The main characteristics of romantic love are craving: an intense craving to be with a particular person, not just sexually, but emotionally.

Most of us make up our minds in the first three minutes of meeting someone whether there's a potential for a relationship.

When you massage someone, the levels of oxytocin go up in the brain, and oxytocin is one of the chemicals that drives attachment.

Hair that looks like it's been naturally sun-bleached makes you seem youthful, like you spend a lot of time outdoors. And that appeals to most people.

The human brain is built to compare; it's Darwinian to consider an alternative when one presents itself.

The Great Depression of the 1930s saw more American unmarried women working from nine to five, mostly in repetitive, boring, subordinate, dead-end jobs. But the number of working women doubled between 1870 and 1940. During World War II it doubled once again.

Of all the foods we share, there is nothing more primordial than meat. It's no surprise that meat-eaters still want a partner who will give, receive and share this primordial symbol of a budding partnership.