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During his State of the Union Address, President Bush pointed out two heroes sitting in the balcony. One was a construction worker and Navy veteran, Wesley Autrey, who jumped on a person who had fallen on the tracks of the New York subway as he was having a seizure.  He saved this man’s life by pinning him down while a train was passing over them. The other hero, Sergeant Tommy Rieman, while on a reconnaissance mission in Iraq, came under heavy enemy fire. Sgt. Rieman used his body to shield his gunner from attack. Although he sustained severe injuries, he refused to be evacuated and continued to fight alongside his men.

My thoughts were drifting from the hackneyed political rhetoric of the Address to those two men. What made them do what they did? Was there anything in their background to prepare them for these incredible acts of heroism? Did they even think about what they were going to do before they actually did it?


The biology of altruism

In several of our previous postings, we dealt with the evolutionary advantages of altruism. In the bees, it ensures the existence of a stable, rigidly hierarchical society. Any deviation from the rules of altruistic behavior in this society is punished by other members of the society. This is called “enforced altruism“.

Aspects of “enforced altruism” are operating in human society as well. For instance, we enforce a “no smoking” policy so as to protect other members of our society. We pay taxes to build schools and educate children regardless whether we have children or not. In this respect, the rationale for the existence of altruistic behavior in human society is quite similar to that of the bee society. Bee biology enforces bee altruism via biochemical substances, called pheromones. In humans, altruism is usually enforced via laws we, humans, design to regulate our behavior. In both bee and human societies, deviation from normative behavior is punished.

This type of altruism, although interesting and important, cannot explain Mother Teresa nor the actions of the two heroes honored by the President.


So, let’s explore altruism a bit more

Altruism is defined as “acts that intentionally benefit another organism, incur no direct personal benefit, and sometimes bear a personal cost.” This definition resonates a lot better with our intuitive sense of altruistic behavior. And unlike the more “biological” or enforced type of altruism, this type is completely voluntary, without the threat of punishment as an inducement to act.


Why do we do it? The prevailing theory

In previous postings, we discussed the principle of reward and its neurobiological basis. We have in the brain a large group of neurons, called the limbic system, which sends its projections to many areas in the brain. This system is responsible for, among other things, the sensation of pleasure, reward, and the feeling of well-being. One of its important projections is to a group of neurons deep in the brain called the nucleus accumbens. This nucleus mediates such diverse pleasurable sensations as optimism, food, sex, and recreational drugs. In fact, in this nucleus resides the anatomical location of drug addiction.

All the evidence, albeit circumstantial, pointed to the nucleus accumbens as the locus responsible for altruistic behavior. After all, ask any volunteer in a soup kitchen and she will tell you that she derives enormous satisfaction from her good works.

Ask any biologist and he would likely volunteer the explanation that, just like food and sex, altruism is associated with a sense of pleasure because “it is good for us”—”us” meaning our species. [Note that altruism, unlike food and sex, is not associated with direct benefits to the individual.] On the whole, this supposition makes perfect sense, although no direct experimental evidence existed to show that this indeed was the case.


The experiment

Scott Huettel, with his graduate student Dharol Tankersley, published an interesting report in the January 21st online edition of Nature Neuroscience. The Duke University group had a group of healthy young adults either engage in a computer game or watch as the computer played the game itself. In some sessions, the computer and participants played for personal gain, while in other sessions, they played for charity. Participants also completed a questionnaire aimed at assessing their personal levels of selfishness or altruism.

The researchers used a technique called fMRI, or functional Magnetic Resonance Imaging, to observe “hot spots” of activity in the participants’ brains as they engaged in these tasks. Those hot spots indicate areas of increased blood flow and metabolic activity.



The nucleus accumbens stayed completely cold—totally uninvolved. Instead, another brain region, called pSTC or posterior Superior Temporal Cortex, lit up, indicating increasing metabolic activity as altruism levels rose.

The pSTC is located in the back of the brain, next to the visual cortex, which is the area where images from the eye are received and processed. Furthermore, the pSTC is not involved in reward at all. As Huettel explains, “the general function of this region is that it seems to be associated with perceiving, usually visually, stimuli that seem meaningful to us. For example, something in the environment that might move an object from place to place.” For example, it allows us to pick out a person on the tracks and an oncoming train from a mass of less important stimuli, like the background chatter of people waiting for the train, moving to and fro.


Why the pSTC?

This is still completely unclear, at least to me. One can offer all kinds of explanations, as Huettel and others do, but they all seem forced and none seem convincing. For instance, the researchers observed that the pSTC showed the greatest activity when the participants watched the computer play the game itself. Huettel’s interpretation: “That gets to the idea of agency—watching somebody else play the game; you are thinking, ‘Oh, the computer pressed the button’—somebody else did that. Altruism may rely on a basic understanding that others have motivations and actions that may be similar to ours.” Maybe… But it doesn’t even come close to explaining the selfless actions of an ordinary person waiting for his subway train, or a soldier shielding his buddy with his body.

As they say in science, much more work needs to be done.

We still don’t know whether or not the pSTC is connected to the nucleus accumbens; new pathways and circuits are being discovered on a regular basis. Other experiments, with different designs, may show different areas of the brain associated with altruism. For instance, this experiment was based on visual stimuli (computer games). But not all altruistic behaviors are based on visual stimuli; can’t blind people be altruistic? I doubt it. Furthermore, wouldn’t it be interesting to see if people with brain damage to the pSTC underwent a profound, and not very attractive, personality change? Time will tell.

In the meantime, although we don’t understand the anatomy and physiology of selfless altruism, we do know that it can make you feel very good and it is, of course, a valuable aspect of human-to-human interaction.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.