It’s tempting to think that luck or misfortune sometimes influences the course of events. But is this idea of leaving things to luck unique to human beings? A British study investigated this question among our closest cousins, chimpanzees.
The authors of this study, published in the journal Biology Letters, investigated this idea using four experiments with chimpanzees at Edinburgh Zoo. The tests were designed to determine whether these great apes sometimes rely on luck to make the right choice.
The primates had to choose between two cups, one containing a treat and the other nothing. In some cases, the researchers guided the chimpanzees’ choice by showing them which cup contained the food reward. In other cases, they let them trust their instincts.
Whether they made the right decision or not, the monkeys were then asked to repeat the experiment. But this time, they had the choice between the cup they hadn’t chosen in the first round, and a smaller one they knew contained a treat.
The size of this treat was proportional to the size of the task, meaning it was smaller than in the first test. The researchers noticed that the chimpanzees were more likely to choose the smaller cup when they didn’t know exactly where the treat was.
Later, the academics made the experiment more complex by adding more cups. The probability of the monkey choosing the right cup was, therefore, much lower than before.
It appeared that chimpanzees were relying on luck to make a decision. Those who had initially chosen the wrong cup played it safe by choosing the smallest cup, which they knew contained a treat. Conversely, those who had previously been lucky tended to be more reckless, choosing the larger of the two cups.
A sense of reasoning?
The findings of this study suggest that, like us, chimpanzees sometimes rely on luck when faced with a dilemma. Or rather, they use their sense of abduction, given that luck is not a very scientific concept.
The term “abduction”, theorised by the American semiotician and philosopher Charles Sanders Peirce, refers to a form of reasoning that proceeds from effect to cause.
In this case, the chimpanzees chose one of the two cups according to their success rate in the first experiment. If they found that cup A contained a treat, they tended to choose this same cup throughout the experiment. Conversely, if they knew that cup A was empty, they were more likely to choose cup B.
“These experiments demonstrate that chimpanzee choices are not governed by a singular simulation of reality, and reflect the dependent relationship between mutually exclusive possibilities,” the study authors wrote.
In this context, the luckiest chimpanzees were not those who had won the favours of fate, but rather those who had some sense of reasoning. It remains to be seen whether these animals are aware of this, and above all, whether they use it in the wild.