Carl Zimmer, one of the best, and most interesting, science writers around, in his blog, The Loom:
Natural selection can favor genes that allow children to grow up healthy. But in order to grow up healthy, they need nurturing from their mothers, both before and after birth. If a baby’s development puts a strain on a mother, she may end up having fewer children. That means she may spread fewer copies of her genes to later generations . That creates conditions in which natural selection may also genes that allow mothers to restrain their children. Our particular way of having kids puts genes in conflict.
I have an article in tomorrow’s New York Times on these conflicting genes, focusing on the visionary work of David Haig of Harvard University. As I explain in the article, Haig first wrote about his theory in the early 1990s. He made a number of predictions about pregnancy and fetal growth, many of which have only been tested in recent years. Many of them bolster his argument.
In articles such as this one, I usually have to struggle over which examples to include and which to leave out. Sometimes extemely cool ones demand a lot of explanation which would swamp the whole piece. In this case, I had to leave out a couple striking examples of how genes in conflict may create some of the most mysterious birth disorders around.