Love, Sex, and Babies
The science behind attraction
"One of the prominent effects of early BPA exposure is that it eliminates a number of sex differences in brain and behavior," Liisa Galea and Cindy Barhain wrote. It turned out that BPA-exposed males have impaired spatial ability (can't find their way out of a maze or to their nest, considered unattractive to females). They also suffer from decreased exploratory ability (incurious and easily lost), and overall reduced attractiveness to the opposite sex. They may even smell different from their peers—in rodents, a sign of unhealthiness. Females are disgusted.
On a population level, how might BPA affect us? Might boys in the U.S. grow up to have poorer spatial skills—and, because it's linked, weaker mathematical ability? Might they have little interest in exploring the world, preferring to hang out at home? Might our national temperament become more placid? Because BPA is lined with obesity and heart disease, will we become fatter and more sedate? And what about our sex lives?
Take a look at human history through the lens of hormones, as Harvard University's Daniel Lord Smail did in his fascinating book, On Deep History and the Brain. Smail introduces a new view in which physiology and culture evolve symbiotically in a process driven by brain chemistry. Caffeine stimulated the body and mind, driving the industrial revolution and the modern corporation. Tobacco help us to focus and be calm. These substances changed the character of society. Now we have environmental toxins such as BPA (and other hormone disruptors such as phthlates and PCBs) that may also change our culture in subtle but very real ways.
Much of the trouble with BPA lies in its ability to fool estrogen receptors into thinking it's estrogen. Imagine a man doesn't know that the woman he's marrying is really an alien in drag, and you have a sense of the danger here. BPA disrupts any process that estrogen normally mediates, affecting brain, body, and behavior. It also tinkers with the way genes express themselves, turning up those that would otherwise be turned off or down. BPA exposure has been linked to breast cancer, heart disease, obesity, diabetes, attention-deficit disorder, increased anxiety, a decreased IQ in children and a low sperm count in men.
One way that BPA tinkers with our systems is by attaching itself to strands of DNA and "turning on" certain genes (removing methyl groups) that are normally turned off—resulting in obesity, cancer, and other problems. This is classic epigenetics—an environmental trigger affects the way that genes behave. Nutrients in green vegetables, beans, eggs, and soy may be protective (in those of us who include enough in our diet) because they turn off genes that BPA otherwise turns on.