I have read it, I have cited it to you, rather than the opposite, and I agree that is their conclusion. However, do you agree they also state that there is “great debate” and not “consensus” on the subject?
No, like I have shown, in both cases climate change is also a common cause. In the two areas without mass megafuanal extinctions- Asia and Africa- there was little or no climate change.
I can equally argue the opposite. Many scientists today are concenred that human’s are cuasing great changes which may lead to extinction. Thus, there’s a desire to show that past extictions were caused by humans.
I’ve been wondering this and maybe you’ve come across an answer: For scientists who advocate the climate change hypothesis, how do they explain the fact that many species of large mammals survived the changes in climate during and between the previous glacial periods? Is there evidence that the end of the last ice age was particularly dramatic or unusual?
No, I cited it you originally, quite a few years ago. But I don’t expect you to remember that, since you always bring it up as if it were the first time we’ve discussed it.
Never mind my above question.
I just got to reading the subsequent posts and I don’t want to fan any flames.
Bison were very nearly deliberately hunted to extinction in a few decades. It was only through determined conservation efforts by a few people that they weren’t exterminated. They went from tens of millions to less than a thousand. This is a pretty famous example of near-extinction that many people have heard of.
You haven’t shown anything of the sort.
This is absurdly false.
No, it wasn’t. Most of the animals that went extinct at the end of the Pleistocene had previously survived just as extreme changes in climate at the end of other glacial cycles. This is in fact one of the most critical objections to the climate change hypothesis.
I don’t mind addressing questions from others. However, I’ve been over this ground so often before with DrDeth that it’s not worth going over it again with him.
Does it matter? OK, let us accept that cite as the Gold Standard then, OK? Let us call it “your cite”. Great.
Does your cite not use the term “great debate” as opposed to “consensus”? Does the cite anywhere say there is consensus? Does it not say exactly the opposite?
Now, as for climate change being one of the causes, does your cite also not state that “evidence suggests that the intersection of human impacts with pronounced climatic change drove the precise timing and geography of extinction in the Northern Hemisphere.” At least as far as NA goes, does that not agree that *pronounced climatic change * is part of the cause?
Does not the cite also say that “human hunting was not solely responsible for the pattern of extinction everywhere”? Was then human hunting solely responsible for the pattern of extinction everywhere?
It seems to me that the lingering presence of elephants in India might be because they don’t compete with farmers. Farmers would cut down forests, driving out the local elephants into the remaining forest. Eventually the land would play out for agriculture, the farmers would move on, the forest would regrow, and the elephants would move back in. Humans and elephants would do this minuet across the landscape for millennia.
Somethign to note in your cite: Colibiri has not, in thei thread, asserted that human HUNTING was responsible for the decline of the species. It is certainly one of the contributing factors in many cases, but I have not seen him assert that human hunting was responsible for all of it. Mostly he seems to be asserting that human colocation with megafauna was responsible.
True, but I did not say he made such a assertion. Others here seem to have drawn the conclusion that human hunting was how man made species extinct, so I needed to make that point clear.
In fact, in other threads, both **Colibri **and Blake have said that human caused changes to the environment- such as mass burning- are a cause. In fact, I agree with them, and I further think that such human caused environmental modifications were a greater cause than actual hunting (I am not sure where Blake and Colibri stand on that issue). The “blitzkrieg hypothesis” where human hunting was the sole cause of extinctions has been completely and totally discredited. Colibri has agreed with me on that.
In fact, we mostly agree. We both agree that humans were a significant cause of the megafaunal extinctions, I just say that climate changes were also critical (esp in NA). I say that the causes of the megafaunal extinctions are a subject of great debate and disagreement among the scientific community, he sez there is “consensus”.
In many island based extinctions, it’s more often the rats that humans inadvertently carried along that caused extinctions. No doubt at all that Humans- even if indirectly- caused many island based extinctions.
No I haven’t (although that was probably one of the most significant human impacts). That just happens to be one of DrDeth’s hobbyhorses, which he will drag into the thread whether anyone has made the claim or not, and then debate this straw man.
The destructive impact of elephants on farms is well documented. In India, elephant herds on stampede would occasionally destroy entire villages. Yes humans were predatory enough that elephants would move on if they had anywhere to go; but rather than starve to death while a field of yummy crops was just sitting there, a herd of three-ton animals would be rather difficult to deter with sharp sticks.
How does this gel with the fact that Africa started out with 6 elephant species, including mammoths, and by the invention of agriculture only three remained?
I hadn’t heard; which African species went extinct and when?
I’m amending my position on this because I was making the mistake of concentrating on the concept of humans deliberately hunting and killing megafauna as a cause of extinction. But that was not really part of the OP, and an invalid assumption on my part.
I stilll contend that the cause of megafauna extinction could be purely environmental, in terms of the capacity of the environment to support the number of species and population sizes. But as Blake,** Colibri**, and others point out, humans are large consumers of environmental resources aside from hunting. Africa was the one continent where human and non-human populations evolved together. Humans were invaders in the other continents, and those environments had not evolved to include their presence. Even without hunting, there was still agriculture, fire, land occupation, and overconsumption of food sources as an impact. Considering that, many species may have survived climate changes or other factors had they not competed with humans for resources. So I think those citing the long evolution of humans and other species together in Africa are right. My apologies for being argumentative over my own mistaken assumption.
The only one I can find (that went extinct in the last 15000 years in Africa) is (wiki)
"The North African Elephant (Loxodonta africana pharaoensis) was a possible subspecies of the African Bush Elephant (Loxodonta africana*), or possibly a separate elephant species, that existed in North Africa until becoming extinct in Ancient Roman times".* One can argue that’s maybe just a sub-species.
There’s also the (wiki)"Elephas recki is an extinct species of African elephant. At up to 15 feet (4.5 metres) in shoulder height, it was one of the largest elephant species to have ever lived. It is believed that E. recki ranged throughout Africa between 3.5 and 1 million years ago. " but it went extinct far too long ago for these purposes.
Possible we could include (wiki) "The North African Elephant (Loxodonta africana pharaoensis) was a possible subspecies of the African Bush Elephant (Loxodonta africana), or possibly a separate elephant species, that existed in North Africa until becoming extinct in Ancient Roman times."
The African Mammoth, Mammuthus africanavus was a Pliocene species.
Ok, so two that went extinct before humans were a factor one way or another, and one that lived in a very marginal habitat until comparatively recently.
Has Colinvaux’s “Why Big Fierce Animals are Rare” been discredited? I’m not looking for an argument, the book came out in the '70s, but his explanations seem as good as any.