Maternal Instinct Is Hard-Wired Into the Brain

Tara Parker-Pope wrote an interesting blog entry in the New York Times Health section, about a scientific study on how mothers respond to their children's cries, because of the innate wiring of the mothers' brain.

The article was interesting, but I was captivated by the reader comments, which were overwhelmingly negative, but also strangely off-base, as if the readers themselves weren't hard-wired to understand their own human nature.

Some comments made the point that if a trait isn't constant and unchanging, it can't be hard-wired. This is silly.  Human development occurs over time, but it's still innate.  For example, women develop breasts many years after they're born, but breast development is obviously innate.  Also, women have their periods sometimes (not all the time), so periodicity can also be programmed into the genes.

Furthermore, some social behaviors, such as "selective mutism", are innate, even as their development relies on experience.  You must first learn what a human face looks like (experience), before you can have an innate reaction (fear, shyness) to faces. But even if a trait requires "tuning" in the context of the environment, that doesn't make it any less innate.  The learning of faces is retained in the brain in a location well-known to the genes a priori, so the genes can exploit this ability later.  Seeing faces can make us shy, because our genes built the innate circuitry to recognize and remember faces in the first place.

The point is... the definition of a "hard wired" trait is not that something is fixed and unchanging from birth.  It's simply a trait whose development is programmed (by our genes) to unfold in the context of (expected) environmental scenarios.