The neuroscience of you, p.4
The Neuroscience of You, page 4
The only problem with anecdotal evidence like this is that we get so captivated by the story that we don’t think about the facts objectively. For one thing, the similarities stand out, but the differences are easy to ignore. It’s not that anyone would have been shocked if the triplets liked different kinds of beer[*]—but the fact that they all smoked Marlboros caught our attention. Which brings me to my second point about statistics and coincidences: To figure out how surprising the similarities between long-lost twins (or triplets) might be, we’ve got to ask the question, “How likely is it that any two random strangers who meet on the street would also be similar in this way?” When it comes to what kind of beer you drink, or what brand of cigarettes you smoke, the answer depends on how popular that choice is. According to a market research article I found, in 1980 when the triplets met, Marlboros were the most popular cigarette with people in their age group, capturing about 40 percent of the market. It’s still remarkable, but somewhat less remarkable than if they all smoked Camel Lights. To be scientific about the question of whether a person’s taste in cigarettes can be genetically influenced, we’d need to look at a bunch of monozygotic twins, separated at birth, and see if the likelihood that they smoke the same brand is significantly greater than the likelihood that any two unrelated people plucked off the street would.[*]
I know, I’m no fun.
But the good news, when it comes to our discussion about nature versus nurture, is that I already had this kind of scientifically skeptical attitude on board when I met One Really Freaking Similar Stranger named Maia on April 7, 2020. There I was, in the middle of writing a book about how your brain makes you you, when I received an email from a twenty-year-old stranger with the memorable subject line “49.5% Match! (You might want to sit down).”
The first thing I noticed while reading the email was how much she “sounded” like me. Though her words were more carefully chosen than mine typically are, they were also a bit silly, and emphatic in a way that was very familiar. Unless something like this happens to you, you might never think you’d recognize yourself in the way someone uses an exclamation point. But I did![*]
The next things that struck me were the similarities in the things she chose to share about herself. Not knowing how I’d feel about being contacted, she strategically kept the email short and sweet. I imagine she thought quite a lot about what she wanted me to know about her, in case she never got the chance to talk to me again. Under those conditions, she chose eight things to share: (1) her love of singing, and the fact that she was studying to be a music teacher; (2) her love of animals, especially horses; (3–6) were brief mentions of hobbies, which included hiking, painting, traveling, and playing Mario Kart; (7) that she was voted “class clown”; and (8) that her Taco Bell order was a Crunchwrap Supreme with spicy potatoes and guacamole.
At this point, the feeling that I was talking to the twenty-year-old version of myself was through the roof. As you will probably figure out by the end of this book, I am also a huge animal lover. Hopefully, you’re holding me accountable here and thinking, Wait. What’s the chance that two random strangers who meet on the street will also love animals? And that would be a valid point. But I think I’m an outlier in how much I love animals. Like, I still go to petting zoos, even though my child is twenty-six—and I stay too long. When I was little, I brought a baby duck home from the feed store because it was cute. I named him Quackers and filled a wheelbarrow up with water so he could swim in my backyard.[*] In my adult life, I have become infamous for finding lost or injured animals, including Hugo, the dehydrated little baby raccoon I found in a gutter and raised in my garage until he was strong enough to be released. In my lifetime, I have had at least twenty different types of pets, starting with sea monkeys and an ant farm, and working my way up through fish and lizards in college, to finally fulfilling my childhood dreams and buying an off-the-track racehorse for myself for my thirtieth birthday.
So what are the odds? According to the most relevant statistics I could find, 4.6 million Americans ride horses for hobby or sport. That’s about a 1 in 71 chance of finding someone on the street who rides horses. But maybe that’s not a fair estimate, since it’s more popular with certain demographics than others.[*]
But what about the other seven things? Love of music? I’m an amateur drummer, but my daughter, Jasmine, did musical theatre throughout high school. Hiking? Definitely. Painting? I don’t have the patience, but my mom, aunt, grandmother, and great-grandmother are all stellar visual artists. Traveling? Definitely, but that’s pretty common for those who are capable. And Mario Kart? I’ve only played a few times, but I always lose—possibly because I like to pick the bathtub as my vehicle of choice. I was not voted class clown, but as you might guess from my Mario Kart vehicle, I’m also not a particularly serious person. In fact, my husband and I, who share the same preteen sense of humor, describe ourselves as “astronauts of stupid.”
What’s kind of funny, in retrospect, is that the most salient thing about the list of Maia’s “fun facts” was her Taco Bell order. No, I am not about to tell you that I eat Crunchwrap Supremes with spicy potatoes and guacamole.[*] That would be wild. But anyone who spent time with me when I was Maia’s age knows that Taco Bell was a huge part of my culture. To be clear, it’s not the fact that we both liked Taco Bell[*] that blew my mind. It’s that I would also probably have chosen to include my Taco Bell order in the “these are the things that you need to know to understand me” package. Suffice to say that reading the email from Maia, and then watching the slideshow her parents had prepared for me, was an unforgettable experience. Though I knew she existed, it was an entirely different thing to watch the life of someone that was created from my DNA unfold across my computer screen.
