Women see masculine-looking men as more unsuitable long-term partners but men with more feminine features are seen as more committed and less likely to stray, researchers said Wednesday.
Scientists at the universities of Durham and St Andrews came to the conclusion by asking more than 400 British men and women to make judgments on character after looking at digitally-altered pictures of men's faces.
The web-based test asked participants to rate the face for traits such as dominance, ambition, wealth, faithfulness, commitment, parenting skills, and warmth.
Men with square jaws, larger noses and smaller eyes were classed as significantly more dominant, less faithful, worse parents and as having less warm personalities.
Those with finer facial features, fuller lips, wide eyes and more curved eyebrows on the other hand were viewed as a better bet for long-term relationships.
Older faces were generally viewed more positively compared to younger ones.
The scientists said there was a "high amount of agreement" between women about what they see in terms of personality when seeing a man's face and they may well use their impression to decide whether or not to engage with him.
"That decision-making process all depends on what a woman is looking for in a relationship at that time of her life," said Lynda Boothroyd, from Durham University's Department of Psychology.
Her colleague, David Perrett from St Andrews, said: "Our results contradict claims that machismo denotes fitness and disease immunity. Masculinity may buy you dominance but not necessarily tip top physical condition.
"Instead women see a healthy guy as the source of wealth, and fit for family life."
The research is published in the latest edition of the journal "Personality and Individual Differences".