If you're a girl, you've been programmed to make sure you keep social harmony. This is a matter of life and death to the brain, even if it's not so important in the twenty-first century. We could see this in the behavior of three-and-a-half-year-old twin girls. Every morning the sisters climbed on each other's dressers to get to the clothes hanging in their closets. One girl had a pink two-piece outfit, and the other had a green two-piece out?t. Their mother giggled every time she'd see them switch the tops - pink pants with a green top and green pants with a pink top. The twins did it without a fight. "Can I borrow your pink top? I'll give it back later, and you can have my green top" was how the dialogue went. This would not be a likely scenario if one of the twins were a boy. A brother would have grabbed the shirt he wanted, and the sister would have tried to reason with him, though she would have ended up in tears because his language skills simply wouldn't have been as advanced as hers.
Typical non-testosteronized, estrogen-ruled girls are very invested in preserving harmonious relationships. From their earliest days, they live most comfortably and happily in the realm of peaceful interpersonal connections. They prefer to avoid conflict because discord puts them at odds with their urge to stay connected, to gain approval and nurture. The twenty-four-month estrogen bath of girls' infantile puberty reinforces the impulse to make social bonds based on communication and compromise. It happened with Leila and her new friends on the playground. Within a few minutes of meeting they were suggesting games, working together, and creating a little community. They found a common ground that led to shared play and possible friendship. And remember Joseph's noisy entrance? That usually wrecked the day and the harmony sought out by the girls' brains.
It is the brain that sets up the speech differences - the genderlects - of small children, which Deborah Tannen has pointed out. She noted that in studies of the speech of two- to five-year-olds, girls usually make collaborative proposals by starting their sentences with "let's" - as in "Let's play house." Girls, in fact, typically use language to get consensus, influencing others without telling them directly what to do. When Leila hit the playground, she said "Shopping" as a suggestion for how she and her companions might play together. She looked around and waited for a response instead of forging ahead. The same thing happened when another little girl said "Dolly." As has been observed in studies, girls participate jointly in decision making, with minimal stress, conflict, or displays of status. They often express agreement with a partner's suggestions. And when they have ideas of their own, they'll put them in the form of questions, such as "I'll be the teacher, okay?" Their genes and hormones have created a reality in their brains that tells them social connection is at the core of their being.