Center for Neuroeconomics Studies determines Testosterone affects Generosity

Wednesday, December 16, 2009

$200 billion was given to charity in the United States in 2005. But what determines the role between selfish and selfless? Apparently, its testosterone.

Testosterone has an impact on generosity, according to a research study, published today in the journal PLoS ONE. In the study, Claremont Graduate University researchers Paul Zak and Karen Redwine raised testosterone levels in male subjects and studied their generosity via computerized games. Their analysis determined that the more testosterone a man has, the more likely he is to be stingy. Less testosterone, more generous.

"This is in line with what we already know, but now there is research to back it up," said Zak, who directs CGU's Center for Neuroeconomics Studies. "Men who are younger are more aggressive and self centered. There is a high level of drive and a high amount of motivation to succeed in, say, stockbrokers, which are typically younger men. Men who are older are more generous with their money and their time. Married men and those with children also have lower levels of testosterone," Zak said. "Women make us men more empathic and more social.

"Additionally, this may help explain why there are more men in the military and more women as nurses and teachers," Zak added.

This is one of the first studies to manipulate testosterone in healthy men to see what its effect on decision-making is.

The game asked each student to split $10 with another. If the other student rejected the split as unfair, nobody got any money. Overall, higher testosterone levels sank generosity by 27%, from an average of $2.15 to $1.57. The more potent the testosterone cream, the stingier the split.

It wasn't just the givers who were affected. The study found that receivers with lots of testosterone coursing through their system – the "alpha males" – expected more money as their fair share.

Zak speculated that the hormone oxytocin would have something to do with the results. In 2007, Zak's team proved that increased levels of oxytocin accounted for increased generosity. Testosterone blocks the effect of oxytocin, hence the drop in generosity when testosterone surges.

And, Zak further stated, "Testosterone is quite dependent on social status. When males become leaders, their testosterone rises. It does so similarly if they win a chess match, have a highly competitive sporting event coming up, or watch 'their' team win on TV. "

For more information, contact Nick Johnson, CGU Online and Public Relations, 909-621-8396