The giants among the animals died worldwide thousands of years ago. Was it a climate change or was it man? Researchers now believe that they can answer this question clearly – and make a conviction.
An Australian-American-German research team around the palaeontologist Sander van der Kaars believes that has found sound evidence to answer an ancient question: Who is to blame for the mass extinction of the megafauna – man or climate change? Kaars and colleagues show with a study published in the „Nature Communications“ about the disappearance of the Australian Megafauna that a climate change had nothing to do with this mass death – the man obviously caused this by its own power.
No matter where you look: somewhere in a time window from 50,000 to 10,000 years before our time, a massive death swept out most of the big animals. In Africa alone, parts of the Great Fauna survived – possibly because only there the man was not an invasive species. Nevertheless, the causes of mass death have been debated for decades: at least in the northern hemisphere, the great dying coincides with major climatic changes. And who or what would be more likely to drive giants like mammoths into the doom: a few scattered humans with spears or a total change of all biotopes?
Sander van der Kaars and his colleagues argue that it probably did not need more than a few people with spears to initiate an „imperceptible overkill“. Kangaroos weighing 500 kilograms, two-ton wombats, 200 kilos birds, 150 kilograms of bagworms, more than a ton of weighing Bagsworms (Tasmanian wolfs) or turtles the size of a VW Beetle had existed 50,000 years ago in many places in Australia. 5000 years later they did not exist anymore.
What was still changing: It was precisely the time window in which man began to spread across Australia. On the other hand, there was no climate change. According to van der Kaars and his colleagues, this also allows conclusions to be drawn about the role of man in mass death in other parts of the world. At least in Australia, apparently man was the only and thus decisive factor.
Barbecue until the point of no return
And this, although the Aboriginal immigrants who immigrated to Australia 50,000 to 60,000 years ago were only very slowly spread over the continent they were new to. Until now, this was the argument that was often put forward to dismiss human beings as perpetrators in the Grossfauna mass deaths. However, it did not need much, as van der Kaars and Co .: Large animals have fewer offspring and a lower population density.
As early as 2006, a calculation showed that it would have been enough if aborigines had killed a large animal per decade per person in order to make their population imperceptibly, but also unsustainably, to a point where the species conservation would no longer be guaranteed . Without even being able to notice this in their own lifetime, people would have used „only a few centuries“ to destroy Megafauna, writes co-author Gifford Miller of the University of Colorado.
That’s what Miller and van der Kaars found in the sediment: in the deeper layers, but only up to a point about 50,000 years ago there are deposits of excrement from large animals and mushrooms that decompose them. Then these ingredients simply disappear in the sediment – this change only lasted a few thousand years. At the end of this process the dominant representative of the largest species in Australia was on two legs – and 85% of all animals weighing more than 50 kilograms disappear.
