Men and women are either more inclined towards promiscuity or fidelity - with your index finger suggesting which category you fall into, researchers say.
While other species are generally either promiscuous or faithful to one partner, humans use both mating strategies.
Previous studies have claimed that humans are in between being a faithful and promiscuous species. But a new collaborative study between Oxford University's Department of Experimental Psychology and Northumbria University found that humans are either more interested in short love affairs or long-term relationships, The Telegraph reported.
To make their findings, researchers analysed a survey of North American and British people, who were asked how they felt about “non-committal” sex.
The researchers discovered that some respondents were more likely to be promiscuous, while others valued fidelity.
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In addition, researchers analysed the photocopies of the right hand from 1,314 British men and women and measured the length of the index finger and the ring finger.
They found that the shorter the index finger in relation to the ring finger, the higher the levels of testosterone that person is likely to have been exposed to in the womb – making them more promiscuous.
One group had a ring finger which was much longer than the index finger, suggesting that they may be more promiscuous, while the other group had fingers which similar in length - meaning they were likely to favour long-term relationships. This pattern of promiscuity was found in both men and women.
Professor Robin Dunbar of Oxford University said that the differences are “subtle” and “only visible when we look at large groups of people”.
He told The Telegraph:"Human behaviour is influenced by many factors, such as the environment and life experience, and what happens in the womb might only have a modest effect on something as complex as sexual relationships."