But what is government itself but the greatest of all reflections on human nature?

I n the last chapter of his book, On the Origin of Species, Charles Darwin wrote famously: ‘‘Light will be thrown on the origin of man and his history.’’ Not many of us have taken him literally. People interested in Darwinian theory have tried to understand the roughly 200,000-year-old origins of Homo sapiens; but they’ve had very little to say about the roughly 5,000-year-old written record that is human history. Nearly 40 years after his boat docked at Falmouth, Darwin did his best to explain the ‘‘low condition’’ of people he’d met aboard the Beagle. The trouble seemed to have something to do with their ‘‘nomadic habits, unfavorable to human progress,’’ he thought. ‘‘Whilst observing the barbarous inhabitants of Tierra del Fuego, it struck me that the possession of some property, a fixed abode, and the union of many families under a chief were the indispensable requisitions for civilization. Such habits almost necessitate the cultivation of the ground.’’ Like most nineteenth-century British aristocrats, Darwin did not consider egalitarianism an asset. ‘‘The perfect equality among the individuals composing the Fuegian tribes, must for a long time retard their civilization,’’ he wrote. But he knew, as well as anybody, that inequality wasn’t always good for the weak—if beneficial to chiefs. He’d visited the natives in Australia, where ‘‘the women are the constant cause of war both between members of the same tribe and between distinct tribes.’’ And he had read about North American Indians, where ‘‘the contest is reduced to a system,’’ no weak man being permitted to keep a wife that a stronger man thought worth his notice. Besides, having been brought up on the classics, Darwin remembered his Horace: ‘‘Nam fuit ante Helenam mulier teterrima belli causa;’’ they’d gone to war for a girl in Troy. For Homo sapiens, as for any other species, the point of politics had always been sex—in an evolutionary sense. Winners became breeders; but losers did not. ‘‘This fact is so notorious it would be superfluous to give instances.’’ Only in the last half century have we started to use Darwin’s theory to solve Darwin’s problem: to understand why some animals are more ‘‘civilized’’ than others. As it turns out, most animals live alone, most of the time. More than 98% of all insect, bird and mammal species are solitary. But a few live in groups. And when they do, some animals—usually bigger, stronger animals—lay or fertilize most of the eggs; and other animals—usually smaller, weaker animals—do most of the work or help. Some animals have been referred to as ‘‘cooperative breeders,’’ or alloparental. They live in societies ranging in size from a handful to hundreds of individuals; and most of those individuals are temporary, or ‘‘facultative,’’ nonbreeders. Roughly 220 species of birds, roughly 120 species of mammals, and a variety of other species are considered cooperative breeders. 6 So what turns hundreds of otherwise fertile individuals into helpers-at-the-nest? One answer seems to be: a hard-to-escape habitat. Cooperative breeders live on clumps of stunted oak along Florida’s old sand dunes; or on patches of lush Maldonado meadow grasses; or under the protective eaves of houses; or in the dense cover of shrubs and thickets. Where prey is abundant and predators are scarce, animals tend to get together in groups, where a handful doi: 10.2990/28_2_102