Taking turns may not just be good manners but part of evolution, new research has revealed.
Not only humans take turns after being taught to be considerate, but a range of other animals do as well, a study by psychologists at the University of Leicester has found.
They say an “invisible hand” may guide us in turn-taking, explaining how it has evolved across many species without the use of language or being taught.
Prof Andrew Colman and Dr Lindsay Browning carried out the study, which is due to appear in the September issue of the journal Evolutionary Ecology Research.
“In human groups, turn-taking is usually planned and co-ordinated with the help of language,” Prof Colman says.
“For example, people living together often agree to take turns washing up the dishes after meals or taking their children to school.
“Humans have never asked the question of how it evolved because it seems so natural, you’re taught it by your parents but all that requires the human aspect of language.
“But turn-taking has also evolved in many other species without language or the capacity to reach negotiated agreements.
“These include apes, monkeys, birds, and antelopes that take turns grooming each other, and mating pairs of Antarctic penguins that take turns foraging at sea while their partners incubate eggs or tend to chicks.”
He said it was “far from obvious” how turn-taking had evolved in animals who look after themselves as part of natural selection.
As part of the study, the scientists said playing “tit for tat” – copying in each time period whatever the other individual did in the previous period – could explain synchronised co-operation but could not fully explain taking turns.
Prof Colman said: “There’s a lot of research into co-operation already. It’s a hot topic in evolutionary biology and social biology.
The paper by Prof Colman and Dr Browning’s research says that “many predatory animals hunt in pairs or larger groups, and this involves synchronised co-operation.
“Tit for tat has been shown to work very well in initiating and sustaining this type of co-operation.
“But where co-operation involves turn-taking, a ‘tit for tat’ instinct could sustain the pattern once it was established but could not initiate it in the first place.
“For example, in a mating pair of penguins who both went foraging or both incubated the eggs at the same time, tit for tat would not be enough to evolve the habit of taking turns.”
The psychologists used theory and computer simulations of evolution through thousands of generations to discover how genetic variations developed and could explain why animals would naturally start to take turns.
“Turn-taking is initiated only after a species has evolved at least two genetically different types that behave differently in initial, unco-ordinated interactions with others,” the paper says.
“Then as soon as a pair co-ordinates by chance, they instinctively begin to play tit for tat.
“This locks them into mutually beneficial co-ordinated turn-taking indefinitely. Without genetic diversity, turn-taking cannot evolve in this simple way.”
Prof Colman added: “In our simulations, the individuals were computer programmes that were not only dumb and robotic but also purely selfish. Nevertheless, they ended up taking turns in perfect co-ordination.
“Our findings confirm that co-operation does not always require benevolence or deliberate planning. This form of co-operation, at least, is guided by an ‘invisible hand’, as happens so often in Darwin’s theory of natural selection.” –(PA)