Study Challenges Evolutionary Theories on Strength and Sexual Partners
A recent study conducted by Washington State University challenges long-held evolutionary theories by revealing that both men and women with greater upper body strength report more lifetime sexual partners.
Cross-Gender Pattern Defies Traditional Assumptions
The groundbreaking study, published in Evolution and Human Behavior, analyzed data from 4,316 U.S. adults collected between 2013 and 2014 through the National Health and Nutrition Examination Survey. The researchers found that stronger individuals, regardless of gender, tend to have more sexual partners in their lifetime, a finding that contradicts the sexual selection hypothesis.
The Sexual Selection Hypothesis and Its Limitations
The sexual selection hypothesis posits that males competed physically for mating opportunities in early human history, leading to increased physical strength as a reproductive advantage. However, this theory does not account for the number of partners women have, predicting little to no relationship between women’s strength and mating success.
Provisioning Theory and Its Relevance
In contrast, the provisioning theory suggests that stronger men could provide greater support and resources to their families, especially through hunting. This could have led to greater preference for stronger male partners, supporting long-term relationships and family stability.
The study found that men with greater upper body strength were indeed more likely to be in long-term relationships, aligning with the provisioning theory.
Unexpected Finding: Women’s Strength and Sexual Partners
One of the most surprising findings was the positive correlation between women’s upper body strength and their lifetime number of sexual partners. This finding challenges conventional thinking that women’s strength would not significantly impact their mating success.
Exploring Assortative Mating
The researchers considered the possibility of assortative mating, where individuals tend to pair with partners of similar physical attributes. Another hypothesis is that physically stronger women may require less male investment or feel more confident in taking risks.
Calls for Further Research
The study highlights the need for more comprehensive research on women’s physical strength and its evolutionary implications for mating success. Lead researcher Smith called for a broader inclusion of women in such studies, emphasizing the importance of ongoing investigations in evolutionary neuroscience.
Abstract Insights
The study’s abstract further delves into the trade-offs between muscle mass and mating success, immune function, and dietary intake. It found a positive relationship between grip strength and energy intake but no significant impact on immune function.
“Our results suggest that sexually dimorphic upper-body strength might have evolved, in part, by increasing male long-term mating success,” the researchers concluded.
Original Research
Original Research: Closed access.
“Strength, mating success, and immune and nutritional costs in a population sample of US women and men: A registered report” by Ed Hagen et al. Evolution and Human Behavior
Conclusion
The study challenges traditional evolutionary theories by revealing that both men and women with greater upper body strength report more lifetime sexual partners. These findings suggest a more complex relationship between physical strength, provisioning, and mating success, calling for further research and broader inclusivity in evolutionary studies.
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