A new book by an economics professor at the University of Texas-Austin reveals what the world of advertising has known for decades - that beauty sells.

But Daniel S Hamermesh also shows that being attractive pays - with good looking employees enjoying more perks and higher pay packets than their plainer colleagues.

Professor Hamermesh has studied what he refers to as the economics of beauty for about 20 years.

In his book Beauty Pays, published by Princeton University Press, he claims good looking people enjoyed perks beyond their pay - such as party invites, business travel and office privileges - while less attractive workers are overlooked and can often be victims of discrimination.

Attractive people are more likely to be happier, earn more money, get a bank loan (with a lower interest rate) and marry equally good looking partners.

As a result, attractive employees are more productive, leading to higher sales and potentially higher profit for themselves or the company they work for.

Less cut and dried is what constitutes attractiveness. Far from being merely in the eye of the beholder, Professor Hamermesh points to a few subconscious factors - such as the symmetry of the face, facial expression and popularity factors (if the person looks like someone popular or famous).

In his book, Professor Hamermesh estimated that attractive people earned on average about £145,000 more in a lifetime than those with below-average looks.

A beautiful woman would earn four percent more, and handsome men three percent more, than their plain counterparts.

When the professor's research became widely known in the early 1990s, he came in for some criticism - namely from comedian Jay Leno, who asked why someone like Dallas businessman and presidential candidate Ross Perot earned more than someone like actor Rob Lowe?

But Professor Hamermesh brushed this off, being quoted in the Sydney Morning Herald as saying: 'We don't talk about individuals; we talk about the average good-looking person and the average bad-looking person. There are always outliers.'

Of course education and work experience were important factors in earnings, but Professor Hamermesh said his new book, based on his research, showed that a person's looks were impossible to ignore.