About a decade ago, at the request of Psychology Today magazine, I had an amusing debate with Richard Dawkins about testicles. Dawkins had famously proposed the metaphor of the "selfish gene" to explain how traits in organisms can be understood from the imagined point of view of a gene wishing to propagate itself. The underlying logic of the metaphor is compelling, yet it doesn't always seem to work gracefully—as in the case of human male genitalia.
The site of human testicles seems a bizarre anomaly from an evolutionary point of view, like positioning the driver of an armored vehicle in a sack strapped to the bumper. If the whole point of the human organism is to pass on genes, why put the repository of those precious genes out front, in harm's way? Why not protect them the way the brain and the heart are protected, with thick bone vaults and, in the brain's case, an elaborate barrier to bloodborne infection?
One popular explanation is that balls need to be cool for the sperm to stay healthy. This is true, but as an evolutionary explanation, it's nutty. Evolution holds all the cards. She could easily have shaped humans so they would have a reproductive chemistry tolerant of normal body temperature. Another idea that has been dangled is that men subtly show off to women how tough we are by being willing to take such big chances with our seed. This idea can be supported by dry mathematical modeling, but really, wouldn't loincloths have undone human reproduction by now if it were true?
These old ideas about balls were bouncing around in my head a week ago when I witnessed a moment in human gene propagation of such high drama and evolutionary dysfunction that it made testicles seem quite unimportant: My wife gave birth to our first child.
I watched as the most exquisite, transcendent moment of human experience was channeled via soggy, bloody, out-of-control bodily functions. Our amazing little girl, already filled with curiosity and engaged in fearless exploration, had to squeeze through a pelvis ill-designed to admit her big brain. My wife's body was painfully torn, though no more than is considered normal. Everyone was exhausted, and were it not for the extended womb of medicine, our baby, like any healthy human baby, would have been so vulnerable as to face poor odds for survival.
Is this any way to run a species? In the precious moments between diaper changes, I've been talking with an old friend, paleontologist Niles Eldredge, about the apparently flawed design of the human organism.
One thing that strikes me is how so many people prefer to think of themselves as having a perfected body form. It doesn't seem so perfect to Niles and me. Take this whole business of walking around upright. I love the way walking rhythms turn into music, and it is a tremendous convenience to have one's hands free, but our erect body plan is unfinished and full of bad structural compromises. Hazardous birth (as a result of that inappropriately narrow pelvis) is only the most appalling; we also suffer from sciatica, knee and foot failures, and on and on.
My wife had it easy compared with the women in adjacent birthing rooms who decided to forgo the epidural. They chose epochal pain for personal reasons. Various people, including members of the hospital's staff, encouraged us, too, to try "natural" childbirth, as though failing to confront another human design flaw were somehow more true to our evolutionary roots. While I respect the choices women make at this most personal moment, I don't think such a thing as natural childbirth has ever existed for the human species.
An image came into my mind as I watched the terrifying, wonderful process of human birth. Imagine a leaping athlete, perhaps a grown-up version of our energetic baby girl, her motion frozen in place by the flash of a camera. The photograph documents all the quirks of a single moment's posture, one the athlete could never sustain. This is the nature of the human species. Ancient technologists—known today as midwives, herbalists, warriors, fire makers, and shamans—long ago learned to protect vulnerable newborns and damaged mothers. That well-intentioned interference had an unforeseen effect: It helped freeze the human body in its current form by easing the selection pressures that are evolution's scalpel.
Niles and I have mused about how evolution might have refined the hominid design if we had given her a chance. A different species might have emerged, one that would remember the likes of us as merely a transitional phase. How might this hypothetical species, which I'll call Eureka sapiens, have turned out?
