Are you faithful or promiscuous? Measure your index finger to find out

A new study of sexual attitudes reveals men and women are both just as likely to want a fling as they are a long-term partner.

They say that men are from Mars and women are from Venus.

But when it comes to our attitude towards promiscuity, it turns out there is no such gender divide.

Both men and women fall into two groups, one more inclined to be promiscuous and the other more inclined to be faithful.

Whereas other species are either one or the other, both mating strategies appear to be used by humans.

The results, published in the journal Biology Letters, are from a joint study carried out by Professor Robin Dunbar of Oxford University’s Department of Experimental Psychology and Professor John Manning of Northumbria University.

Previous physical comparisons between humans and other mammals suggest that humans are midway between being a faithful species and a promiscuous species.

What our fingers say

However, the new study, titled “Stay or Stray? Evidence for Alternative Mating Strategy Phenotypes in Both Men and Women” suggests that in fact there are two distinct sub-populations of humans: one that is more interested in short-term flings and another that prefers to form long-term commitments.

The researchers analysed the answers of 575 North American and British people about their attitudes and desires towards “noncommittal” sex.

Some of the respondents were more likely to be promiscuous, and others more likely to value sexual fidelity. However, the divide was not along gender lines.

The study also looked at photocopies of the right hand from 1,314 British men and women and measured the length of the index (second) finger and the ring (fourth) finger.

The shorter the index finger in relation to the ring finger (the 2D:4D ratio), the higher the levels of testosterone that person is likely to have been exposed to while developing in the womb, and the greater their sexual promiscuity will be as an adult. This is true for both men and women.

One group had a ring finger which was much longer than the index finger, suggesting that they may be more promiscuous.

The other group had fingers which similar in length, meaning they are more likely to seek longterm relationships. Again, the split was not along gender lines.

“This research suggests that there may be two distinct types of individuals within each sex pursuing different mating strategies,” Dr Wlodarski said.

“We observed what appears to be a cluster of males and a cluster of females who are more inclined to ‘stay’, with a separate cluster of males and females being more inclined to ‘stray’, when it comes to sexual relationships.”

Professor Dunbar added that the differences are “subtle” and “only visible when we look at large groups of people”.

He said: “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.”