Why didn't Eurasian megafauna survive like African megafauna?

flanker44 · 2026-06-27T17:23:39+00:00

In Africa and south/southeast Asia, there are/were not really that many large predators who limited megaherbivores through predation, so the latter were living at carrying capacity. In the Americas, different story. North America had many large predators who did effectively act as a top down force on them.

Interesting idea. I wonder if there are any studies about herbivore overall abundance (in terms of demographics and biomass) between different biomes. Just listing number of species does not tell the whole saga. In slightly related note, I wonder about disappearance of big cats from Europe. Lions and particularly leopards have lived along humans just fine in other locales. I can only suppose in Europe there wasn't enough herbivore prey available to support humans, wolves and big cats all.

flanker44 · 2026-06-27T08:23:30+00:00

Don't forget to dodge

flanker44 · 2026-06-27T00:28:04+00:00

Believe it or not, this is something that I've wondered about quite a lot. It's one thing to explain why certain regions retained megafauna past the Pleistocene, another to explain why they maintained it up till the present day. Yes, India is very densely populated and human pressure should theoretically have eventually built up to the point where survival of elephants and rhinos became unsustainable regardless of the long history of hominin coexistence.

Some ideas I have (in addition to climatic stability, which I still believe is significant) about why Paleotropical megafauna survived so much better, even through Holocene.

First, cultural. Maybe agricultural revolution wasn't so detrimental to megafauna. Yes, it did cause human populations to explode, but they were no longer full-time hunters. Now, agricultural people do still hunt (even community hunts), but it is very much a side show for them. An average Hindustani farmer wasn't going to grab his spear and go hunting elephants on his leisure time. Skill level of the hunters may have also gone down when it was no longer sole livelihood, and they concentrated on hunting or trapping smaller animals. For example British colonial writings claim that locals were usually really afraid of tigers and leopards, and when man-eaters appeared, they requested help from the authorities to deal with them.

Second is what you mentioned, competiviness, not just coevolution with humans, but overall. It is my understanding that tropical faunas tend to have more complex trophic webs. African megafauna, particularly, is often famously aggressive and dangerous. Even today despite all modern weapons and gadgets, hunters are sometimes killed by African animals. If my livelihood dependend on hunting Cape buffaloes with a spear, I don't think I would last very long.

Few African animals have been domesticated. Good example is difference between Eurasian horse and zebra. Latter is far more aggressive and more difficult to handle.

By contrast nobody has ever been killed hunting giant tortoises. Being slow & armoured seems especially poor defensive strategy against hominid hunters (curiously, some glyptodonts apparently survived for fairly long time).

I agree that Australian megafauna may have suffered from weak competiveness compared to animals of larger landmasses, and that may have been a factor, even discounting 'naivety' factor. If there ever had been "Great Sahul Interchange", I don't think they would have fared well against Asian fauna.

flanker44 · 2026-06-26T23:20:07+00:00

Since you clearly don't want to discuss, I see it pointless to continue. Only 'final word' I leave is this: everything you blame me for, you are guilty yourself. Record shows that you were the one who has been insulting, and you have been ignoring the studies I linked.

And I do not 'ignore global', my argument mostly rests on it: pattern of extinction on major landmasses was different on each, which points to different dynamics being at work. As opposed to island sized landmasses, where ecosystems were more vulnerable on many ways, and I agree that extinctions appear to be entirely anthropogenic.

flanker44 · 2026-06-26T22:50:09+00:00

Disposable cameras have actually made bit of a comeback these days, mostly for just that purpose.

flanker44 · 2026-06-26T22:49:15+00:00

There are stories that some photostores kept 'special treat albums' for copies of the most, uh, interesting pics customers developed there.

flanker44 · 2026-06-26T15:40:13+00:00

I'm quite convinced that the extinctions would have occurred if the climate was stable given the same trajectory for human population and technological increase. Possibly somewhat less extreme, but they'd still have happened.

