Tag Archives: relationships

How Can Evolutionary Psychology Help Explain Intimate Partner Violence?


Jaimie has been out of town for nearly a week at her annual industry conference. Despite having been together for over a year, her boyfriend, Johnathan, still feels anxious when she is away on business trips. His anxiety has deepened because Jaimie has been “too busy to talk on the phone.” When Jaimie does finally return home, Johnathan ignites an argument, accusing her of spending time with her male co-workers. The argument escalates to shouting, with Johnathan accusing her of cheating on him while away. As Jaimie continues to plead her innocence and faithfulness to Johnathan, he pins her against the wall, with his hand around her neck, as he threatens to strike her if she refuses to admit her infidelity.

At some point in their lifetime, 10 to 35 percent of people experience intimate partner violence. (The numbers vary depending on the sample studied and precise definition of “intimate partner violence.”)

Why is violence among partners so common? Social scientists have proposed several theories, which primarily fall under two umbrellas: sociological explanations, and biological and psychological explanations. (Because the existing literature primarily focuses on violence in heterosexual relationships, my discussion is limited to violence between a man and a woman.)

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This post originally appeared at Behavioral Scientist on 21 September 2017.

Why Men Have More Sex Partners Than Women


I got to my office the other morning with the goal of organizing my last data set needed for my PhD dissertation. The study is a small survey data set of 52 heterosexual couples, mostly adults in their 20s, who reported on a variety of self-report sexuality and relationship measures — pretty standard psychological research.

My topical expertise in psychology centers primarily around human sexuality. After years of studying in this area, there are two observations about human sexuality that I have more or less taken for granted at this point:

(1) Men have more sex partners than women, on average. This means that if you approach a random man on the street and ask him how many people he’s had sex with, his answer is likely to be larger than a random woman’s answer to the same question. (I don’t recommend using this approach strategy, however.)

(2) The variance, or range, of the number of sex partners within the sexes is different, with men as a group having a greater range as compared to women as a group. This means that it is likely that the most sexually successful man you know has a much larger number of sex partners than the most sexually successful woman who you know.

After my data were organized, I ran a simple analysis comparing the mean average number of lifetime sex partners between men and women to see if these basic observations held. It was unsurprising to see that my data conformed to both points: In my sample, men had a higher mean and a larger variance compared to women in their response to the question, “How many partners have you had sexual intercourse with in your lifetime?”

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This post was originally published on my Medium account on 16 July 2019.