What's Love Got To Do With It? The Biochemistry of Love and Attachment by Nina Bingham

Tina Turner sang, "What's Love Got To Do With It?" (1984); this song became Turner's most successful single (www.wikidpedia.com, 2012). The words are:

"You must understand
That the touch of your hand
Makes my pulse react
That it's only the thrill
Of boy meeting girl
Opposites attract

It's physical
Only logical
You must try to ignore
That it means more than that."

Turner was pointing out the "chemistry" of love in her song. Is sex, love and attachment purely biological and out of our control, or is it a uniquely human expression of our most passionate selves?

While we'd like to believe that humans completely and consciously choose who we love, science indicates otherwise. The etiology of attachment, love and sex are human behaviors which can be correlated to both neurobiology and sex hormones. Love and attachment is also an evolutionary development of the brain to perpetuate our species, and bond us to one another : "It is humbling to consider even the most sophisticated and noble of human behavior is rooted in mammalian biology," and that, "Human social bonds, although more complex, are also mediated by (evolutionary-induced) nuerocircuitry" (Stein, Vythilingum, 2009). Proponents of Evolutionary Psychology believe that mammals and birds have evolved three systems for survival of the species: (1) Mating (2) Reproduction (3) Parenting. Sternberg (1986) has argued that love also comprises three components: (1) Intimacy (2) Passion (3) Commitment. Sounds similar in pattern to animal mating strategies, does it not? So what are the psychobiological underpinnings of the behaviors of love and attachment?

Brain Imaging:

"Functional brain imaging studies indicate that maternal love, romantic love, and longer-term attachment are mediated by distinct but overlapping neurocircuitry. It is noteworthy that the neurocircuitry of love and attachment overlaps in part with that which mediates sexual arousal. The neurotransmitters Dopamine, seratonin and norepinephrine play key roles in the cognitive-affective phenomenon. Prosocial peptides, such as oxytocin and vasopressin, which are released during sex and lactation, may facilitate dopamine release in reward centers, and enhance memory, thus presumably strengthening the social bonds with particular individuals (Stein, Vythingum, 2009). Dopamine is a neurotransmitter that allows humans to experience pleasure. During pleasurable activities such as sex, eating and drinking, hormones are released in the brain, and the so-called neurological "Reward Pathway" is activated. Regions of the brain which control memory are also activated, to reinforce repeated pleasurable behavior (Hormones, Sex and the Brain, 2012). This is how addictive behaviors are formed and reinforced.

Sex Steroids:

There are three sex steroids that effect sexual behavior and partnering: testosterone, estrogen and progesterone. Although men and women share the three hormones, men have much higher levels of testosterone than women, and women have higher estrogen and progesterone levels than men (Hormones, Sex and the Brain, 2012). Higher levels of testosterone (T), considered the male sex hormone, seems to spell less marital bliss for U.S. males. "Booth and Dabbs (1993) found that men with higher T have a 43% increased incidence of divorce and were 31% more likely to have separated because of marital discord, relative to men with lower T. They also found that men high in T were 12% more likely to have hit their wives and 38% more likely to have engaged in extramarital sex; in general, these men had a lower quality of marital interaction." It seems women do actually prefer a more sensitive guy! In addition to sex steroids, there is one Peptide hormone in particular that plays an important role in attachment and bonding, and that is oxytocin.

Oxytocin:

In landmark studies by Bowlby (1969), it was found that infants can be classed as: securely attached to their caregivers, or insecurely attached. "Attachment security is characterized by the individual's confidence to rely on attachment figures to achieve care, safety, and protection, and, when alone, to have access to internalized attachment relationships" (Buchheim et al., 2008). In a recent landmark study, "When given doses of oxytocin, 69% of subjects who before had insecure attachment increased their rankings to "secure attachment" and decreased overall in insecure attachment responses. Moreover our results concur with recent findings from nueroimaging studies in healthy humans, demonstrating that looking at pictures of significant others showed marked overlap with regions that showed high densities of oxytocin receptors" (Bartel and Zeki, 2004). Peptide hormones play an important role in both human and animal bonding: "Animal research points to the peptide hormones oxytocin and vasopressin as being intimately tied to pair bonding" (van Anders, Grey, 2007). Behavioral scientists know that hormones influence human partnering. But what about the decidedly-human experience of falling in love?

Falling In Love:

"The experience of falling in love is associated with altered endocrinology. Hormones can influence how attractive both men and women are perceived to be..." (van Anders, Grey, 2007). And, "There is evidence that OT enhances the perception of faces in males, and increases gaze to the eye region of the human face" (Guastella, 2008). This substantiates the old adage, "Beauty is in the eyes of the beholder." Really, attraction seems to be in the hormones of the beholder. "OT enhances bonding, while reducing the impact of socially aversive cues" (Heinrichs et al., 2004). Interestingly, "Oxytocin (OT) reduces social aggression and threat responses" (Lim, Young, 2006).


Conclusion:

The chemistry of love and attachment is both neurological and hormonal, with peptide hormones of oxytocin and vasopressin taking center stage, as well as the sex steroids of testosterone in men, and estrogen and progesterone in females. More than ever I'm wondering with Tina, "What's love, but a sweet old-fashioned notion?"

References:

Capella University. Hormones, Sex and the Brain Video. (2012). Retrieved from: http://media.capella.edu/CourseMedia/COUN5225/Hormones/wrapper.asp

Bowlby, J. (1969). Attachment and Loss, Vol. 1, Basic Books, New York.

Bechheim, A., Heinrichs, M., George, C., Pokorny, D., Koaps, E., Hennigsen, P., O'Conner, M.F., Gunder, H. (2008). Oxytocin enhances the experience of attachment security. SciVerse, Psychoneuroendocrinology. Volume 34, Issue 9, pp. 1417-1422.

A. Bartel, S. Zeki, (2004). The neural correlates of maternal and romantic love. Neuroimage, 21 (2004), pp. 1155–1166.

van Anders, S.M., Gray, P.B. (2007). Annual Review of Sex Research, Vol. 18, pp. 60-93, 34 p.

Guastella, A.J., Mitchell, P.B., Dadds, M.R. (2008). Oxytocin increases gaze to eye-region of the human face. Biological Psychiatry. 63: 3-5.

Heinrichs, M., Melnlschmdt, G., Wipplch, W., Ehlert, U., Hellhammer, D.H. (2004). Selective amnesic effects of oxytocin on human memory. Physiological Behaviorist. 83: 31-38.

Lim, M.M., Young, L. (2006). Neuropepticlergic regulation of affiliate behavior and social bonding in animals. Hormonal Behavior, 50: 506-517.

Wikipedia.com. (2012). What's love got to do with it )song). Retrieved from: http://en.wikipedia.org/
wiki/What%27s_Love_Got_to_Do_with_It_%28song%29

Stein, D.J., Vythilingum, B. (2009). Love and Attachment: The Psychobiology of Social Bonding. CNS Spectrums. 14 (5): 239-242.

Sternberg, R.J. (1986). A triangular theory of love. Psychological Review. 93: 119-135.

Capella university. (2012). Hormones, Sex and the Brain Video. Retrieved from: http://media.capella.edu/CourseMedia/COUN5225/Hormones/wrapper.asp