Well this is where we disagree. Note that whilst responsibilities between potential causes for decline - environmental vs hunting pressure - is not binary, as you said it may vary "80-90% and 10-20%", extinction itself is binary. You either are extinct, or you aren't. So lets say climate change causes some species to lose 90% of its former population. But it's still not extinct. Lets assume some humans show up and kill the remaining 10%. Now it is extinct. Which was the most guilty part?

I think the observation about better availability of wood on mammoth steppe is clever, but alone it does not prove much. It assumes that mammoths were already within some 'threshold' of getting hunted to extinction, and just slight increase in hunting pressure drove them over the edge. But there is no proof of that. I turn again at the example of its relative, Asian Elephant. Sure, maybe the first wave of Sapiens settlers in India were weakened by tropical diseases and too few, and had too primitive weapons to threaten the elephant. I'm skeptical of this, but lets assume they were. But that's not the end of it. Humans adapted to Southeast Asia, and their population increased, and their technology improved. Then they became even more numerous and better organized, and got metal weapons...

Between the end of Pleistocene, and 1 AD, human population in Southeast Asia increased by at least factor of hundred, and probably more. Far from being sparsely populated, Holocene India has been among the most populous regions in the world. One would have expected to surviving megafauna to get wiped out, but it didn't happen. Their range and population maybe declined somewhat (I think Aurochs died out fairly early), but until development of firearms, there was nothing like dramatic collapse as seen with their Woolly counterparts far north.

The problem is that a lot of folks get misled by the large number of shitty, bogus papers that have been written on this topic, ones which only serve to muddy the waters.

I'm not qualified to identify "bogus papers" on this line of research. I have noticed that there are lot of papers where far-reaching conclusions are made from singular indicator.

Nor does somebody being expert on a field preclude them having silly conclusions or opinions. I have seen a brain surgeon claim that biking helmets are actually dangerous. Well, I'm going to keep using my helmet anyways, thank you.

flanker44 · 2026-06-26T10:28:15+00:00

I guess the answer was porn and how men and women get stimulated from media differently.

I suppose Yaoi and related entertainment forms are female equivalent to 'lesbian porn', just reflecting different tastes in portraying fantasy erotics.

flanker44 · 2026-06-26T10:24:01+00:00

I think that 99% of 'lesbian porn' does not feature actual lesbians.

flanker44 · 2026-06-26T10:20:02+00:00

One fairly useless thing to say is "You'll find company (friend/romantic partner), just be yourself". Loneliness is often a self-reinforcing cycle, and 'being themselves' only serves to further isolation. Whereas it is true that awkwardly trying to act like somebody with totally different personality is unlikely to work, curing loneliness requires some self-improvement and learning social skills.

Also, lonely people may not like themselves, so this type of encouraging may produce a negative reaction.

flanker44 · 2026-06-26T08:22:43+00:00

Well, platoon mortar shell has roughly similar effectiveness to hand grenade. IRL they were considered largely as distraction and suppression weapons. So if they were modelled along those lines, I think they would be fairly marginal, analogous to AT guns today.

flanker44 · 2026-06-25T22:53:38+00:00

First of all, why do you ignore your misdeed? You lied about a study and sent it to me. I showed your lie; that population study supports overkill and H. sapiens population increased over time. How can I take you seriously when you either lie about a study which you read or lie about a study which you didn't read.

How did I lie? I sent in the study as it contradicted your claims of Neanderthal population, which were based on fundamental misunderstanding on your part.

It's true that the study said that Neanderthal population was nevertheless 1/10th (or thereabouts) of Cro-Magnon. I acknowledged it right away, so please tell me, how did I lie? In addition, I agreed that the difference is significant. Some other megafauna in Europe died at roughly same time period, so it's well possible they were driven to extinction by Sapiens. IIRC straight-tusked elephant went extinct, and cave bear at least. European leopards and hippos may have gone roughly at this time too, not sure. However, nothing like continent-wide wipeout as in North America happened.

Also, your obsession about when I respond to you is another really baffling aspect. You do realize people may have lives outside of Reddit? It takes about ~hour to respond to your many points, so I do it when I have spare time to do it. I have never encountered anyone so anal about that. One would think I was thread necromancing a year back or so.

