BIG KILL: Hunters killed off more than 50 species of large animals in Australia, including Diprotodon optatum pictured here.
Image: © Science/AAAS/Drawing by Peter Murray
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Around 40,000 years ago, the giant kangaroo disappeared from Australia. So did Diprotodon (rhinoceros-size wombats) and Palorchestes (tapirlike marsupials) as well as supersize birds, reptiles and some 50 other so-called megafauna—big animals. And now a record of fungal spores pulled from the swamp at Lynch's Crater in the northeastern corner of the continent reveals humans as the culprit.
"The megafauna declined soon after the time that we know people arrived in the region," explains zoologist Christopher Johnson of the University of Tasmania, lead author of the report published March 23 in Science. "We conclude that humans, not climate, caused the extinction."
The basis for the charge rests on two mud cores—one stretching from around 130,000 years ago to 24,000 years ago and the other ranging from roughly 50,000 years ago 3,000 years ago. The long core reveals how the local environment reacted to two previous periods of cooling and drying. Judging by the Sporormiella fungus—which only releases its spores when in the dung of plant-eating animals—big animals fared well during these climatic changes, munching happily on the changing vegetation of the area.
That changed roughly 41,000 years ago, when the number of spores in the core "dropped almost to zero," the researchers wrote. The record in mud also notes an increase in charcoal from large-scale fires and new types of vegetation—eucalyptus trees and the like with grasses beneath, much as seen today. A shift in climate could alter plant populations, but this vegetation change actually precedes by roughly 10,000 years the most recent climate shift within the core's age, to cooler and drier conditions. "Climate change played no role in megafaunal extinction in Australia," Johnson concludes.
Using the second core, the researchers then focused on the period between 43,000 years and 38,000 years ago to try to understand how humans eliminated the megafauna. Humans could have hunted them to extinction or set fires that changed the landscape so much that large herbivores could not survive. But examining the core in 100-year increments showed that the shifts in vegetation happened after the near disappearance of Sporormiella spores—not before as would have been expected if fire-triggered vegetation changes had caused the extinctions. "It could not have been vegetation change due to firing of the landscape, as other people have proposed, because those things followed megafaunal decline," Johnson argues.
In fact, the disappearance of the big plant-eaters seems to have set the stage for fires, allowing the buildup of the dry grasses and other fine fuels that spur burning like the catastrophic wildfires still seen in Australia today. At Lynch's Crater, the disappearance of the large plant-eaters saw an increase in grasses within 300 years, then acacias, eucalyptuses and other hard-leaved plants within 400 years, and, ultimately, a rise in the pollen from forest trees some 1,600 years later. Even today, many of the plants still extant in Australia boast features such as protective spines that would discourage grazing by megafauna or big fruit and seeds that could only be dispersed by large animals that no longer exist—a landscape shaped by ghosts. "These plants are now anachronistic," Johnson observes.
The findings seem to close the case against modern human hunters, although they remain to be confirmed at other sites throughout the continent. And, on every continent except Africa, human arrival and large animal extinctions seem to coincide, so the case may also extend globally. (The reason large animals did not vanish in Africa is perhaps because they co-evolved with us and learned to be wary of this stalking, hairless, upright ape.)
An analysis of ancient DNA from extinct species such as woolly mammoths and rhinoceroses suggests that "climate has been a major driver of population change over the past 50,000 years," according to a 2011 Nature paper that also suggests climate and humans may have colluded to push such species to extinction. (Scientific American is part of Nature Publishing Group.) Johnson, for one, isn't sure climate should be blamed. "Extinctions in other parts of the world were remarkably similar in pattern and severity to those that occurred in Australia," he notes. After all, human hunting wiped out similar species from in neighboring New Zealand less than a millennia ago. "This seems to strengthen the view that human impact—mainly hunting—was the predominant cause in other places as well as in Australia."
As for the specific weapons and techniques, they remain unknown. "It is almost certain that hunting of large animals was one of the things [early Australians] did, but we'll probably never know exactly how they did it," Johnson says. In this case, it wasn't the weapons that fingered the perpetrators but an absence of fungal spores that reveals an ancient human deed.
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50 Comments
Add CommentHow large of a human population does it take to wipe out a species? How can a sparse population have that kind of effect? How can they eat that much meat, use that much hide, etc.?
Reply | Report Abuse | Link to thisCould the reason the humans finally arrived, whatever that might be, also be the cause of the demise of those species? Why were there no humans before that point? Or rather, was there a reason other than, "we just ain't got there yet?"
A change that allowed or forced humans to populate a new area could certainly affect other species.
I think you are giving humans too much credit, and plants not enough credit. These must had been very slow docile, or incredibly stupid animals to hang around and let a predator stock and kill them. Were there no other predators looking for these animals in the millions of years they were on this planet? I don't think humans could out run any of these animals could they, or dig enough traps to kill them all off? It looks like one of those animals could feed a couple dozen humans and there were not a billion humans on this planet at that time, was there?
Reply | Report Abuse | Link to thisThere are some plants, if over grazed, will produce a poison to keep the animal or insect from over grazing them. Maybe the animals couldn't adapt to the plants poison and died from arsenic and old lace.
JDoors.."How can they eat that much meat..."
Reply | Report Abuse | Link to thisThey wouldn't necessarily have to eat all. If they could kill a large animal they could feed off of it for maybe two or three days and then on to the next kill. Scavenger could clean up the remaining carcass, just like happens now when lions kill more than they can eat.
Also, "The megafauna declined soon after the time that we know people arrived in the region," explains zoologist Christopher Johnson...
Arrived? I thought the Aborigines were 'indigenous'?
Also, "The megafauna declined soon after the time that we know people arrived in the region," explains zoologist Christopher Johnson...
Reply | Report Abuse | Link to thisArrived? I thought the Aborigines were 'indigenous'? Indigenous in this case just means the first to invade not evolved independantly.
According to http://en.wikipedia.org/wiki/Indigenous_Australians
Reply | Report Abuse | Link to thisthe 'indigenous' Australians evidently arrived about 45,000 years ago, although some have estimated an arrival up to 125,000 years ago.
I think the issue JDoors raises is that the estimated human population of the planet 8,000 years ago was less than 3 million people. Genetic analysis indicates that following the Toba supervolcano erruption about 75,000 years ago the global human population dropped to less than 10,000 people. It seems unlikely that a very significant population of humans could have existed around 40,000 years ago in Australia.
More troubling to me is the closing paragraph:
"As for the specific weapons and techniques, they remain unknown. "It is almost certain that hunting of large animals was one of the things [early Australians] did, but we'll probably never know exactly how they did it," Johnson says. In this case, it wasn't the weapons that fingered the perpetrators but an absence of fungal spores that reveals an ancient human deed."
As I understand, not even stone weapon points have been found to support any hypothesis of how a relatively small population of humans could have killed off a large population of enormous animals. I don't find the absence of fungal spores to be compelling evidence that humans hunted Australian megafauna to extinction.
There's too much room for observational bias when general conclusions are drawn from two solitary boreholes. Fires used to drive animals out of sanctuary may have been the trigger. Once the open scorched areas were exposed to climate conditons, the forest areas were burnt off in a quilt pattern over thousands of years. Driven from their habitat, all the stresses overwhelmed some species. The key clue may not be in the marsupials, constrictor snake, and herbivores; it may be in the extinction of all the giant bird species.
Reply | Report Abuse | Link to thisAs usual it was probably a combination of factors that led to the demise of megafauna, including predation pressures from early humans. It's sad, isn't it, to think of our ancestors as the primogenitors of mass extinctions? Modern education has reinforced and inculcated the cult of the Noble Savage into our consciousnesses. Sad to say, but that aspect of Mankind has probably never existed; why do we take for granted that primitive Man was a wise steward of his environment?
Reply | Report Abuse | Link to thisAmerican Indians, before the advent of horse-back hunting, would drive entire herds of grazing animals off precipitous drops; probably not a lot, but in modern concepts of subsistence hunting, even once is too much. There is also evidence of modern extinctions (last thousand years) in North America. As wise as Modern Man is when it comes to the world around them, why would our ancestors come off as any more conscientious?
I wonder how many species will survive the nuclear war that is coming soon. Ruminants are supposed to be hit hard.
Reply | Report Abuse | Link to thisFor a refreshing alternative, a documentary you might want to check out is "Radioactive Wolves". It's about the wildlife revival in the evacuated region of Chernobyl.
Reply | Report Abuse | Link to thisWhile a nuclear war can't be ruled out, you should have been around in 1962 when there was far more reason to be worried than people knew. The world was then truly in immanent jeopardy!
Reply | Report Abuse | Link to thisObviously, humans did it. And they did it almost everywhere else too- the end Pleistocene mass extinctions.
Reply | Report Abuse | Link to thiswell good for you. But in fact, it would be exceptional if we found abundant evidence of kills, given that we rarely find fossils regardless of when or how the animal died. Additionally, there is abundant evidence from population biology that shows that it doesn't take much overkill each year to drive a population extinct within a few hundred years. And if there were no human population controls except other humans- think of how rapidly the yearly predator load could expand. And primitive humans can be exceptionally wasteful in hunting, for example the American Indians with their bison cliff jumps. Why be frugal when it's so easy to stalk and kill an animal that is unafraid of you?
Reply | Report Abuse | Link to thisHumans did it, from Europe to Asia to everywhere else, and it didn't take modern technology to do so.
Actually, a similar Sporormiella study in North America also showed results consistent with human hunting and not any interaction with climate or vegetation or fire that killed off megafauna there. The more sporormiella spore studies are done, the more conclusive this evidence will be. Much more quantitative and precise than mere fossil evidence, I might add. Another similar approach is the ancient-DNA studies that have looked at DNA not just in a few bones but broadcast by hair etc. and preserved in permafrozen soil. Although that only works in polar regions.
Reply | Report Abuse | Link to thisYes I think they could.
Reply | Report Abuse | Link to thisThose species didn't evolve in the presence of humans as did African big game. Technological advances in hunting equipment and the ingenuity of the human brain could easily have pushed them over the edge.
Thank heavens it wasnt global warming.
cockroaches will do find.
Reply | Report Abuse | Link to thisthey studied that at Oak Ridge.
A continent of marsupial Dodo birds, clueless to their own extinction...sad.
Reply | Report Abuse | Link to thisYou may be better informed than I and other 'primitive' humans on this subject, but how many cliffs do you think there are on the Great Plains? Makes for great imagery, though!
Reply | Report Abuse | Link to thisIn America and elsewhere, stone-age peoples left evidence of stone projectile points used to hunt bison and other large animals dating back to more than 60,000 years - no fossil evidence necessary. As I understand (also inferred by this article), the same is not true for Australia. They would have had to use some other method to hunt and kill the enormous beasts discussed here.
By the way, as I understand human populations would have been subject to predation by some of the megafauna preditor species.
Sorry, but I'm particularly unconvinced by your positive declarations.
I watched an interesting TV show a couple of years ago. Kind of a "Mythbusters" type of thing. The researchers built an artificial mammoth ( or part of one) with hide approximating that of a modern elephant, then hung bags of liquid behind it to simulate vital organs. Olympic level javelin throwers were then recruited to throw recreated stone tipped weapons at the mock up.
Reply | Report Abuse | Link to thisYeah... not much happened. The spears barely pierced the hide. Unlikely that much more than flesh wounds were inflicted.
Using a more modern analogies (let's say 17th or 18th century, where did stone age hunters co-exist with large animals?
Africa? Did the natives wipeout all of the elephants? No. The best they could do is poison one from time to time and follow it around for a week until it died.
North America? Did the natives wipe out all of the bison with spears bows and arrows? No. The best they could do is drive a few over cliffs to kill them.
This tells me there is something fundamentally flawed with the view that Ice Age man was this "super-predator".
Besides, I fgind it highly implausible that Australian aboriginals would have forgotten how to make "secret weapons" capable of bringing down massive game.
Natural climate change still gets my vote.
There were a number of carnivorous Australian megafauna species, including marsupial lions, several > 20 ft. long reptiles including a running terrestrial crocodile, several large flightless birds and even a rat-kangaroo. Please see http://en.wikipedia.org/wiki/Australian_megafauna
Reply | Report Abuse | Link to thisAustralian megafauna were not all naive Dodo birds...
The question I'll also pose is: How many of you have actually gone hunting? Harvested an animal? With a rifle? Not that easy. With a bow and arrow? approximately 10X harder. With a spear? Yeah... good luck with that one.
Reply | Report Abuse | Link to thisHunting is a very taxing and difficult activity, even with soething as superior to ancient technology as a modern compound bow.
The point that I'm making is that it is easy to armchair quarterback and blame Ice Age man. But do some field research; go out with a spear in hand and give it a go. See how it works out for you.
Granted you don't have the skill level, nor the physical strength, but if any of you could come home with a pocket gopher or even a rabbit I'd still be surprised.
Actually, the evidence you speak of of humans in the Americas leaving spearpoints going back 60,000 years does not exist. You can't date a rock with precision, only biological materials. The proposed evidence for biological materials can be explained by reworking (mixing) of soil layers, wildfires, etc. Not just can, but it IS explained by that by experts.
Reply | Report Abuse | Link to thisHumans may have been occasional prey to predators but less so for predators who haven't learn to hunt them, plus humans knew how to defend themselves.
Cliff falls of bison is just an example of wasteful killing, but look it up they did exist wherever the conditions were ripe. But that isn't necessary for overkill to occur. Relatively slight overkill especially of slow-breeding large animals is sufficient.
"Sorry, but I'm particularly unconvinced by your positive declarations." Well then. Regardless of what you think about positive declarations, you need to look at the evidence. Same goes for Shoshin. (by the way, your argument about hunting mammoths is not only untrue (google elephant hunt spear to see current examples of hunter-gatherers doing this), but basically amounts to an argument that aliens must have built the Pyramids because we don't see how they did it (actually I think they have a pretty good idea now)). Can't just pick and choose which facts to believe here.
Regarding hunting by native predators, you clearly don't have an understanding about these things. Animals react to certain cues, including sight and smell, that they acquire over long periods. This is why African elephants, for example, go into conniptions when they scent humans. If they aren't endowed with that response they are relatively helpless. I'm not an expert on animal behavior but it might be something similar to how children need to be taught to look both ways. They don't have an innate fear. No one tells rabbits and deer though.
OK, I think I'm done arguing with fact-free people. It's not about my comments or your opinions, it's about the evidence.
I appreciate your opinions, but they are fact free. Googling "elephant hunt spear" brings up information about elephants being hunted with steel tipped spears. Hardly the same as stone age weapons.
Reply | Report Abuse | Link to thisAs to your digression about aliens building pyramids, that was uncalled for. Try sticking to the topic.
South American hunters in the jungle have skills we cannot field test. They're to amazing. More of a testimony to what we lost in modern times.
Reply | Report Abuse | Link to thisI don't see how a small primitive human population can hunt a species to extinction, let alone ALL large animal populations. They didn't have the technology to hunt anything extensively. This sounds like post hoc ergo propter hoc, the logical fallacy that because one thing happened after another means the one caused the other. The fact is there is absolutely no way anyone can ever verify this unless they go back and time and see it happen...heck, they can barely verify it now.
Reply | Report Abuse | Link to thisSad to say Jimmy, but in science, if you can't test it it does not exist, no matter how amazing you might think it might be.
Reply | Report Abuse | Link to thisYou stated:
Reply | Report Abuse | Link to this"Actually, the evidence you speak of of humans in the Americas leaving spearpoints going back 60,000 years does not exist."
I had stated:
"In America and elsewhere, stone-age peoples left evidence of stone projectile points used to hunt bison and other large animals dating back to more than 60,000 years - no fossil evidence necessary."
I could have perhaps worded better, but I intended to assert only that stone-age projectile points have commonly been found in association with human habitation, with some dated back to 60,000 years (using standard archeological dating methods). Also note that humans in North America did not cause the extinction of bison until Europeans wiped them out with repeating rifles.
As I understand, no ancient stone projectile points (especially none dated back to the megafauna extinction) have been found in Australia. IMO, it's unlikely that humans hunted the Australian megafauna to extinction.
In addition to the long continued survival of large mammals in Africa, there is the long continued survival of the buffalo in North America. The hunting hypothesis seems to be motivated by a political animus against a perceived "noble savage" myth. The buffalo example shows quite clearly that cliff kills alone are insufficient to drive a species to extinction. The notion that people on foot habitually fired grasslands and dry woods as a hunting technique is on the face of it insane.
