The Moral Molecule

Posted by Paul Zak
29 January, 2014

Consider the lowly lobster.

The scary-looking crustacean Homarus americanus has never been thought of as particularly moral, or particularly romantic (unless, of course, the context is drawn butter and a good white wine). Heavily armored and heavily clawed, these beasts are highly aggressive, highly territorial, and, at least in captivity, known to dine on one another.

But when the mood is right and the lights get low, lobsters actually can be kind of sweet, with a courtship ritual that’s like a soft-focus scene from an old French film. It all begins when the female sprays a seductive perfume into the male’s grotto, then scuttles inside to slip out of her shell. Just as in so many movie scripts, finding the right mate requires letting go of that tough, protective exoskeleton. But for a lobster, leaving the shell behind means being utterly vulnerable until a new one grows back, a creature she would ordinarily treat as a competitor, if not an outright threat. The chemical signal that allows her to suspend her wariness just long enough for the tryst, and for the growth of a new shell, is an ancient precursor of oxytocin. A related chemical that will show up later in our morality tale prompts the male to watch over her, protect her, and treat her gently.


Can we call what we see in lobster courtship ‘trust’, and moral behavior in response to trust? That the most basic, physiological mechanism for all our moral impulses dates back to a time long before animals ever ventured onto dry land. And it all began with sex. The fact that the precursors of trust and of reciprocity are so primal, that the ancestral DNA of our moral behavior is embedded in cells throughout the body, and that it is all rooted in reproduction, suggests pretty clearly that what we now call morality is not some civilizing afterthought, or a frill that runs counter to nature, but, in fact, something deeply connected with basic survival. If the biology of reproduction seems like a lowly and unlikely starting point for the kinds of lofty issues that would later concern prophets and priests and philosophers, ask yourself which would bother you more: that your spouse fudged a little bit on last week’s expense account, or that he or she had a little socially constructive outcome is very near the core of every moral system in every culture on the planet. First it established bonds between mates, then between that mating pair and their offspring, and then between the members of that nuclear family and their immediate kin and companions.

How we came to know what we know about how this all works is a remarkable detective story. But the answer to this ‘who dunnit?’ gets us into the most important question yet to be resolved by us as a species. Under the influence of oxytocin, it’s not too hard for us to behave with generosity, care, and concern toward those with whom we share a deeply personal bond. The bigger challenge is this: How do we extend that kind of virtuous behavior to those with whom we have almost nothing in common, and with whom we will never have a face-to-face encounter?

To begin to answer that question, we need to get a running start with an evolutionary story that goes back about seven hundred million years. The first characters we meet in this tale are sea creatures so primitive that their nervous systems operate more like computer code than what we’d think of as a brain. For computers, the choice is always binary, meaning that there are only two options. For these ancient beasts, the binary choice was not between a one and a zero but between yes and no, approach or withdraw. A hunger impulse would prompt an advance. A harsh or painful stimulus would prompt a withdrawal. A threat would stimulate stress hormones that would prompt either a withdrawal or a show of hostility – the famous fight-or-flight response.

Evolution of choice

The clusters of chemicals that orchestrated these stop/go responses operated like rocket thrusters guiding a spaceship. Working in opposing teams, they turned on and off, pushing our most ancient ancestors in opposite directions at different times. If the animal was programmed correctly, it would zig when it should zig and zag when it should zag, and it might just stay alive long enough to reproduce. More complex animals such as the lobster actually have to get together to mate, but the anxiety-driven fight-or-flight response that’s always made animals wary of one another was too valuable to set aside. After all, wariness also helps animals survive. What was called for, then, was a temporary suspension, triggered by the right circumstances, a kind of truce that would last just long enough for courtship and mating, then fade when the tryst was over.

This all began in ancient seas, when all animal life was marine life and well before we get to the scene with the guys wearing white robes were discussing virtue in the brilliant sunlight of Athens, but even so, the moral dimension of the oxytocin family of molecules began to emerge well back in time. The trigger point was when the reproductive plot thickened with the addition of another element that has driven males and females crazy ever since: choice.

From The Moral Molecule by Paul Zak © 2013, published in the UK by Random House.

by Paul Zak

Human beings can be tenderly compassionate and yet also shockingly cruel. What if there was a master control for human behaviour? Nurture it and people are loving and generous. Ignore it and they revert to violence and greed.Click here to buy.

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