A pod of 61 whales beached themselves at Farewell Spit in New Zealand last Monday. Officials decided to euthanize the 18 that were still alive by Wednesday. It is not clear why whales beach themselves, but one theory holds that when a sick individual heads to shore to die, others follow. Is suicide a thing in the animal kingdom?
There is plenty of evidence that animals engage in self-destructive behaviour. In addition to the beached whales, ducks and dogs have been observed drowning themselves, cows have walked off cliffs, and naked mole rats (like some insects) leave the colony to die when infected with a communicable disease.
It is not clear whether any of these behaviours are comparable to human suicide, because suicide involves a set of higher-order cognitive abilities. It requires an awareness of one’s own existence, an ability to speculate about the future, and the knowledge that an act would result in death. There are indications that certain animals have some of these capacities. Dolphins, many primates, magpies and elephants can recognise themselves in a mirror, suggesting self-awareness. Some animals know how to pretend during play activities, which indicates an ability to imagine counterfactual worlds. Still, no one really knows which animals, if any, can combine these capacities to perform an act similar to human suicide.
This made me to remember the whale washed ashore in Nigeria in August, 2001. Nigerians and other relevant authorities did not bother to investigate the incident either for environmental protection or for educational purposes. It amazes me how the said whale was left at the mercy of area boys, scavengers and spectators.
Unlike our experience in 2001, the whales were not made a public show but the relevant authorities and government agencies are taking keen interest in unraveling the misery behind the suicide mission.
Victorian scientists are particularly interested at unveiling the misery. According to historian Edmund Ramsden in an article in 2010 states that the humane society is eager to prove that animals experience human-like emotions and animal suicides have offered a proof. A series of such suicide stories began to appear in periodicals in 1845: One involved a depressed Newfoundland dog that repeatedly leapt into the water, kept its limbs still, and held his “head determinedly under water for a few minutes.” Other dogs drowned or starved themselves after losing their owners. A deer jumped from a precipice to avoid capture by hunting dogs. A duck drowned itself after the death of its mate. Scorpions were thought to sting themselves when surrounded by fire.
This made researchers to engage in a fierce and ultimately inconclusive debate over whether any of these behaviors should be considered suicide. (Except for the scorpions, which clearly were not attempting suicide—they’re immune to their own venom.)
Even when scientists can explain the neurobiological basis of an animal self-destructive behavior, it is still not clear whether it’s fair to call the act suicide. The parasite Toxoplasma gondii affects the brains of rodents and causes them to be attracted to their mortal enemy—the cat. It would be easy to dismiss this kind of rat suicide as irrelevant to our own behavior if not for some hints that infection can play a role in human suicides as well.
In a 2009 study of patients with recurrent mood disorders, University of Maryland researchers found that those with high levels of Toxoplasma gondii antibodies were more likely to have attempted suicide. This study was preliminary, though, there’s no sign of a causal connection.
No matter the motivation, self-destruction appears to be something that exists in even the simplest life forms. Single-celled marine algae engage in programmed cell death when exposed to stresses that they’re fully capable of overcoming.
Researchers recently discovered that the “suicide” of some cells promoted growth in the survivours. Like infected mole rats or bees that abandon the colony to prevent an epidemic, algae die for the good of the community.