NATURALIST Charles Darwin's theory that music's primary function is sexual courtship may have been proved right, according to new research.

His argument has been supported by a study from the University of Sussex which shows during the most fertile phase of their menstrual cycle, women prefer sexual mates who can make more complex music.

The study, published today in The Proceedings Of The Royal Society B, could account for the early origins of music, and why creative individuals are considered so desirable for short-term sexual relationships.

Benjamin Charlton, the paper's author, said: "The findings of this study provide the first support for Darwin's original contention that music evolved via sexual selection."

Dr Charlton's study of nearly 1,500 women, with an average age of 27.9 years, who were not breastfeeding, pregnant or using hormonal contraception, involved two experiments.

The results showed women only preferred composers of more complex music as short-term sexual partners when the risk of conception was at its highest.

Control experiments on women's preferences for visual artists failed to show an effect of conception risk, Dr Charlton said.