There has long been an adage that it isn't what you know that's important for getting ahead in the business world, it's who you know. Now it appears that what really counts is what you look like.

According to research by U.S. economists, the more time you spend combing your hair and polishing your shoes in the morning, the more money you are likely to earn once you finally make it into the office. And, perhaps surprisingly, the effect is more pronounced for men than it is for women.

That backs up a growing body of economic literature that tells us that the better looking you are, the more likely you are to do well in life.

"There is a general understanding that people are judged on their appearance," said Fiona Line, diversity adviser to the U.K.'s Chartered Institute of Personnel and Development. "What is important is that companies should be recruiting based on talent, not on what people look like, however strong an instinct that might be."

Leaving aside the rather obvious counterexample of Bill Gates, who didn't exactly forsake a career in Hollywood to get into the computer industry, there is no disputing the basic data.

Jayoti Das and Stephen DeLoach of the Martha and Spencer Love School of Business at Elon University in North Carolina took the 2005 American Time Use Survey, which studied how 13,000 individuals filled up their day. They then compared that with earnings data.

"For men, every extra 10 minutes daily grooming increases their weekly wages by 6 percent. However, women would have to nearly quadruple their daily grooming time to receive that much in additional wages," the pair reported.

In countries from the United States to the United Kingdom, Australia and China, research has shown that those of us who might be mistaken for the back end of a bus are likely to earn much less than people who regularly find themselves mistaken for George Clooney.

Of course, nobody wants staff turning up in the office if they look like they spent the night sleeping on the streets. And putting some effort into your appearance might well be taken as a sign of commitment to your work and organization.

Unfortunately, within most large corporations, showmanship, it seems, is now rated more highly than ability or intrinsic worth. Presumably, businesses are assessing staff according to their looks because appearance rather than substance is what they are mostly about. If you want a pay increase, invest in a better haircut. That's how things work in a business culture dominated by vanity and pretense.

Of course, that's how we ended up with companies such as Enron Corp. — it looked great, but there was nothing inside.