A recent report in Personality and Individual Differences is super exciting. This work is an intersection between evolutionary psychology & molecular genetics. Specifically, Lewis et al. (in press) examined how sexual jealousy is related to androgen receptor (AR) gene.
Women increase their reproductive success by pursuing short-term and long-term mating strategies. Why? Physically attractive men are considered “sexy,” and women who mate with sexy men produce sexy offspring. Due to underlying superior genetic quality, attractive men are favored by women in general. Previous studies have shown that sexy men are highly androgenized.
Here is where AR gene came in. AR gene is polymorphic, with varying number of CAG codon repeats across individuals. Some individuals have more repeats than others. Studies have shown that those with more repeats have lower transcription factors and AR proteins, leading to lower physiological response to androgen (more CAG repeats, lower androgen, less sexy?)
Reasoning & Hypotheses behind
So sexy men (higher androgens), recognized by short sequences in CAG repeats of AR gene, can get women easily because women prefer these sexy men, especially for short-term mating. Women might engage in short-term sex for higher “genetic quality” of offspring while being engaged in long-term relationships with someone, possibly less sexy. That way our ancestral women and modern-day women would get “good” genes and committed resources/ paternal investment from someone else. Good for them.
This is when less sexy men came in. Less sexy men, who would be less androgenized, could not easily purse short-term mating with women. Therefore, these guys might be more watchful toward their partners’ behaviors.
In this study by (Lewis et al., 2016), less sexy men, recognized with longer CAG repeats on AR gene, would be more cognitively and emotionally jealous of their partners’ behaviors with other guys (Even when these guys might be just friends, for sure!). Those guys with shorter CAG repeats would be less sexually jealous of their partners because they themselves are more oriented toward pursuing short-term mating (They are popular!) .
Indeed, the hypotheses were supported. Cognitive and emotional jealousy scores on their female partners were correlated with longer CAG repeats of AR gene in men.
Those with longer sequences of CAG codon repeats are more likely to be sexually jealous when they read about ambiguous social and environmental cues (for e.g., she is unusually critical of her partner, she starts asking her partner if he still feels the same love for her). These guys with longer sequences of repeats were also more likely to be emotionally upset when they responded to these unclear cues toward their partners.
Of course, these findings do not necessarily mean you will be always be more jealous if you have longer repeats of CAG on AR gene. You might be able to modify your jealousy degree. I know, it is difficult!
Read the full report here:
Lewis, D.M.G., Al-Shawaf, L., Janiak, M., & Akunebu, S. (in press). Integrating molecular genetics and evolutionary psychology: Sexual jealousy and the androgen receptor (AR) gene. Personality and Individual Differences.