Last week's episode of Quirks and Quarks, the Canadian Broadcasting Corporation's national science radio program, had a fascinating segment on the role of vasopressin in monogamous commitment. Males in some species of pair-bonding mammals have their lifelong attachment triggered by vasopressin release, and studies of men in monogamous relationships find a correlation between low vasopressin levels and high levels of marital strife.
The whole program is really fascinating, covering the science of pheromones, the role that estrogen plays in female fidelity, and many other romantic elements of science.