Reply | Report Abuse | Link to thisIt seems quite clear that the whole suite of environmental changes brought by humans resulted in the megafaunal extinctions, things like new plants and more fires accidentally spread by humans. These unintentional factors are why Africa did not have a megafaunal die off, because that was the original habitat and there was nothing new imported. Then in places like North America, the accidental factors were insufficient to kill off the buffalo. Hunting per se could not have been a major factor. We know for a fact that humans would hunt the buffalo mercilessly if they could.
I don't have any opinions about the extinctions, but your idea that the low population of humans 75,000 years ago meant the population still had to be low 40,000 year agos is seriously flawed. Assuming 10,000 people after the volcano, even if the human population doubled only ever 1,000 years after that -- every 1,000 years, after 35,000 years it would have increased 2 to the 35th power, about 35,000 times. 35,000 x 10,000 = 350,000,000, more than we think were on earth only a few thousands years back. Populations even in Australia, would probably have been at the maximum sustainable level within a few thousand years of their arrival. So the assumption humans were too scarce to have a major impact is not well founded.
Reply | Report Abuse | Link to thisWait, my math is terrible. 2 to the tenth power is about 1,000, 2 to the 35th is about 1,000 x 1,000 x 1,000 x 30
Reply | Report Abuse | Link to thisSo the poplulation from 75,000 BC to 40,000 BC would have gone up 30 Billion times if it only double every thousand years. 35,000 years is a long time.
I'm getting drawn into this mess. The non-extinction of bison does not indicate much does it? I don't know their reproduction rates, but as I understand it, a female produces a baby every two years or so and the young animal is ready to reproduce in maybe three or four years.
Reply | Report Abuse | Link to thisWhereas, in the megafauna we have left, elephants, hippos, rhinocerous, doesn't it take something more like human time spans for reproduction? With no predators at all, megafauna can't reproduce at the same rates, they will overpopulate and starve themselves out won't they? Buffalo are pretty tough but wolves, bear and cougars still eat them.
On the other hand, with no means to preserve meat, (or is this a bad assumption) why kill something big and presumably very dangerous?
From the viewpoint of the more recent arriving British the Aborigines were indigenous...
Reply | Report Abuse | Link to thisNo matter where we go, we are an extinction event in progress. Yet we somehow deny that we are the cause. Mother Nature does her own work, but she could learn from us. We keep becoming more efficient every cycle. I am impressed that this time it was not a Judeo-Christian vilian. I wonder if it will take 40,000 years and 7 continents to realize we have impact on all of the environment including the weather. No matter what the naysayers naysay.
Reply | Report Abuse | Link to thisIn closing sorry big guys but even the plant eaters scared our hairy old ancestors. You had to go... I wonder if killing them off had any effect on the climate in that continent. It sure went from lush to dust in a quick geologic time.
Has anyone analyzed the soil samples for spores of Microsporum Canis and alike?
Reply | Report Abuse | Link to thisWhat if humans, the most invasive species on Earth, and/or their co-travelers, like dogs, rats etc. all around the world brought diseases with them, that were not lethal for the travelers - they had meanwhile passed generations of natural selection - but for the fauna in the target areas?
Diseases that can easily jump from one species to another one, like Microsporum Canis, or maybe rabies?
Small mammals with short generation cycles are adaptive enough to survive these diseases, big mammals with long cycles don't.
This is rather an explanation based on Darwinian principles of natural selection, than on the creationist approach of "someone did that", but I consider that nevertheless far more plausible. Especially if you consider how small the human populations was, and how big Australia is.
This entire "Hunters and gatherers" concept is the biggest "Journey to Abilene" that I have ever seen.
Correction, sorry: The forth paragraph should begin: "Populations of small mammals...".
Reply | Report Abuse | Link to thisIt's not the individuals that adapts, but the species.
Some of this animals were supposed to be 10' tall, and be carnivore. For sure, every one in these day's world would have eliminated that kind of kangaroos, it they had the opportunity to.
