# Adaptive Functions of Long-Term and Short-Term Romantic Relationships



## David Baxter PhD (Nov 27, 2007)

‘Forever and a Day’ or ‘Just One Night’? 
By Liga Klavina
23-10-2007

*On Adaptive Functions of Long-Term and Short-Term Romantic Relationships*
A happy, fulfilling, faithful and ‘till death do us part’ type of relationship seems to be an ultimate aim for most people. If you consider the typical storyline of popular fairy tales, like, Snow White and Cinderella, they portray an attractive couple overcoming number of difficult circumstances to rejoice committed relationship and “live happily ever after” and ”till death do them part”. The main actors in these screenplays are young, attractive and healthy individuals at the peak of their reproductive age, and willing to commit to each other for the rest of their lives.

Having grown up with such screen plots, we often wonder why our own love-path resembles more an awkward stumbling through the confusing mating and dating labyrinths with dead-ends and wrong exits taken. The mismatch between fairy tale scenario and real life set-up can be especially painful for women, who are since early age exposed to the image of the extremely handsome prince on a white horse, who is wealthy, athletic, and sufficiently witty to challenge severe obstacles to win her heart, and, moreover, inhibiting all potential desires to hurry to other princesses whose hearts could be conquered. Many young boys grow up believing in finding a gorgeous young woman, who would turn a blind eye to other outstanding men, and give birth to his, and only his, sons and daughters. Keeping all the ‘prince-and-princess-forever-together’ stories in mind, any break-up can be heart-breaking as you realize that he or she was not 'The One' and that all this time and investment is down the drain.

The ironic part in this is that for many people investing in maintaining a life-long committed relationship may not even be the most beneficial strategy, at least not during their entire lifetime. Now consider this storyline, which is far from a fairy tale, but close to reality. A young guy, let's call him Damien, is following an intense Spanish language class. In the socializing event after the first class he gets to talk to a young student – Mary. Damian is not the most ambitious and wealthy young man neither is he looking for a long-term partner with whom to settle down, and he is probably too adventurous and irresponsible to be considered a good potential father. Yet, he is a very good-looking, tall, and athletic guy, with masculine facial features, smooth skin, shiny hair and broad shoulders. He just seems so healthy, vibrant, and full of energy, that it does not go unnoticed by women. Despite the fact that Mary’s family is encouraging her to look for a guy that would be at least serious “boyfriend-material”, and preferably, “husband-material”, she is very attracted to Damian. They engage in a passionate relationship during the few weeks that the course takes place, but once out of sight, they do not pursue seeing each other. This is in an example of short-term mating and the trade-offs people are willing to make.

*Are we evolved to be monogamous or polygamous?*
The evidence is controversial. Some reports indicate that most marriages in preindustrial cultures are socially monogamous; whereas others show evidence for polygamous mating systems (see Schmidt, 2005). The evidence that humans possess neurophysiological system of pair-bonding and attachment (Hazan & Zeifman, 1999) speaks for the argument of human monogamy. However, there is abundant evidence that men with high status have multiple partners and higher reproductive success in foraging societies and across cultures (Betzig, 1986). Just like other polygamous primates, human males compete for mates and can be physically aggressive; and females benefit from genetically fit short-term mates, as it increases the fitness of their offspring.

Evidence of short-term mating existence in humans is cross-cultural – infidelity, poaching, cuckoldry, sex-specific jealousy, premarital sex are prevalent (Buunk, Angleitner, Oubaid, & Buss, 1996). Besides, like other short-term oriented primates, humans have moderate sexual dimorphism and secondary sexual characteristics and engage in non-conceptive sex.
Evidence from different domains is pointing to the fact that humans have evolved different mating strategies, and are able to functionally adjust mating strategies depending on individual characteristics and environment. As summarized by Gangestad and Simpson (2000), humans have been facing trade-offs between effort investing in parenting and mating and have evolved pluralistic mating strategies (e.g. men with less genetic benefits to the offspring may invest more in parenting effort than mating effort).

*Why do we have adaptations for short-term and long-term mating strategies?*
The ovulation of women is hidden, which is a source of parental uncertainty for men resulting in risk of investing in another man’s offspring. Thus for men mate-guarding becomes important and thus they tend to be more concerned about sexual infidelity. Men, relative to women, find it harder to forgive and are more likely to terminate a current relationship after sexual infidelity than an emotional infidelity (Schakelford, Buss, Bennett, 2002).

On the other hand, parental invest of women in offspring is rather costly (due to a lengthy pregnancy, risks to health during delivery, lactation, and long period of offspring dependency), whereas men have a significantly lower investment in reproduction – ironically, the minimal investment is not even that costly: intercourse. Due to the high cost of a woman’s minimal investment in offspring, women are the choosier sex for whom resources provided by men are crucial. In environments where food resources are scarce and/or there is a high prevalence of predators, surviving of offspring would be endangered in case of an absence of the father's investment. Nowadays a woman is active in the job market, and is able to raise a child independently. However, research finds no correlation between amount of women’s economic participation and their preferences for qualities related to parental care (Gangestad, 1993). Although the availability of birth control significantly reduces the potential costs of short-term mating for women, costs remain higher than for men.

