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What Happened to Ancient Megafauna?

nautil.us

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Re: What Happened to Ancient Megafauna?

#11

Post by AlotOfReading »

linearrust wrote: post #3

> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses. Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? > I think work over the past few decades has rather…

They don't know any particular specifics. Our understanding of human organization during the late pleistocene and early Holocene is poor, bordering on non-existent. However, I don't find it particularly hard to imagine humans as a major factor, even if I have some doubts about this particular argument.

First, you have to understand that about the late quaternary extinctions, we know not all quaternary extinctions were anthropogenic. Ecosystems were experiencing a lot of different stressors around that time, and by the time extinction actually happens there may have been only small populations left for centuries or millennia. Ecological resilience is also a bit of a funny thing. You might think that you make 10 species extinct has 10x more impact than just 1 extinction, but there isn't a linear relationship. In many ecosystems, there's very little impact from most local extinctions as the graph thins out until all the systemic resilience is gone and the whole thing suddenly collapses into a new state. Did that proximate cause(s) of the last extinction cause the rapid shift?

Fantastically deadly hunters like humans that are specialized to megafaunal hunting being able to push the most vulnerable and stressed parts of the ecosystem over the edge isn't an obviously absurd argument to me.

Re: What Happened to Ancient Megafauna?

#12

Post by alfiedotwtf »

linearrust wrote: post #3

> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses. Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? > I think work over the past few decades has rather…

Thinking out loud… I wonder if it could still be true based on the fact that the larger the animal, the longer the gestation period.

For small animals like rabbits, it’s about 30 days - so their chances of “multiplying like rabbits” is obvious - you’re not going to wipe out rabbits faster than the supply.

As you move up the size scale, the gestation period gets longer and longer, and each kill gets harder to replace (wales come in at around 18 months!). Kill a mega-sloth and its chances of species survival dramatically drop!

Re: What Happened to Ancient Megafauna?

#13

Post by alfiedotwtf »

AlotOfReading wrote: post #8
cryptonector wrote: post #5

This guy ( https://www.youtube.com/@Antonio_Zamora ) makes a very solid argument that in the Younger Dryas a meteorite impactor hit the ice sheet over the Great Lakes, sending huge ice chunks flying that created elliptical craters that then quickly refilled that are called the Carolina Bays, and which are ubiquitous in the South East, and which point back at the impact point(s) (I think he says there were two impact…

There's a real danger in getting misinformation from YouTube channels. The Younger Dryas Impact Hypothesis has been extensively refuted multiple times. The latest such paper ( https://doi.org/10.1016/j.earscirev.2023.104502 ) is pretty exhaustive in exploring the history of these ideas and how they fall short.

YouTube is like the anti-Wikipedia. It’s easy to create videos and the only check are comments buried 200 comments down

Re: What Happened to Ancient Megafauna?

#14

Post by Xen9 »

defrost wrote: post #7

The linked nautil.us article is a one sided poor summary of what is still an ongoing debate with strong beliefs on either side. Two people are quoted: * Jens-Christian Svenning, director of the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere at Aarhus University. He’s also the lead author on a recent paper published in Cambridge Prisms: Extinction that argues it was not clima…

Darwin (1) near consistently included each and every argument & counter-argument to the point where it becomes boring and unreasonable to go any further (2) was absolutely explicit of what was NOT included to the point that there were redunant remarks about that!

---

The view of Smith is laughable, for the human population has changed by more than few orders of magnitude since those times.

Yet it would be plausible that a global MF ecosystem was distrupted somehow.

Another possible reason megafauna died: they eat plants and grew on top of an ecosystem where there was not much competition for plants, and then an increase in efficiency of bacteria, bugs, invertebrates and other compact herbivore species in consumption of the limited amount of plant food pulled the legs under them. Whales were not herbivores, and possibly therefore not subject to same mechanisms (though saying this sort of ruins the metaphor of pulling legs from underneath).

Re: What Happened to Ancient Megafauna?

#15

Post by deadbolt »

linearrust wrote: post #3

> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses. Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? > I think work over the past few decades has rather…

> The most devastating blow for the buffalo, wolves, bears, etc was habitat loss.

Wasn't the most devastating blow to Buffalo the campaign by settlers to slaughter them, since they were important to the native Americans?

Re: What Happened to Ancient Megafauna?

