The rise of “the hookup culture” at colleges, they argue, can be attributed in part to the increasing scarcity of men on campus—an oversupply of sellers works to a buyer’s advantage. Sexual economics also suggests that many women look unkindly on promiscuous members of the same sex out of the same impulse that makes retailers angry when Wal-Mart comes to town: they are being undersold, and now they have to give discounts or lose customers.

Hughes isn't buying it: