Note: I preached a version of this sermon on July 11, 2010 (Proper 10C) at Wicker Park Lutheran Church in Chicago

Sisters and brothers, grace to you and peace from God our Father and the Lord Jesus Christ. Amen.

This week a new book has been causing some interesting chatter. It’s called Sex at Dawn: The Prehistoric Origins of Modern Sexuality, and it’s by a psychologist and a doctor–married to each other, by the way–who seek to explain our culture’s strange attitudes toward sex and relationships in terms of our evolution as a species. It’s not a new idea. It joins titles like Sex on the Brain, Why is Sex Fun?, The Moral Animal, Male Female, It’s Not You, It’s Biology on a bookshelf weighed down with supposedly scientific answers to the question, “Why are we the way we are? And why do we do the things we do?” 

Now there’s nothing wrong with applying the lessons of modern science to any given aspect of human life. Some people do it rigorously, a lot of people do it sloppily. The problem comes when we try to draw moral conclusions from these scientific findings. The authors conclude that we didn’t evolve as a sexually monogamous species, and that therefore our attempts to live up to that ideal today are as often as not doomed to failure. They’re not against monogamy, but they compare choosing monogamy to “choos[ing] to wear tight corsets, or ill-fitting shoes, or to live on chili-dogs and ice cream.” “All these behaviors” they say, “run counter to our evolved nature” and “they will cost us over time.”

This is a compelling argument, especially for people–and I suspect that includes most people–who have struggled with lifelong fidelity at one point or another.  It is tempting to say, “this is just not how nature made me.”  And maybe it isn’t. But nature does not teach us right and wrong.  Evolutionary biology is a powerful field, but it can’t educate us in what is good or noble.

Sex, after all, isn’t the only part of our lives that is said to be shaped by our evolutionary history. Consider our Gospel lesson today. What would we make of the famous story of the Good Samaritan if we looked at it through the lens of our evolution as a species? A man is robbed and beaten and left for dead on a dangerous stretch of road. A priest and a Levite both pass by on the other side. In most of the commentaries, this hardness of heart is explained in terms of the danger of ritual uncleanliness, which the priest would incur by touching a bloody person. But it goes deeper than that.  Humans evolved to be very sensitive to potentially dangerous situations. A bleeding man on the side of the road is a pretty good sign that you’re in a dangerous situation. So it’s entirely natural for a person to steer clear of it.  In fact, to come to the aid of a bleeding man on a dangerous road is quite risky and, it might be said, unnatural.  

But eventually a Samaritan comes along and helps the injured man. He binds his wounds, brings him to an inn, and pays for his continued care. All of this behavior, too, seems to conflict with the way we evolved. Humans are supposed to share their resources with those who are closely related.  We need our resources for ourselves and our children, so we can’t very well be giving things away to unrelated humans and thereby endangering our own evolutionary survival. Yet that is what the Samaritan does.

And to top it all off, this good deed takes place across ethnic lines. The ability to recognize kindred groups is also part of our evolution. It is said to be entirely natural to identify with people we consider to be like us and to discriminate against people we perceive as being different. People even argue that what we call racism is an evolutionary adaptation. Samaritans and Jews saw themselves as different, even competing groups. To show altruism to a person of the other group was a highly unnatural thing to do.  

So here are three evolutionary imperatives: to keep yourself out of dangerous situations; to keep your resources close to your own genes; to favor those of your own group while shunning members of other groups. Jesus says that being a true neighbor, the way God intends us to be, requires us to overcome these imperatives. To put it simply, we evolved to walk on the other side of the road as quickly as possible. The behaviors Jesus calls us to follow all, as the authors of Sex at Dawn put it, run counter to our evolved nature; they will cost us over time.

So would you conclude from this fact, if it’s a fact, that all of our ideas about altruism are just a bunch of unrealistic religious mumbo-jumbo that we’d be better off without? Altruism is really hard, after all. We’re not very good at it. So maybe it’s best to forget the whole thing and live the way evolution made us to be.  

Some people really do think that way. But a lot more of us, I would hope, see the difficulty of being a Good Samaritan as part of the greatness of this story. Jesus didn’t know anything about evolutionary biology, but he knew about danger, he knew about selfishness and generosity, he knew about racism. He knew that these are powerful forces in human life.  

But Jesus also understood that we are more than the sum of our fears, our grasping, and our tribal feelings. By God’s gracious call we can even resist these impulses, if not always then at least sometimes. Even wanting to resist them is a form of resistance.  

So yes, monogamy is hard. Altruism is hard. We would be wise to refrain from judging people who fall short of these ideals. After all, I drove past a thousand bad situations this morning in order to come be with you, my church family. But these hard things are given to us to teach us about the life of God. In the God of Jesus Christ, love is total and unreserved, fear is banished, hands are open, and all of us are capable of greater things than a shelf full of books could help us imagine.