#16

Post by hnfong »

AlotOfReading wrote: post #8
cryptonector wrote: post #5

This guy ( https://www.youtube.com/@Antonio_Zamora ) makes a very solid argument that in the Younger Dryas a meteorite impactor hit the ice sheet over the Great Lakes, sending huge ice chunks flying that created elliptical craters that then quickly refilled that are called the Carolina Bays, and which are ubiquitous in the South East, and which point back at the impact point(s) (I think he says there were two impact…

There's a real danger in getting misinformation from YouTube channels. The Younger Dryas Impact Hypothesis has been extensively refuted multiple times. The latest such paper ( https://doi.org/10.1016/j.earscirev.2023.104502 ) is pretty exhaustive in exploring the history of these ideas and how they fall short.

In your link, the first words of the abstract is:

"A series of publications purport to provide evidence that..."

So even published papers contain such "misinformation", it isn't specific to Youtube. I have no training in the areas of archaeological evidence, so I don't know what to make of the paper, but it looks like people are just arguing about evidence of whether there was an asteroid impact.

It's interesting though that the title of the paper is called "Complete Refutation" of the hypothesis and not of the evidence. If you're nit-picky enough you'd notice that the YDIH isn't a "scientific" hypothesis per se since hypotheses about what happened in the past doesn't really give testable predictions, and actually what they did in the paper was to refute all the evidence of the hypothesis -- but it seems to me it's still theoretically possible for new evidence to come up that definitely supports YDIH.

Also, AFAICT this only rules out the asteroid impact. It still doesn't rule out the possibility that the abrupt climate changes during the Younger Dryas causing stress to the megafauna population, which presumably is another thing.

Re: What Happened to Ancient Megafauna?

#17

Post by BurningFrog »

nkrisc wrote: post #10
linearrust wrote: post #3

> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses. Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? > I think work over the past few decades has rather…

> Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? Consider that African megafauna have co-existed with early hominids and eventually humans for millions of years. They may have simply adapted to human predation successfully enough to survive, as one factor. Whereas in North America and elsewhere you have th…

Right, we're a native species to Africa, so its whole ecosystem evolved with us.

I think of this when I hear about "poachers" killing animals in African nature reserves. How often is that hunter gatherers who been there for thousands of years, and whose hunting is/was really part of the ecosystem?

Re: What Happened to Ancient Megafauna?

#18

Post by shawn_w »

alfiedotwtf wrote: post #12
linearrust wrote: post #3

> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses. Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? > I think work over the past few decades has rather…

Thinking out loud… I wonder if it could still be true based on the fact that the larger the animal, the longer the gestation period. For small animals like rabbits, it’s about 30 days - so their chances of “multiplying like rabbits” is obvious - you’re not going to wipe out rabbits faster than the supply. As you move up the size scale, the gestation period gets longer and longer, and each kill gets harder to replace…

The number of offspring in each litter tends to drop with increasing size, too.

Re: What Happened to Ancient Megafauna?

#19

Post by arthurbrown »

defrost wrote: post #7

The linked nautil.us article is a one sided poor summary of what is still an ongoing debate with strong beliefs on either side. Two people are quoted: * Jens-Christian Svenning, director of the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere at Aarhus University. He’s also the lead author on a recent paper published in Cambridge Prisms: Extinction that argues it was not clima…

Could you provide some more details about the Tasmania example? Seems humans reached Tas "at least" ~40,000 years ago from my simple searching, which isnt too far off from the generalised 50,000 mentioned in the article.

Which species went extinct before then?

https://www.sciencedirect.com/science/article/pii/S030544032...

Re: What Happened to Ancient Megafauna?

#20

Post by hanniabu »

BurningFrog wrote: post #17
nkrisc wrote: post #10

Earlier quoted context omitted.

> Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction? Consider that African megafauna have co-existed with early hominids and eventually humans for millions of years. They may have simply adapted to human predation successfully enough to survive, as one factor. Whereas in North America and elsewhere you have th…

Right, we're a native species to Africa, so its whole ecosystem evolved with us. I think of this when I hear about "poachers" killing animals in African nature reserves. How often is that hunter gatherers who been there for thousands of years, and whose hunting is/was really part of the ecosystem?

Comparing hunting with rudimentary weapons to hunting with modern firearms is insane
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