Kayt Sukel on Love

Last Friday, the Cognitive Science department at Carleton hosted a talk by Kayt Sukel, a science writer with a recently published book about the neuroscience of love, sex and relationships. While I enjoyed the talks I attended by Paul Thagard and Zenon Pylyshyn, their main job is to do research, and so their talks were fairly functional. Kayt, on the other hand, writes for a more general audience - unsurprisingly, her talk was really entertaining. There was a lot of laughter, and only a little bit of blushing. But it was super interesting, too, and I wound up buying her book afterwards. Got it signed, too, and her dedication made me smile - “to love and other indoor sports”.

At any rate, before the talk I was looking around her site and read a handful of articles. My favourites:

• 5 sex myths busted by science
• Orgasm unlocks altered consciousness - weird as it may seem to people not doing a degree in cognitive science or philosophy, this is really interesting to me. The same topic actually came up once in my philosophy of mind class, when we went over an argument to the effect that orgasm is one proof of qualia. It was a weird lecture, but was theoretically interesting.
• I donated an orgasm to science - the story behind the above article.

With all that being said, below are the notes I took from her talk. If you’re interested, find a link to buy Kayt’s book from her site!

That Crazy Little Thing Called Love

If we’re going to study love scientifically, we’ll need an operational definition for what we’re actually looking for

• Love has been written about for hundreds of years, and we can recognize it even in old plays and paintings - so it’s something that has persisted in humans for a while
• At the 1995 Wenner-Grom Symposium, the topic was “Is there a neurobiological basis for love?” The goal was to gather the best and brightest and figure out an operational definition for love
• Their definition: love starts with motherhood, then we leave our mothers and search for that same kind of bond elsewhere

Love on the brain

Bartels & Zeki (2000) was the first published study on the neurobiology of love

• They found significant deactivation in the frontal cortex when participants were looking at loved ones, by comparison to when they were looking at images of physically similar people
• The frontal cortex handles executive control and is responsible for a lot of our inhibition - so people are less inhibited when looking at loved ones?

Fisher, Aran & Brown (2005), in a similar study, found activation in three key areas that are related to attachment, lust, and sex drive

• They proposed that these three areas, while distinct, had overlapping functionality - they worked both together and against eachother
• In theory, this is what allows us to transition between different relationships with the same person - from platonic attachment to lust, from lust to love, and so on

The smell of love

But, for starters, we can mostly agree that love starts with attraction in some form or another

• Now we need to define attraction - where does it come from? Most of the time, when you ask people what attracted them to their partner, it seems like they’re just guessing
• As it turns out, the biological basis comes from our odour-print - this is largely determined by what’s called the MHC, a gene cluster that primarily influences the immune system
• People with optimal immune system compatibility tend to be attracted to each other, even if they say the reason was something else
• See the “dirty t-shirt studies’ - interestingly, immune system dissimilarity was a major factor in the choices women made, but so was similarity to their father
• The authors explained their results by saying that the women needed to find a mate whose scent they could still recognize (hence similarity to their father), but was as dissimilar as possible while still being familiar

Is love a drug?

When people claim to be madly in love with a new partner, there are changes in:

• Dopamine (involved in reward systems)
• Oxytocin (related to pair bonding in monogamous prairie voles)
• Vasopressin (related to monogamous behaviours - when you block it in the aforementioned voles, they stop being monogamous)
• Serotonin (mood regulation)
• Neurotrophins (chemicals that aid in growth of the brain, sort of like fertilizer)
• Sex steroids (i.e. testosterone)

In particular, here’s how these chemicals were affected:

• Serotonin went down, dopamine went up (serotonin sometimes acts as a brake for dopamine, so these two effects may be related)
• Oxytocin went up, reflecting the formation of a bond
• Neurotrophins and testosterone also went up
• However, two years later, the couples who were still together and in love were studied again - these chemicals had all returned to their baseline levels
• Perhaps these changes early in the relationship reflect a need to solidify the bond, and after the bond is formed, things start to settle down

Love may actually be the blueprint for drug addiction, as many similar chemicals are involved

• This explains the change in focus, lack of attention to other things, and phsyiology of both phenomena
• Perhaps drugs actually hijack the subsystems for love?

