Male and female friendships are maintained by different psychological dynamics. More women reported having a best friend than did men. Men were also more likely to have a romantic partner but no best friend compared to women

While both men and women cultivate close relationships, the dynamics of these relationships appear to be quite different. A study published in Adaptive Human Behavior and Physiology sheds light on the differences between men’s and women’s romantic relationships and best friendships.

Forming close bonds with others is an integral part of being human. From an evolutionary standpoint, people need secure and supportive relationships to survive and to reproduce. Be it a romantic relationship or a close friendship, there are certain attributes that characterize intimate relationships.

“Over a number of years studying friendships, we had become increasingly aware of very consistent sex differences in both social skills and sociality,” explained study author Robin I. M. Dunbar, a professor of evolutionary psychology at the University of Oxford.

“These human patterns paralleled sex differences that are widely present in Old World monkeys and apes (the group to which humans belong). People do not often study sex differences in social style (bizarrely, some disciplines even forbid the study of sex differences in anything), and it seemed to us there might be something important that we were missing.”

The researchers noted that one common feature of close relationships is similarity — people tend to create relationships with those who are like them.  Evidence also suggests that similarity matters more for certain traits than others, but it is unknown how these traits might differ across male and female relationships. Dunbar and his colleagues set out to pinpoint the traits that support intimacy within relationships and to unearth any sex differences that might be at play.

The researchers recruited 260 participants between the ages of 18 and 80 to complete an online questionnaire that asked them about their close relationships. The participants completed scales to assess the level of intimacy within their romantic partnerships and best friend relationships. They also scored themselves, their partners, and their best friends according to 13 attributes (e.g., intelligence, kindness, athleticism).

In line with previous research, both romantic relationships and best friendships were more similar trait-wise than they would have been if the data had been randomly distributed — supporting the idea that people form relationships with those who they perceive to be similar to them.

Next, the researchers examined how the similarity of each trait contributed to the level of intimacy in a given relationship. Interestingly, sex differences emerged.

For romantic relationships, women appeared to look for similarity in partners to a greater extent than did men. Women rated the intimacy of their romantic relationships higher when they and their partners were more similar in terms of finances, dependability, outgoingness, and kindness. For men, the intimacy of their romantic relationships was not significantly linked to partner similarity on any of the traits.

“Despite all the similarities, the two sexes do live in rather different social worlds,” Dunbar told PsyPost. “They have different interests, different foci and different social styles. One is not better than the other — they are just different ways of achieving the same long-term goal. But it does mean that both sexes need to be aware of that and make the appropriate allowances.”

The dynamics of male and female friendships were quite different. Women’s friendships were most intimate when they and their best friends were most similar in terms of things that seemed to affect the quality of the relationship itself, such as education, humor, and happiness. Men’s friendships were most intimate when they and their best friends were most similar in ways that affect involvement in social activities, such as finances, outgoingness, and social connection.

Dunbar and his colleagues noted that these differences could reflect the fact that women prefer to socialize one-on-one while men prefer to socialize in groups. Notably, same-sex best friendships were much more common (78% among male respondents and 85% among female respondents) than opposite-sex best friendships.

The findings add to the existing evidence that men and women have a fairly different outlook on friendship. While both male and female respondents were equally likely to have a romantic partner, more women (98%) reported having a best friend than did men (85%). Men were also more likely to have a romantic partner but no best friend compared to women.

The researchers say these findings support previous evidence that men have social circles that tend to include a collection of casual friendships, whereas women tend to have smaller social circles that include one or two more intimate relationships.

“These differences appear very early in life (long before serious influences of socialization have a lasting effect) and they are also present in monkeys and apes. That said, the differences are not absolutes: as with all traits, physical and psychological, they lie on a continuum, and the two sexes overlap,” Dunbar said.

“A better understanding of individual differences would be highly desirable if we want to understand their origins. While it is always the case that behavior can be tweaked in one direction or another during socialization, what we don’t really know is which components can be adjusted in this way and which not, or by how much. The one thing we should never do is presume on ideological grounds that we know.”

“Our job as scientists is to understand and explain the world. We cannot do that if we assume that we know the answer before we even start,” Dunbar added.

The study, “Sex Differences in Intimacy Levels in Best Friendships and Romantic Partnerships”, was authored by Eiluned Pearce, Anna Machin, and Robin I. M. Dunbar.