Monash University, CU-Boulder show steep decline in megafauna shortly after 45,000 years ago
From the UNIVERSITY OF COLORADO AT BOULDER
New evidence involving the ancient poop of some of the huge and astonishing creatures that once roamed Australia indicates the primary cause of their extinction around 45,000 years ago was likely a result of humans, not climate change.
Led by Monash University in Victoria, Australia and the University of Colorado Boulder, the team used information from a sediment core drilled in the Indian Ocean off the coast of southwest Australia to help reconstruct past climate and ecosystems on the continent. The core contains chronological layers of material blown and washed into the ocean, including dust, pollen, ash and spores from a fungus called Sporormiella that thrived on the dung of plant-eating mammals, said CU Boulder Professor Gifford Miller.
Miller, who participated in the study led by Sander van der Kaars of Monash University, said the sediment core allowed scientists to look back in time, in this case more than 150,000 years, spanning Earth’s last full glacial cycle. Fungal spores from plant-eating mammal dung were abundant in the sediment core layers from 150,000 years ago to about 45,000 years ago, when they went into a nosedive, said Miller, a professor in the Department of Geological Sciences.
“The abundance of these spores is good evidence for a lot of large mammals on the southwestern Australian landscape up until about 45,000 years ago,” he said. “Then, in a window of time lasting just a few thousand years, the megafauna population collapsed.”
A paper on the subject was published online Jan. 20 in Nature Communications.
The Australian collection of megafauna some 50,000 years ago included 1,000-pound kangaroos, 2-ton wombats, 25-foot-long lizards, 400-pound flightless birds, 300-pound marsupial lions and Volkswagen-sized tortoises. More than 85 percent of Australia’s mammals, birds and reptiles weighing over 100 pounds went extinct shortly after the arrival of the first humans, said Miller.
The ocean sediment core showed the southwest is one of the few regions on the Australian continent that had dense forests both 45,000 years ago and today, making it a hotbed for biodiversity, said Miller, also associate director of CU Boulder’s Institute of Arctic and Alpine Research.
“It’s a region with some of the earliest evidence of humans on the continent, and where we would expect a lot of animals to have lived,” Miller said. “Because of the density of trees and shrubs, it could have been one of their last holdouts some 45,000 years ago. There is no evidence of significant climate change during the time of the megafauna extinction.”
Scientists have been debating the causes of the Australian megafauna extinctions for decades. Some claim the animals could not have survived changes in climate, including a shift some 70,000 years ago when much of the southwestern Australia landscape went from a wooded eucalyptus tree environment to an arid, sparsely vegetated landscape.
Others have suggested the animals were hunted to extinction by Australia’s earliest immigrants who had colonized most of the continent by 50,000 years ago, or a combination of overhunting and climate change, said Miller.
Miller said the extinction may have been caused by “imperceptible overkill.” A 2006 study by Australian researchers indicates that even low-intensity hunting of Australian megafauna – like the killing of one juvenile mammal per person per decade – could have resulted in the extinction of a species in just a few hundred years.
“The results of this study are of significant interest across the archaeological and Earth science communities and to the general public who remain fascinated by the menagerie of now extinct giant animals that roamed the planet – and the cause of their extinction – as our own species began its persistent colonization of Earth,” said van der Kaars.
In 2016 Miller used burned eggshells of the 400-pound bird, Genyornis, as the first direct evidence that humans actually preyed on the Australian megafauna.
The new study also included Research Professor Scott Lehman of INSTAAR. The study was funded in part by the U.S. National Science Foundation and the German Research Foundation.
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If Mann – sorry, Man was responsible, perhaps Mr Trump should publish an apology on behalf of the human race?
Population is the key.
Take today for example. We could never go straight back to hunter gatherers today because there are too many of us. Let’s say hunter gatherer starts tomorrow. Within a few weeks people are going to bed hungry and getting some meat for the family becomes the number 1 concern. Everybody is out hunting within a few weeks besides all other kinds of conflict.
Within a year, we have killed off just about all the animals and cut down every tree for firewood and cooking.
If the aborigines grew rapidly in population 45,000 years ago due to the abundant resources, well, they would have taken many species to extinction.
