Sexual chemistry

Making the right choice when finding true love is an important business, so how do we go about selecting a mate?

Many factors add up to make us desirable to potential partners. There's the obvious stuff like symmetrical features and good skin - which showcase a healthy development, immune system and good genes. Women look for tall men with masculine faces, kindness, wealth and status. Men prefer young, fertile women with a low waist-to-hip ratio and who are not too tall. Neither sex is very keen on people who wear glasses.

Beauty can come at a price however.

Other factors are less obvious. Research suggests that humans are attracted to partners who resemble themselves and - slightly disconcertingly - their parents too. Smell appears to be important as well; people are often more attracted to the smell of those who have different combinations of some immune system (MHC) genes to themselves. Mates with dissimilar MHC genes produce healthier offspring that are better able to thwart disease. People with similar MHC genes even prefer the same perfumes.

Suitors of some species such as birds, and even mice, attract their mates with complex songs or showy displays. Intelligence and talent are prized by people too. As are expensive gifts and even cheap love tokens. Even being in a relationship can make you more attractive to potential mates.

Other factors are more random - a woman's attractiveness and pheromones can fluctuate with her hormone levels and menstrual cycle. As a consequence, taking the pill can inhibit a woman's ability to select an appropriate mate.

In concert, these many factors mean the path to true love can be somewhat unpredictable.

Many people with hectic lifestyles today are turning to the internet, online lonely hearts, dating websites and speed dating to help them track down a partner. Love by wire may have started much longer ago however. See here for six tips to woo your lover.