Chapter 4

 One of the possible causes for the physiological difference between the male and female brains is evolution. Over time, the maternal females won out over other females who weren’t and so their genes were passed on while the other ones died out. Maternal instinct, protecting and nurturing, is vital to a child’s survival into maturity where they could have offspring and continue passing on the gene. That would be an advantageous trait to the longevity of a species.  Male aggression could be linked to that as well, a father who protects his offspring, fights for food, and the perfect cave (haha). That aggressive trait would also be vital for the survival of a lineage and appeal to natural selection. 

Its interesting that during “prime years”, females become less assertive and more insecure while males become more dominant. It almost seems like that combination of traits during those mating years would make it easier to pair off, like evolution considered relatively modern human traits (such as insecurity and monogamy) along with the overwhelming amount of mate’s people could choose from, and came up with a quick solution. Because the textbook said that as humans age, those differences recede and the opposing traits rise up. But maybe that's an ignorant notion. 

As for a female’s brain being wired to “enable social relationships” and males not as much, I can’t really think of any other particular reasons why. Maybe it was just the next step, money has replaced brute strength and there is no more battle for resources (yet), so there’s been a shift in focus. Why both male and female haven’t both developed that wiring, I don’t know. Perhaps in time.