To conclude, short-term mating for women is rather costly as it is associated with risk of raising a child without investment of the father. Short-term mating for men is less risky, or even beneficial as it could provide an opportunity to have offspring at very low cost. Parental uncertainty in humans is a reason why men would be motivated to guard their mate from other men willing to mate with her. As human males invest highly in their offspring compared to most other species, they want to avoid mistakenly investing in another man’s offspring. Why are not all men engaging only in short-term mating and why are women engaging in short-term mating at all?

Due to the high cost of short-term mating, women are the choosier sex. They tend to make sure that the man is truly willing and has the resources to invest in a long-term relationship. On top of that, women ascertain the potential father to have good parenting skills and good genes to “contribute” to their future offspring. Hence, no matter to what degree men desire short-term mating, finding a partner is not always a possibility. Quite naturally, not every man can attract a high number of short-term mates. For them a beneficial strategy is to invest in one long-term partner and children. Men who are not as attractive as those who engage in short-term mating can trade it off with other qualities – high parental effort, investment and fidelity.

However, women do engage in short-term mating. Research shows that women prefer high social status in long-term mates; conversely, for short-term mates they (like men) prefer physical attractiveness (Li & Kenrick, 2006). Short-term mating for women can be considered as an opportunity to obtain good genes for offspring. Studies comparing behavior of women in fertile (ovulatory) phases to non-fertile phases of their cycle provide good evidence. Women prefer both the scent of symmetrical and masculine male faces more during fertile phases of their menstrual cycle than during their infertile phases (Thornhill & Gangestad, 1999). In another study, women’s preference for men who displayed social presence and direct competitiveness with other men increased on high-fertility days, but only in a short-term mating context (Gangestad, Garver-Apgar & Simpson, 2007). Women who assessed their partners as being relatively lower in sexual attractiveness in high fertility periods than in low fertility periods reported greater desires for extra-pair relationship (Haselton & Gangestad, 2006). Other studies show that self-grooming and ornamentation through choice of attractive outfit increase during the fertile phase of the menstrual cycle (Haselton, Mortezaie, & Pillsworth, 2007). To summarize, engaging in short-term mating with a man of high genetic quality can be beneficial for women. Periodical shifts in the hormonal levels during fertile phases can accordingly produce substantial changes in women’s self presentation, sexual behavior, and preferences in the opposite sex - increasing genetic benefits to an offspring in case of pregnancy.

On top of that, environmental changes have been found to contribute to shifts in trade-offs of mating behavior. If local environment demands parental care of both parents and resources are scarce, investment is preferred over good genes. In other words, women tend to choose a man who is able to provide for their offspring rather than choosing for short-term mating with a man who can provide good genetic fitness. If pathogens prevail in local environments, good genetic fitness can be prefered over investment (Low, 2000).

Human mating strategies are also sensitive to the ratio of men and women in the local environment. For instance, it has been shown that women become more sexually unrestricted as the sex ratio decreases, that is, when women outnumber men in the mating pool. One explanation is that in cultures where there are fewer men than women, men become a limited resource, and women engage in short-term mating more frequently in order to compete with other women. On the contrary, when sex ratios are high – men outnumber women - men have to meet women's desires for long-term relationships in order to be able to compete. In a cross-cultural study mating strategies were correlated with the national sex ratio (Schmitt, 2005). Results showed that women indeed become more unrestricted and willing to engage in short-term mating as sex ratio decreases.

To summarize, it seems that people are able to modify their mating strategies if conditions – either individual or environmental circumstances - have changed (for example, a childless woman who is approaching the end of her reproductive years might be more likely to engage in short-term mating than a woman who is in the beginning of her reproductive years).

*What are the implications of adaptations for different mating strategies for human psychological processing?*
A compelling example shows how far two seemingly unrelated domains mating strategies can reach. In mythology and literature the idea of Muses inspiring artists is long-existent (e.g., the 9 Muses in Greek mythology). Also, popular language discusses how inspiring falling in love can be, anecdotal evidence shows that women are attracted to artists (e.g., groupies of rock bands), while artists become more successful when women are present to be impressed (see for example periods from Pablo Picasso's work). In a set of experiments researchers investigate the effects of mating motivations on creativity (Griskevicius, Cialdini & Kenrick, 2006). Participants were shown pictures of attractive opposite sex members, and were consequently asked to pick one and imagine a date with him or her. They then completed a task to assess creativity. Results show that for men primes of attractive women increased their level of creativity, irrespective of it being a short-term or long-term mating context. However, creativity of women increased only when they were primed with a desirable long-term mate. These findings can be explained by theories of sexual selection (Darwin, 1871). Human creativity, like peacock’s tail, might have evolved because it is preferred by the opposite sex. It is a good indication of genetic fitness as it is costly to maintain. Some forms of creativity are undoubtedly beneficial for survival, whereas some creative displays – like poems, melodies and, drawings have higher social value than survival value (Miller, 2000). Additionally, this study also demonstrates gender differences – for men primes of both short-term and long-term mate triggered increased creative displays, whereas for women only long-term mate prime evoked higher creativity display, to further illustrate implications of different mating strategies of men and women.

