What is the oldest argument in Australian science? The argument about what hunt caused the extinction of the Pleistocene megafauna, including the giant kangaroos and marsupial Tapirs, and the uber-echidnas, is probably the oldest in Australian science.
Sir Richard Owen, an English anatomist, suggest in 1877 that big animals driven extinct by the hostile agency of man. This means that hunting was responsible for the extermination of these large animals, a process now known as overkill. Others suggested that climate change was the reason, and it was.
Owen’s view has been support by a series of studies in a variety of disciplines, including geochronology and palaeoecology. The argument does not stop there. But why?
Many Australian archaeologists are against overkill. They’ve search for direct evidence that megafauna kill, but they haven’t found it. There are no large piles of bones in ancient campsites, no diprotodon skulls with spears embedded in their ribs and no arsenal of specialized weapons to bring down large prey. There are very few archaeological sites that have megafauna and human remains in close proximity.
Megafauna-hunting was not a reality for some archaeologists. This conclusion is often state with such confidence that it dismisses any non-archaeological evidence as overkill.
Megafauna Were Hunt To Extinction
They haven’t asked the crucial question: If megafauna were hunt to extinction by humans, how much evidence should we be able now to find from archaeological sites? According to a new paper, archaeologists Todd Surovell (Brigid Grund) suggest that the answer is either very little or none.
Surovell & Grund first point out that the time period in which archaeological evidence could have found of the killing of megafauna is only a fraction of Australia’s total archaeological record. Between 50,000 and 40,000 year ago, people arrived in Australia. This is also when animals such as diprotodon disappeared. Comparing fossil and archaeological dates shows that humans and megafauna spanned only about 4,000 years across continents. Modelling suggests that extinction would have occurred in less than 1,000 years if hunting had been responsible.
This means that less than 8% of the Australian archaeological records covers the period of human megafauna interaction. Overkill evidence should be rare, so it is not a “smoking gun”. Surovell & Grund demonstrate that finding such evidence can be even more difficult than it seems, and for two reasons.
The first was that when people arrived, their numbers were small. Therefore, living sites found at low density. Site density increased exponentially as the population grew. The earliest sites are therefore more rare than the later ones.
If megafauna were to have become extinct, the population of megafauna could have declined as people grew. As the number of sites grew, the percentage of sites that could have held evidence of megafauna killings was also falling. Sites that could preserve this evidence make up a small percentage of the total archaeological record, possibly less than.01%.
Second, archaeological material is subject to erosion and weathering, and can also be broken down and weathered. Old sites eventually get buried beneath sediments. It is less likely that archaeological sites can be found from Australia’s earliest occupation. Also, most of their contents will have vanished.
The earliest archaeological sites in Australia often only have a handful of stone tools. These tools can only tell us very little about the interaction of the first Australians and any other animals or plants.
As scientists, our fundamental task is to test hypotheses with evidence. We need evidence that will differ depending on whether the hypothesis is true, false, or in between. If overkill didn’t occur, megafauna-killing hunt evidence should be rare in archaeology. Surovell’s and Grund’s analysis shows that even if there was overkill, evidence of the killing should be rare. Failure to find evidence of overkill does not prove that the hypothesis is true.
Archaeological Evidence Of Killing
However, this does not mean that the archaeological evidence of killing or absence of such evidence is ineffective in testing the overkill hypothesis. Surovell & Grund demonstrate that it is possible to use archaeological evidence of killing by comparing the archaeological records from Australia, North America, and New Zealand. While all three countries lost their megafaunas with the arrival of humans, this occurred in Australia a long time ago and in New Zealand 700 years ago. North America is intermediate. Human arrivals and extinctions occurred between 14,000 and 13,000 years ago.
We apply the same logic to all three cases. If megafaunal extinction was cause by overkill, the archaeological evidence should be abundant in New Zealand, scarce in North America, and almost absent in Australia. This is exactly what we found.
There is overwhelming evidence that New Zealand’s moa were hunt heavily. This makes it clear that overkill was their main reason for extinction. Although there are undisputed kill sites in North America for mastodons, mammoths, and other species, the evidence is much less than that found in New Zealand. Megafauna-killing is not yet supported by Australian archaeology. The archaeological evidence in Australia supports the overkill hypothesis, but it is far from being disproven.