Locked Away

The results are in. The ultrasound was conclusive. And despite my previously described hunch that our growing baby is a boy, she turned out to be a girl. We are, of course, ecstatic. A healthy baby and a girl to boot! As everyone tells us, girls are simply more fun.

As I was reading in my pregnancy book the other day, I came across an interesting bit of trivia about baby girls. At this point in my pregnancy (nearly 6 months in), our baby’s ovaries contain all the eggs she’ll have for her entire life. As I mentioned in a prior post, the fact that a female fetus develops her lifetime supply of eggs in utero represents a remarkable transgenerational link. In essence, half of the genetic material that makes up my growing baby already existed inside my mother when she was pregnant. And now, inside me, exists half of the genetic material that will become all of the grandchildren I will ever have. This is the kind of link that seems to mix science and spirituality, that reminds us that, though we are a mere cluster of cells, there’s a poetry to the language of biology and Life.

But after stumbling upon this factoid about our baby’s eggs, I was also struck by a sense that somewhere someone seemed to have his or her priorities mixed up. If our baby were born today, she would have a slim chance of surviving. Her intestines, cerebral blood vessels, and retinas are immature and not ready for life outside the womb. Worse still, the only shot her lungs would have at functioning is with the aid of extreme medical intervention. The order of it all seems crazy. My baby is equipped with everything she’ll need to reproduce decades in the future, yet she lacks the lung development to make it five minutes in the outside world. What was biology thinking?

Then I remembered two delightful popular science books I’d read recently, The Red Queen by Matt Ridley and Life Ascending by Nick Lane. Both described the Red Queen Hypothesis of the evolution of sex, which states that the reason so much of the animal kingdom reproduces sexually (rather than just making clones of itself) is to ‘outwit’ parasites. In short, if each generation of humans were the same as the next, parasites large and microbial could evolve to overtake us. By mixing up our genetic makeup through sexual reproduction, we make it harder for illnesses to wipe us out. Like the Red Queen from Lewis Carroll’s classic, we keep running in order to stay in the same place (which is one step ahead of parasites and disease).

Just as there are parasitic organisms and bacteria, one might say that there are parasitic genes. For example, mutations in the DNA of our own replicating cells can cause cancer, which is essentially a self-made, genetic parasite. Moreover, retroviruses like HIV are essentially bits of genetic material that invade our bodies and can insert themselves into the DNA of our cells. And the ultimate road to immortality for a parasitic gene would be to hitch a ride on the back of reproduction. Imagine what an easy life that would be! If a retrovirus could invade the eggs in the ovaries, it would be passed on from one generation to the next without doing one iota of work. It’s the holy grail of parasitic invasion – get thee to the ovaries! According to Matt Ridley in another of his books, The Origins of Virtue, the human germ line is segregated from the rest of the growing embryo by 56 days after fertilization. Within two months of conception, the cells that will give rise to all of the embryo’s eggs (or sperm, in males) are already cordoned off. They are kept safe until they are needed many years in the future.

So perhaps my little baby’s development isn’t as backwards as it seemed at first. Yes, lungs are important. But when you’ve got something of value to others, it makes practical sense to hurry up and lock it away.

3 responses

  1. Pingback: Recommended Reading: Locked Away | have kids, will blog

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