What Lambert’s rodent brain slices are revealing is nothing short of revolutionary, challenging the loud pundits and long-held cultural views that only mothers are wired for nurture.
Lambert, one of a small but growing number of scientists who study the biology of father behavior, is finding that not just mothers experience surges of hormones associated with bonding and nurturing. The same hormones increase, though not to the same degree, in fathers.
Rat mothers are not the only ones whose brains become sharper, making them more efficient foragers and more courageous and level-headed than females without offspring. Lambert has found that the same is true of fathers’ brains. Fatherhood makes the male California deer mouse smarter, too.
Perhaps her most astonishing finding is that the mere presence of a pup is so powerful that it restructures even the brain of a virgin male common deer mouse, a member of what she calls a “sperm donor” species.
Unlike the monogamous, naturally nurturing male California deer mouse, the male common deer mouse typically goes his merry way after copulation, leaving all the caregiving to the female. But the longer the “sperm donor” common deer mouse is exposed to a pup, Lambert’s most recent studies show, the more his brain becomes wired to nurture.
“It’s time that matters: face time, pup time,” Lambert said. “That’s what’s so fascinating. We can take a male animal not predisposed to nurture and, with more time with pups, start seeing changes to the landscape of the brain.”
Could those brain changes turn a “naturally deadbeat dad,” as she calls them, into a nurturing, caregiving father?
“It’s certainly a possibility,” Lambert said.
What’s a father for?
Lambert’s work on paternal brains and behavior is shaking up some basic assumptions about parenting. So is other emerging research on fatherhood, including studies showing that expectant human dads produce higher levels of the hormone responsible for breastfeeding and that fathers’ testosterone levels drop after a baby is born.
“Her results are really quite stunning,” said Patricia Churchland, a professor at the University of California at San Diego who writes frequently about the intersection of brain science and philosophy. “What she’s finding about exposure to pups and the effect on the paternal brain is really very new and very, very important.”