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.