Presence of ‘warrior gene’ triggers aggressiveness in people

January 24th, 2009 - 3:12 pm ICT by IANS  

Washington, Jan 24 (IANS) The presence of the “wrrior gene” triggers aggressiveness in people as a respone to provocation, according to new research. The study, co-authored by Rose McDermott, professor of political science at Brown University, asked volunteers to cause physical pain to an opponent they believed had taken money from them by administering varying amounts of hot sauce.

The research team included Dustin Tingley of Princeton University, Jonathan Cowden of University of California-Santa Barbara (UCSB), Giovanni Frazetto from the London School of Economics, and Dominic Johnson from the University of Edinburgh. Their experiment synthesised work in psychology and behavioural economics.

Monoamine oxidase A is an enzyme that breaks down important neurotransmitters in the brain, including dopamine, norepinephrine, and serotonin. The enzyme is regulated by monoamine oxidase A gene (MAOA).

Humans have various forms of the gene, resulting in different levels of enzymatic activity. People with the low-activity form (MAOA-L) produce less of the enzyme, while the high-activity form (MAOA-H) produces more of the enzyme.

Several studies have linked low-activity form of MAOA with aggression in observational and survey-based studies. Only about a third of people in western populations have the low-activity form of MAOA.

Some 78 subjects took part in the experiment over networked computers (all were male students from the UCSB). Each subject (A) first performed a vocabulary task in which they earned money, said a UCSB release.

Then they were told that an anonymous partner (B), linked over the network, could choose to take some of their earnings away from them. The original subject (A) could then choose to punish the taker (B) by forcing them to eat unpleasantly hot (spicy) sauce - but they had to pay to do so, so administering punishment was costly.

In reality, the “partner” who took money away was a computer, which allowed the researchers to control responses. No one actually ingested hot sauce.

Their results demonstrate that low-activity MAOA subjects displayed slightly higher levels of aggression overall than high-activity MAOA subjects.

The findings were published in the Proceedings of the National Academy of Sciences.

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