In the process of sexual selection, how did the partner develop a preference for a certain feature?

Hair removal is cultural and the hairless female ideal dates back less than a century. Along with less concealing clothing, less corsetting and shorter hemlines came the shift from emphasizing fashion to emphasizing a physical, active figure. So far there is no selection of an inheritable trait for hairlessness, just for those women willing to spend time and money to achieve the look.

The hair removal ads began in Harpers Bazaar in 1915. HB was a popular woman's magazine targeting a more elite audience but it was not one of the most widely read of the women's magazines. Ladies Home Journal finally followed with hair removal ads in 1934 showing this culture had moved into the mainstream. Upperclass women had the time and money to pamper themselves with this version of femininity and Gillette had created the safety razor making it possible. The first woman's razor was marketed in 1915 to replace pumice stones and depilatory creams or waxes as the clean method of removing 'unsightly' body hair. This coincided with sleeveless gowns and the sheer materials in women's evening wear and accessories like flesh colored nylons for the new social dances like the tango and other popular dances.

Sexual selection of inheritable traits is just one type of natural selection. It works when mates are selected on the basis of some quality of shape or color by a genetically controlled fixed patterned behavior. It isn't that females "want" or are even aware of the selection bias. Sexual selection arises from a range of female behaviors regarding mate selection.

Females have a range of mating behaviors. Those females with the behavior trait to evaluate potential mates >before mating< had more surviving offspring. Those surviving offspring had both more of the males-with-the-variation and more judgmental females likely to choose that male trait.

Soon the females that did not recognize and mate with males-with-the-variation began to disappear from the population just as males lacking the trait also vanish from the population. This judging and increasing the trait spirals into pushing the variation to extremes and in establishing the female behavior of only selecting males based on that trait. There was no goal only successful behavior that happened to match an observable variation with real quality. The females with behaviors that selected for other male variables did not have more offspring so the behavior did not establish.

This female behavior/ male quality selection is seen in peacock tails, weaver bird nests and flamingo feather colors.

oftentimes it is random; it relatively is, a woman who prefers a male with a function it relatively is purely possible with staggering wellbeing will produce offspring that are extra probably to proceed to exist. for example, male peacocks with the main captivating tail, a bower chicken with the main intricate bower, a crimson-winged blackbird with the reddest shoulder patches, and so on.