This from the remainder bin:
There’s also preliminary but tantalizing evidence that fatherhood can change the brain. A 2006 study found enhancements in the prefrontal cortex of the father marmoset. After childbirth, the neurons in this region showed greater connectivity, suggesting that having young children could boost the part of the brain responsible for planning and memory, skills parents need when having kids gives them more to keep track of. The neurons also had more receptors for vasopressin, a hormone that has been shown to prompt animal fathers to bond with offspring.