The study, by researchers at University College London, University of Warwick and the London School of Economics and Political Science, shows that extended courtship enables a male to signal his suitability to a female and enables the female to screen out the male if he is unsuitable as a mate.

Professor Robert Seymour, UCL Mathematics, said: “Courtship in a number of animal species occurs over an extended period of time. Human courtship, for example, can involve a sequence of dinners, theatre trips and other outings lasting months or even years.”

The research, published this month in the Journal of Theoretical Biology, uses game theory to analyse how males and females behave strategically towards each other in the mating game. The mathematical model considers a male and a female in a courtship encounter of unspecified duration, with the game ending when one or other party quits or the female accepts the male as a mate. The model assumes that the male is either a ‘‘good’’ or a ‘‘bad’’ type from the female’s point of view, according to his condition or willingness to care for the young after mating. The female gets a positive payoff from mating if the male is a ‘‘good’’ male but a negative payoff if he is ‘‘bad’’, so it is in her interest to gain information about the male’s type with the aim of avoiding mating with a “bad” male.

“With both sexes there is a significant cost of time which could be spent on other productive activities,” said Seymour. “Why don't people and other animals speed things up to reduce these costs? The answer seems to be that longer courtship is a way for the female to acquire information about the male.”

The team think that by delaying mating, the female is able to reduce the chance that she will mate with a bad male. A male's willingness to court for a long time is a signal that he is likely to be a good male. Long courtship is a price paid for increasing the chance that mating, if it occurs, will be a harmonious match which benefits both sexes.