On a quiet snowy morning on the sagebrush prairie of Wyoming, you might hear a strange, musical drumming sound. Following it, you could observe a small party of birds that offers a key insight to human relationships.

Lost among the sagebrush hummocks, you have found a "lek" -- a meeting place where a circle of female Sage Grouse intently study the performance of a few of males. As they inflate their air sacks and strut, the males are competing for a desperate chance to save their genes in a winner-take-all contest. The females will choose the single bird that looks like the best genetic specimen. Then they will mate, leave the lek and afterward raise their chicks in solitude. The males pass on into genetic oblivion, and make no further contribution to supporting their offspring.

Why has the Sage Grouse chosen to abandon the two-parent child rearing system? The answer may lie hidden in the featureless landscape around you. Unlike more familiar birds in nests above our back yards, the ground-dwelling Grouse has no way of defending a territory. Since the male bird has nothing to "bring to the table," the female bird is better off getting the best genes she can and then raising her chicks alone -- a strategy that works for other animals as varied as insects and deer.

Could the same harsh imperative be changing the face of human families? In America, where black households earn only 63% of their white counterparts, and black men earn only 83% as much as African American women, we find about 70% of children are raised by single mothers -- a trend that is growing in all demographic groups. Perhaps the institution of marriage could be salvaged by restructuring society so that males have better income opportunities that will make them valuable husbands. Otherwise we may be condemned to live in a world where men live only for the glorious opportunity of competing in "leks" such as a bars and sports arenas, mate with as many women as possible and then, like the male Sage Grouse -- vanish from families forever.