But we need evidence that the population grew to something like a million. Were there ever that many. Once you get a lot of people and start making resources hard to obtain again, the hunter gatherer populations fall. Maybe too late for for some species but then an equilibrium is established.
In North America, the early Indians found resources that were easy to obtain, but the population never increased to really high levels until agriculture came in the Americas. This is where the population booms were. Same story in Europe, the Middle East and Asia. Was Australia different. How many humans were in Australia 45,000 years ago.
No. Population is not the key in megafaunal extinctions. Most top predators are quite specialized in the areas they live, and increase or decrease in numbers according to their main prey or preys numbers. That’s why top predators do not extinct their preys. Man is at the same time top predator and opportunistic omnivore, which is very rare. Cultural developments made man an extremely efficient hunter and success no longer depended on prey abundance. Megafauna was the prey of choice and their rate of reproduction is low. Unless they were very shy and fearful of man, or dense forest dwellers, they were hunted above replacement rate all the way to extinction.
I don’t see why this is such a difficult concept to accept. We haven’t changed. We recently became top predators in many marine ecosystems, with high success rate due to cultural developments and we have driven every large species that we hunt, whales, sharks, tuna, almost to extinction by hunting them above replacement level.
You raise an interesting point. The prevailing arrid conditions in Australia would lock in people as subsistence hunter gatherers, preventing the progress to widespread early agriculture. The megafauna and who knows what else would be doomed.
Javier – I’m not sure why you start with “no” – what you say – which I agree with – does not seem to contradict Bill’s points.
Another factor is sudden arrival of humans. Here is another hypothesis. Africa is where humans – from ancient australopithecines all the way to behaviourally modern, evolved. Yet Africa is the continent with the most, not least, surviving megafauna. An apparent contradiction. Unless you propose that in Africa, megafauna and evolving humans arrived slowly at a synergy of coexistence together. Whereas in places like North America and Australia, they “suddenly” arrive in a boat, fully modern, into an ecosystem where humans are unknown. Carnage and extinctions follow. We acted as a destructive invasive species in these places, but not in Africa.
Quite right
North American large grazers possibly “overkilled”:
Horse, Tapir, Camelops,; browsers: Mastadon, seven genera large ground sloths.
sthwest is WA so the claims of the spores found in oceans?
where?
cos the east coast landing of much at all, would be a lot far fetched to me.
wouldnt finding aboriginal poop and megafauna dna in that be rather better “proof”
This conflicts with popular impression that the first Australians were wise and in perfect harmony with nature. Sort of like the early western perceptions of the Maya, that they were these philosopher kings of the jungle, studying the stars and cosmos. Now it is accepted that Mayans were in frequent wsrs, blood thirsty and extremely political slaving and sacrificing humans, etc. The first settlers of Australia were Paleolithic humans. Emphasis on humsn, with all the instincts and capabilities that implies.
Yuval Noah Harari in his book “Sapiens” tell the same story re America – within 2000 years of sapiens arrival, 34 of 47 genera of large mammals went extinct.
I am not a weatherman, but I am a biologist.
Megafauna . . . super big animals . . . is generally an adaptation to cold. The deer in Saskatchewan are 3 times the size of Texas deer. Greater volume of body yields less relative surface area, greatly reducing heat loss.
A warming climate is the Occam’s Razor for the end of megafauna. There may be another explanation, but it will take more than speculation, or some egg shells, to prove it.
The megafauna of Oz had survived many warmings and coolings of their environments, which temperature changes weren´t extreme in the Pleistocene.
Elephants ? Rhinoceros ?
Further back large dinosaurs….T rex
http://www.livescience.com/29231-cretaceous-period.html
Large creatures doing quite nicely in a warm climate
Some mammals adapted to the cold by becoming larger and hairy but it is not a necessary adaption [huge mice?] and it doen’t mean that large animals aren’t suited to warmer areas
Anyone have the recipe for BBQ eggs? Sounds intriguing.
(Note: It is fun to watch watermelons explode)
The recipe for an egg is a chicken
The recipe for a chicken is an egg
1j8
It’s obvious to every rational person that the first arrival of people and the extinction of megafauna coincided everywhere. In New Zealand, the cooking ovens holding the large bones of the now-extinct moas are found all over. Those big birds were early KFC, people, say yum yum. This is not rocket science.
