Recent research challenges the notion that insecure attachment has some evolutionary adaptive benefits. It appears that secure attachment may have benefits for individuals, improving their chances of producing offspring, while anxious and avoidant attachment styles reduce the odds of producing offspring. The new findings appear in the journal Evolutionary Psychology.
Attachment styles, which refer to the way individuals form and maintain relationships throughout life, are regularly explained through an evolutionary lens. Yet, despite this widespread conceptualization of attachment styles from an evolutionary viewpoint, empirical investigations into their direct associations with fitness are sparse.
“Attachment, both the affective relation between a child and a caregiver and romantic attachment – between the mating partners, is one of those major topics in psychology. It is studied in developmental, social psychology, but also in the psychology of individual differences,” explained study author Janko Međedović, a senior research associate at the Institute of Criminological and Sociological Research in Belgrade.
“Due to a fact that the processes similar to attachment exist in many species, psychologists often posit that attachment is evolutionary adaptation with multiple functions – enabling caregiving to babies and children (thus facilitating survival) and later in life enabling successful mating (thus facilitating reproduction). Therefore, secure attachment, both to caregivers and in a romantic context is mostly considered to be adaptive.”
“However, there are individual differences in attachment – individuals who are not secure exhibit anxious or avoidant attachment behavior (some authors believe that there are other types of insecure attachment but we used this model in our current research),” Međedović told PsyPost. “Despite evident maladaptive behavioral consequences of insecure attachment, there are scholars that even they can produce some adaptive outcomes.”
“Interestingly, the research that directly test these opposing hypotheses are extremely rare. Hence, we conducted the study where we examined the associations between anxious and avoidant romantic attachment styles (opposite pole of these dimensions represent secure attachment) and various indicators of evolutionary fitness.”
The researcher surveyed a sample of 448 Serbian adults (average age 41.67) regarding romantic attachment, short- and long-term mating patterns, motivations favoring parenthood, perceived obstacles of becoming a parent, reproductive success (age of first birth, number of children, and grandchildren), and care for biological relatives. They found that anxious and avoidant attachment were negatively associated with many of these fitness-related outcomes.
“We obtained systemic negative associations between insecure attachment (especially avoidance) and fitness measures. Therefore, our data are congruent with the former hypothesis: secure attachment has adaptive function,” Međedović said.
“Our data is interesting because it shows the role of attachment in mating, family planning, observed family size, and parental care. Individuals who have secure bonding to their romantic mates have longer partner relationships, higher parenthood motivation, they tend to have more offspring and elevated parental care. Individuals who are clingy to their partners or frightened that their partner will leave them (anxious) together with the ones that are not emotionally committed to their partners with limited intimacy (avoidant) have the opposite pattern of outcomes.”
“Does this mean that evolution favors long-term mating, because it is related both to higher fertility and elevated parental care? Perhaps not in all ecological conditions, but this certainly seems like an interesting hypothesis,” Međedović told PsyPost.
The findings are in line with previous research, which has found that the duration of a person’s longest romantic relationship is positively related to parental investment and number of offspring. But as with any study, the new research includes some caveats.
“The study sample was not a representative one, therefore we cannot make conclusions about natural selection. Furthermore, the number of participants with grandchildren was rather low – this can as well be solved with larger and representative samples,” Međedović explained.
“If positive relations between secure attachment and reproductive success would be obtained on representative samples as well, that could mean that secure attachment is under positive directional selection and that it may continuously evolve. However, this rests upon future studies that will collect data on large and representative samples.”
“Ideally, the studies of this kind should be prospective in their nature: attachment should be assessed earlier in time, while the fitness outcomes should be measured later,” Međedović said. “This is the only way to make conclusions about causality and consequently – about natural selection. Finally, the examined links may be affected by culture, therefore, the data should be collected in various cultures including the non-WEIRD (Western, Educated, Industrialized, Rich, and Democratic) countries.”
The study, “Fitness Costs of Insecure Romantic Attachment: The Role of Reproductive Motivation and Long-Term Mating“, was authored by Janko Međedović, Ana Anđelković, and Jovana Lukić.