Tasmanian devils with an aggressive streak are biting off more than they chew, and it could be the key to slowing the spread of their deadly facial tumour disease.
Researchers have been surprised by a study which found biters, rather than the bitten, are contracting the devastating disease.
Devils are renowned for their aggressive snapping, especially when fighting over a meal and even when mating.
University of Tasmania scientists found devils with more bites were less likely to have the disease, whereas those with fewer bites had a higher incidence.
"We found very surprising, or counterintuitive, results," says Dr Rodrigo Hamede, whose paper has been published in the British Ecological Society's Journal of Animal Ecology.
"They're biting the tumours of other devils that are less aggressive and that's how they are becoming infected."
Hamede tracked 300 devils near Cradle Mountain in Tasmania's northwest between 2006-2010.
Infected devils averaged 0-4 bites and non-infected 5-15.
Mouth injuries sustained from crunching bone or echidna quills make aggressive devils susceptible to the infection when they bite a tumour on another animal.
The disease has wiped out 80 per cent of Tasmania's devil population, but the findings offer some hope.
Hamede expects a fast-tracking of evolution so devils and the disease begin to coexist and ensure each other's survival.
It could mean devils will become less aggressive because the behaviour helps them live longer, and the disease is expected to become less virulent.
There is some evidence the process is already under way in the Cradle Mountain population, with some diseased devils surviving for longer and some tumours regressing.
"[This disease] is 100 per cent lethal, so in a way animals have to learn to coexist with DFTD [devils facial tumour disease]," Hamede says.
"This is also in the interest of the tumour itself, to leave devils alive, because if we run out of devils we also run out of tumour."
The next stage of the research will gather more detailed information on what makes devils more or less aggressive in the hope of devising a plan to help evolution along.