It’s funny how they (and all the other large mammals) survived for 1.8M years of massive global climate change but the period just after we arrived (like in the Americas) was what “hastened their demise” rather than the humans with clubs they hadn’t had time to evolve to be scared of, eating every last one of them.
> There are indications that the legs of Genyornis were gradually adapting to this drier climate, but the species would have remained under considerable pressure. This environmental stress is thought to be why the birds had higher than expected levels of bone disease at around the same time.
In this case it sounds like climate change was in fact a stressor, though I believe you're right--even without climate change this bird would have gone the way of the moa. Perhaps a better phrasing would have been "Already under stress from climate change, they are thought to have been eaten to extinction."
Which landmass / culture / epoch are you trying to describe here?
I'm not trying to deny anything. I'm sure there were pockets of what we (modern) might recognise as agriculture, though not pastoralism (for obvious reasons).
My question was actually just what it looked like, an earnest question to chrisco255, replying to elmomie, about the context of their statements.
GP seemed to be talking global, and so did parent - which would make sense in the context of climate change (a global phenomenon) and also massive human population growth (also mostly global, resulting form settlements / agriculture).
For most of the globe agriculture was not possible. While canines were probably domesticated in the glacial period, they served as hunting partners primarily. It's actually quite hard to build fencing over large amounts of land area (like sheep and cows require) that is capable of keeping animals in, unless you have metal to cut wood with. The United States had open cattle ranging until barbed wire was invented in the 1870s, since it was too difficult to fence. And open ranging was only possible after horse domestication.
We also do not see evidence of grain domestication or any kind of real farming until the start of the Holocene 10K-12K years ago. The climate was not particularly friendly to farming, and without access to metal, farming is orders of magnitude more difficult.
The original article is about Australia alone, and 45K years ago, Australia probably had a human population in the low thousands, with it being on the frontier of human expansion at the time. There is no evidence of massive human population at that time or any time before 12K years ago. In fact, there's several population bottlenecks where they think the total number of humans alive globally was around a few thousand.
I know living, brush, or ha-ha type fences would have been possible - but agree all of those were easier with some metal utensils.
The thing about climate change in prehistory is that it drives changes to human life. Archaeologists put glacial maxima on their timelines because it's such an important factor when trying to understanding human migration, the spread of new technologies that do better in drier or wetter climates, the shift to different food sources, and so on. This predates the current climate-aware political landscape.
If 90% of a species is killed off by climate change, and if for hundreds of thousands of years that species survived glacial maxima in reservoir populations in areas that are now populated by starving humans who kill the remaining 10%, was it the climate or the humans who wiped out the species? The changing climate killed more, but the humans were the differentiating factor, so which one do you point the finger at?
I don't think it's right to call that denialism.
If we're the differentiating factor, I'd have to blame us. Am I right in understanding that these species were normally being thinned during each glacial maxima, such that it was already a set part of their evolutionary environment? If that's right, then aren't we the ones to blame?
Otherwise, is a murderer merely a "contributing cause" to someone's death if the victim happens to be sick at the time of the killing?
My main point was that I don't think it would be denialism for someone to say "no, the species was pushed to the brink by climate change anyway, we know other species went extinct prior to human colonisation, and even though humans arguably made it worse there's no conclusive evidence". Glacial maxima are hundreds of thousands of years apart and given the timescales involved it's hard to say whether a species is adapted to them or whether it just got lucky.
Associate Professor Karl-Heinz Wyrwoll has littered his article with qualifiers:
* During the last few decades, human-induced climate change has been a pervasive theme in the scientific literature.
* Ruddiman’s research, while not without its critics, suggests that these resultant climatic changes ...
* This is the idea that early agriculturalists caused an anomalous reversal ...
* He showed that vegetation clearing, overgrazing and burning may have had an impact ...
* Tom Lyons’ “bunny fence” experiments have drawn attention to likely climate impacts and feedbacks ...
etc.
I'm neither agreeing nor disagreeing with the notions put forward, just highlighting that the article is not as you paraphrased it.
There is evidence that aborigines affected the climate, but there is not proof.
We back burn areas most likely to cause uncontrollable bushfires in the future
Most of the continent requires fire, with the notable exception of Tassie and some rainforests scattered throughout the mainland
Adaptation and species selection has resulted in what we have now -- as distinct from finding ourselves in a land that happens to need regular burning.
Contrast us with comparable latitudes (15-35 from the equator) on other landmasses.
In Brazil, transpiration from the Amazon rainforest produces more water vapour than the amount of water transported by the Amazon river. This is known as an atmospheric river (e.g. [1]) and is now seen as critical to the Brazilian climate. I think the theory is that wide spread burning in Australia destroyed the atmospheric river there, which led to a much drier continent than existed before humans arrived.
[1]: https://www.noaa.gov/stories/what-are-atmospheric-rivers
What is certain is the same change in global conditions that allowed humans to walk to Australia and later filled the moat coincided with the fall off in megafauna. There's correlation, but causation??
The divided opinions:
Climate change not to blame for late Quaternary megafauna extinctions in Australia (2016) https://www.nature.com/articles/ncomms10511
Humans killed most of Australia’s megafauna: study (2017) https://www.australiangeographic.com.au/news/2017/01/humans-...
Did people or climate kill off the megafauna? Actually, it was both (2019) https://theconversation.com/did-people-or-climate-kill-off-t...
Humans coexisted with three-tonne marsupials and lizards as long as cars (2020) https://theconversation.com/humans-coexisted-with-three-tonn...
It turns out humans coexisted with the megafauna over about 80% of south-eastern Sahul for up to 15,000 years, depending on the region in question.
In other regions such as Tasmania, there was no such coexistence. This rules out humans as a likely driver of megafauna extinction in those areas.From https://digital-classroom.nma.gov.au/learning-modules/ancien....
> The first people probably came to Australia from around the area that is now Timor. To get to Australia, they must have made a canoe voyage of about 90 to 150 kilometres of open water, which would have been a remarkable maritime achievement
The timing aligns with the genetics and with artefacts: https://www.nma.gov.au/defining-moments/resources/evidence-o...
Jokes aside bet they tasted good.
This is not a thing. Species don't require generations to learn to be afraid of other species that hunt them. Species have encountered new species since the beginning of time. If it took 1000 generations to learn such a thing, nothing would have ever made it.
It's not as if there's a shortage of dangerous predators in Australia, even to this day.
Just because an article hand waves an explanation doesn't make it so.
As another example, urban populations of animals have evolved to tolerate noise in the span of very few generations.
Giant flightless goose- very tasty!
https://en.m.wikipedia.org/wiki/Gal%C3%A1pagos_wildlife
We have actual evidence that it is a developed instinct. If you’ve ever been to the Galapagos islands, it’s extremely obvious. The sea lions and pelicans casually walk up to the counter at the fish market as if they’re just regulars shopping.