We all know that women like pink and men prefer blue, but we have never really known why.

Now it emerges that parents who dress their boys in blue and girls in pink may not just be following tradition but some deep-seated evolutionary instinct.

Researchers have found that there could be sound historical reasons why women have developed a heightened appreciation of reds and pinks, while men are drawn to blue.

“The explanation might date back to humans’ hunter-gatherer days, when women were the primary gatherers and would have benefited from an ability to home in on ripe, red fruits,” Anya Hurlbert, who led the team of researchers, said. “Culture may exploit and compound this natural female preference.”

While blue was liked universally, this preference stood out among men as it was not balanced by a parallel liking for pink, the study found. This, too, could have deep-seated natural roots: water that appears blue is more likely to be clean, and the colour is also an indicator of fine weather.

The scientists from the University of Newcastle upon Tyne, who were led by Dr Hurlbert and Yazhu Ling, averaged people’s overall preferences. The male favourite was a pale blue while the female favourite was a lilac shade of pink.

The participants in the study were Chinese and British. The Chinese students showed a marked preference for red. As red symbolises luck and happiness in China, this indicates that cultural norms are also involved.

“I can only speculate but I would favour evolutionary arguments again here,” Dr Hurlbert said. “Going back to our savannah days, we would have a natural preference for a clear blue sky because it signalled good weather. Clear blue also signals a good water source.”

In the study, which is published in the journal Current Biology, the scientists showed pairs of colours to 208 volunteers aged between 20 and 26, who had to select which they preferred by clicking with a computer mouse.

While most of the participants were British white Caucasians, a sub-group of 37 were Chinese. Both groups showed similar sex-related preferences, with women liking blues and pinks while men liked mainly blues.

“Although we expected to find sex differences, we were surprised at how robust they were, given the simplicity of our test,” Dr Hurlbert said.

There is already evidence that human’s ability to see in colour is likely to have evolved because of the usefulness of being able to distinguish red fruits from green backgrounds.

The female role as gatherers while males hunted could have favoured a particular preference for reds and pinks, the scientists said.

Pinks are also involved in showing changes in emotional states, and might be picked up preferentially by women. “Again, females may have honed these adaptations for their roles as care-givers and ‘empathisers’,” the researchers said.

Dr Ling said the team was now seeking to investigate further the extent to which these preferences are innate, by studying infants and different age groups. Her own favourite colour? “A very paleish pink,” she said.

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