Shadows of Forgotten Ancestors

In many species the alpha male systematically threatens any other male attempting to mate with any female in the group, especially when conception is possible. Because of clandestine impregnations by subordinate males—kleptogamy—in which the females are often willing partners, the alpha does not always succeed; but he’s highly motivated to try. This is true within female dominance hierarchies as well. In domestic fowl, for example, the alpha female tends to attack any female that so much as walks up to an adult male during the breeding season. In gelada baboons, in which there is a female dominance hierarchy, high-ranking females do not, on average, mate more frequently during ovulation than do the lower-ranking females; but the lower-ranking females rarely give birth. Something about their inferior status diminishes their fertility. Perhaps they are advertising ovulation when in fact no egg is released, or maybe they have many spontaneous abortions. But whatever it is, their low status prevents them from having babies. In marmosets, subordinate females tend to suppress their ovulations, but when they are freed from the female dominance hierarchy, they quickly become pregnant.

²¹ Thus, genes contributing to high status in the female hierarchy—large stature, say, or superior social skills—get preferentially passed on to the next generation. This tends to stabilize a hereditary aristocracy.

In cattle and many other animals, the alpha male may try to gather around him a harem of females and chase away the other males, but his success is often limited. When the breeding time has passed, the males return to their solitary ways and the females (and young) resume their own social grouping. Among deer this is called a hind group and entails its own dominance hierarchy. Commonly, the leader of such communities is determined not by bluff, threat, or fighting ability, but by age: The oldest fertile female leads. (The same convention is adopted among all-female herds of African elephants; even when composed of hundreds of elephants, the social structure is extremely stable.) These groups seem to be organized around protection. When attacked, they form a diamond- or spindle-shaped pattern, with the alpha female in front and the beta bringing up the rear. If the pursuers are gaining, the beta female may valorously stop short and engage the leading predator. As the rest of the group makes its escape, the alpha and beta may then exchange sentry duty.

In skirmishes the advantages of the dominance hierarchy are clear. Even female mammals who evince little enthusiasm for individual dominance nevertheless arrange themselves into battle hierarchies in times of trouble. So dominance hierarchies have at least two functions, extremely useful both for individuals and for the group: They reduce dangerous and divisive fighting within the group (promoting what we might call political stability); and they are optimized for inter-group and interspecies conflict (providing what we might call military preparedness).

A third purported advantage of dominance hierarchies is that they preferentially propagate the genes of the alphas, those who are physically or behaviorally fit. We might imagine a common conditional strategy for everyone in the group that would go something like: “If I’m big and strong, I intimidate; if I’m small and weak, I retreat.” This benefits everyone one way or another, and the sole focus is on the “I.”

Being human, we naturally feel some whiff of resentment when we imagine ourselves dropped into such a dominance hierarchy with its craven submissiveness and manifest cruelties. Being human, we might also imagine the pleasures of a well-run social machine in which everybody knows his place, in which nobody gets out of line and causes trouble, in which deference and respect to superiors is routinely shown. Depending on whether we come from a more democratic or a more authoritarian upbringing, schooling, or society, we might feel that the benefits of the dominance hierarchy outweigh any affront to freedom and dignity, or vice versa. But this discussion isn’t yet about us. Humans are not red deer or hamsters or hamadryas baboons. For these species the cost-benefit analysis has been made. For them, law-and-order is the higher good. That there are innate individual rights and liberties of hamsters, needing institutional protection, is not a self-evident truth.

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