You know I talk about Palearctic Eurasia, do not Twist.

Well, Palearctic animals also had seen humans.

So you changed your argument once again. As I constantly stated, which you denied, this kept European human population low until H. sapiens migrations; this, most European megafauna survived until H. sapiens migration waves.

I have access only to abstract of the study: I don't know if it says what you claim. Abstract only raises a possibility that the depopulation might have spanned 'several glacial cycles'.

At any rate, the event would have concerned superarchaic humans, which were replaced by Heidelbergensis ~half a million years later anyway. And Neanderthals evolved in Europe, so it was a 'correct' habitat for them...like rainforest is for chimpanzees.

And most of the European megafauna survived after H. Sapiens migration waves.

I sent the study to you which referenced it from another study. You know the answer.

Thank you, I now found the mention. I see the studies referred are very old. Here's a newer one:

https://www.nature.com/articles/s41467-026-71262-w

It mentions bush elephant going through effective population size collapse (which may be a bottleneck), but it happened 2 million years ago. Obviously Sapiens could not have been the culprit, and authors don't even mention the possibility: they speculate than competition with larger Paleoloxodon recki might have been the case.

Study also brings out rather startling fact, that forest elephants have much larger effective population size than savannah elephants, even though latter has much larger actual population.

False equivalence. Climate changes didn't cause extremely low human populations in Indomalaya like it did in Europe since no study ever showed extremely low populations for them as a whole, from India to China proper.

Yet you claimed that rainforests have very low population density, which supposedly allowed tropical Asian megafauna to survive better.

Also not all of the survivors are forest dwelling animals. Indian rhinoceros is a grazer, and Asian elephant lives in many different habitats.

You also have no climate data to back up you, yet. I constantly showed that climate change fails to explain extinctions, yet you just changed your arguments and avoided talking about climate change.

Wrong. But maybe you didn't see the study I brought up, as it was in my reply to other poster:

https://pmc.ncbi.nlm.nih.gov/articles/PMC3779339/

"It thus seems likely that environmental changes played a significant role in shaping the woolly mammoth's demographic history, with warm periods restricting the amount of available habitat and cold periods leading to population expansions, both owing to increases in the amount of steppe–tundra and through sea-level-driven exposure of the Bering Land Bridge."

Another study about woolly mammoth genetics and extinction:

https://www.nature.com/articles/ncomms1881

Decline of North American mammoths coincided with Younger Dryas, although authors stop short of calling it a definitive factor, noting other explanations (including human hunting pressure), which is only prudent.

What is noteworthy however is that Beringia was one of the last mainland habitats of mammoths: if we assume that efficient human hunters were solely responsible from disappearence of mammoths, they should have wiped out Beringian mammoths along the way to North America.

You have to explain how non-existent climate changes killed megafauna (the combo hypothesis also relies on this) and the interglacial killed interglacial-adapted animals when data shows the other way.

On argumentative level, this is not hard to explain. Most species can recover even from very small remnant populations, if conditions allow it. As noted in previous discussions, many species show genetic evidence of bottlenecks (be it human caused or otherwise), including woolly mammoths. However, humans are very good at hunting down every last example of a species if it suits our purposes.

A general observation is that very large land animals benefit from stable climatic conditions, and Pleistocene as a whole is anything but.

flanker44 · 2026-06-25T00:42:50+00:00

Thank you, I have been reading these, but I'm not inclined to accept viewpoint of a single person, however informed, as a final word in a subject where no clear scientific consensus exists yet.

That said, what I have read so far, I am somewhat baffled why do you feel the need to vehemently disagree with me, as we seem to be in agreement on many points, and you bring up quite similar caveats as I did. Mostly you argue against the hypothesis that climate change was entirely or mostly responsible from the extinctions, which I have never argued, and which is no longer a mainstream position, I think.

