Four years ago, Angela Stimpson agreed to donate a kidney to a complete stranger.
"The only thing I knew about my recipient was that she was a female and she lived in Bakersfield, Calif.," Stimpson says.
It was a true act of altruism — Stimpson risked pain and suffering to help another. So why did she do it? It involved major surgery, her donation was anonymous, and she wasn't paid.
"At that time in my life, I was 42 years old. I was single, I had no children," Stimpson says. "I loved my life, but I would often question what my purpose is."
When she read about the desperate need for kidneys, Stimpson, a graphic artist who lives in Albany, N.Y., says she found her purpose. She now blogs about her experience and encourages others to become donors.
People like Stimpson are "extraordinary altruists," according to Abigail Marsh. She's an associate professor of psychology at Georgetown University and one of the country's leading researchers into altruism.
Marsh herself was the beneficiary of extraordinary altruism when she was 20. She got into a freak highway accident and ended up stalled in the fast lane facing oncoming traffic. A man dodged traffic to come to her aid and help get her car started. He saved her life, she says, then disappeared before she could ask his name.
Marsh wanted to know more about this type of extraordinary altruism, so she decided to study the brains of people who had donated a kidney to a stranger. Of the 39 people who took part in the study, 19 of them, including Angela Stimpson, were kidney donors.
Marsh took structural images to measure the size of different parts of their brains and then asked the participants to run through a series of computer tests while their brains were being scanned using functional MRI. In one test, they were asked to look at pictures of different facial expressions, including happiness, fear, anger, sadness and surprise.
Most of the tests didn't find any differences between the brains of the altruistic donors and the people who had not been donors. Except, Marsh says, for a significant difference in a part of the brain called the amygdala, an almond-shaped cluster of nerves that is important in processing emotion.
The amygdala was significantly larger in the altruists compared to those who had never donated an organ. Additionally, the amygdala in the altruists was extremely sensitive to the pictures of people displaying fear or distress.
These findings are the polar opposite to research Marsh conducted on a group of psychopaths. Using the same tests as with the altruists, Marsh found that psychopaths have significantly smaller, less active amygdalas. More evidence that the amygdala may be the brain's emotional compass, super-sensitive in altruists and blunted in psychopaths, who seem unresponsive to someone else's distress or fear.
AUDIE CORNISH, HOST:
Turning to another study now, this one on altruism. New research suggests extraordinary acts of kindness may be rooted in the brain. Michelle Trudeau reports.
MICHELLE TRUDEAU, BYLINE: Altruism is when you help somebody else at a cost to yourself. So you're sacrificing for another; you're taking a risk or suffering pain.
ANGELA SIMPSON: My name is Angela Simpson. I reside in Albany, New York, and I am 46 years old.
TRUDEAU: Angela is a graphic artist. She is also an extraordinary altruist. Back in 2010 Angela donated one of her kidneys to an unknown recipient.
SIMPSON: The only thing I knew about my recipient is that she was a female and she was residing in Bakersfield, California.
TRUDEAU: The surgery to remove Angela's kidney occurred at a transplant Hospital in New York City.
SIMPSON: And my kidney was shipped to California immediately after it was extracted.
TRUDEAU: Angela's altruistic act begs the question why would someone donate a perfectly healthy part of their body to a total stranger? Go through the risk of major surgery and do it willingly - even happily - for no pay, no remuneration and anonymously? Here's how Angela explains her decision.
SIMPSON: At that time in my life I was 42 years old. I was very single. I had no children; you know, very, very fortunate - loved my life. But I really felt like I would question often what is my purpose?
TRUDEAU: So when she heard about the critical need for kidney donations - over 100,000 people in the U.S. today are waiting for a kidney transplant...
SIMPSON: To really be able to help somebody unconditionally was, like, an awe moment.
TRUDEAU: So she did it, she says, simply because she could. Professor Abigail Marsh has her own story of altruism, too.
ABIGAIL MARSH: I think I was 20 years old and I was driving home to my parent's house in Tacoma, Washington.
TRUDEAU: Long story short - A freak highway accident. Her car spins around and stalls in the fast lane. A stranger stops, dodges through traffic, helps her to safety saving her life and then disappears. A true altruist - risking his own life to help someone he didn't know and would never see again. This propelled Abigail Marsh toward her professional career, one of today's leading researchers of altruism. Now at Georgetown University, Marsh studies what she calls extraordinary altruists - most recently a study of 19, including Angela from around the country who donated a kidney to a stranger.
MARSH: And we brought them to Georgetown for testing.
TRUDEAU: Psych testing, brain imaging studies, extensive background profiles, etc. But says Marsh...
MARSH: Most of the test that we did didn't show any differences between the altruistic donors and people who had not been donors.
TRUDEAU: All pretty normal - except for a telltale difference in a part of our brain called the amygdala. It's an almond shaped cluster of nerves; it's our emotional radar. And it was significantly larger in altruists compared to those who'd never donated an organ. Additionally, Marsh reports that the amygdala in altruists is supersensitive to fear or distress in another's face.
MARSH: They showed this very specific increase in amygdala activation in response to others' fear.
TRUDEAU: Now in previous research Marsh reports some polar opposite findings in a group of psychopaths. Using the same tests as with the altruists Marsh found that psychopaths have smaller, less active amygdalas. The brains' emotional radar in psychopaths was blunted and relatively unresponsive to someone else's distress or fear. For NPR News, I'm Michelle Trudeau. Transcript provided by NPR, Copyright NPR.