A recent study suggests that fatherhood is associated with a fall in testosterone levels. Reflecting on the diverse influences of the five children we love dearly on our lives as a couple, my wife said ruefully in response: Maybe the kids siphon it out of you!
There are, however, more biologically plausible cases to make.
As ever with biology, the forces in play are all about survival. Leaving aside the constraints of culture and considering just the biological influences, a new father with high levels of testosterone might be more inclined to wander off the domestic reservation than one with lower levels. A father whose testosterone levels fell at the birth of a child might face lesser temptations to wander off and be more inclined to stick around and defend hearth and home.
If the tendency to wander put the survival of offspring at risk, natural selection would fight against it. Fathers whose testosterone levels fell with the birth of a child would wind up with more surviving children, who in turn would receive -- and pass along -- the very genes that produced the response that promoted survival.
For us organisms, biology is bedrock. There are greater depths of scientific truth, of course -- in chemistry and physics. But understanding these don't help us live. The spin of our electrons matters, but it's hard to link it to our behavior.
The influence of brute biology in our lives and culture, in contrast, is on constant display -- never farther away than the nearest magazine, newspaper or television channel. The products that are sold to us, and the tales that are told to us, reek of biology.
Cologne and perfume reek of biology, tapping into responses of our nervous systems to scents. The true origins of such responses reside in moieties like pheromones, which help one nervous system identify another, with which it might make beautiful music. Or, at least, offspring.
Much of the biological action, of course, is about making babies, because that is biology's best shot at immortality. Make babies who make babies, and successful genes can go on forever. The action that isn't about making babies is all about survival, in the service of staying alive to...well, make babies. And around we go.
Biology is often the cornerstone of bad behavior. The pattern is well-established: Powerful, successful men (often with attractive, intelligent, successful wives) find themselves caught up in high-profile sex scandals. We somehow always manage to seem a bit surprised, as well as appalled, although I suspect our surprise is more feigned than real. And of course, for every high-profile peccadillo of this sort, there are countless others too mundane to tempt the paparazzi.
There are many variations on the theme of infidelity, but let's focus on the one that prevails: Middle-age (or older) guy with middle-age wife cheats with younger woman.
The scenario was beautifully castigated by Diane Lane's character, Sarah, in the movie "Must Love Dogs":
"All that matters to you guys is the tushies are tight and the bellies are flat ... "
This seems a rather damning indictment. Is it true that guys don't care about intelligence, compatibility or anything else of profound significance -- but care only about the tone of tummy and tush?
No, honestly, it's not true that guys feel that way. But it probably is true that guy biology feels exactly that way, without even the good grace to be ashamed.
Biology is not about personal priorities, or cultural priorities, or ethical priorities. It's about the imperatives of survival and procreation. It is designed for a natural world and is often anachronistic in the modern world. Examples related to obesity and chronic disease abound. We love sugar, salt and dietary fat because in a "natural" world, all are scarce, and more of each would tend to foster survival. The connection those now share to chronic disease is a New-Age contrivance.
From a strictly biological perspective, young women of just the right shape and proportions are apt to be most helpful in the unthinking enterprise of passing genes forward to the next generation.
But there's some irony in this. The men caught up in high (or low) profile infidelities are generally, absolutely not interested in making babies! Making babies takes them from the frying pan to the fire. It's the last thing they want.
So it is ironic that the true origins of the biological impulse they are indulging reside in what they don't want -- and yet they harbor the fantasy that they are using their power, prestige and leverage to get what they do want. They cultivate the fantasy that they are in charge.
But brute biology is driving this train.
Why bother to call all of this out?
Peter Parker's Uncle Ben, in the "Spider Man" movies, famously gave us: "With great power comes great responsibility." Logic dictates what must follow: the less power, the less responsibility. But we don't want an "I'm not responsible" defense in the service of chronic disease, domestic violence or life-shattering promiscuity.
We generally contend that knowledge is power. Ignorance, then, is surely weakness. If we don't understand why bad behaviors occur, they will recur. Those who do not learn from the follies of history are destined to repeat them.
If we mistake the impulses of brute biology for our own decisions and priorities, we are likely to act on them. If we understand them for what they are, we have a far greater capacity to say: "I hear you, but you can forget about it! I'm in charge here." If we pause to analyze the enemy force of brute biology, we have our one, best hope of disarming it. Whether that relates to food choice, physical aggression or sexual discretion.
We should long since have met the enemy that imposes so much modern misery and acknowledged it is us -- our own primitive selves. It is the job of our modern selves to know this, and by knowing, exert power over it. DNA is amazing stuff, but we should not be ceding control of our personal destinies to it.
Follow David Katz, M.D. on Twitter: www.twitter.com/DrDavidKatz