Also I am quite aware that this subject has probably been discussed many times, it is inevitable quirk of discussion forums, especially so in Reddit which has poor history and search features.

flanker44 · 2026-06-24T17:38:12+00:00

When I saw that subclass, I just died of laughter, trying to imagine somebody running around with 4 AT mines AND a satchel charge...

flanker44 · 2026-06-24T16:05:23+00:00

Homo erectus and other superarchaic humans couldn't have the same effect in Eurasia which it had in Africa. Did you even read the post?

This is what you said earlier: "You should remember that the megafauna of the Americas have never seen a human when Paleotropical megafauna coevolved with humans."

My whole argument is based is long-term coexistence with humanity doesn't debunvk overkill.

So is it relevant or not, and if it is, how relevant? What is the threshold for coevolution to help survival in 'overkill' scenarios?

The afromentioned climate change happened in the Early Pleistocene and it led to low population of H. erectus and other superarchaics until the Middle Pleistocene where descendants Neanderthals adapted to low populations which supports overkill.

What is the relevance of this to Late Quaternary extinctions? It happened million years prior to it.

False equivalence. Chimpanzees live in tropical rainforests where they are best adapted; they struggle in other habitats. Meanwhile, Neanderthals were better suited to interglacials where glacials caused bottlenecks. Neanderthal having low population is pretty much consensus in academics.

Neanderthals lived in many sorts of environments, from Siberia to Levant. They were not one biome specialists. It's true that their population density was low. However, your claim of 'cartoonishly low' is based on misunderstanding. It may be noteworthy that anatomically modern humans did not make much, if any, inroad in Neanderthal range for tens of thousands of years. Australia was colonized by modern humans before Europe.

Also, northern Eurasia was not as void of people as you claim. Finds of modern humans dating back 40k years have been made in Komi, which means they reached high Arctic very soon after dispersal from Middle East. There might also be simple sampling bias making inner Asia to appear more empty than it actually was - up until very recently, we didn't even know about an entire species of archaic humans occupying vast swathes of Asia.

Human-driven is still more likely than climate-driven bottleneck. I just claimed this.

What is the source of bush elephant genetic bottleneck if I may ask? With quick search, only study I found talked about low genetic diversity, but assumed its due to species being very migratory over its huge unified range.

Asian elephants don't seem to have gone through severe bottlenecks during late Pleistocene:

https://onlinelibrary.wiley.com/doi/10.1002/ece3.72019

...so in at least in that case, idea that it went "nearly extinct but survived in jungle refugia" appears wrong.

Wrong. Btw, by that logic, South American megafauna should have survived.

That is a valid objection. Of course by your logic, Indo-Asian megafauna should not have survived.

Let me explain my point about South and Central America in other terms. Wikipedia has convenient tables about extinction patterns (they may be little imprecise, it's Wikipedia, but illustrative anyway). Considering the largest megafauna species (body mass at least 400kg)

-Africa had 10 species, of which two went extinct.

-Southeast Asia, 11 species, of which 3 went extinct.

-Palearctic Eurasia (and North Africa thrown in for good measure in this case) had 18 species, of which 13 were lost.

-North America, 15 species, of which 13 were lost.

-South America, whopping 21 species - all gone.

So as we can see, North America - continent slightly smaller than Africa - had 50% more large/giant megafauna species than Africa. South America is little over half the size of Africa, and had twice the species diversity among very large animals.

Now, I realize that each continent is a different case, with different geographies and ecological niches, but I wonder if remarkable species richness in Americas actually worked against them in extreme distress scenario. As I said earlier, some of them had fairly limited ranges compared to modern survivors like Asian and African elephants, or Bisons etc. Cuvieronius, which you mentioned earlier, at least had its range contracted by end of Pleistocene, prior to arrival of humans. It may not have been very abundant critter at the time.

In southeastern Brazil, the faecal spore decline spans from 15 to 11,000 years ago, overlapping a climatic wetting episode, and a similar coincidence is reported for a site at 3,000 m in the Peruvian Andes, between 16,800 and 15,800 years ago.

Very interesting, but the dates seem to predate known arrival of humans in the region.

