Tuesday, August 12, 2008

Invasive species implicated in killing prehistoric animals

New findings show that it's likely that an invasive species killed off large marsupial species in prehistoric Australia.

What invasive species would that be? Home sapient, the most invasive around.

ScienceDaily has the story.

Humans Implicated In Prehistoric Animal Extinctions With New Evidence

Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The new study provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived.

The findings suggest that the mass extinction of Tasmania's large prehistoric animals was the result of human hunting, and not climate change as previously believed.

While the ScienceDaily article makes it sound like this is amazing news, but the idea of a human cause of the megafauna's extinction is hardly a novel idea, and it has certainly been investigated before. PNAS had a good overview article on it back in 2002 Explaining the Pleistocene megafaunal extinctions: Models, chronologies, and assumptions by Brook and Bowman.

The focus of these investigations have mostly focused on whether there were an overlap of human and megafauna inhabitation of Australia, but other studies have shown that even if there were, the extinction might still be at least partly caused by climate changes - see e.g Prolonged coexistence of humans and megafauna in Pleistocene Australia (.pdf) by Trueman et al.

According to the ScienceDaily article, new findings puts humans as the culprits.

Previous research by Professor Flannery and Professor Bert Roberts of the University of Wollongong, Australia, has shown that 90 per cent of mainland Australia's megafauna disappeared about 46,000 years ago, soon after humans first settled the continent. But humans did not reach Tasmania until a few thousand years later, when the island became connected to the mainland by a land bridge as sea levels fell during the last glaciation. "The Tasmanian results echo those on mainland Australia, putting humans squarely back in the frame as the driving force behind megafaunal extinction", said Professor Roberts.

It should perhaps be pointed out that human driven extinction could be cause indirectly, e.g. through changes to the living habitats by the burning of forests etc. or by animals brought along by the humans (e.g. dingos).

Unfortunately it appears that the study the ScienceDaily article refers to haven't appeared online yet - it should be published in the Proceedings of the National Academy of Sciences of the USA (PNAS), so I expect it to be only a matter of time before it's available (though probably behind a paywall).

While looking after the article, however, I did come across to one that's seems somewhat related:
Species invasions and extinction: The future of native
biodiversity on islands
(.pdf) by Sax and Gaines. It does address the role of humans in the recent extinction of species.

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