"The generally accepted rule is pink for the boy and blue for the girl."

"The reason is that pink being a more decided and stronger colour is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl." So said the Ladies' Home Journal back in 1918, which makes Ben Goldacre wonder what the evolutionary biologists think they are doing when they figure out the genetic basis for the female preference for pink.

Here's the story he's reacting to.

"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."...

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.

The great thing about this kind of speculation is that if the results were different, you'd be able to make up reasons why men and women evolved to prefer whatever they ended up preferring. As Goldacre writes, it's like "just so" stories.

For example, assume the study showed that men prefer stripes and women prefer polka dots or men prefer pastels and women prefer dark colors. Your assignment is to explain why evolution would produce that result. You know you can come up with something!