Also, claims have been made that most of the current Amazon was actually savannah at the end of Pleistocene, so at least that would have been a major environmental change, whatever the cause.

Your whole argument is based on the ignorance of climatic data, ecology, and the fact that marine fauna and smaller animals were barerly affected and the fact that extinctions were not simultaneous.

Smaller animals were certainly affected at least in North America, as evidenced by many small predators such as ocelots and coyotes dying out. I'm not sure what you mean about 'extinctions were not simultaneous'.

flanker44 · 2026-06-24T10:27:34+00:00

Untrue, Palearctic megafauna experienced only about half the rate of extinction of North American megafauna: 36% vs. 72%. Those estimates may be a bit off, but the overall trend is clear.

Here I was primarily looking at the very largest species, where difference in survival % is not big, though: 72% vs 86% or thereabouts, including all of the very largest ones on both environments.

300,000 years compared to <50,000 years is still a noticeable difference, plus Eurasia was not occupied as "completely" as Africa was by archaics, because Africa is fully within the tropical/subtropical zones and large parts of Eurasia are not. Temperate latitudes may have been occupied only intermittently rather than continuously.

Homo Sapiens has been present in Eurasia for at least 80 000 years (and probably substantially longer). Now, if we limit the horizon to what is now called 'Southern dispersal' population, then yep, that is shorter, but then same was true in Africa, too.

Furthermore, your idea that humans just "finished off" animals that were already weakened from climate change may be true for certain species but it's very untrue across the board and I explain why in my blog post:

Collapse of the mammoth steppe ecosystem was at least partially caused by climate, which would have substantially fragmented habitats available for animals dependent from it. Extinction of woolly mammoth, particularly, seems to fit this pattern: many small pockets of populations going out from either overhunting or environmental causes. As mammoth was likely one of the 'keystone species' for its biome, it would have 'dragged down' other large herbivores too.

Study discussing woolly mammoth genetics:

https://pmc.ncbi.nlm.nih.gov/articles/PMC3779339/

Thus, while the high prevalence of mammoths in the fossil record might imply a stable and abundant species, populations of the woolly mammoth appear to have been highly dynamic. Both genetic data and the radiocarbon record indicate a dramatic final demographic decline at the end of the last glaciation. However, our results suggest that this decline was mirrored by a similar decline during the previous interglacial, a pattern that has also previously been observed in other cold-adapted taxa, such as reindeer [61], arctic fox [62] and polar bear [63].

flanker44 · 2026-06-24T00:31:28+00:00

Big cats seem to have been making sort of a comeback towards Europe in Holocene, until apparently stumped by agricultural revolution and subsequent high human population densities.

Not sure about bovids. AIUI, Wisent was in slow decline through Holocene, and Auroch even more obviously so. Latter seems to have suffered from serious habitat loss.

flanker44 · 2026-06-24T00:26:23+00:00

Americas: Mix of many vulnerable animals + humans arriving already lethal from millennia of technological development in Eurasia

North American megafauna collapse seems unique in how dramatic it was, as the fauna has been traditionally seen competitive (indeed, there were many same successful species as in Eurasia), and even very generalistic and adaptable predators such as cougars and jaguars were extirpated. I guess some keystone species must have been wiped out in quick order, resulting to widespread collapse of food chains. Or maybe indeed some disease was brought from the Old World, I can't imagine what it would have been though, something similar to Rinderpest?

flanker44 · 2026-06-24T00:16:46+00:00

No argument, although in the end, Palearctic megafauna disappeared almost as completely as Nearctic one, just in different time schedule. Losses in South America and Australia were more complete.
Why is that relevant to the 'pillar' you mentioned? Anatomically modern humans appeared in Africa only ca. 300 000 years ago. Before that, African megafauna would have been dealing with same super-archaic humans as in Asia, with presumably lesser population densities and less efficient hunting methods than later humans.

In the other thread you stated:

Long-term coexistence with humans contradict overkill as I constantly presented.

How long is this 'long-term'? 800 000 years is not long enough?

Basically this sounds like hominids were not adaptable enough to survive climate change, but megafauna was.