Her origin story starts the summer before I began graduate school, when I decided to become an ovum donor.[*] It’s a choice I’m proud of—one that allowed me to help an incredibly kind family that had trouble conceiving on their own while earning a bit of money to help support my own child, who was four years old at the time.
And here’s where my nature-versus-nurture story takes an interesting twist. When it comes to shared experiences, my daughter, Jasmine—the best friend I gave birth to—and I are as close as it gets. We grew up together. Because I was only nineteen years old when I gave birth to her and was a single mom until I met Andrea twelve years later, Jasmine and I did everything together. When she was little, there were months at a time when we were never physically separated. As we went about the maturation process (she usually a few steps ahead of me), many commented on our similarity to the Gilmore Girls.[*] I can see it, except for the fact that I’m way less cool than Lorelai, and she’s a little less nerdy than Rory. Oh, and we’re real.
Like the Gilmore Girls, Jasmine and I overlap a lot in our “likes” (trash television, Zumba, Irish food, and ’90s hip-hop, to name a few) and “dislikes” (anything even remotely scary, people who drive too slow, artsy films,[*] and having our feet tickled, for starters), but we have very different temperaments. She is chill (except when driving), and I am not. She’s a deep, careful thinker, and I’m fast, spontaneous, and impulsive. While raising her, I never thought, Jasmine is exactly like me. I always thought, We make a perfect team.
Maia, on the other hand, seems to have a freakishly similar temperament. If the number of exclamation points in her email weren’t a dead giveaway, most pictures of her hold some clue to our shared personality traits. We are both clearly high on the extraverted scale—I like to call it “pizzaz,” but the kids these days might also call it “extra.” Suffice to say that neither of us blends in very well. The other day, Maia sent me a picture of herself cruising around with Pepper, her pet bearded dragon, in this giant pink aquarium-backpack thing she bought so that he could come have adventures with her. Wow.
What might the similarities and differences I share with these two amazing young women with whom I also share half of my genes reflect about the role that genes and environments play in shaping our brains? In the pages that follow, I’ll describe some of the ways that our brain design is influenced by nature and nurture independently, and how those two things interact. In Part 1, I’ll focus on biological features. However, as you’ll learn, even the smallest aspects of our biology are also shaped by our environments. When applicable, I’ll talk about the heritability of different traits, or the percentage of variability that is estimated to come from genetic influences, based on twin studies and the like. Then, as we shift into Part 2, our focus will turn to the jobs we ask our brains to do, and how our life experiences and biology interact to shape the way we go about accomplishing them. Throughout this process, I have no doubt that you’ll be thinking about how you came to occupy the “difference space” you currently inhabit, and I’ll do my best to provide clues along the way. But before we go there, I’d like to add a few more words about what you should and shouldn’t expect to find in the pages that follow.
You probably think this book is about you, don’t you?
It’s about time to address the elephant in the room—the fact that I haven’t told you anything specific about how your brain works yet. But you’re still here, which, I hope, is a sign that I’ve at least got you thinking about it. In the pages that follow, I plan to provide you with a solid foundation in the neuroscience of you—one that describes both how biological engineering differs across brains (in Part 1) and how the jobs they do provide the testing grounds for bringing out the differences between us (Part 2). Of course, to fit what I’ve learned in twenty-plus years into a book that wouldn’t warp your brain like the Knowledge test, I had to make some tough choices about what to put in and what to leave out.
My decisions about what to include were largely driven by the aspects of brain design that can most easily be reverse-engineered. As a result, many of our discussions will be centered on characteristics like handedness or personality traits—things you either already know about yourself or that can be measured using the assessments you’ll find in the book. But keep in mind, if you find yourself wanting to know more about how your brain works, feel free to check out the “Research” link on my website, chantelprat.com, at any time. There you’ll find a variety of links to brain games that you can play to get more time-sensitive measures of some of your own brain’s design features.
Whenever possible, I also chose to discuss topics that have been thoroughly studied, with multiple lines of converging evidence. Unfortunately, this is the exception rather than the rule with individual differences in research in neuroscience. Many of the experiments I describe have been conducted within the past five years. Try to keep this in mind as you read. This is a new field, and the cutting edge can also be the bleeding edge. I imagine that in another five years, what we know will have changed substantially. At least, I hope that’s the case, because there is still so much about you that we don’t know! Given where the field is at, my goal is not to give you all the answers but to give you the tools to be able to think about what we do and don’t understand about how different brains work.
When it comes to what I’m not going to talk about in this book, one of the biggest topics is what makes one brain better, or worse, than another. It just doesn’t make sense to me, even though I was born before the “every brain gets a trophy” generation. As the taxi-driver experiment illustrates, you’ve really got to be thinking about the match between a brain and an environment to decide whether it’s a good fit, rather than talking about the absolute “goodness” of a particular design feature.
