You’ll never look at a handshake the same way again.
How firmly people hold their hands offers a fascinating insight into their sex lives, according to a new study.
The researchers looked at the upper body strength, primarily grip strength, and sexual behaviors of 4,000 men and women.
They found that stronger men were more likely to have long-term relationships, while stronger women were more likely to have a greater number of sexual partners.
For men, scientists at Washington State University believe this shows that greater upper body strength is a “favorable natural selection trait,” making them a more attractive partner.
They say more research is needed to understand the connection in women.
Commenting on this finding, lead author and anthropologist Caroline Smith said: “People have assumptions about men’s sexual behavior and how it relates to evolution.”
“In addition to acquiring more sexual partners, establishing long-term relationships was probably also important for men in evolutionary history.”
A major new study on the sexuality of more than 4,000 people has revealed that a firm handshake indicates a higher body count in both men and women.
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Similarly, a previous study found that women who exercised more had a greater number of sexual partners.
Researcher Dr Lee Smith, from Anglia Ruskin University in Cambridge, said at the time that exercising regularly reduces depression and boosts confidence.
He explained: “We know that participation in physical activity increases self-esteem, and it is possible that self-esteem is related to greater confidence when engaging in sexual activities with new partners.”
In the recent study, Ms. Smith and her consulting professor, WSU evolutionary anthropologist Ed Hagen, analyzed data from 4,316 American adults obtained from the 2013-2014 National Health and Nutrition Examination Survey.
They primarily looked at grip strength, which is a common measure used to approximate upper body strength.
This was then compared to participants’ survey responses about their sexual behavior.
Scientists say the findings support an evolutionary theory of mating based on “provisioning.”
Since human babies require a lot of care and resources, especially from women during pregnancy and lactation, men were most desirable as companions when they could provide meat through hunting, which for hundreds of thousands of years before the modern era required upper body strength.
Stronger human males, who also stayed and helped provide more food resources to those children as they grew, would also better ensure their survival.
While there are theories about men’s strength in relation to reproductive success, there are not as many about women’s strength, in part because women are not typically included in these types of studies.
There was no obvious explanation in this study’s data for why women with greater upper body strength also had a greater number of lifetime partners.
The researchers controlled for many variables, including general health and testosterone levels, but the connection still held.
They cited some potential theories, including that it’s due to “selective mating,” meaning that physically stronger people tend to associate with each other more frequently.
It could also be that women who are physically stronger “need less male investment or feel they can take more risks.”
Ultimately, they say more studies with women would be needed to uncover more evidence of the reasons behind this connection, as well as “a better understanding of human evolution in general.”
“I think it is important to continually test our theories, especially by expanding our research questions to include women,” Ms. Smith concluded.