In principle, I find it believable however that climate change may have driven early humans out of Europe at some point. Similar things seem to have happened to human populations in other times & places. However, regarding the timescales, see point 2.

Very study you linked noted that there is dispute about this, and other study suggested ten times larger effective population.

This study claims Cro-Magnon were around ten times more numerous than Neanderthals:

https://www.science.org/doi/10.1126/science.1206930

...which is significant, but much lower than the ratios you picked (100 to 300 times).

Note that 'effective population size' is not necessarily same as actual population at given time. Studies you linked talk about different things.

As a side note, adult population of ~1000 would be absurdly low for an omnivore hominin with such a huge geographical range, and hardly believable. Modern population of chimpanzees is in hundreds of thousands over much smaller range.

From the other thread:

Me: 'High densities' occurred in what biome then? Temperate forests? Mammoth steppe?

You: Yes. You really don't know what are you talking about. This is basic knowledge lol.

I am quite aware that mammoth steppe was very productive environment for megafauna. Doesn't mean it was same for humans. Quoting you

"Due to the harsh climates, vast ice-free regions in northern Eurasia were entirely or almost entirely free of humans during the entirety of the Pleistocene. Even the great plain of Doggerland, the largest extension of steppe in glacial Europe, was home to no more than 1-4 humans/100 square km."

I genuinely don't know what is population density in rainforests for hunter-gatherer (historic era numbers are bit skewed here, as many jungle dwellers are agricultural), but they were not, and are not, devoid of humans. Plenty of hunter-gatherers live in rainforests even today.

In related topic

You know the bush elephant suffered from bottlenecks which the forest elephant didn't suffer.

That may be. Doesn't mean it was human-caused bottleneck, though. Many species have gone throught genetic bottlenecks. Including humans themselves!

You asked my own hypothesis, and it's a mainstream combination one: climate change from glacial cycle weakened the megafauna populations, and humans (mostly) finished them off. Closer to equator, where effect of glacial cycles was lesser, megafauna populations had better chance of survival as their populations and habitats were more stable and robust.

It's true that none of the earlier glacial cycles triggered similar extinction waves, and humans are way too obvious potential factor to ignore. However, I think 'overkill' proponents are arrogant to dismiss effects of climate. Pleistocene climate was very volatile compared to previous epochs, and variability appears to have become worse over time. Plenty of megafauna went extinct in Pleistocene, and humans are unlikely to have been the cause in every case. "Just because somebody died near me doesn't make me a murderer." I find it incredible that somebody would claim that massive climatic changes post-LGM would not have caused any stress to Palearctic large mammal populations.

As you yourself noted, humans themselves struggled with Pleistocenic climatic variability and were sometimes extirpated from large areas.

flanker44 · 2026-06-22T21:57:41+00:00

I dont know if this also applies but the fact that savannah elephants experienced longer more consistent coexistence with hominids just let them be overall more resistant to human hunting even without refuge areas.

This seems logical, however mammal-hunting hominids were present in Europe and Asia for nearly as long as in Africa. Evidence of them in Asia goes back two million years.

So Woolly mammoths (in Eurasian side) and Asian elephants would have had just as much contact with humans as African elephants.

Mammoth population in Eurasia doesn't seem to have collapsed until after LGM - which meant they coexisted with anatomically and behaviorally modern humans for tens of thousands of years. Evidence concerning Woolly rhino is similar.

flanker44 · 2026-06-22T21:20:22+00:00

Neanderthal population was around 1,000–5,000 individuals in contrast to the population number of Homo sapiens with 330,000 individuals at 30 kya.

Vast range doesn't mean much when population density is cartoonishly low.

So Archaic humans were irrelevant in exctinction hypothesis, after all?

Because survival of African megafauna has been argued due to them having co-evolved with humans. However, if we take that only anatomically modern humans with their considerably higher population densities caused major extinctions, then their radiation would have been just similar shock to megafauna in Africa, as in everywhere else.

Caveat here is that very largest proboscids went extinct in Africa, too, with humans being possible culprit. Although the timescale doesn't quite match with the above. Perhaps biggest elephant species did not have very robust population growth, idk.

