The typical answers to these questions are: "Try to save them" and "Instantly."

Attempting to save someone who is drowning, even if that person is a stranger and even at risk to one's self, is done without any real consideration. It is a reaction rather than a decision. There is no tangible net gain for the person attempting the save. It is simply an instinctive good deed.

Even if you are skeptical about the typical person's willingness to save a drowning stranger, imagine how hard it would be for them to walk away and leave the struggling person to die.

What if there were a one-hundred dollar bill floating by in the water? It could sink or float away out of reach, so the situation is still time intensive like the drowning, but this is clearly a decision rather than a reaction. For example, the person would probably spend time considering whether it was worth getting their clothes wet for $100. How would the people react at their next destination if they arrived all wet? Would they have time to go home and change their clothes? Unlike the drowning, this situation has a very clear net gain of $100.

The purpose of the examples above is to illustrate that we instinctively know human life is valuable, even the lives of strangers who may not affect our futures. If we are near someone who is in danger, our bodies have a "fight or flight" response similar to the one we would have if we ourselves were in danger. Our hearts pound and our adrenaline flows; we become alert and ready to act. This is a gut reaction, not a learned behavior, and is common to everyone regardless of their religious beliefs. It is in our genes and therefore subject to natural selection.

Couldn't this behavior be considered counter intuitive to natural selection? If I were more fit than the person in danger next to me, why would I care? I could reduce my competition by one simply by not acting. Dr. Richard Dawkins says in his book "The Selfish Gene" that this behavior, called reciprocal altruism, is unique to species’ with the ability to recognize other individuals and who have a long enough memory to remember previous good deeds done for them. I will use an example to illustrate how it may have evolved.

Imagine a community of hypothetical mammals that are completely altruistic. They share their food, clean parasites off of each other and behave almost selflessly. As a group they survive better than they do individually. Although this may sound ideal it is not a behavior conducive to a stable population. What would happen if a mutation produced an individual that was slightly less altruistic than his peers? I will use Dawkins' nomenclature here and call our selfish mutant a "cheat" and his selfless peers "suckers." A cheat always returns less than he receives. For example, our cheat could take advantage of the suckers, perhaps by stock piling their food, which they would give up readily, for only himself. He would survive better at their expense and produce more offspring. In turn, some of the cheat's offspring could give birth to individuals who were even more selfish and the situation would repeat itself. Eventually there would no longer be a community of suckers, but rather a community of cheats.

What if the suckers remembered who had cheated them and held a "grudge," no longer sharing food or cleaning parasites off the cheater? An individual who recognizes cheats could avoid being exploited and survive better than those who could not. This means that over evolutionary time the tendency for individuals to be able to recognize cheats would increase. Put simply, the suckers would get wise and become "reciprocal altruists." They would help everyone but cheats, who would no longer be able to survive as well as non-cheaters. So the reciprocal altruists would survive better than the cheats and better the suckers and eventually dominate the population. The point I want to emphasize is not so much that altruistic individuals who hold "grudges" survive better, but that cheaters or non-altruistic individuals tend to be selected out of the population. Thus evolves a genetically enforced practice of "you scratch my back and I’ll scratch yours."

This shouldn’t sound like anything revolutionary. What if there were two candy vending machines at your work, one that always worked properly and another that usually stole your money without giving you any candy. Which one would you give your money too? Those who could remember that the machine stole their money and could also remember which machine it was would know not to use it. The "cheating" machine would be less successful, receiving little or no money compared to working machine.

At the heart of this idea is that essentially every good deed is ultimately selfish. For species that can recognize each other and that possesses a long enough memory, the drive to perform altruistic acts exists because it increases their chances of survival. I wrote earlier that we instinctively know human life is valuable. According to Richard Dawkins we know this because we instinctively know our own lives are valuable.

Lest we become pessimistic about human nature, I’d like to point out that the end behavior, regardless of its evolutionary origins, is that we are genetically predisposed help one another. It is important to call extra attention to the word "predisposed." Man is a complex creature, subject to many varieties of influences that can affect our behavior. At our core, however, before we succumb to any other influence, is a drive to help others "survive." It is in our genes to "scratch each others backs." In addition, man also has the unique abilities of foresight and will power. We can predict how our actions might affect the future and have the will to delay short-term gratification in order to create a better long-term outcome. Over time, with the onset of new technology, the community that man identifies himself with grows larger and larger. Man can apply what he knows instinctively to this bigger picture.

I want to address one other human behavior and how it may have evolved. This particular behavior stands out as being more instinctive than others because of the way it compels us to act, even to the point of behaving irrationally. It can be the source of ecstatic joy or the deepest sorrow. Poets, novelists and songwriters have mused about its nature for centuries. Of course, this behavior is love.

If love were not instinctive we would reason and then decide to be in love. It would be more like marriage. You could weigh the pros and cons, perhaps even pick a date and send out announcements declaring that you have decided to fall in love. We all know that this is not how love works. Even the language and imagery we use to describe love reveals we have no control over it. People FALL into love, or are shot by cupid's arrow, or are bitten by the love bug, or fall in love at first sight. Marriage is a decision; love is instinctive.

