Thursday, March 16, 2006
Mom and fetus duke it out
…Why is pregnancy such a struggle? Women die of it. Millions suffer injuries, infections or disabilities.
…According to the New York Times, David Haig, a biologist at Harvard, thinks the whole process could use some work.
…Mom and baby, he says, may be working against each other—competing.
…Evolution-wise, he says, the child that can get more resources than the parents want to give tends to live and reproduce.
…First thing, the fetus grows aggressive blood vessels to extract nutrients.
…Haig says 6% of women get high blood pressure (pre-eclampsia). Haig says the fetus may be injecting some substance to up the return of nutrients from the mother’s blood. Indeed a protein has been found in the blood of mothers with the condition—and this protein tends to keep the mother from repairing her vessels, thus her BP rises.
…Haig also explains the shutting down of genes from one parent over the genes of the other from an evolutionary standpoint. Depending on which genes are not expressed, the baby will be a weak feeder or timid about exploring new environments.
…In mouse brains, at least, the exploring new territory genes are the mother’s, not the father’s. In general, Haig says, the mother’s genes tend to benefit the group, the father’s the individual.
…That is what generated the hate mail. Hey, he says, we’re talking science here.