Evolution of love and monogamy

Since we see this weird response at the initial development of a romantic relationship, maybe it’s necessary for some evolutionary benefit

• A few ideas: having one dedicated partner provides more reliability than looking for many mates over time - they’ll always be around to protect from predators, search for food, and so on
• If love has these evolutionary fitness benefits, then we could suppose there’s a drive to find it

Actually, a lot of studies on love and attachment are done on prairie voles

• As it turns out, they’re a pretty good model for humans, as the relevant brain areas are very similar
• Strangely enough, only 2-3% of mammals are monogamous, so it’s hard to find a species to study
• In prairie voles, if you block their oxytocin receptors, they stop being monogamous and go search for other mates - even ignoring lifelong partners
• Closely related vole species that aren’t monogamous have less vasopressin receptors in the areas of the brain related to attachment - if you modify their genes so they have more vasopressin receptors, they show more monogamous behaviour
• Menawhile, if you surgically remove vasopressin receptors from prairie voles, they become less monogamous as well

In humans, things are a bit harder to study, but there are interesting differences between men and women:

• In men, having a certain variant of a gene that relates to vasopressin receptors correlates with more dissatisfaction in marriage
• For women, a gene related to oxytocin receptors leads to the same correlation

Is monogamy "natural” in humans? This is probably the wrong question to ask

• These kinds of genetic factors are just probabilistic, not deterministic - correlation with dissatisfaction in marriage doesn’t mean a gene will cause people to be unfaithful

Love and parenthood

Motherhood changes the volume of a few areas of the brain

• This is easy to explain, since women have to be host to a growing parasite for nine months - physiological changes could easily lead to brain changes as well
• Maternal love seems to overlap with romantic love in neuroimaging studies, and involve similar chemical changes

Dads actually have neural changes as well, with an increase in oxytocin

• Why does this happen to men, who don’t become pregnant?
• Oxytocin levels seem to correspond to the type of interaction parents are having with their children - for mothers, it relates to nurturing behaviours like cuddling their child, while for fathers it’s more physical, explatory play like gently tossing the child into the air
• Perhaps it’s beneficial for the child to have these two different types of interactions from two different parents

Conclusion and questions

Some people have asked whether studying the neurobiology of love will ruin the mystery and excitiment of love

• Samir Zeki disagrees: “Learning about DNA allowed us to replace the mystery of heredity with awe towards its mechanics”

Oxytocin was first discovered in relation to labour/child delivery

• Delivering a child associates a lot of oxytocin with them - this is like a shotcut to attachment
• However, with adopted children, this isn’t the only way to get the same attachment
• This is similar to how sex is a shortcut to attachment and bond formation - plenty of people form romantic relationships in other ways

Do the chemical changes in parents stay over time, such as after children move out?

• No real studies on this yet
• Anecdotally, many parents find it hard when their children have all moved out

The chemicals involved in love are similar to those involved in long-term stress responses - perhaps they just signify important things in our lives

Psycho-social approaches have advanced understanding of a lot of things like heart problems in medical fields - perhaps they would help in the study of love, too

• However, it’s very hard to get funding in the US for anything that is even remotely related to sex and love, much less to start investigating psychological and social factors

What about relationships that form solely online, where the influence of odour-prints would be removed?

• Think of people who have met up in person, after dating online, only to find that there was no real connection
• This makes it seem like online dating is good for making introductions to a lot of people relatively quickly, but it’s best to meet face-to-face early on in order to see if there’s real compatibility
• What people say they want doesn’t always match what they actually want, which is a notorious problem for online dating sites

Perhaps, in the t-shirt studies, women have inherited preferences from their mother - which is why they go looking for someone similar to their father

• Or maybe they are unconsciously looking for a mate who is equally good as their father was to their mother