Testosterone, Male Sex Hormone, Also Makes Guys Honest

Sex hormone makes men more aggressive, but also conscious of their image.

ByColumn By Lee Dye
October 16, 2012, 7:34 PM

Oct. 17, 2012 — -- Testosterone, the bad boy among sex hormones, has a sweet side. Researchers in Germany report they have found that the stuff that makes men aggressive and confrontational also makes them less likely to lie.

The surprising discovery flies in the face of all that we have been told about testosterone for the past few decades. It's why a guy is more likely than a gal to punch someone out in an effort to prove himself manly, or the baddest dude in the bar. Women have testosterone too, but not nearly as much as men do.

Recently, however, scientists have challenged the view that the hormone is the root of all evil. No one is saying it doesn't play a major role in male sexuality. But a number of scholars now think that's not all there is to the story.

"Popular perceptions of the effect of testosterone on 'manly' behavior are inaccurate," Pennsylvania State University researchers concluded in a recent study. "We need to move away from such simplistic notions by treating testosterone as one component along with other physiological, psychological and sociological variables in interactive and reciprocal models of behavior."

In other words, there's a lot more going on here than one hormone making guys act like jerks in an effort to impress the ladies.

Much of the misperception probably lies in the fact that much of what we thought we knew about testosterone came from animal studies. Castrated rats, for example, became meek when deprived of the hormone. But when scientists gave them a shot of testosterone, they were ready to fight.

But there's a lot of difference between humans and rats. As scientists are now pointing out, the human social system is a very complex matrix of interactions and reactions, quite unlike the world of the rat.

Researchers at the University of Bonn have added significantly to the changing view of testosterone by carrying out a clever experiment to see how the hormone affects honesty. According to the old image, you would think men would be willing to lie more while cruising on an enhanced level of testosterone if it proved rewarding. But that turned out not to be the case.

The researchers recruited 91 young men for a two-day experiment. On the first day, each participant had gel containing testosterone rubbed on his upper arm. About 24 hours later, after the hormone had enough time to be absorbed by the body, the men returned to the lab. About half the participants had received a placebo, not testosterone.

Each participant was seated in a private booth and told to roll a six-sided dice repeatedly and record the number facing up each time. They would be rewarded financially based on the numbers -- one Euro for 1; two Euros for 2, and so forth, except for the number 6. They would get nothing for a number 6.

No one else was present. Each man was alone; absolutely no one would know if he was cheating. Even the researchers were unable to monitor the activity. So how did they learn that participants were less likely to lie if given testosterone? The answer is in the details.

Since rolling dice produces purely random results, the participants who received a placebo should have ended up with essentially the same tally as those who were hyped up on testosterone.

"Statistically, the probability for all numbers on the dice to occur is identical," neuroscientist Bernd Weber said in releasing the study, published in the peer reviewed journal PLOS One. But the participants who received the placebo earned significantly more Euros than the others, and since the results were random, they clearly must have fudged the facts.

But here's the clincher. The placebo group claimed they had far fewer worthless sixes, which would be statistically impossible. Unwilling to sacrifice Euros, they lied.

There was some cheating on both sides of the aisle, but the testosterone made a difference. Those guys lied a lot less.

So why would a hormone that is supposed to make men aggressive and concerned chiefly about themselves be less likely to lie, especially if no one else would ever know?

The German scientists believe testosterone also raises concerns over self-image, and lying to make a few bucks is not particularly noble. Unless you are a total loser, it's hard to feel good about yourself if you just lied.

That conclusion is in line with a large mega-analysis of global research on the role of testosterone led by Christoph Eisenegger of the University of Cambridge and published in the journal Cell last year. Eisenegger and colleagues at the University of Zurich concluded, "The role of testosterone in social interaction in humans might be best conceptualized as bringing motives for seeking social status to the fore."

It isn't just sex, or manliness. It's how the rest of the world sees us, and that doesn't always depend on aggression.

Research is difficult because testosterone doesn't just influence social behavior, it is also influenced by the nature of that behavior. Eisenegger's group noted that "testosterone levels rise within minutes in anticipation of both physical and non-physical competitive situations," whether it be tennis or chess.

Male prisoners who have committed violent crimes, including rape and murder, have been found to have very high levels of testosterone, which has been blamed for their aggressive behavior. But now scientists like Eisenegger are asking if they committed those crimes because of testosterone, or whether the higher level of the hormone is the result – not necessarily the cause – of that very behavior.

"'Testosterone poisoning,' now part of the language is a popular explanation for excessive 'manly' behaviors such as boasting, violence and pugnaciousness," the Penn State researchers concluded in their study. But "in fact there is little empirical support for these popular assertions.

"It is already clear that there is no simple one-to-one relationship between testosterone and machoism or aggressiveness or sexuality."

So testosterone has been getting a bum rap. You doubt us? Want to fight about it?

ABC News Live

ABC News Live

24/7 coverage of breaking news and live events