly arid. They not only thought that was normal, they thought (and often think) that beavers recolonizing these landscapes are destructive nuisances rather than animals that could make stream valleys more fertile and floods less destructive. This view is changing in some places faster than others, but it’s still delightfully strange to people like me.

Comment by Heteromeles

I do tend to agree with Diamond that Australia is out, though, because the limited agriculture seems to have been pushing the limits of the possible. It’s just too variable here. And there’s never been a domesticated marsupial, although quolls would be worth the attempt IMO (bias: I want a pet quoll).

I’d like to read an explanation of the beaver issue, and ideally some exploration of (AFAIK) the odd prevalence of trees that produce edible items in NA after the loss of the human population. “they didn’t farm but they planted fruit trees everywhere” is a bit like the Australian view that aboriginies didn’t farm because their burning and seed-spreading doesn’t meet British standards (and vice versa, completely fucking the place in 10 generations doesn’t count as farming, at best it’s a form of mining)

(yep, wordpress has made me dance in circles again. you might get several copies of this comment, or maybe wordpress just threw them away)

Comment by Moz of Yarramulla

There are a lot of places where beaver lakes could theoretically be a cheap and effective solution to a lot of existing problems, but I’m not sure how practical it is as a proposal before the gigadeath. Is there a good economic and political solution for allowing beaver-cultivation in places that they don’t currently occupy? Even if managed land abandonment is feasible without genocide I have to wonder about how viable it is to expect beavers to deal effectively with the remains of current and past land uses. Some of it they might deal with better than anything we can do, but I hesitate to imagine them as a cure-all for both natural decline and all the human-mess issues including salinized soil, invasive species, mine tailings, and whatever other hazards and pollution issues get left behind.

I see your alternate-history challenge and propose the Romans crossing the Alps with mammoths to conquer Carthaginian Iberia, taking Hannibal by surprise.

Comment by anonymous coward

As I responded to Moz, I think the questions you asked are best answered in Ben Goldfarb’s Eager: The Surprising, Secret Life of Beavers and Why They Matter. There’s actually a growing movement to rewild beavers across the US. Not that it’s my choice, but I’d say that helping beavers survive the coming altithermal is one of the smarter things that northern hemisphere humans can do.

Comment by Heteromeles




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