Humans: Destroyers of Mega Fauna

One mass extinction who's cause had eluded researchers and scientists, was the extinction of Mega Fauna ,during the last 100,000 years. However, the mystery may have come to a close. Researchers from Aarhus University have concluded after a global analysis , that the “overkill” hypothesis is indeed the strongest factor that led to the mega fauna extinctions. The climate change hypothesis, weakly played a role in the extinctions but was observed to only play a weak role in the extinctions. The climate change was only extreme in certain regions like Eurasia, beyond this region, the extinction of mega fauna is ascribed to the invasion of humans into new regions and preying upon the indigenous species.

Summary: The study unequivocally points to humans as the cause of the mass extinction of large animals all over the world during the course of the last 100,000 years.

References:
Aarhus University. (2014, June 4). Humans, not climate, to blame for Ice Age-era disappearance of large mammals, study concludes. ScienceDaily. Retrieved June 4, 2014 from http://www.sciencedaily.com/releases/2014/06/140604094108.htm

 

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Sure it does. no surprises there. Cro-Magnon baby needed a new pair of mastodon moccasins, and lunch. Has the fact that humans killed off much mega fauna ever been in doubt? We need look no further than the near extinction of the American buffalo. How long ago was that? Not very long ago, was it?

 

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Doubt?
YES
In the americas, man and mega-fauna coexisted for thousands of years.

as/re

By whom?

It seems most likely that climate change and disease were the most likely culprits in the extinctions of the North American mega-fauna.

 

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I see your point, sculptor, and there is something in it. However, consider that in Australia (maybe not so much nowadays) whatever animal was sacred to the local Aborigine's thrived in that group's area because they were not hunted.. For example if they held the wallaby tribe, then the wallaby was always more abundant in their region. So humans seemingly do have much influence on animal populations.

Also how about animals like the saber-toothed tiger, the mammoth, etc.? It is said there were still mammoth in the islands off Siberia when the first pyramid was being built. Now if humans in North America even as late as 40,000 years ago, may they not have hunted mammoths, and had a major effect on their population seeing how there are no mammoth later on?

Surely, it's most reasonable to say men were a contributing factor, perhaps even a large or the largest one, but that their activity is not he whole story.

 

Arne:
The island is wrangel island, the dwarf mammoths there may have survived till about 3600 years ago-------remember that this is an island, an isolated refuge.
The solutreans and later the clovis were the only ones thought to have hunted the mega-fauna(with spears with foreshafts that could break away from the spear shaft). They likely came over by boat, and there is no evidence that they were anything but very small populations. Their culture disappeared about the same time as the mega-fauna about the same time as the plunge into and bounce out of the younger dryas wherein temperatures might have changed 15 degrees C in fifty years with jumps of 5-6 degrees in just five years.
And, that is truly rapid climate change with rapid flora change in tow.

If indeed there was an ice free corridor through which massive waves of migrations came out of asia with dogs, they were most likely following herding animals which would have brought pests and pathogens along with them.

We cannot rule out

, but the likelihood of men being

seems remote.

To the best of my knowledge, the number of solutrean and clovis sites with mammoths obviously killed by men(like a broken spear point in a bone) can be counted on one hand. Even finding the artifacts in situ with mega-fauna bones is rare.

The jury is still out, but i think you know which way I'm voting on the current evidence.
If that changes i might also.

 

The NA animals that went extinct at the beginning of the current interstade had survived, as genus or even species, at least three prior interglacials.

In each of them immigrant species from Berengia had migrated into North America, bringing whatever disease etc they had. This combination of climate change and disease.competition had never wiped out the entire megafauna of NA before - replaced one bison variety with another, maybe, but not killed off 50 large species of vertebrate including several entire genera without affecting anything on land under 40 pounds, anything flying except carrion eaters and large predators, or anything in the lakes and streams at all.

No large flora are known to have gone extinct during the Younger Dryas. No small fauna are known to have vanished then, either.

It does not take a large population of humans to rapidly exterminate vulnerable megafauna. By the peak of the extinction wave, the human population was large enough to have populated the entire NA continent from Mexico to Hudson Bay.