For related reasons, I’m not going to spend a lot of time telling you how to change your brain. While I’m all for a growth mindset, I also think many of us would be better off if we could stop to understand and (dare I say it . . .) embrace the way our brains work. There’s a reason they do the things they do, even if they drive us nuts (literally and metaphorically) in the process. Of course, I will talk to you about the kinds of experiences that may have gotten you where you are, and will occasionally provide little life hacks for things I think we could all use help with—like counteracting the effects of chronic stress on the brain. Still, at the end of the day, my hope is that your idea of what might be “better” or even “normal” will expand to incorporate more dimensions in the space of how we’re different.
Another thing I’m not going to talk about is group differences, like the difference between the male and the female brain. Doing so is really just a way of moving from the “one-size-fits-all” approach to the “one-size-fits-everyone-in-this-bucket” approach. It’s not necessarily better. In fact, it can be a lot worse if not done thoughtfully, because things like “maleness” and “femaleness” are very strongly entangled in nature/nurture interactions. For example, from the moment a baby is born, adults use language differently with males and females. A baby’s biology, from moment zero, shapes their experiences based on the expectations people have of them.
And even if you could separate nature from nurture when it comes to sex differences, the most frequently reported differences between male and female brains—things like the idea that females have more symmetrical brains than males do—are not consistently found in the literature. What this means is straightforward, if you ask me: For any brain design feature of interest, there will be differences between people, period. Deciding whether groups (say males versus females) are significantly different from one another involves using statistics to show that the differences within a bucket are smaller than the differences between buckets. This depends a lot on how many people are in the buckets, and how representative the people in the buckets are. As you’re probably starting to guess, I’m not a big fan of putting people in buckets anyway, so we’re just not going to go there.
And finally, a word about how I’ve chosen to report the science, and the scientists responsible for it, in this book. I hope I’ve already convinced you that brains are complicated, and by extension, that neuroscience is hard work. I believe that the people conducting this research are all trying their best to solve pieces of really difficult problems. I respect that act, in and of itself, tremendously. As a result, I’ve decided neither to use honorific titles nor to talk about the universities these scientists are working at. One practical reason for this is that it can be hard to tell if the person who wrote a research article has already gotten an advanced degree or if they’re conducting amazing research while in training. I’d hate to get it wrong, but I’d also hate for you to think that if the first author of a paper doesn’t have a “Dr.” title, the paper isn’t trustworthy.[*] This is also the reason I’m not going to tell you whether Author So-and-So is from an Ivy League school or not. Unless it’s somehow relevant to the story, I don’t think it should matter. Almost all of the research discussed in the pages that follow has gone through the peer-review process. This certainly doesn’t mean that it’s flawless—but it does mean that other scientists with relevant expertise have agreed that the science is sound. And most of this research is conducted by teams of scientists. As much as everyone on the team deserves credit, I think you would get really tired of reading paragraphs of names every time I described a study. So I made a choice to reserve the limelight for the first author on these studies, who—by convention—is the one who does most of the writing up of the research. Some authors prefer to refer to the work based on the most senior or most recognizable name in the group, but I wanted to be as transparent as possible when assigning credit.
Occasionally, I will mention details like how many participants were in a study. This does matter. All other things being equal, the more people in a study, the more likely it is that the findings from that study will withstand the test of time. And speaking of things being equal, while I would love to say that I’ll report how representative the populations studied were, demographics other than age and sex are rarely reported. Unless there’s something noticeably out of whack (like a study includes only males for no good reason), I probably won’t talk much about the characteristics of the participants studied. But this is clearly a place where I’m hoping my field will grow.
So now that we’ve laid the foundation for being responsible consumers of neuroscience, let’s roll up our sleeves and get to work learning about your brain. Because, as Brené Brown said, “People are hard to hate close up. Move in.” And I can’t help but wonder whether taking you all the way in, to the place where we’re all pink and squishy, might help you to appreciate the nuances of yourself, as well as others who are different from you. Because in the hundreds of conversations I’ve had with friends, family, and strangers about my research, two things stand out: First, almost everyone is interested in neuroscience and the window it can provide to the self. Statements like “I’m not wired that way” show a lay understanding that something about the way your brain works makes you you. And second, many of us feel a little bit weird. After learning what I do for a living, you wouldn’t believe how many strangers have told me, “You could write a whole book about my brain!” And as it turns out, they were right.
PART 1
BRAIN DESIGNS
How Differences in Brain Engineering Shape the Way You Think, Feel, and Behave
Bus rides are great exercise for the imagination. During the commute to and from work, my wandering mind often takes me places far away from my physical surroundings. Like the dreams I have at night, the contents of my daydreams vary from the fantastic (Jason Momoa is bringing me a drink with an umbrella in it. I can feel the warmth of the sun on my face.) through the mundane (Don’t forget to send an email to so-and-so about such-and-such) to the horrific (Someone grabs the wheel of the bus and turns it sharply. We are careening toward the guardrail on the bridge that protects us from the water below.). In each scenario, the content of my conscious awareness, my mental reality, so to speak, has very little to do with the physical reality that my body is occupying.