Reply | Report Abuse | Link to thisI never know if you are serious, so I will point to the land and animal management we accomplished with the American Bison. As usual I am assuming you are making fun so I hope humor never goes extinct. Only some of your bad jokes are lethal.
Reply | Report Abuse | Link to thisHuman's "couldn't do it"? Apparently you haven't examined the near extinction of the bison in North America. Humans certainly can do it.
Reply | Report Abuse | Link to thisMy point exactly. One of our favorite forms of warfare is biological and removing the food source. It was very effective with the Native Americans and part of the reason we built the trans continental rail road was to cut off the south to north migration of the bison and when that didn't work well enough we had the massive kill off.
Reply | Report Abuse | Link to thisEvery time man has migrated out of Africa the Mega-fauna has become extinct except for some of the nocturnal species. With the weaponizing of Africa since the 19th Century we have seen the same devastation of mega-fauna with most ranges shrunk and migration paths decimated. What is also sinful if the word ever applies is that the great white hunter culls the alpha of the species not the weak and the sick as a normal predator/prey arrangement works.
But we continue to deny we are the cause of any of the crap the earth is facing. We have created one of the largest extinction events since the end of the Cambrian. Go people go, because at this rate we will be gone sooner than later. We just don't get that we are dependent on the feedback and ecosystems that put food on our table and O2 in our atmosphere.
ErestPayne, I hear you, I doubt many do.
Sharps 45-90 vs. pointed stick.
Reply | Report Abuse | Link to thisNot much of a comparison.
Please try again with something that makes a bit more sense.
You are very far out my friend. Only have to look at more recent extinctions to see that humans can wipe out a species very quickly. If you watch how animals respond to others who are non-threatening you see the gazelle and antelope/buffalo and wart-hog temperate in the presence of each other. That is how animals who have never seen a person often treat us, why would they be scared? There was a time in continents other than Africa when people could walk up to animals and spear them, obviously the pre get wise, but it isn't instantaneous; additionally these mega-fauna breed and mature slowly, so it is easy to destroy their population via continual decimation.
Reply | Report Abuse | Link to thiswe have fuelled our success by winning the top of the food chain competition wiping out wonderful organisms in the process. So, its the way things go in this Darwinian world, but maybe we are just little too good at it, too efficient and smart compared to our fellow residents of this small, pale blue dot. Maybe we will be the victims of our own success? Just how many organisms have ceased to exist in the name of our proliferation? The complex nature of the relationships between flora and fauna on both land and sea mean that the repercussions of our actions are unquantifiable and in not too distant future then maybe the Earth will no longer fulfil our needs? There are too many people . This is a fact. I don't think it is enough for us to 'simply' be more sustainable in habit and culture. 40ka our existence was what today we would call 'sustainable' but clearly that wasn't the case.
Reply | Report Abuse | Link to thisspot-on. there is a site in France where it has been shown that we herded mammoth of the cliffs and then butchered their carcass in-situ - the bones clearly show the butchering marks from palaeolithic tools. We are too good at being good hunters...
Reply | Report Abuse | Link to thiswe have fuelled our success by winning the top of the food chain competition wiping out wonderful organisms in the process. So, its the way things go in this Darwinian world, but maybe we are just little too good at it, too efficient and smart compared to our fellow residents of this small, pale blue dot. Maybe we will be the victims of our own success? Just how many organisms have ceased to exist in the name of our proliferation? The complex nature of the relationships between flora and fauna on both land and sea mean that the repercussions of our actions are unquantifiable and in not too distant future then maybe the Earth will no longer fulfil our needs? There are too many people . This is a fact. I don't think it is enough for us to 'simply' be more sustainable in habit and culture. 40ka our existence was what today we would call 'sustainable' but clearly that wasn't the case.
Reply | Report Abuse | Link to thisFor an understandable explanation of the Sixth Great Extinction, I suggest you to to the e-zine Izlwane, which addresses this topic and read: http://www.izilwane.org/the-sixth-great-extinction.html
Reply | Report Abuse | Link to thisActually because these are non-linear connections, we may have already created the cascading crash of ecosystems and I don't think there is much we can do but watch and chronicle the event. As the earth slowly warms the tundra areas and the Gulf of Mexico will release CH4 in such amounts that it will create a feedback system. This will more than likely create more atmospheric moisture which may or may not create an ice age but with that much green house gas available and our tendency to over react I am counting on a fast rise of temperature.