Although quadrupeds also have dangling testicles, theirs are protected by powerful hind legs. Eureka sapiens might have seen the balls migrate into the belly, like the ovaries. To cool them, air-intake vents around the belly button, like those on the hoods of sports cars, might have evolved. The Eureka sapiens female pelvis might be able to spread apart, like the jaws of snakes. We actually have the rudiments of this ability: The hormone progesterone may sometimes cause a woman's pubic bones to separate a little bit just before childbirth. Eureka sapiens babies would remain in the womb for at least a full year and would be born with more robust digestive tracts, so they wouldn't need to cry so much. Colic is at least as hard to explain as an advantageous adaptation as vulnerable testes are.
It's a triumph of morality and compassion that Eureka sapiens is not to be. Had birthing technology not intervened, natural selection would have worked out many of our kinks, but only in a most cruel process. Whatever is genetically determined about you, including the color of your eyes and aspects of your personality, is precisely what was left over after all your failed would-be ancestors were either eaten by other organisms (whether large like a lion or microscopic like a virus) or for some reason died heartbroken, unable to reproduce. You are the descendant of the descendant of the descendant of what was left bleeding but alive on the sidelines after evolution's violent filter swept over deep time.
Some species, like the impressive cockroach, have gone so long unchanged that we tend to think of them as genetic masterpieces, as judged by the ultimate critic: unwavering stability in the context of evolution. But nothing in biology is permanent or perfect. All biological designs are to a greater or lesser degree in transition.
Humans are unusual, though, in that we have more or less stabilized ourselves at what would normally be a transitional, problematic stage—"more or less" because, while technology lets us minimize many of the old evolutionary selection pressures, it also introduces new ones; for instance, we are right now breeding ourselves to be tolerant of chemical pollutants. That said, the fallacy that our design is perfect has recently been matched by an equally fallacious mirror-image notion: that flaws in our genetic heritage are absolutely bad and must be completely discarded.
In vitro fertilization is giving prospective parents the ability to decide which embryos to implant and which to discard. As is often noted these days, we are sliding down the slippery slope toward designer babies. In recent months parents-to-be in England made news by requesting to discard embryos merely because they carried dormant genes—ones that could potentially contribute to disease in the grandchildren, but only if, as adults, those embryos eventually chose mates with the same recessive genes.
The problem with this approach is that it assumes there's no good reason for a feared gene to be present. Just as imagining that our genetic legacy must be perfect misleads people into trying "natural" childbirth, so others are led astray by the notion that an incontestable set of "bad" genes must be discarded because nature screwed up.
I return to the image of the leaping athlete: Although the leap wasn't completed, the trajectory wasn't random and the intermediate pose wasn't meaningless. Just because our genetic evolution was thrown for a loop by the sudden appearance of technologies like midwifery, that doesn't mean that our seemingly damaging genes are always entirely without benefit. Stella Man, a researcher from Queen Mary, University of London, recently discovered that Cx26, a gene associated with deafness, also plays a role in helping wounds heal. It's even possible that "harmful" genes might have some slight coloring effect on qualities like intelligence or character.
We humans are incomplete creations, lacking the enduring evolutionary refinement of the cockroach. In an earlier column (June 2006), I explained that it's impossible to know for sure what a big software program will do in advance. In the same way, it is impossible to predict the precise value of a gene. We'll never know the full implications of our genes because it would be too cruel to perform the evolutionary experiments that would provide the knowledge.
There are certainly some genes that are indefensible. The one for Huntington's disease—a purely genetic disorder that is both deadly and untreatable—is an example of what we can safely call a mistaken gene to which we should owe no allegiance.
But there is also value in assuming that inconvenient but survivable genes might be there for a reason. It is rational to give them the benefit of the doubt, or at least to encourage a culture of diversity among parents of the future, who will be able to reject genes, so that we don't reduce our own biodiversity based on partial knowledge.
It would be easier to coast to extremes, striving either for an imaginary natural perfection or a fallacious artificial one that wipes out all the genes we fear. Instead, we must chart an approximate middle course, in keeping with the intermediate state in which we froze our genetic identity.