Back in the stateroom with the Swedes and the Japanese, Franklin remembered a TV series about psychology he’d once been asked to present. It had folded directly after the pilot, a loss nobody much regretted. One item in that show reported an experiment for measuring the point at which self-interest takes over from altruism. Put like this, it sounded almost respectable; but Franklin had been revolted by the actual test. The researchers had taken a female monkey who had recently given birth and put her in a special cage. The mother was still feeding and grooming her infant in a way presumably not too dissimilar from the maternal behaviour of the experimenters’ wives. Then they turned a switch and began heating up the metal floor of the monkey’s cage. At first she jumped around in discomfort, then squealed a lot, then took to standing on alternate legs, all the while holding her infant in her arms. The floor was made hotter, the monkey’s pain more evident. At a certain point the heat from the floor became unbearable, and she was faced with a choice, as the experimenters put it, between altruism and self-interest. She either had to suffer extreme pain and perhaps death in order to protect her offspring, or else place her infant on the floor and stand on it to keep herself from harm. In every case, sooner or later self-interest had triumphed over altruism.
Barnes, Julian. A History of the World in 10 1/2 Chapters