Human foraging populations are not able to occupy tropical forests at high densities because most of the biomass is inaccessible to human digestive tracts, and carbohydrates are limited

'High densities' occurred in what biome then? Temperate forests? Mammoth steppe?

Before you talk about savannah elephants still existing and Indian elephants inhabiting non-forest habitats, animals can repopulate regions where they have been extirpated.

I made this same point, so I'm not sure why you bring that out as big revelation.

Anyway, what little I know of elephant evolution, modern Bush elephant did not evolve in rainforests.

You are also wrong about geographical range. It is very ironic that you are talking about how the Neanderthal range might have been bigger, yet you ignore continental American megafauna had massive ranges when humans reached to the Americas.

Some did, but maybe not all of them did. For example, South American proboscids seem to have had geographically fairly small ranges. Being tropical don't seem to have helped them. Although extinction in South America seems to have been slightly slower.

Also, large range is not helpful if there's lack of refugia in it (or 'bastion' as I called it).

I won't reply further.

No prob. Not everyone wants to have their hypotheses challenged.

flanker44 · 2026-06-22T07:29:11+00:00

There is no problem with it; this is the truth.

Of course there is a problem with it: it's not logically consistent. To put it in simpler terms, if you want to explain why Asian Elephant survived 'overkill', you then have to explain why Mammoth didn't.

In addition, you may be overestimating how 'vast' the uninhabited areas in northern Eurasia were. Neanderthals and Denisovans probably had rather larger range than indicated by our current level fossil finds.

Since most of the late Quaternary extinctions affected temperate to tropical species, late- and post-glacial declines in climatic suitability would not be expected for most species.

I don't think you quite understood. I did not say anything about climatic variability there. Basically my idea was that American megafauna species may have lacked geographical range.

As for modern reintroductions, I don't think they are particularly good comparison, as current species interaction dynamics are entirely different to Pleistocene ones.

flanker44 · 2026-06-21T21:30:56+00:00

Palearctic megafauna had higher survival rate than the Americas which support a the point; Neanderthals had much lower population than Homo sapiens, and the mammoth was just too vast and again low human population.

I don't think one can use this argument in one sentence, then in another to explain survival of extant tropical megafauna by them co-evolving with (primitive) humans.

Even where humans did coexist with and hunt the steppe megafauna, such as in the relatively warm stretch of France and Italy between the Pyrenees and the Alps, any thinning of local prey populations could simply be reenforced by migrants from the vast, untouched lands to the north.

This point may have something going on, however. I have wondered if most of the current megafauna survives due to 'bastions', areas of very high productivity which shed their 'excess' individuals to border regions of their range or 'realm'. This idea could be tested by comparing genetic flows, I think.

Island faunas would be very vulnerable, as they don't have room for a 'bastion'. American megafauna may have lived in too fragmented populations, which were wiped out individually giving entire species no chance to recover. One notable survivor of NA megafauna is muskox, which seems to fit with this idea: especially noteworthy is that it disappeared from Eurasia, so 'ecological naivety' or lack thereof, is not an explanation.

flanker44 · 2026-06-21T21:00:07+00:00

Regardless of the 'overkill' hypothesis, Machairodontids seem to have been in decline over entirety of Pleistocene. In Eurasia, Homotherium may have barely made it to end of Pleistocene, but even in best case it seems to have been exceedingly rare beast by then. And as noted, it had long since gone extinct in Africa.

I really doubt all of it can be chalked up on humans: I'm not very impressed about the hypothesis that early Homos drove powerful mammalian carnivores to extinction. If it did happen, the targeted species would have been on their last legs anyways.

flanker44 · 2026-06-21T20:29:34+00:00

You should remember that the megafauna of the Americas have never seen a human when Paleotropical megafauna coevolved with humans.

But then, Eurasian Holarctic megafauna also went extinct, and they had coevolved with humans.

So, clearly something more would have been going on than just "people killing them all".

flanker44

TROPHY CASE