The New York Times runs a series of short videos titled “Modern Love” (does David Bowie know about this?). The latest installation is narrated by a 71 year-old woman who describes the experience of falling in love at her age, comparing it to her younger days. She talks about differences in preparing for dates, perceptions of the concept of ‘soulmates,’ the sense of urgency, jealousy, ephemerality of life and relationships, and the pain of loss. Pretty thorough for a 2 minute video.   

To me, the most interesting part is that love really can strike at any age, illustrating the gap between proximate and evolutionary levels. Evolutionary hypotheses for the origin of pair-bonding (and love) often highlight some function related to reproduction. Robin Dunbar  summarized four possibilities: 

“In the grand evolutionary scheme of things,  pairbonds are likely to evolve for just four reasons. One is to allow a male to monopolise mating access to a female, so as to ensure that he, and he alone, has paternity. The second is to reduce the risk of offspring being killed by predators. The third is to reduce the risk that the offspring fall prey to infanticidal males. The fourth is to enable the male to contribute to the business of successful rearing.” (Dunbar 2012: 237)

For a handful of reasons, Dunbar argues that the bulk of the evidence for the origins of human pairbonding supports the infanticide-prevention hypothesis, where a female solicited male protection for her young, as well as for herself (the bodyguard idea).  Dunbar then adds once pairbonds became an established part of our species’ behavior, paternal care and provisioning became possible.

Where does romantic love come in all of this? Given the intensity of the experience, it’s almost a given that love was reworked into our neurobiology by natural selection so that we could form strong bonds that would be difficult to dissolve. This could have reproductive payoffs in terms of protecting and provisioning young, as well as those created by increasing odds of paternity and protection from aggressive males. For example, Dunbar notes how common sexual harassment and rape are around the world, particularly during war conditions when social order disintegrates. One disturbing recent study found that nearly 25% of men in parts of Asia admitted to committing at least one rape.

However, exactly when this occurred in our evolutionary past is still debatable, as is how long pairbonds were built to last. Nor did it have to happen this way. Sarah Hrdy (2011) has suggested that humans evolved as cooperative breeders reliant upon allo-parenting, but there is no intrinsic reason that the extra care had to come from biological fathers. 

However romantic love got its start, in the present it can take on additional functions that go well beyond facilitating reproduction.  Children can experience ‘crushes’ or infatuation, as can individuals who are advanced in age. And there seem to be consistent features in the neurobiology of early romantic love that transcend ethnicity, gender, and sexuality (Zeki and Romaya 2010; Xu et al. 2011). According to Xu et al., “early-stage intense romantic love in Chinese students was associated with activation in the dopamine-rich regions of the VTA (ventral tegmental area) and caudate as found by Aron et al. and Ortigue et al. for American students, and Bartels and Zeki for a London group” (p. 255). I would guess the same is true for age. If romantic love as a biological phenomenon got its start as a part of a reproductive program, I can’t think of a reason why natural selection would have to keep it solely within those parameters. 

Today, we can tack on other components to our romantic attachments several steps removed from our ancestors’ experiences. In addition to looking for someone who would make a good genetic and/or parental contribution to our offspring (not exactly the most romantic courtship line), we may seek a partner who can provide companionship. Someone who can make us laugh, share sex/passion with us, stimulate our minds with conversation, enjoy music or play tennis together, go to religious services with us, share domestic chores, have someone to travel with and share our adventures, etc. 

In a sense, companionship is almost an evolutionary bonus. In genetic terms, the quality of a life matters little compared to whether or not our genes are passed along for yet another generation, to keep passing the baton along before we inevitably drop out of the race. But in human terms, that seems awfully callous. Love may have gotten its start to grease the reproductive skids, but we’re fortunate that it didn’t end there.

 “For small creatures such as we, the vastness is bearable only through love.” ― Carl Sagan.

References

Dunbar R. 2012. The Science of Love and Betrayal. Faber and Faber. Link

Hrdy S. 2011. Mothers and Others. Bellknap. Link

Schmitt DP. 2005. Sociosexuality from Argentina to Zimbabwe: a 48-nation study of sex, culture, and strategies of human mating. Behav Brain Sci 28(2):247-75; discussion 275-311. Link

Xu X, Aron A, Brown L, Cao G, Feng T, Weng X. 2011. Reward and motivation systems: A brain mapping study of early-stage intense romantic love in Chinese participants.  Human Brain Mapping, 32(2), 249-257.

Zeki S, Romaya JP. 2010. The Brain Reaction to Viewing Faces of Opposite- and Same-Sex Romantic Partners. PLoS ONE 5(12): e15802. Link