When David Haig finished college in Australia with a degree in biology, he found a job in a New South Wales government office rubber-stamping documents to record mortgage tax payments and property transfers. His tour in the bureaucracy lasted two years. “I decided there was more to life than rubber stamps,” he says, reminiscing in his office at Harvard University’s Botanical Museum. Haig returned to his biology studies at Macquarie University in Sydney, earning his doctorate in 1989.
While he was there, he became absorbed in the study of an unsolved problem in evolutionary biology. Researchers were learning that the process of conceiving a child is not nearly the tender, rhapsodic intertwining of the mother’s and father’s genes that one might imagine. Instead, it’s the start of a survival-of-the-fittest struggle that begins inside a fertilized egg and continues throughout pregnancy.
Natural selection usually had been thought of as a competition among species in the wild. Now it appeared that natural selection was operating within each fertilized human egg, as each parent’s DNA competed for control of the developing offspring, each with a different evolutionary goal.
Haig’s dreary rubber-stamp work oddly foreshadowed his biological studies. The fetal genes locked in this battle for survival, researchers had discovered, were “stamped,” or imprinted, with molecules that marked them as coming from either the mother or the father.
Only about 100 of the tens of thousands of genes that make up the human genome are marked with these gender-specific stamps, subsequent studies showed. But even though they are uncommon, they are critical for survival. If the imprinting process goes awry during gestation, it can lead to serious illness, or even death, of the fetus or the mother.