I recall attending a dinner some 40 years ago at the University of Melbourne at which the guest speaker was Geoffrey Blainey, then Professor of Australian History at the University (this was while I was teaching chemical engineering at the University). During his address he commented that Aborigines had fire which they used for hunting and which they were never known to put out. He commented that James Cook in his journal while travelling up the East coast of Australia in 1769/70 (?) wrote that the land appeared to covered in a pall of smoke. He stated that he considered this hunting technique was responsible for the disappearance of giant marsupials, citing the discoveries of piles of bones at the bottom of cliffs, believing that the animals were driven over the cliffs by deliberately lit brush fires.
Well, is CO2 not the gas of life?
What if the too low CO2 concentration caused the extinction?
If one goes through the ice cores from the NOAA site (ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok) there are these values for CO2 in the CO2.txt file last modified 12/08/1997 12:00:00 AM:
Barnola et al,Nature, 329, 408-414 (1987)
Depth ice Age Gaz age CO2 ppmv mimimum maximum
m years years value value
700.3 42320 38660 207 211 203
748.3 45970 42310 178.5 196.5 173.5
775.2 48000 44350 200 205 190
Just wondering if the very low CO2 values did not cause starvation or low growth for the plants that stood at the basis of the huge fauna?
The 173.5 value is the lowest from the whole sample and it looks like it was just 42 k years ago?
Well, according to fossils recovered from the La Brea Tar Pits, junipers and other plants were suffering from CO2 starvation during the last glaciation: http://www.pnas.org/content/102/3/690.full?sid=5e3bdf35-c2a6-4fe7-b336-eea3917571f2
Excerpt from the abstract:
Here we report on δ13C of Juniperus wood cellulose, and show that glacial and modern trees were operating at similar leaf-intercellular [CO2](c i)/atmospheric [CO2](c a) values. As a result, glacial trees were operating at c i values much closer to the CO2-compensation point for C3 photosynthesis than modern trees, indicating that glacial trees were undergoing carbon starvation.
Thanks for the feedback and the link. Form the abstract it becomes clear:
” By scaling ancient c values to plant growth by using modern relationships, we found evidence that C3 primary productivity was greatly diminished”
Here another post about CO2 starvation which explains why CO2 does not tend to go lower once a certain low limit is reached – massive negative feedback – read plants no more growing
http://people.earth.yale.edu/sites/default/files/files/Pagani/6_2012%20Beerling%20JEcol.pdf
” lower limit of [CO2] a is buffered by a strong negative feedback, ca used by a diminished capacity
of land plants to weather Ca- and Mg-bearing silicates as[CO2]a falls to critically low ‘starvation’ levels (Pagani et al. 2009)”
I remember having read also about megafauna in the Eurasian area and the disappearance of specific plants. I think there is not enough such research and we do not yet understand the constrain of 200 and lower CO2 ppm on whole ecosystems.
Here one about “trees that miss the mammoth” in NA.
http://www.americanforests.org/magazine/article/trees-that-miss-the-mammoths/
What it fails to consider is that trees have a high dependency on CO2 concentration.
Of course humans are again mentioned, and for sure they did their part, but what is missing from the whole picture is the strain put on the whole system by the low CO2 content.
If the basis of the food pyramid is severely constrained that what happens with the whole ecosystem? And of course huge animals are the first to have a problem finding the needed food as they need now to look on a larger area. The energy balance works no more for them.
Megafauna mostly live on C4 plants (like grass). So when C3 trees had a difficult time were actually good times for megafauna.
tty says: January 22, 2017 at 10:22 am
Megafauna mostly live on C4 plants (like grass).
You mean megafauna that survived? Yes, I agree.
Wondering if you can point to any study of what the extinct megafauna was eating?
In one example I gave was a tree “missing” megafauna, so that was not grass, but certain tree fruits.
I remember there was also a study about extinct megafauna in the Eurasian continent, and surprise, surprise, the plants that were at the basis were also gone. I’ll need to try to find it again.
ok found something – forbs not grasses which are classified as C3 plants:
http://www.sussex.ac.uk/broadcast/read/23194
“The study challenges the prevailing view that the Ice Age “mammoth steppe” (which fed the Ice Age megafauna – giant mammals including woolly mammoths, woolly rhinoceros, bison and horse) was grass-dominated.
