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Nature is “red in tooth and claw,” as Alfred, Lord Tennyson wrote in the poem “In Memoriam A.H.H.” In that now-famous line, Ten­nyson was considering, pre-Darwin, the apparent callousness of nature. Nature is not cruel; it is simply indifferent, and these behaviors show a disregard for other living things, rather than malice.

Humans alone are capable of cruelty, and sexual coercion and rape are immoral and criminal acts. Describing nonhuman behavior in these terms trivializes rape.

We do need to talk about dolphins, though, as their sexual behav­ior is concerning and much discussed. We humans have a strange relation­ship with dolphins. We are often in awe at their intelligence and grace, and the tricks they do for us in captivity and in the wild. And they have nice smiley faces.

This post is adapted from Rutherford’s new book.

Dolphin is a loose and informal name for several different groups of cetaceans, including the Delphinidae (ocean dolphins) and three classes that live in rivers or estuaries (Indian, New World, and brackish). They are smart and have large, complex brains. They also have complex societies, among them notably (but certainly not exclusively) the bottlenose dolphins best studied in Shark Bay in Australia. Two or three male Shark Bay dolphins will form a gang that swim and hunt with each other, called a “first-order” pair or trio. Sometimes two pairs will team up and form a second-order alliance.

These Shark Bay dolphins are also viciously violent. When breeding season comes around, there is fierce competition for access to females, as happens in many sexual species. In most cases in nature, that competition is between individual males. The bottle­nose dolphins have a different tactic: They form gangs.

Alliances are an essential part of the mating strategies of the males. First-order partnerships will single out a female, rush at her, and then herd her away to have sex, which is coercive (this is a general assumption, because it is rarely seen). During this aggressive corralling, the female repeatedly tries to escape, and does so in about one of every four attempts. The males restrict her attempts at freedom by charging in, and bashing her with their tails, head-butting, biting, and body-slamming her into submission.

Second-order alliances do the same, but the team-up makes a ratio of five or six males to one female. The males are often closely related in these alliances, so as a means of transferring their genes into the future, this fits perfectly well within evolutionary theory. On occasion, they form looser “super-alliances,” where multiple second-order gangs will join forces—up to 14 individual males—to corral a single female. These gangs don’t tend to be closely related.

It should be noted that forced copulation has not been directly witnessed, as far as I am aware. The evidence comes from obser­vations of the precopulatory behavior, and physical evidence of violence on the females. Many people say semi-jokingly that in contrast to their cute and smart image, dolphins rape. There is no doubt that sexual coercion is part of their reproductive strategy, as it is in many organisms, and that the behavior is violent. But we must be careful not to anthropomorphize their behavior, whether it be cute, smart, or horrid.

Infanticide is another unpleasant behavior seen in dolphins. It often gets translated into murder in the popular press, but it should be noted that in plenty of other organisms, both males and females kill the young of others within their own species as a reproductive strategy.

A female lion lactates for more than a year when she is nursing cubs, and during this time won’t breed. Males acting alone or sometimes in packs will kill her young in order to bring her back to being fertile so they can then sire a pride. Mother-and-daughter teams of chimps in Tanzania have been seen killing and eating the babies of other parents for reasons that are not clear. Alpha-female meerkats will kill the litters of subordinate females so that they will be free to help nurture the alpha’s litter. Female cheetahs get around all these issues by copulating with multiple males. Their sperm mixes internally in the female, and she will give birth to offspring of several paternities in a single litter.

There are plenty of reports of dolphin calves washed up on beaches with extreme injuries. One study in the 1990s reported nine that had died of blunt-force trauma, including multiple rib fractures, lung lacerations, and deep puncture wounds that were consistent with bites from an adult dolphin.

Are dolphins murderers or rapists? No, because we cannot apply human legal terms to other animals. Is the behavior distasteful to us? Yes, but then again, nature does not care what you think.

This walk through some of the grimmer aspects of the behavior of animals serves as a reminder that nature can be brutal. The struggle for existence means competition, and competition results in conflict and sometimes lethal violence. We recognize these behaviors because humans compete and can be horrifically violent.

But we are not compelled to act violently. The evolution of our minds may have gifted us the ability to craft tools that enable mas­sacres. But it has also furnished us with choices unavailable to our evolutionary cousins. We are different because, with behavioral modernity, we have eased our own struggle for existence away from the brutality of nature, so that we are not obliged to kill others or force sex upon females in order to ensure our survival.


This post is adapted from Rutherford’s new book, Humanimal: How Homo sapiens Became Nature’s Most Paradoxical Creature.

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