(CNN) -- The longest debate since humans have been having debates is whether we are good or evil. It underlies the stories of Adam and Eve, Cain and Abel, Jesus and Judas.





What is our human nature? Of course, the answer is we can be both good and evil. But what determines which part of our character emerges?





About a decade ago, my lab made an unexpected breakthrough in the understanding of good and evil. We discovered that the neurochemical oxytocin makes people trustworthy. We then found oxytocin was responsible for many other moral behaviors, from being generous to sacrificing to help a stranger.





Wait -- morality is chemical? In my TED talk, I describe how I made the unlikely discovery of the moral molecule, how I was roundly discouraged from even looking for such a chemical, and what drove me to persist in my search.





In these experiments, we tempt people with virtue and vice using money (share with others: virtue; selfishly keep everything for yourself: vice). Using money to understand how and why humans make decisions is a field now called neuroeconomics.





Money gives us a convenient way to measure how much someone cares about another person. For example, in one experiment we randomly matched strangers in the lab by computer and put $10 in an account for each of them. In each pair there was a decision-maker 1 (DM1) and a decision-maker 2 (DM2).





All participants got these instructions: DM1 can give up some or all of his or her $10 and transfer it to DM2 by computer but cannot talk to, or meet, the other person. Whatever is transferred is removed from DM1's account but is tripled in DM2's account.





Then, DM2 gets a computer message identifying how much has been received from DM1 and a reminder of the total in his or her account. Next, the software asks DM2 if she or he wants to send some of this larger pot of money back to DM1.





The amount sent back comes out of DM2's account one for one and is not tripled -- it's a pure loss to DM2. For example, if DM1 transfers $8, he or she would keep $2 and DM2 would receive $24 (=3 x $8). The total in DM2's account would be $34 ($24 + $10).





If you were DM2, what would you do -- keep it all or share some back with DM1? We found that 90% of DM1s send money and of the DM2s who receive money, 95% return at least some of it. Usually both DMs in a pair leave the lab with more than $10, sometimes much more.





The DM1 to DM2 transfer is understood to be a measure of trust, while the DM2 to DM1 transfer measures trustworthiness. By taking blood from participants, we found that the more money denoting trust DM2 received, the more oxytocin his or her brain made. And, the more oxytocin on board, the more money was returned to DM1. All this happened without any face-to-face interactions, revealing how easily the oxytocin system activates.





TED.com: How we read each other's minds





Morality has traditionally been the domain of theologians and philosophers, often providing prescriptions of what we must do. But in the past decade, neuroscientists have started analyzing brain activity while people think about, and engage in, moral or immoral acts. These findings have changed the inquiry into morals from prescriptive to descriptive. As I discuss in my talk, I have even done studies that have manipulated brain chemistry in human beings to show that oxytocin directly causes people to be moral.





I also talk about what having a chemical that affects morality means for individuals, organizations and entire societies. For example, does "my chemicals made me do it" absolve people from legal or moral responsibility? If we have a moral molecule, where does evil come from?





By the way, oxytocin doesn't only cause morality in a laboratory setting -- I've done studies in churches, on sports fields and among
What does he say the experiment shows? Who does it make people willing to help? What does oxytocin do? What does the experiment show? What can oxytocin make people more willing to do?
the neurochemical oxytocin makes people trustworthy. neurochemical oxytocin directly causes people to be moral. we tempt people with virtue and vice using money being generous to sacrificing to help a stranger.
question: What does he say the experiment shows?, answer: the neurochemical oxytocin makes people trustworthy. | question: Who does it make people willing to help?, answer: neurochemical oxytocin | question: What does oxytocin do?, answer: directly causes people to be moral. | question: What does the experiment show?, answer: we tempt people with virtue and vice using money | question: What can oxytocin make people more willing to do?, answer: being generous to sacrificing to help a stranger.