Attachment and Monogamy as Studied in People and Rodents

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Biology 202
2002 First Paper
On Serendip

Attachment and Monogamy as Studied in People and Rodents

Ashley Farrell

"It had to be you, it had to be you
I wandered around, and finally found - the somebody who
Could make me be true, and could make me be blue
And even be glad, just to be sad - thinking of you."
-Written by Gus Kahn and Isham Jones (10)

The mystery of monogamy has puzzled the human race for a long time. Monogamy is usually reasoned to be the result of an attachment that is strong enough to make someone be true to their loved one. Writers, artists, great lovers, the broken-hearted, and many other people, have entertained the question: if there is such a thing as monogamy, what is responsible for it? Recently scientists have started to seriously ponder the same question. Within the past few years exciting studies and experiments have been done with the intent to delve into this complicated question, which ultimately pertains to love. In 1999, scientists at Emory University led experiments with voles and mice to study monogamy. (1) In 2000, scientists from the University College of London studied the brain activity in a group of people who were "truly, deeply and madly in love" entitled The Neural Basis of Romantic Love. (2) Although no conclusions can be reached, many interesting observations are being made about monogamy and romantic attachment.

Prairie voles are monogamous creatures, so much that eighty percent of the time males refuse to mate with any vole other than their first mate, and both parents tend to their offspring. (3) Montane voles, who are a very closely related species to prairie voles, are polygamous. (4) Both female and male montane voles leave each other and their offspring after mating. "Prairie voles spend more than 50% of the time in close physical contact with each other, whereas montane voles spend less than 5% of the time in close proximity to other individuals." (5) After studying the social patters of other species of voles, like pine and meadow voles, it is apparent that two neuropeptides are responsible for the difference in social interaction. (4) Oxytocin, in females, and vasopressin, in males are the two chemicals which help prairie voles to be monogamous. (4) These same chemicals are present in montane voles, but do not have the same effect. (5) Oxytocin and vasopressin are released after the prairie voles mate, so that they form an "attachment." (1)

When the scientists injected male prairie and montane voles with vasopressin, the prairie voles reacted to a female much more than usual. (4) The montane voles, however, did not react significantly to the female vole. (4) The difference in behavior is explained by different vasopressin receptor patterns between the prairie and montane voles. To further test this, the scientists made a mouse with an extremely similar vasopressin receptor pattern to that of the prairie vole. (4) The mouse became more sociable with the female mice. (4) He did not become monogamous, but his social patterns were greatly affected. (4) From this mouse experiment, they were able to conclude that it is not the amount of chemical in brain that had an effect, but the pattern. (6)

When non-monogamous behavior is shown in humans, one often wonders if it is due to a lack of love and a low level of attachment. The study on romantic love does not explain what love is, but shows where love is in the brain. Seventeen people, who were determined by a lie-detector test and a questionnaire to be really in love, had brain scans taken when showed a picture of their loved one, and some close friends. (7) The friends had known the subject at least as long as the loved one, but totally different parts of the brain lit up on the brain scan when showed a picture of a friend than their lover. (2) The parts of the brain that were activated when the picture of the significant other was shown were the "regions implicated in happy states, attention to one's own emotional state and especially social interactions which involve assessing one's own and other people's emotions and states of mind." (2) The parts of the brain that were deactivated were the parts of the brain that are activated when experiencing depression and when these parts are artificially inactivated, they treat depression. (2) It is clear that love creates an intensely happy state in the brain, but this study actually has an even greater implication: the areas activated by drugs, such as cocaine, overlap with the areas activated by romantic love. (2) So, can love really become an addiction? This is a popular question which might hold more weight than we’d like to give it. If love is an addiction, than is attachment a genuine feeling, or just an effect from the ‘drug?’

Another study shows that changing a single gene in a normally solitary roundworm affects it’s eating behavior. (8) When a specific gene is changed, the asocial species eats with the group of normally social roundworms, whereas it would normally eat by itself. (8) This indicates that there is, at a simple level at least, a biological reason for social interactions. Monogamy has not yet been directly linked to a certain chemical, and neither has attachment or love. This is because love and personal relationships are very complex. Love can produce many different bodily symptoms ( i.e. sweating, dizziness) and far more emotional feelings. (9) Love is an abstract concept and thus is hard to be objectified by scientists. Countless studies will need to be done, because all studies and experiments having to do with love will almost certainly be fallible. To attempt to solve the puzzle, one must look at all the different components of love, such as monogamy and attachment, in order to get to the bigger picture. When we do have it all figured out (yeah, right) the song "It had to be you" will hold a whole new meaning. We’ll no longer wonder why it had to be that one person, but will appreciate them even more because of those (presently mysterious) reasons.


(1)Monogamy May Be in the Genes, Discovery Channel Canada

(2)The Neural Basis of Romantic Love, Published Papers from the Laboratory of Neurobiology

(3)Love is All in Your Head -- Or is it in Your Genes?, Web MD Health site

(4)Increased affiliative response to vasopressin in mice, site

(5)Neuroendocrine bases of Monogamy, site

(6)Insel, Young discover ‘sociability gene’ in prairie voles, emory university site

(7)The Science of Love, ABC News site

(8)Dinner together and mating forever -- Is it in the Genes?, Web MD Health site

(9)What is love, medically speaking? Sonoma county medical association site

(10)It had to be you, The Sinatra Songbook

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