Humans didn't cause problems for everything we get blamed for but DNA evidence in a paper suggests that the ancient New Zealand megaherbivore, moa, a distant relative of the Australian Emu, did go extinct shortly after Polynesians arrived  in the late 1200s.

All nine species of New Zealand moa, the largest weighing up to 250 kilograms, have been gone for centuries and other studies suggest that huge populations of moa had collapsed before people arrived and hence influences other than people were responsible for the extinction, like climate change killing the vegetation. Instead, the authors say humans killed the environment and that killed the moa.

The new paper analyzed the gene pools of four moa species in the 5,000 years preceding their extinction using ancient DNA from more than 250 radiocarbon-dated specimens. The larger data sets provided greater insight into what was happening to the populations of an extinct megafauna, allowing a detailed examination of the extinction process.

The genetic study was led by Professor Mike Bunce from Curtin University's Department of Environment and Agriculture, situated in Perth, Western Australia.

"Characterizing a people's interactions with the environment is a fundamental part of archaeological research – it has been portrayed anywhere on a scale from the harmonious to the catastrophic," Bunce said. "Elsewhere the situation may be more complex, but in the case of New Zealand the evidence provided by ancient DNA is now clear: the megafaunal extinctions were the result of human factors. 

"Lessons can certainly be learnt from the historical study of megafaunal extinctions. As a community we need to be more aware of the impacts we are having on the environment today and what we, as a species, are responsible for in the past."

Dr. Morten Allentoft, Post-Doctoral Fellow at the Centre for GeoGenetics in the Natural History Museum in Copenhagen, performed the genetic work and said, "There is nothing in our ancient DNA data that suggests that any of the four species moa was already on the way out when humans arrived. Our detailed genetic analyses, using variable nuclear markers similar to that used in forensic DNA profiling, show that moa gene pools were extremely stable throughout their last 5000 years. 

"If anything it looks like their populations were increasing and viable when humans arrived. Then they just disappeared."