Forget chat up lines, speed dating is nothing more than a beauty contest - and is all about looks and not personality, claim scientists.

Researchers have found that the bigger the group of potential mates to choose from the more likely individuals are to make a decision based on looks and sex appeal alone.

This is because their mind blanks at the choice and they revert to basic instincts, scientists believe.

In primates and birds, the larger the group, the better the chance that non-dominant individuals have of being chosen as a mate.

Alison Lenton at the University of Edinburgh, and her team looked at whether this is true for people too.

Speed-daters race through a series of "mini dates" of about five minutes then invite whoever catches their fancy to get in touch again later.

The team studied 118 sessions with groups of between seven and 36 people, and found to their surprise that as the size of the group grew, the offers became skewed towards just a few individuals, while the least popular ended up with fewer or no offers.

Researchers found that in smaller groups, people trade off different qualities in prospective mates – physical attractiveness for intelligence.

But faced with too much choice, however, they resort to crude approaches such as choosing solely on looks.

When we have to make a quick decision like this, we don't have much else to go on – and that's because of our largely monogamous nature, said the team.

Monogamous species have fewer secondary sexual characteristics such as peacocks' colourful tail feathers.

Does it matter? Not if what you're looking for is a quick fling, Miss Lenton told New Scientist.

Research suggests that we don't look too hard for signs that a short-term partner is our ideal mate.

(Agencies via China Daily November 17, 2008)