The real reason that so many women have to spend so much time getting ready, by Ana Swanson.

In a highly unscientific poll, 27 of my female colleagues at The Washington Post reported putting an average of five products on their face that morning, and keeping two additional pairs of shoes at their desk. The two male colleagues I asked averaged half a product and one extra shoe each.

You might dismiss all this female primping and preening as vanity or silliness. Yet a fascinating new paper from two sociologists suggests that women do have good reason to spend so much time and money on their appearance: If they don’t, they risk losing a substantial amount of money.

Better grooming for women leads to more money, statistically speaking.

[A] long-running national study of more than 14,000 people to look at the association between attractiveness and income … asked people a variety of questions about their income, job, education, personality and other attributes. Interviewers also rated their interviewees on how attractive and how well-groomed they appeared.

Like past studies, the research showed that attractive people tended to earn higher salaries. But that wasn’t all. Their research suggested that grooming – practices such as applying makeup and styling hair and clothing — was actually what accounted for nearly all of the salary differences for women of varying attractiveness. For men, grooming didn’t make as much of a difference.

Physical attractiveness is correlated with many other advantages:

Numerous studies in the past have shown that people who are considered physically attractive have many advantages in life. In school, attractive people tend to be more popular and receive higher grades. In courtrooms, they receive shorter prison sentences. Research shows attractive people are more likely to be hired and promoted in the workplace, and end up with higher earnings.

Researchers have various explanations for this. Some say it’s discrimination against people who are seen as unattractive. Some think there is a subconscious bias, a “halo effect,” in which we assume that, because people are beautiful, they have other positive personality traits, too. Studies indicate that attractive people are often perceived as more intelligent, more trustworthy and more cooperative.

Wong and Penner’s research supports some of these ideas. They find that, controlling for other differences such as age, race, class and education, individuals who were rated as more attractive by an interviewer earned about 20 percent more than people who were rated as having just average attractiveness.

Wong and Penner don’t find any significant gender differences in the financial returns people receive for being considered attractive. They find that women earn less than men, and that unattractive people earn less than attractive people, but that attractiveness is not more or less important for women than for men.

Grooming, not so much innate attractiveness, correlates with bigger pay packets:

However, the researchers did find a big difference between men’s and women’s salaries when it came to grooming. Controlling for factors such as age, race, education and personality traits like agreeableness and conscientiousness, they compared how interviewers rated people on attractiveness, how they rated the same person on grooming, and that person’s salary.

They found that a substantial amount of attractiveness was the result of grooming, and here’s where they found gender differences, Wong says. “For women, most of the attractiveness advantage comes from being well groomed. For men, only about half of the effect of attractiveness is due to grooming.”