Members of the opposite sex can spot whether someone is after a one-night stand or something more permanent just by looking at their face, scientists said yesterday.
On men, a square jaw, large nose and small eyes are more likely to betray the look of lust than of love.
Women found men with softer features more likely to opt for commitment.
But the Durham University-led research found that while men can judge whether a woman is footloose-and-fancy-free or not, there is no common facial detail to explain it.
About 700 heterosexual people took part in the survey carried out by Durham, St. Andrews and Aberdeen universities.
In one study, 72 per cent of the 153 participants correctly identified the sexual attitudes of a group of men and women in their 20s after being shown photographs or facial images.
Published in the journal Evolution and Human Behaviour, the research also showed that women who were open to short-term sexual relationships were usually seen as more attractive.
They tended to have wide eyes and large lips, such as the actress Angelina Jolie.
Women were usually interested in men who appeared to be more likely to want a long-term relationship.
The research tended to confirm earlier findings which found that women see masculine men as more likely to be unfaithful and worse at parenting.
The men and women also tended to opt for complete opposites.
Dr Lynda Boothroyd, from Durham University’s Psychology Department, said: “This shows that these initial impressions may be part of how we assess potential mates — or potential rivals — when we first meet them.
“These will then give way over time to more in-depth knowledge of that person as you get to know them better, and may change with age.”