Reply | Report Abuse | Link to thisThe honey bees are already in distress which bodes badly for agriculture and we have more than done enough damage to the ocean to hope for it to replace food for 9 billion people which we will probably see before the crash hits.
To add insult to injury, Yellowstone and Cascadia are ticking away and when they go so goes what we consider civilization. Once we lose law and order and might becomes right science will be a nice afterthought and slash and burn will take off as the agriculture by grunt replaces the advances we have created over the last century.
Oh come on it can't get that bad can it.... What would H. G. Wells say?
It's not my idea about early populations - please see:
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/World_population_estimates
It states that McEvedy & Jones estimated that the global population 10,000 years ago was 4M; Thomlinson estimated it to be from 1M to 10M. References below:
Colin McEvedy and Richard Jones, 1978, "Atlas of World Population History," Facts on File, New York, ISBN 0-7139-1031-3.
Ralph Thomlinson, 1975, "Demographic Problems: Controversy over population control," 2nd Ed., Dickenson Publishing Company, Ecino, CA, ISBN 0-8221-0166-1.
The wikipedia entry also contains links to entries describing the population bottleneck identified through analyses of human DNA mutation frequencies that coincided with the Toba supervolcano eruption about 70,000 BCE. It cites a population estimate based on the DNA analyses of between 1,000 and 10,000 breeding couples following the Toba eruption.
Regarding reproduction rates, I understand they are generally lower for larger animals - they tend to require longer gestation periods and smaller broods. That was likely a factor in whatever causes actually produced megafauna extinctions, as well as the extinctions of the larger dinosaurs (of course, their extinctions cannot be attributed to humans).
Re. predators of megafauna, I repeat my comment #19:
There were a number of carnivorous Australian megafauna species, including marsupial lions, several > 20 ft. long reptiles including a running terrestrial crocodile, several large flightless birds and even a rat-kangaroo. Please see http://en.wikipedia.org/wiki/Australian_megafauna
In the Americas, megafauna include the Saber-Toothed cats, short-Faced Bear and Dire-Wolf among other predators. Please see:
http://en.wikipedia.org/wiki/Quaternary_extinction_event
Again, I take you with a bucket of squid. The mega-fauna died off about 13,000 years ago. Yellowstone blew its stack about 250,000 years ago. Maybe it was metric years? Again when dealing with bucket of squid, I say calamore. But if you are searching for truth, maybe a meteor/asteroid impact (some signs of that) over the NW US and a upwelling of volcanoes in Siberia. Something weird happened because a lot of Mammoths and Mastodons were flash frozen with undigested food in their mouths.
Reply | Report Abuse | Link to thisI guess the ideals in Decipher make as much sense as any thing else because unless your were there (in which case you wouldn't be here) who knows for sure. I defer to the squid. I say go C60 go go go for unburnt Carbon in all its better forms. You know diamonds, graphine, nano tubes, composites and batteries. But burning it is so passe.
Wait a minute... What planet are you on. I don't think the continent of Australia has moved that much in a mere 13,000 years. Hmmm too much see food.
Reply | Report Abuse | Link to thisI think I'll leave it with the immortal words of Elaine Benes, 'The Dingos ate my baby' !
Reply | Report Abuse | Link to thisMy faith in science to move toward correct conclusions is shaken by the amount of time this crazy idea has persisted, apparently without serious question.
Reply | Report Abuse | Link to thisIt is certainly and interesting theory, but it fails so immediately and completely by any reasonable analysis that it should have been discarded quickly.
Re Australia: the influx of humans was too small to totally devastate the fauna so rapidly over so large and area.
In North America, the mammoth and cave lion is often used to make the point. If man killed off the mammoth in North America, how did that kill off the lions, who we are quite certain were not on the menu - or on the "easy pickings" list for hunters. Even had it been true about the mammoths, is someone (everyone?) claiming that the lions hunted mammoths by preference, AND that they were unable to hunt or eat bison or deer, or antelope or elk -- all of whom survived quite handily until Europeans with guns arrived.