To know what goes on in the mind of a rogue trader – and that of every reckless gambler – it helps to be a bird-watcher. The yellow-eyed junco is a type of
sparrow found in Mexico and the southern USA. Thirty years ago, three evolutionary biologists at the University of Arizona carried out a series of experiments with seven yellow-eyed juncos that had been caught in the south-east of the state. The experiments were designed to test the birds’ gambling instincts, and the results were intriguing. One bird at a time was placed on a perch in an aviary 3.5 metres from two dishes covered with paper so that it could not spy the contents. The bird was trained to realize that if it flew to the first dish, it would always find two millet seeds to eat; if...
the seeds being replenished every thirty seconds. This meant that, whichever one they chose, they would get plenty to eat unless they were very unlucky. The juncos responded by being risk averse: in nineteen out of twenty-five cases, they chose the sure thing – the dish with two seeds – rather than risk finding nothing. Next, the birds were starved for four hours, and the seeds were replenished only every minute. That tipped the birds into what the scientists called ‘a negative net energy budget’ – gaining two seeds each time they made a choice would not provide enough food to satisfy...
The choices are instinctive rather than intellectual, and they make evolutionary sense for the species. ‘Facing the possibility of starvation, animals are willing to gamble on the “strike-it-rich” policy of risk-prone foraging,’ writes Barry Sinervo, a professor of ecology at the University of California. ‘Some foragers will have a string of bad luck and starve. Some will have a string of average luck and still starve. However, there will always be those lucky few that experience a string of good luck. It is those lucky few that survive and pass on genes to the next generation.’