Hormone May Have Link to Generosity

The natural hormone oxytocin may play a part in our generosity.


Nov. 6, 2007 — -- When Ted Turner donated $1 billion to the United Nations in 1997, he made headlines around the world. Today, he is known not only as a billionaire and founder of CNN, but also as a philanthropist and someone invested in making the world a better place.

Many people give away their money or time with no expectation of benefits in return. Now some scientists believe they may be one step closer to unlocking the biological secret behind generosity

A study published this week in the journal Public Library of Science suggests that a chemical in the body may be responsible for this behavior. Researchers found that subjects in the experiment who were given a nasal spray dose of oxytocin, a hormone that acts on the brain, were willing to give away 80 percent more money compared to those taking a placebo nasal spray.

"There are no good models to explain why people give away so much money and so many resources," said study author Paul Zak, a professor of economics and director of the Center for Neuroeconomics Studies at Claremont Graduate University in California.

"Some people give away money for social status or to impress friends, but many people give away $100 or $1,000 anonymously to someone they don't even know," he said. "Why do we do that? What drives us to care for other people?"

The answer to those questions may lie with our ability to empathize with others -- to put ourselves in another's shoes and to feel what others are feeling.

In 2005, individuals in the United States donated $200 billion to charity and more than 65 million people volunteered to help charities. When asked why they gave away their money and time to help strangers, 96 percent said they felt compassion toward others.

"Charitable giving is driven by empathy," said Zak. "We are a socially connected species."

And this empathy may be driven in part by the effects of the body's own oxytocin on the brain, Zak's research suggests.

Stephanie Brown, an assistant professor of general medicine at the University of Michigan Medical School, agrees.

"This is one of the first studies to suggest that the effect of oxytocin on helping behavior is dependent on certain social cues," she said.

But oxytocin alone is unlikely to make people any more generous. "There has to be trust or empathy as a moderator to determine if oxytocin is going to have an effect," Brown said.

To test the role of empathy, Zak and his colleagues had participants play the ultimatum game. Participants were divided into teams of two, and one subject in each pair received $10. The participant with the money was then asked to offer some amount of this money to their partner whom he or she did not know and could not see.

The second person could either choose to accept the offer, in which case the money was split as agreed upon, or reject the offer, in which case both participants received nothing.

"This game forces the person with $10 to think about how much the other person needs," said Zak. "You really have to take into account others' behaviors and feelings."

Researchers found that when participants were given oxytocin through a nasal spray, participants playing the ultimatum game were 80 percent more generous in their offers to split the money.

"People left the lab with less money," said Zak. "But they weren't necessarily unhappy.

"We are designed to care about others. The reason we are charitable is that we can't help it, we have a built in brain mechanism that connects us to other people."

Brown calls this brain mechanism the "care giving system."

"When people give out of compassion or because they really care about someone, there is a biological system at its roots," she explained. "There is a neurohormonal mechanism in the brain that exists because of a need to raise helpless offspring."

And it is this care giving system that oxytocin appears to affect. Oxytocin is a chemical that facilitates social interactions and bonding with our spouses and children. Previous studies have shown it may also be involved in trust.

Zak proposes that oxytocin cranks up the empathy and attachment we feel toward others. When we are more empathetic, we become more generous -- which explains why participants infused with the hormone gave away more of their money.

Brown agrees. "There are hormones, including oxytocin, that motivate us to suppress immediate short-term interests to take care of someone else," she said.

"It's obvious that people are all over the map when it comes to generosity -- some people are quite generous, others, not so much," said Bill Harbaugh, an associate professor of economics at the University of Oregon.

"Previous studies to understand this have focused on easily observable characteristics like gender, age, and religiosity. This paper provides a way to understand the biological and chemical foundations of the differences that we all observe in everyday life."

Of course, outside of the lab, people are not inhaling oxytocin. Our bodies make this hormone, which means further research is needed to determine how natural levels of oxytocin affect generosity.

"What this important paper does is reveal a chemical pathway that alters generosity," said Harbaugh. "So to understand why people give, we need to understand the factors that determine the production and uptake of oxytocin. How much of this is genetic, how much of it is acquired, and what are the interactions?"

And whether or not generosity is innate or acquired, writing that check to charity or volunteering your time at the soup kitchen may pay off in the long run.

"People who behave more empathetically tend to be happier, live longer, and are less sick," said Zak. "Social connections are associated with a longer, healthier life.

"Although it might be monetarily costly to be generous in the short run, there are long-term health benefits."

ABC News Live

ABC News Live

24/7 coverage of breaking news and live events