The collection of behaviors that make up love have been dictated by thousands of years of cumulative natural selection. Why is love so powerful? It deals directly with how we mate and pass on our genes. Love has evolved to become the best way to ensure our slow-developing children reach adulthood and in turn have children themselves. Love creates families, or small communities where members help each other survive. Love makes parents protective of their children, afraid to even let them out of their site.

Granted, this is mundane compared to cherubs firing aphrodisiac laden arrows. Nobody will write a song about my definition of love. But as we have discovered with heliocentrism and evolution, the truth science reveals is often humbling and decentralizing. Love is not about us, but about successfully passing on our genes.

Imagine two distinct communities, Alpha and Beta. Residents of the Alpha community experience love the way we know it today. In the Beta community, however, the are genetically wired to practice a precursor of love, a beta version where parents don't bond quite as strongly with their babies. Which community would survive better and produce more offspring?

Imagine a subtler difference, such as the grandparents in the Beta community don't bond with their grandchildren as they do in Alpha. Which community is better suited to raise the most healthy children? If a community loves in a way that provides a consistent incremental benefit to their net population over time, their community will grow faster than their competitors and if all else is equal, will eventually possess the dominate genome.

Again, before we become pessimistic about human nature, it is worth noting that love still remains as probably the most powerful experience a person can have in their short time on Earth, and since there is no life afterward, it is no less important for having been demystified.

Of course in a large population there will be exceptions, people who do not appear to instinctively value life or love in a manner that benefits their family or children's survival. These exceptions may be genetic, such as it potentially is in the double Y chromosome mutation, or they may be a result of the many other influences we are constantly bombarded with from the moment of our birth. One thing to keep in mind, however, is that when we hear about the crimes committed by these people it can affect us emotionally. We don't process the information, decide it is saddening and then become affected. We just react because we instinctively sympathize with the victim. We instinctively know it is wrong.

This is a corollary to reciprocal altruism. We sympathize with victims and know that crimes are wrong because we know that we would not want to be victims ourselves.

I have tried to illustrate why I think it is human nature to love and to help others. Over the course of evolutionary time, people who loved better and practiced reciprocal altruism better also survived better and passed those genes on to their children.

How does the scientific view of human nature compare to the Christian view?

Below are some points that I think demonstrate why the Christian outlook is pessimistic, unrealistic and does not provide the moral absolutes Christians claim are necessary to know the difference between right and wrong.

Christianity proposes that man is sinful at birth. In fact man's nature at birth, before he has made a single willful decision, before he has performed any action of consequence, warrants an eternity of suffering. In addition to this, man is often only credited with his failures while his successes are attributed to God. The sole survivor of a plane crash is saved by a miracle while the other hundred passenger’s deaths are blamed on man. God is not blamed when someone is afflicted with cancer, but receives the credit if they are cured.  The media declares it a miracle when teams of fertility doctors and the latest technology and research enable a previously infertile woman to have a baby.

The Christian model maintains that people do good or, perhaps more accurately, avoid evil out of fear of punishment, but is this really how things work? Do people really reflect on their hopes and fears for the afterlife before making moral decisions or do they follow their instincts? In my opening example of the drowning stranger, would someone really stop to consider that they might go to Hell if they didn’t attempt the save, or go to Heaven if they did? This would mean that all good works are only  insincere attempts to win God’s favor.

Bible stories are read to children to help them build a moral foundation, but what do these stories really teach? What would happen if a government were to take these stories seriously and use God’s actions as models for its policies? Below are a few possibilities.

• People would be punished for the crimes of their parents. In fact, not just their parents, but also their ancestors from thousands of years earlier—even if their crime was only eating a restricted fruit. (Adam and Eve)
• If a city’s crime was overwhelming the government could decide to kill everyone who lived there, children and babies included, in order to get a fresh start, just as God did with the great flood. (Noah’s Ark)
• It would be acceptable to put citizens through inhumane tests for no reason but to prove their loyalty. (Abraham and Isaac, Job)
• Governments could sentence people to life in prison not for crimes, but for beliefs or lack of beliefs, just as God will do to me (for an infinitely longer sentence) for not accepting him as my savior.

It should also be pointed out that the "love thy neighbor" commandment is really reciprocal altruism! It is genetically apart of all of us because our ancestors who practiced it survived better than those who did not.

Of course, changing what you believe about human nature doesn’t change the actual state of human nature, so the issue is academic. Crime rates do not go down or up if you believe man is inherently good or sinful. I think it does illustrate, however, that people need not be fearful of a world without God.

The two questions that I am probably most often asked by Christians are, "If there is no God, who will ultimately hold man accountable for his actions?" and "Without God, how can man know the difference between right and wrong?"

It is people who hold each other accountable for their actions. This is the idea central to reciprocal altruism. To use my earlier example, the "cheating" candy vending machine doesn’t receive any money, while working machine exchanges good deeds (candy) for good deeds (money).

How can man distinguish between right and wrong without God? When we have been treated poorly or have been victimized we have an emotional response. We become angry or upset without any conscious consideration. It is an instinctive reaction.  It is not necessary to consult the Bible first in order to determine if we have been hurt. Conversely, when we are the recipient of generosity, our mood improves. We feel good and want to return the favor.