Instead, the DNA analysis reveals that the dry steppe tundra on which the animals lived and fed was dominated by forbs (herbaceous vascular plants that are not grasses, sedges and rushes), which provided more nutrients to the grazing animals than grasses.
The composition of the mammoth steppe-tundra of course changed over time, but is now effectively extinct. Its components still exist, so it will reemerge during the next glacial cycle. However its largest and most characteristic herbivores are gone. Horses, bison, ibex, saiga antelope and some others still survive, often in modified form.
Its fauna resembled the Serengeti, with mammoths for elephants, woolly rhinos for the black and white rhinos, horses for zebras, bison for wildebeest, saiga for some antelopes, etc.
Gloateus Maximus
January 24, 2017 at 8:09 am
However its largest and most characteristic herbivores are gone. Horses, bison, ibex, saiga antelope and some others still survive, often in modified form.
Exactly. Why horses, bison etc survived and others not?
Was wondering if we do not have the case where herbivores feeding on C4 plants survived, whilst the ones feeding on C3 plants died, as the respective plants got rare/seldom due to CO2 starvation during the ice age.
But Perfesser Flim Flammery told us in his book it was climate change!
So, what was the Aboriginal population of Australia in the 1700s? (about 400 years ago).
If one believes Wikipedia, it was ” between 315,000 and 1.25 million, mostly concentrated in the fertile south east of the continent.”
If this figure is correct, than if one goes back 45,000 to 150,000 years ago the aboriginal population most likely would have been less than cited in Wikipedia.
So basically, the continent of Australia was devoid of humans (land area of Australia is 2.9 million square miles) until the Europeans showed up in large numbers.
Note that the upper estimates for the Native American population in 1492 in what is now the lower 48 US states tops out at about 5 million and the land mass of this area is about 3.12 million square miles; not much larger than that of Australia , but about 4 times the native population of Australia .
When the evil white man showed up in North America in what is now the USA, the land was teeming with wildlife.
The fact is that Australia and even North America, even as late as 1500 , were almost devoid of humans. There are today more folks in Queens and Brooklyn, NYC than lived in all of Australia and North America in 1500.
The idea that humans wiped out the wildlife of Australia 50,000 years ago is laughable.
…………..in the 1700’s……….. I meant to say about 300 years ago.
The environments of Australia and North America 300 years ago were very different. Many American Indians were farmers.
The environment of Australia was also different before the arrival of humans. The earliest Aboriginal population probably ballooned at first, then crashed after killing off the megafauna.
“When the evil white man showed up in North America in what is now the USA, the land was teeming with wildlife.”
It was a lot less teeming in 1500 than in 1700 after disease had virtually wiped out the native population. Have a look at Cahokia next time you’re in St Louis. That wasn’t built by a few wandering hunter-gatherers.
Dear John,
Come and have a look. Check the carrying capacity of most of Australia.
A lot of Australia is needed to support one big animal.
People arrive with pointed sticks. It’s all over for the big things.
Maoris in New Zealand did for the Moa very quickly
Dodos were wiped out very quickly as they weren’t scared of people.
They ended up in Dutch sailors’ cooking pots.
There’s no suggestion that aboriginal people in Australia wiped out the wildlife 50,000 years ago.
There is a suggestion the the aboriginal people wiped out the big stuff…
“Monash University in Victoria, Australia”
OK
” and the University of Colorado Boulder”
What country is that in?
The preference for hunting megafauna over lesser fauna is one of simple economics. The meat of a 1000 kg will feed the tribe a lot longer, and with a lot less work, than the meat of
The preference for hunting megafauna over lesser fauna is one of simple economics. The meat of a 1000 kg will feed the tribe a lot longer, and with a lot less work, than the meat of a 1 kg tree-dwelling mammal or bird.
“New evidence involving the ancient poop of some of the huge and astonishing creatures that once roamed Australia indicates the primary cause of their extinction around 45,000 years ago was likely a result of humans, not climate change.”
Think that was evident for archaeologists since ever.
Remember me doing similarly claim some time ago on “wuwt” labeled ‘laymen may tell what scientists are not allowed.’
Cheers – Hans