Key Points:

A New Zealand scientist who claimed that Maori carry a "warrior" gene that makes them more prone to violent and aggressive behaviour stands by his research, saying his findings were distorted by politicians and the media.

Controversy over the claim has again flared after Dr Rod Lea said his research was justified as it could help reduce Maori rates of smoking and alcohol addiction.

Dr Lea made headlines last year when he told an international conference in Brisbane there was an over-representation of the monoamine oxidase gene, dubbed the "warrior" gene by US researchers, in Maori men.

Australian reports quoted Dr Lea suggesting the gene, also associated with risk-taking and addiction, had links to criminality.

Dr Lea, a genetic epidemiologist at the Institute of Environmental Science and Research (ESR) in Wellington, went on to play down controversy and defend his findings.

But his research has been labelled short-sighted and irresponsible by some of the country's leading researchers in this month's New Zealand Medical Journal.

Otago School of Medical Sciences senior researcher Tony Merriman and Christchurch School of Medicine and Health Sciences senior researcher Vicky Cameron say the findings failed to account for environmental influences.

They also criticise the tiny sample - 17 Maori males - Dr Lea used to reach his conclusions. There was no evidence that the MAO-A gene ever conferred "warrior" qualities on Maori males.

The pair conclude that the research aided by "the lack of scientific investigative journalism" combined to do science and Maori a disservice.

Wellington School of Medicine and Health Sciences head Peter Crampton and senior teaching fellow Chris Parkin said the damage was compounded by the high level of media interest following the death of the Kahui twins and the "generally negative portrayal of Maori in the media".

Dr Lea blamed misreporting by the media for unnecessary controversy.

"As alluded to by Merriman and Cameron, the extrapolation and negative twisting of this notion by journalists or politicians to try to explain non-medical, antisocial issues like criminality need to be recognised as having no scientific support whatsoever and should be ignored."

The basis of his research was to assist in strategies to reduce Maori over-representation in smoking and alcohol addiction statistics.

Dr Lea also said: "It is well recognised that historically Maori were fearless warriors. Indeed, reverence for the 'warrior' tradition remains a key part of Maori cultural structure today and one that many New Zealanders take an obvious pride in, especially in the sporting context.

"In an effort to explain the significance of our research findings we reason that the MAO-A gene may have conferred some selective advantage during the canoe voyages and inter-tribal wars that occurred during the Polynesian migrations and may have influenced the development of a substantial and sophisticated culture in Aotearoa."

He said, however, that publicity about the research had prompted a rethink on ESR policy. The institute had created a working group comprising Maori academics, iwi members, researchers and scientists, to develop best-practice procedures for genetic research involving Maori.


Research Row

* Dr Rod Lea, a genetic epidemiologist at the Institute of Environmental Science and Research in Wellington, made headlines last August when he claimed Maori carry a "warrior" gene that makes them more prone to violent and aggressive behaviour.

* He said his research could assist in strategies to reduce Maori rates of smoking and alcohol addiction.

* He also said his original findings were distorted by politicians and the media.

* In the latest row, academics described his research as short-sighted and irresponsible, and criticised the tiny sample - 17 Maori males.