From:
http://news.bbc.co.uk/2/hi/health/4152298.stmAsymmetrical men 'are a turn-off'Women look for symmetry in a man when it comes to reproduction
Women whose partners have asymmetrical bodies are turned off by them and attracted to other men at certain times of the month, a US study suggests.
This is not down to conscious choice, but is related to survival of the fittest and a desire to pass healthy genes to offspring, say the authors.
When a woman is fertile near ovulation her partner preference shifts, the New Mexico University team found.
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Attraction also peaked around ovulation time.
But at this time many of the women whose partners were asymmetrical tended to fantasise and become attracted to men other than their partner. Women with symmetrical partners generally did not.
Dr Nick Neave, a psychologist at Northumbria University, said the findings made sense and backed what was already known about human attraction.
"Females, like males, are always looking to enhance their reproductive success by trading upwards.
"They are always on the lookout for males with better genes or that have high social status/wealth as both enhance their reproductive success - offspring have better genes or access to better resources, both of which enhance their future reproductive success.
"Males simply go for women younger than their current partner as they are thus also able to enhance their reproductive success by producing healthier offspring."