A recent article in Time looks at various examples of alleged animal suicide, taking as its starting point the recent distressing film about Japanese slaughter of dolphins, The Cove. Animal-rights activist Richard O’Barry, who features in The Cove, is convinced that animals can commit suicide, having allegedly seen Kathy, a dolphin in the 1960s television show Flipper, sink to the bottom of her tank and stop breathing.
To take the discussion onto a rather more rigorous level, the article references a recent piece by a colleague of mine, Dr Duncan Wilson from the University of Manchester’s Centre for the History of Science, Technology and Medicine. Together with Edmund Ramsden from Exeter, Duncan has just published an article in the history of science magazine Endeavour (subscription required), looking at how animal “suicide” has been interpreted through the ages.
Drs Ramsden and Wilson go back to Aristotle’s story of a stallion that threw itself over a cliff when it realised it had inadvertently mated with its mother (this seems rather unlikely, in my opinion), but concentrate on 19th century views of animal suicide, and convincingly show that accounts of animal suicide reflect the values of the society in which they are recounted. In particular, during the 19th century, “Humane groups such as the Royal Society for Protection of Animals (RSPCA) seized upon popular accounts to claim that animals shared with humans the capacities for grief, love, despair – and, moreover, that they possessed enough intelligence to plan and execute their own deaths.”
A series of cunning experiments were carried out as part of the growing debate over the nature of animal behaviour – are animals conscious, or is their behaviour “instinctive”? The paragraph on scorpions is worth citing:
“Romanes relayed several accounts where scorpions had killed themselves after being ringed with fire, but noted cautiously, ‘such a remarkable fact unquestionably demands further corroboration before we accept it unreservedly.’ E. Ray Lankester, professor of zoology at University College, London, took up the challenge and, reporting to the Linnaean Society late in 1882, claimed that he had observed a scorpion repeatedly trying to strike itself after he administered chloroform into its glass container. This he believed to ‘throw light on the old tradition’, and tended ‘to confirm its accuracy.’ In 1883, Morgan endeavoured to dispel this belief. He designed a set of experiments ‘sufficiently barbarous…to induce any scorpion who had the slightest suicidal tendency to find relief in self-destruction.’
He surrounded them with fire, condensed sunbeams on their backs, heated them in a bottle, burned them with phosphoric acid, treated them with electric shocks and subjected them to ‘general and exasperating courses of worry.’ Though he witnessed scorpions striking at their backs, this, Morgan explained, was an instinctive attempt to remove irritation. Those who ignored or rejected this fact were ‘not accustomed to accurate observation.’ In 1887, Alfred Bourne provided further evidence that questioned ‘the phenomenon so graphically delineated by Byron’. Scorpions, he claimed, were immune to their own venom.“
The point of Ramsden and Wilson’s article is to show how attitudes to animal suicide have changed over time, and have been shaped by the overall views of any given society: “Through shifting archetypes of animal suicide, we can trace the history of perspectives on self-destruction – we see the victim and hero of ancient philosophy and romanticism, the martyr or sinner of the Judeo-Christian tradition, the automaton and the neurotic, lost amongst the masses of modernity. When scientists, philosophers, writers or theologians have reflected upon the nature of suicide, they have, persistently, reflected on the natural world.”
So where does that leave one of the real, solid examples of animal “suicide” – the worker bee stinging a perceived threat, but dying in the process? The bee’s sting is famously barbed, and as the bee tries to fly away, it pulls out its innards, including the venom gland which not only continues to pulse venom down the sting, but also releases alarm pheromones which attract other bees. The downside is that the bee dies. This video shows the process, and how to get a sting out (it takes an awful lot to provoke the poor bee into stinging…):
The explanation for this behaviour is that the bee is protecting its hive, and thereby its genes. Worker bees are generally sterile (though they can produce male eggs under certain circumstances), so the only way it can make a genetic contribution to the next generation is by helping the hive, with which it shares a high proportion of its genes. From a gene’s eye view, this is not suicide at all, but merely the death of one carrier of those genes, to preserve the life of many more carriers.
So – apart from the examples of social insects, DO animals commit suicide?