I find these theories attributing mass megafauna extinction to changes in climate rather unconvincing, for very simple reason: it would be an extreme coincidence that dozens of species that lived there for literally millions of years all just happened to go extinct right around when humans showed up.
Now, I certainly believe that climate changes at the time also played a role: for all we know, these might have even been responsible for most of the animal population reduction, through shrinking the habitat etc. But without the humans killing off the rest, they’d have survived, just like they did during climate changes for previous millions of years — it’s not like the climate just suddenly became unstable recently, after millions of years of high stability.
But yes, the overall point is that humans have produced cultural technology that made us just too good at hunting for it to be sustainable source of calories for majority of population, and this has already been true for many millennia.
I would encourage you to read the current literature. The evidence is more compelling than you might expect. Actually Meltzer’s 2020 paper (linked in my previous comment) touches on this exact concern under the subheading, “Getting past the Impasse”. There was another good paper that broke down how the end of the Pleistocene was radically different from previous glacial transitions and how the effects of that likely played into the extinctions. Combined with the revelation that most mammoth “kill sites” were actually more likely to be scavenged… it’s not at all an unlikely picture.
Thank you for recommendations. It’s been a while since I last skipped sleep to read on these topics, so maybe it is in fact time to catch up with recent ideas. My priors are still strong on humans being ultimately responsible, especially as the entire field is filled with a lot of wishful thinking about the noble nature of savage people, living in harmony with each other and environment.
I suspect it's a combination of both - climate change put the megafauna population under stress, and then humans showed up and dramatically exacerbated their woes.
The extinction of moa in New Zealand is entirely attributable to over-exploitation by humans. The extinction of megafauna in Australia seems to have been climate change + human hunting + human modification of the environment. https://en.wikipedia.org/wiki/Fire-stick_farming
> it would be an extreme coincidence that dozens of species that lived there for literally millions of years all just happened to go extinct right around when humans showed up.
Or, it could be that the same climate shift which allowed the humans to show up also was bad for the megafauna.
Hunting rifles almost never go bang, and it is pretty rare that a deer just falls over dead, yet if the two happen at the same time, it is hardly a coincidence.
The linked article might address this better than I have (I haven't read the article yet)
The humans have shown up many hundreds of thousands of years before the extinction of the megafauna, so these 2 events did not have the same cause.
While in the first part of the coexistence between hunting humans and big animals the extinction of various species was more gradual, in Africa and Eurasia, in more recent times the big animals have disappeared almost immediately (at geologic time scales) after the arrival of humans, e.g. in Australia, America and various big islands.
During hundreds of millions of years, there have been many extinction events, and the biggest animals have always been the most affected by them.
Nevertheless, soon after some big species became extinct, other previously smaller species have grown in size, to fill their place.
There has never been a time with a so low abundance of big animals as since the humans have spread all over the world, and it is obvious that no other big animals will emerge naturally, as the cultivated lands have left too little space for them.
The only way for some big terrestrial animals to appear again would be through genetic engineering and they could live only in reservations, like in Jurassic Park.
But it's not a coincidence - the climate conditions changing was what enabled humans to move into the continent. Still, I'd be surprised if human activity wasn't a significant contributor towards species extinction in this case.
Now, I certainly believe that climate changes at the time also played a role: for all we know, these might have even been responsible for most of the animal population reduction, through shrinking the habitat etc. But without the humans killing off the rest, they’d have survived, just like they did during climate changes for previous millions of years — it’s not like the climate just suddenly became unstable recently, after millions of years of high stability.
But yes, the overall point is that humans have produced cultural technology that made us just too good at hunting for it to be sustainable source of calories for majority of population, and this has already been true for many millennia.