Dirty Minds: Your love life is supposed to be complicated

Kayt Sukel’s Dirty Minds is a book about neuroscience that has questions, not answers. That alone should be enough reason for you to pick it up. Sukel’s agenda is not to tell her reader how the human mind works. It is to convince her reader that our minds are complicated messes – they are dirty, in the cleanest sense of the term1. Our mind is the result of a rat’s nest of neurons bathed in a complex soup of hormones interacting with our environment. The point is not that our dirty minds have been solved, but that they are so damned interesting.

If you need another reason, a lot of the book is about sex2. Really, it is about research into the neurological basis of love. It covers relationships, parenting, even a wee bit of religion, and sex; but, when you say “and sex”, you might as well say “it’s about sex”. 

Sukel helps her reader understand the history of neurological study of love, the process of discovery, complications of the research, where research is heading, and the limits of our understanding. In doing so, Sukel does not give in to the temptation to present the human mind as a pristinely evolved tool, the epitome of adaptation to one’s environment. It is instead a kluge, built haphazardly on top of what previously existed. It is “dirty”. Dirty Minds presents complex question without simple answers – well, without answers at all, just suggestions, hints.

The book feels like a discussion about love and sex one might have over coffee with friends, not a neurologist. The choice to use accessible language, instead of technical jargon, was a good one, especially when dealing with the sensitive and complex issues of love, sex, and the mind. Technical jargon can streamline discussions between colleagues, but it is also intimidating, inaccessible, and can make folks feel stupid3. On the other hand, I am more used to the neurologist and found the casual language distracted me at times. I think most of my pedantic quibbles with Dirty Minds can be traced back to the use of such casual language, speaking of which…

Epigenetics is presented as the major mechanism for generating difference in gene expression between individuals. While certainly important, this ignores a number of other fascinating mechanisms, such as transcription factors and alternative splicing of RNA, that can generate variability in gene expression between individuals and cells. In keeping with the theme of Dirty Minds, variation in gene expression is even more complicated than presented.

Sukel uses the cliché of nature versus nurture in two variations to emphasize that the neurobiology of love is extremely complicated and that the research is still developing. It is also a trope of popular neuroscience that authors are almost required to include to help orient their readers. I do feel that those goals could have been achieved in both cases with more nuance.

First is the classic nature versus nurture framed as biology (your genetic predispositions ) versus behavior (your interactions with your environment). While researchers often try to remove environmental variables from experiments, this isn’t because we think environmental interactions are unimportant. We do it because they are so important and complex that they can make it impossible to understand the basics of a system before we can try to tackle more complex issues.

Second is the portrayal of the brave epigeneticists versus the bull-headed molecular geneticists devoted to described in the book are portrayed as brave prophets standing up to implacable devotees of genetic sequence determinism. The acceptance of epigenetics may not have been as rapid as its advocates would have liked. This is in part due to resistance to new ideas. It is also due to real issues with the research and reaction to overselling of claims, such as the ability to inherit epigenetic modifications from generation to generation (can occur for certain genes, but not common). The debate, however, is not about a dichotomy between epigenetics and traditional molecular genetics, but about how much influence epigenetics has relative to other mechanisms. The correct answer is somewhere between “a lot” and “none”, and will vary from gene to gene.

Having just spent some time on pedantic quibbling, I’d like to spent a few moments on pedantic praise. First, Sukel does a good job of treating purported sex differences with caution. Sex is an easy variable to look at because there are usually only two, easily defined states4 in research studies. We look sex differences more often than anything else and, therefore, we find them, whether real or not.  In non-human studies, we usually use statistics to correct for sex effects as a confounding variable. In human studies, sex effects often headline the press release. Ironically, many of the sex differences we are so interested in discovering may be the result of differences in the way our culture treats the sexes and our interest in their differences.

A lot of the research presented in Dirty Minds is based on functional magnetic resonance imaging (fMRI) studies. Interpretation of fMRI results has been controversial within the field. This has been exacerbated by simplified reporting that does not place the technology in appropriate context. Sukel, however, is very clear that fMRI measures blood flow in different regions of the brain as a proxy for neural activity – that it does not actually measure neural activity. She also makes clear that, while the resolution of fMRI is impressive compared to previous techniques, it is still poor compared to the scale at which the brain actually operates. By not being afraid to discuss the limitations on the research she describes, Sukel brings home her point that the study of the neurobiology of love is a developing science that may never solve our dirty minds.

Reading Dirty Minds won’t give you that comfy feeling that you now know how your mind works. Rather than being a pessimistic message, this is a hopeful one that, if the machinations of your mind and your “heart” leave you confused, exhausted, anxious, and unsure of who you are, then you are the one with a solid grip on reality. Those moments when people act like they have it all figured out? Probably just the hormones taking over.

1. Unless you happen to feel that any discussion of sex is inherently “dirty”. According to book sales, millions of Americans (implausibly stereotyped as bored, middle-aged, middle class housewives) disagree with you. Also the entire internet2.
2. Including a section in Chapter 12 where she talks about twiddling her lady-bits for science. Honestly, it is about as titillating as the phrase “twiddling her lady-bits”, but I feel that way about full-body latex suits, and lord knows the internet disagrees with me about that one too.
3. One of the benefits of being classified as “interdisciplinary” is you get to go to a lot of seminars/meetings where you don’t know the jargon and get to feel very stupid.
4. To researchers, sex describes an individual’s allotment of sex chromosomes. For the vast majority of people (particularly those participating in these studies), there are only two states: XX and XY. There are other possible combinations of chromosomes, but these are usually not included in studies that are not focused on the effects of these infrequent states. Gender generally refers to an individual’s self-perception and exists on a spectrum.


Author: Josh Witten


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