The minority of large vertebrate species that survived (bison, moose, grizzly bears, timber wolves, eagles and smaller vultures, etc) shared some features different from the extinguished - they were smaller and faster reproducing, they lived in habitats difficult for humans to live and hunt in, they were not serious predation threats to humans or competitors for food, and they were recent immigrants from Berengia, where they had coexisted with humans for tens of thousands of years.

If the colonization by humans of North America did not usher in a wave of human caused extinctions, that would be unusual in our experience - every human colonization of new territory that we can investigate in this matter has caused such extinctions, from the Maori wiping out the megafauna of New Zealand to the various extinction events in the Polynesian and Hawaiian islands. Why should the ones we don't know as well have been radically different?

 

You have to look further than the last 200 years or you deprive yourself of information.

Bison latifrons
Bison crassicornis
Bison priscus
Bison antiquus
Bison bison

http://museum.sdsmt.edu/exhibits/173690/

An interesting article describing the rapid (current) evolution of the bison.

http://rapidcityjournal.com/news/an...cle_8cdcc134-144f-11e1-94bd-001cc4c03286.html

Three influxes of bison and one type remains out of at least five. Yes humans hunted at least some of the now extinct megafauna. However there is plenty of ongoing research which indicates many of these animals slipped off the edge due to changing environments and the inability to adapt.

Inbreeding tends to occur in isolation:
http://www.sciencedaily.com/releases/2014/03/140325095820.htm

Change in forage:

One of the key food sources of the large mammals- the protein-rich forbs -- did not fully recover to their former abundance. This likely proved fatal for species like woolly rhino, mammoth, and horse in Asia and North America. Even though it became warmer again after the end of the Ice Age the old landscapes did not return.

http://www.sciencedaily.com/releases/2014/02/140205133252.htm

and finally

The review concludes there is only firm evidence for about 8 to 14 megafauna species still existing when Aboriginal people arrived. About 50 species, for example, are absent from the fossil record of the past 130,000 years.

http://www.sciencedaily.com/releases/2013/05/130506181711.htm

 

YD et impact event anyone?

 

Focusing on North America here:

Protein rich northern meadowland forbs remained important constituents of the landscape in many large areas of the continent, including some areas that had supported these megafauna throughout the last three glacial advances and retreats. Several species of megafuana dependent on them survive still (moose, several species of deer, antelope) - and several species not apparently dependent on them vanished suddenly (giant sloth, giant beaver, teratorns, big cats and bears and wolves, etc).

Circumstantial evidence of that kind is worth pondering, but in North America a short gap in a fossil record that spans a glaciation (landscape altering event on a huge scale) is not solid.

Of the remaining 36 species of Australian megafauna that vanished for some (obviously unusual) reason(s) in that 130k window, how many are absent from the very recent fossil deposits by simple accident of geography, ecological pattern, or human search?

Besides: the disappearance of 14 species - including entire genera, not just varieties - of continental megafauna in a few thousand years is a notable event in itself. The fact that the event likely includes a share of 50 others simply highlights.

Influential by presumption, but too short, too small, too localized, to universal in its influence, and not severe enough to explain a continental extinction wave among megafauna only. The glaciation itself they had survived - a far more significant climate cooling event than the YD.

Another possible event recently supported with some indicative evidence would be a significant meteor impact on the remaining ice sheet. Again, this does not explain the species distribution or scale of the extinction wave, but it would have added severity to other pressures - boosted the odds.

The pivotal observation, however, is this one: every well-known and well-investigated human colonization of a formerly human-free land area of this planet has been followed by a wave of rapid and human caused extinctions among the large resident warmblooded fauna. The pattern is without exception, and has solid if complex mechanistic explanation supported by empirical observation. The presumption, the null hypothesis, the conventional basis of organization, would have to be that the pattern extends to those human colonizations we still know little about.

If the discussion is about the range or scope of some group of extinctions, or the fate of some particular animal that seems to have been different, or the exact mechanistic sequence of events (such as the advent and effects of widespread landscape burning by humans, the effects of rats, etc), or the roles of other circumstances such as climate fluctuations, then that is one thing. If the argument is that humans colonized some region of the planet without wiping out any significant portion of the large warmblooded fauna, then we need to see some serious evidence and sound reasoning. How did that happen?

