It strikes us that a skeptical and dispassionate extraterrestrial ethologist studying our unendearing species might reasonably conclude that Homo sapiens are, for the most part, automatons with overactive and highly verbal public relations departments to apologize for and cover up our foibles.17
* It’s not the taste of the blood that attracts her, but the warmth If she drops onto a butyric acid-scented toy balloon filled with warm water, she will readily puncture it and, an inept Dracula, gorge herself on tap water* One promising finding in artificial intelligence is the discovery that distributed data processing—many small computers working in parallel without much of a central processing unit—does very well, by some standards better than the largest and fastest lone computer Many little minds working in tandem may be superior to one big mind working alone
Chapter 10
THE NEXT-TO-LAST REMEDY
When all the world is overcharged with inhabitants,
then the last remedy of all is war …
THOMAS HOBBES,
Leviathan, II, 301
Once organisms get really good at sex, once they evolve the plumbing and the passion for it, there gets to be a danger: So many competent, DNA-exchanging beings may be born that they will improvidently gobble up all the food or nutrients or prey, and then almost everyone, including their close relatives, will die. This must have occurred innumerable times in the history of life.
Take a being as modest as a bacterium, weighing in at a trillionth of a gram, and let it reproduce with no impediments. In the second generation there will be two bacteria; in the third generation, four; in the fourth generation, eight; and so on. If we imagine that none of those offspring die, then in 100 generations they will collectively weigh as much as a mountain; in 135 generations, as much as the Earth; in 150 generations, as much as the Sun; and in 185 generations, as much as the Milky Way galaxy.
Of course, such prodigious increases in mass are arithmetic exercises only. They could never occur in the real world. For one thing, the replicating microbes would soon run out of food. Your descendants cannot weigh as much as a mountain if there’s not a mountain’s worth of food to eat—much less an Earth’s worth or a Sun’s or a galaxy’s. There is only so much food available. Thus, your descendants will quite soon be in competition with one another for scarce resources. But because of the enormous power of exponential reproduction, an organism with even a slight advantage in finding or utilizing food rapidly supplants the competition (or at least its descendants do). Fast reproducers generate large populations, and competition for resources; they provide the raw material for a natural selection that efficiently magnifies small differences in fitness, differences that might be too small or subtle for even the most skilled naturalist to notice. This was the central argument of Darwin’s unpublished 1844 manuscript on evolution, and of his article in the Proceedings of the Linnaean Society of London for 1858.2
So what happens in fact when there’s too much crowding? Some responses seem to serve a larger purpose. Sibling shark embryos fight to the death in utero. In many nonhuman mammals, brothers and sisters of the same litter compete for access to nipples; often, there is a least competent infant, unsuccessful in elbowing its way to a nipple—the runt of the litter, who becomes progressively weaker with each failed attempt to nurse. The Virginia opossum has thirteen teats and, generally, more than thirteen pups per litter. Only those who regularly get to a teat live. Such competitions weed out the weak. Those species with more teats than pups permit weakling and unaggressive youngsters to reach adulthood. If they are unlikely to compete successfully as adults and pass their genes on, their mother has, from the point of view of her genes, been wasting her time nursing such pups. Those mothers with fewer teats or more pups have a selective advantage. Concern about cruelty and suffering doesn’t, so far as we know, enter into it.
Cities aside, we humans routinely experiment on crowding animals into confined enclosures. The institutions responsible are called zoos; some are much more pernicious than others. A well-known problem of zoos is that many of the inmates are somehow less able to “breed in captivity”; another problem is sustained and violent conflict, usually between males of the same species. Zookeepers have learned that if they wish to maintain their “inventories,” they must often separate the males. Experiments have also been performed in the laboratory to study overcrowding. In all of these cases it’s important to remember the artificiality of the circumstances. An option available in the wild is unachievable in captivity: No matter what the provocation, a caged animal cannot flee conflict and make a new start somewhere else.
Norway rats have been bred in scientific laboratories since the middle nineteenth century. Artificial selection has elicited—partly through unconscious choices by laboratory personnel—a strain of rats that is calmer, tamer, less aggressive, more fertile, and with significantly smaller brains than their wild ancestors. All this is a convenience for those experimenting on rats.3
In a now-classic experiment,4 the psychologist John B. Calhoun let Norway rats reproduce in an enclosure of fixed size until the number of occupants, and therefore the population density, was very high. He made sure, however, to provide everyone with enough to eat. What happened?
As the population increased, a range of unusual behavior was noted. Nursing mothers became somehow distracted, rejecting and abandoning their infants, who would wither away and die. Despite the surplus of ordinary food, the bodies of the newborn would be greedily eaten by passersby. An adult female in heat or estrus would be pursued relentlessly, not by one, but by a pack of males. She had no hope of escape, or even sanctuary. Obstetrical and gynecological disorders proliferated, and many females died giving birth, or from complications soon after. When crowded together, the rats lost their inclination or ability to build nests for themselves and their young; their desultory constructions were amateurish and ineffective.
Among the males Calhoun distinguished four types: the dominant, highly aggressive ones who, although “the most normal,” would occasionally go “berserk”; the homosexuals who made sexual advances to adults and juveniles of both sexes (but, significantly, only to nonovulating females): their invitations were generally accepted, or at least tolerated, but they were frequently attacked by the dominant males; a wholly passive population that “moved through the community like somnambulists” with nearly complete social disorientation; and a subgroup Calhoun calls the “probers,” uninvolved in the struggle for status but hyperactive, hypersexual, bisexual, and cannibalistic.
If there were no differences between rats and people, we might conclude that among the consequences of crowding humans into cities—other things being equal—would be more outbreaks of street fighting and domestic violence, child abuse and neglect, soaring infant and maternal mortality, gang rape, psychosis, increased homosexuality and hypersexuality, gay bashing, alienation, social disorientation and rootlessness, and a decline in traditional domestic skills. It’s suggestive, surely. But people are not rats.