There are serious ramifications to all this marketing, the Moores say. The tidal wave of pink toys and clothes suggests there’s only one way to be a girl — pretty, princessy and fashion-minded. And this segues disturbingly quickly into often sexualized images of tween girls a few years older, says Lyn Mikel Brown, an education professor at Colby College in Maine and co-author of the book Packaging Girlhood. The not-so-subtle pressures of this marketing can damage self-esteem and feed worries about body image and appearance later in life, the sisters say. They also link it to a celebrity-obsessed culture that undermines adult women by glorifying glamour figures like Paris Hilton while neglecting those women engaged in more serious pursuits.

Nearly a century before the geologist M. King Hubbert began calculating peak oil, the economist William Stanley Jevons discovered, to his horror, peak coal. In The Coal Question, published in 1865, Jevons raised the questions which haunt sustainability advocates to this day: “Are we wise in allowing the commerce of this country to rise beyond the point at which we can long maintain it?” He estimated Britain’s coal production would reach a peak in less than a hundred years, with calamitous economic and Malthusian consequences. The engine of coal’s demise would be the same invention that was created to conserve it: the steam engine. But it made burning coal so efficient, that instead of conserving coal, it drove the price down until everyone was burning it. This is Jevons’ Paradox: the more efficiently you use a resource, the more of it you will use. Put another way: the better the machine–or fuel–the broader its adoption.