Note that the Australian attribution to climate change for most does deal with mechanism - the climate change was continent wide, the fire regime supposedly predates human firing (this depends on the date of human colonization, of course - the window is not large, for the natural fire regime advent), and the aborigines supposedly had no adequate hunting gear (a dubious claim that casts a bit of doubt on the whole article - Kalahari bushmen hunt and kill African elephants, which are large and intelligent and well-experienced with humans, using gear no more "adequate").

 

Being familiar with "domesticated" cats as I am, and I am sure most people are, I think the self-domesticated is the way it must have happened. Cats don't stand for much training, nor do they need it. I've had kittens who instinctively know what the litter box is for.

Years ago I had the opportunity to stay in a Frisco flophouse that was chock full of rats in part because a large building had recently been demolished next door. They were getting into my food, so I set traps, and every morning and every evening when I came in, six traps would be sprung - sometimes with still living rodents inside. I took to emptying them out the window. it was a six-story drop onto an air conditioning unit. In no time, there was a regular group of felines who knew when to wait and what to wait for. So did I domesticate them, or had they domesticated themselves?

Have you got any numbers on the toll wind farms and tall buildings take on birds? Surely, it's not another billion.

 

Fraggle, my friend, it was a rhetorical question (re:did I domesticate them, or had they domesticated themselves?).

I think that cats have never stooped to domestication, and excepting tinkering with genetic engineering, they never will. If they hang about human places to find food, well, that just shows that they're realists, and enjoy easy pickings. Who can blame them?

In Walden, H.D. Thoreau observes that cats return easily and readily to life in the woods, and that even a house cat seems to be quite at home there.

When my children had a Ratatouille there was an extra bit at the end, in which the fat brother rat of the main character explains that while dogs think of human beings as their masters, rats see us as equals. He also mentioned that cats think themselves far superior to humans, and I think that was about right.

Anyway, we digress from the OP...

 

In support of the YD et impact hypothesis:
This from Firestone:

read more at:
http://journalofcosmology.com/Extinction105.html

Lacking anything else approaching reasonable standards of evidence, this seems like the most likely reason for the extinctions, and demise of the clovis culture.

more at:
http://scitechdaily.com/cosmic-impact-sparked-devastating-climate-change-caused-mass-extinctions/

http://www.pnas.org/content/104/41/16016.long#sec-24

Why do so many people feel the need to blame sapiens sapiens without any direct evidence for the event?

 

If you are talking about the American Indians, it is important to consider that there were only about one million of them in all of North America in Pre-Colombian times, and North America is huge.

I'm not saying that they weren't responsible stewards - they were, or that they were bad hunters - they weren't, but you are right, they and mega-fauna coexisted for thousands of years.

Does any one have any estimate of how many people were living in South America as of 1492? I would also be interested to know how many Aborigines lived in Australia when the Europeans arrived.

 

estimates vary widely
there is the low count camp and the high count camp and a lot in between.
The high count guys think upwards of 112 million in the americas with 90% in meso and south america. The archaeologists looking into the settled agrarian population of the amazon basin (see terra preta) seem to think that the population there peaked around 3-400 ad, with another marked decline around 12-1300 ad, then the coup de grâce of disease from the europeans. High count there would have up to 50-60 million people at their maximum, down to as low as 10 million in the amazon basin in 1492.
Recently, satellite data has found many more abandoned terra preta settlements throughout the amazon basin than had been guessed at previously. Previously, it was assumed that most of the amazon population was in the eastern part of the basin, and along rivers. This also seems to have been in error.

Low count for the time of the demise of the megafauna would be less than 1000 people in north america.

All is a guess, archaeological evidence remains elusive.

 

Uh
hmm
.......
perhaps we need to define "civilization" ?
Civilization as a development of, or distinct from culture?

 

My question is how did the megafauna of sub-Saharan Africa and south Asia survive
until modern times amidst their human presence? North of the Mesoamerican culture
area there must have been millions of square miles where the human population was
little if any denser than in sub-Saharan Africa, and less dense than south Asia, and
the same is true for South America outside the northwestern quadrant with its relatively
advanced cultures. If there are large tracts where elephants, rhino and big cats still
hold out tenuously in the wild in sub-Saharan Africa and south Asia, then the missing
megafauna of the Americas should have survived at least until first European contact.

I will not be satisfied with any indictment of the original inhabitants of the Americans
on this matter until someone can provide a convincing explanation for why they were
so much more effective large animal killers than the sub-Saharan Africans and the South Asians.