The curious science of breasts

Florence Williams's excellent book shines light on a much-misunderstood part of the body.

Possibly the most famous breasts in the world. Photo: Getty Images

The temptation, when reviewing a book all about breasts, is to stuff the copy full of nudge-nudge-wink-wink allusions. Is the writer making good points? Or has she boobed?

But for once, I’m going to take the high road and exorcise such childishness up top (up top!) because Breasts is a seriously good book. It’s well written, scientifically literate, engrossing and occasionally terrifying.

Florence Williams didn’t think much about her breasts until she got pregnant with her first child: then suddenly, they were “wondrously utilitarian”. She appreciated fully that they weren’t just glitzy baubles but an integral part of the survival of the species.

From here, she weaves a fascinating thread, exploring both the aesthetic and useful properties of her subject. There is a recurring theme: men of science do love to interfere with breasts, often with unpleasant or dangerous results. They pioneered injecting them with silicone; they decreed that breastfeeding was unhygienic in comparison to the bottle. The male-dominated scientific establishment continues to argue that breasts evolved mainly to attract a mate, when in reality their milk-dispensing properties seem more valuable. (In biology terms, it’s a question of sexual v natural selection.) “The debate over breast evolution is important,” writes Williams, “because the creation stories colour how we see breasts, how we use them and how we burden them with our expectations. Because the dominant story has been all about the visuals, it discounts what’s actually in breasts.”

She’s right. In our sex-saturated culture, most people have seen hundreds, if not thousands, of nipples but we still have a sketchy understanding of what goes on underneath them. The breast is the “only organ in the body that is not fully grown by adulthood”: they only reach their full potential during pregnancy, when their cellular architecture changes in preparation for lactation.

Some scientists now believe this process can explain the dramatic differences in breast cancer rates between childless women and mothers. By the end of pregnancy, stem cells in the mammary glands differentiate into “cancer- resistant, high-performance dairy equipment”. In those who have children later, or not at all, this differentiation never happens and the cells are more susceptible to going cancerously rogue. Williams has to steer a careful course through the science here: it’s inevitably more complicated than a non-specialist can easily digest and so can easily be co-opted into a “Have babies early or your cancer is your fault!” narrative. She does this admirably: pointing out, for example, that while a woman who has her first child before 20 has half the breast cancer risk of one who waits until her thirties, there are some aggressive cancers that are encouraged by the hormone bath of pregnancy.

This is a book crammed with quirky, thought-provoking facts: for example, breastfeeding expends the same amount of energy every day as walking seven miles, a third of a woman’s metabolic output. The first person to have breast implants, Timmie Jean Lindsey of Houston, Texas, still has the original pair inside her 50 years on, at the age of 80. The surgeons offered to pin her ears back, the cosmetic surgery she wanted, if she would be a guinea pig for their new procedure; not something that would fly with ethics boards today. Still, she was lucky not to get the “safer” Même implants popular in the 1980s, as these were discovered in 1991 to contain polyurethane foam originally destined for carpets. “The manufacturer of the foam was apparently surprised to learn where it was ending up,” records Williams.

But the most arresting material in the book must be the effect of our environment on breasts, particularly the ones used for feeding children or “budding” increasingly early on the ribcages of young girls. Williams explains how many plastics – fundamental to the modern world – leach oestrogen-like substances into our food and toiletries, with worrying consequences. One in particular, Bisphenol A (BPA) is everywhere and the more we know about it, the more alarming it seems. In mice, it causes high percentages of abnormal eggs to form in the ovaries. In humans, it appears to hit both sexes – low sperm counts for him, invasive cancer-like breast cells for her. The EU has banned BPA in baby bottles but it’s still all around us – and Williams notes that many of the scientists researching it have decided to give up bottled water.

Synthetic oestrogens might also be contributing, alongside better diets, to increasingly early puberty. In 2011, a third of black girls between the ages of six and eight were budding breasts. This has grave repercussions: a girl who gets her first period at the age of 12 has a 50 per cent higher risk of breast cancer than one who starts at 16.

All in all, Williams makes a compelling case that “breasts are bellwethers”. Humans are the only species to have them permanently (apes couldn’t fill an A-cup when they’re not lactating) and yet they are the only organ without its own medical specialism. We should show them some respect.

Breasts: a Natural and Unnatural History by Florence Williams, W W Norton, 352pp, £15.99