In her book Maxxed Out: American Moms on the Brink, Katrina Alcorn asks mothers, "Do you ever feel as if being a parent has turned you into an expert multitasker? It probably has." Alcorn continues:

Studies show that in mammals, caring for their young is associated with improved learning ability and fearlessness. For example, experiments show that mother rats outsmart their childless counterparts at navigating mazes and capturing prey. That's because in pregnant and nursing mice, dendrites, the special cell structures that are necessary for communication between neurons, are doubled. And glial cells, which are important communication conductors, are also doubled. This is what allows mother mice to learn mazes more quickly than others. (Sorry, dads, I have not read anything indicating that fathers experience a similar boost in brainpower.)

Of course, even with our extra dendrites and glial cells, we mothers still have our limits. Studies show that the amount of multitasking working parents do has doubled since the mid-'70s. Research also shows that too much multitasking [temporarily lowers our IQs]. It makes us do stupid things. And yet, life with young children often requires an absurd, stuntman level of multitasking—something we do more than half our waking time.