If mating motivations can indeed affect our mental processing in the form of changes in levels of creativity, can it go even further by affecting lower levels of perception? Could it determine what catches our eye and does not let go of our attention? Recent experiments provide confirming evidence (Maner, Gailliot, & Rouby 2007). When primed with a mate searching goal, participants’ attention was captured (they were less quick to switch attention to another stimulus) by primes of attractive-looking compared to average-looking members of opposite sex, but only for sexually unrestricted participants. On the contrary, when primed with mate guarding goals, participants’ attention was captured by physically attractive members of their own sex, but only for participants who were concerned with potential same-sex competitors. Motivations of mate searching and guarding can direct attention to persist on functionally relevant stimuli (mates or rivals, respectively) in a very early phase of processing and in a fast and automatic manner.

In conclusion, evidence from comparing humans with other polygamous primates indicates that we have adaptations for short-term mating. Also, behaviors of extra-marital sex, poaching, and jealousy across cultures confirm these adaptations. However, abundant psychological, neurological, and anthropological evidence shows that humans have evolved adaptations for long-term monogamous relationships. It has been concluded that people can choose the most adaptive mating strategy depending on their quality as a mate and shifts in ovulation (for women), age, environment, and local mating pool. Moreover, recent evidence shows how influential mating relevant goals can be for our psychological functioning – starting from low-level processing to elaborative displays of creativity. The mating and dating business is not a fairy-tale scenario for most of us; it deals more with finding the best trade-offs between what you can get for what you invest. So keeping track of what is out there and what you need, what you and your partner are willing and/or able to give seems to be an “adaptive strategy”. However, keep in mind that mating goals bias our attention in an automatic manner.

*Glossary*
_Sexual Dimorphism_ is the existence of physical differences between the sexes, other than differences in the sex organs, evolved by means of sexual selection.

*References*
Betzig, L. (1986). _Despotism and Differential Reproduction: A Darwinian view of History_. New York: Aldine.

Buunk, B. P., Angleitner, A., Oubaid, V., & Buss, D. M. (1996). Sex differences in jealousy in evolutionary and cultural perspective: Tests from the Netherlands, Germany, and the United States. _Psychological Science_, 7, 359-363.

Darwin, C. R. (1871). _Descent of Men and Selection in Relation to Sex_. London: Murray.

Gangestad, S. W. (1993). Sexual selection and physical attractiveness: Implications for mating dynamics. _Human Nature_, 4, 205–235.

Gangestad S. W., & Simpson, J. A. (2000). The evolution of human mating: Trade-offs and strategic pluralism. _Behavioral and Brain Sciences_, 23, 573–644.

Gangestad, S. W., Garver-Apgar, C. E., & Simpson, J. A. (2007). Changes in women's mate preferences across the ovulatory cycle. _Journal of Personality and Social Psychology_, 92, 151-163.

Griskevicius, V., Cialdini, R. B., Kenrick, D. T. (2006). Peacocks, Picasso, and parental investment: The effects of romantic motives on creativity. _Journal of Personality and Social Psychology_, 91, 63-76.

Haselton, M. G., Mortezaie, M., & Pillsworth, E. G. (2007). Ovulatory shifts in human ornamentation: Near ovulation, women dress to impress. _Hormones and Behavior_, 51, 40-45. 

Haselton, M. G.; Gangestad, S. W. (2006). Conditional expression of women's desires and men's mate guarding across the ovulatory cycle. _Hormones and Behavior_, 49, 509-518.

Hazan, C., & Zeifman, D. (1999). Pair bonds as attachments: Evaluating the evidence. _Handbook of attachment_ (pp. 336-354). New York: Guilford Press.

Li, N. P., & Kenrick, D. T. (2006). Sex similarities and differences in preferences for short-term mates: What, whether, and why. _Journal of Personality and Social Psychology_, 90, 468-489.

Low (2000). _Why Sex Matters_. Princeton, NJ: Princeton Univeristy Press.

Maner, J. K., Gailliot, M. T., & Rouby, D. A. (2007). Can't take my eyes off you: Attentional adhesion to mates and rivals. _Journal of Personality and Social Psychology_, 93, 389-401.

Miller, G. F. (2000). _The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature_. New York: Doubleday.

Schakelford, T. K. Buss, D. M. & Bennett, K. (2002). Forgiveness or breakup: Sex differences in responses to a partner’s infidelity. _Cognition and Emotion_, 16, 299–307.

Schmitt, D. P. (2005). Sociosexuality from Argentina to Zimbabwe: A 48-nation study of sex, culture, and strategies of human mating. _Behavioral and Brain Sciences_, 28, 247-311.

Schmidt, D. P. (2005). Fundamentals of Human mating Strategies. In D. M. Buss (Ed.), _Handbook of Evolutionary Psychology_ (pp. 258-292). New York: Wiley. 

Thornhill, R., & Gangestad, S.W. (1999). The scent of symmetry: A human pheromone that signals fitness? _Evolution and Human Behavior_, 20, 175–201.


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