The epigenome

The epigenome is something like a link between your DNA and your environment. This article from Wired describes it as a part of your genetic makeup that’s handed down from your forebears, and that changes according to your environment. The epigenome consists of biochemical reactions that affect whether or not a particular gene is expressed. The article focuses on ways that we will be able to predict and treat certain diseases, particularly cancer, as our understanding of epigenetics grows. I remember reading in one of Matt Ridley’s books that nature and nurture are like the length and width of a rectangle: just as you need both the length and the width to calculate the area, you need both nature and nurture to explain a creature’s behavior. I wonder if the epigenome is part of what connects the two. At any rate, it’s a fascinatingly complex development in our knowledge of living things and their DNA.

http://wired.com/news/medtech/0,1286,68468,00.html?tw=wn_tophead_4

Brain fitness

Here’s an article from Wired about maintaining your mental fitness as you age. Cognitive fitness is probably as important as physical fitness for quality of life, if not more so. These days people are paying more attention to keeping their brains fit in the hopes of warding off problems with memory or other cognitive functions as they age. The article describes various programs and activities that are being developed toward this end. I’m all for keeping your brain active, and in fact I plan go on writing, and running this web site or whatever its later equivalent will be, until I’m a very old woman. However, I’m a bit dubious about making up activities to exercise the memory or the brain. Aren’t there enough mentally stimulating activities available already? Turn off the TV and read a book, or work a crossword puzzle, or build something with your hands, or listen to some music that requires a little effort to understand.

We don’t necessarily need to spend a lot of time and money developing Granny Einstein programs when there are so many opportunities for using your brain. Three days a week I work out on an elliptical machine in a huge room at the gym with a bunch of other people treadmilling away, and I think sometimes about how exercise used to be a vital part of survival, rather than something artificial that had to be added onto our lives. I can see that there’s not much need for my meager muscular contribution to human welfare these days, so I can live with the artificiality, but with mental exercise, I’d rather beef up our popular culture to the point where it provides some needed mental stimulation rather than tacking on a lot of mental treadmills for people to labor away at. The joy of engaging your mind in something challenging might well be part of the reason that cognitive fitness enhances people’s later years. In all fairness, maybe that’s the goal for some of the programs being developed, but the article didn’t seem to say much about encouraging activities that are integral to a person’s interests and lifestyle.

http://wired.com/news/medtech/0,1286,68409,00.html

Art: Bringing minds into contact

Recently I was driving home after running some errands, upset over difficulties in a relationship that’s important to me. As I sat at a stop light, seething with a mix of unhappy emotions, the Largo from Handel’s Xerxes began to play on my tape deck. Even if you don’t recognize it by name, you might recognize the music. I have long loved this piece for its slow gentle dignity and its mood of meditative serenity. In a complex emotional reaction that I’m not sure I entirely understand, the music brought the sadness in my mind to the forefront (ahead of the anger and frustration), and it also brought a welcome feeling of acceptance and even peace. Since I’ve known this music for years, through many different moods and events, and it’s been around for centuries, I felt my problems of the day being cast in more manageable proportions. Set against the emotional ebb and flow of everyday life was the tranquil beauty of the music, steadfast in time.

Several years ago at a world music festival I remember jotting down some notes about how maybe art is one of the answers to the problems of being thinking meat. I’ve thought a lot since then about how art does this. I don’t know why we evolved in such a way that we create art. That’s a topic for another day. What I’m speculating about here is the ways that art can make it easier to be a thinking mortal animal on this planet.

At the music festival I was thinking that music lets us share our feelings, so we know we’re not alone, and create something beautiful out of them, so we can experience the grace that, as U2 sang, makes beauty out of ugly things. A Cajun band, for example, sang about the homesickness of Acadians for their homeland. A Mongolian woman sang of the long journeys the men used to take in search of salt to bring back home, and the loneliness of the women who waited for them to come back. The artists who created this music took painful experiences and transformed them, through some alchemy of the mind, into beauty (art can also turn misery into humor or food for thought). Art simultaneously shares the specific details of another person’s experience, and tells a more generic story that most people can identify with (for who has not been homesick, or missed a beloved person who was far away?). We’ve all been there. There is some poignance and perhaps even beauty in the sadness, and comfort in knowing that you are not alone.

The specific details of some art—novels, songs, some poems, some paintings—let us share in the lives of other people that we will never have the chance to know, and to experience things far beyond what we could otherwise cram into our time on this planet. One of the troublesome things about being thinking meat is that we are here for such a short time. There are so many times and places and minds we will never know. We are born with curious and thirsty minds, but we’re always encountering limits to how much information we can soak up about the world. Art lets us experience vicariously some of these worlds that would otherwise be closed to us.

In particular, art can allow us to share the thoughts and emotions of people who lived in other times. If we’re lucky enough to create great art, it lives on after we’re gone. Even for most of us, who can’t reasonably expect to leave any masterworks behind, it’s comforting to sit in a concert hall or read a book or look at a painting that some other person conceived long before we were born, and to touch the mind of someone else. Carl Sagan wrote of how amazing an activity reading is: “You glance at a thin, flat object made from a tree…and the voice of the author begins to speak inside your head. (Hello!)” I think that experiencing the arts in general begins a similar amazing process. It gives me a feeling of continuity, of being a part of an interchange of ideas much bigger than myself, something that I hope will go on long after I am gone. For all the inherent fragility and transience of each human mind, we can still reach out to other minds across sometimes vast gaps of time and space.

A couple of months ago I was at an early music concert on campus and heard a Psalm setting by Handel, a passionate piece that was intricately put together and beautifully performed. Audience and performers alike were caught up in the dense interweaving of voices, human and instrumental, and at the end of it I turned to the woman in the next seat, whom I did not know, and we smiled broadly at each other before breaking into applause. Imagine leaving behind something that can inspire 40-odd people to rehearse and perform it several hundred years later, and total strangers to grin at each other like delighted children upon hearing it. I didn’t write it, or even perform it, but I felt like my narrow spot in space and time was somehow widened by the experience.

One thing we can gain emotionally from art is the knowledge that emotions come and go, that people survive them, and that it can sometimes be possible to stand back from them and take a wider view. Wordsworth said that poetry “takes its origin from emotion recollected in tranquility”. And that tranquil recall can help the artist shape a balanced, more orderly view of the emotional events. Art involves picking out the most telling details or selecting just the parts of experience that tell a particular story, and recognizing a pattern in the welter of emotions and experiences that make up our lives. (Even abstract art often involves an element of selection and composition.) Art frames life in a meaningful way by shaping happenings into some kind of a form, often a narrative. It gives us at least the feeling of having some control over life. Julian Barnes, in Flaubert’s Parrot, wrote that he could understand why people prefer books to life: “Books make sense of life. The only problem is that the lives they make sense of are other people’s lives, never your own.” True, but in books, or music, or paintings, we can sometimes see things that help us decide on the meaning we will give to our own lives, even—especially—at times when we are eternally left in the dark about some essential aspect of the situation.

And when we know, or have decided on, a meaning, we can shape our emotions accordingly to some degree. Art can be an excellent way to do this. When I was angry and bitter about my problems the other day, there was not much I could do at the moment, and dwelling on the anger and bitterness were not helping me get through my day any better. The music fostered a mood of sadness and resignation, which set my mind at rest so I could accept where I was and go on with something else. I was surprised at how quickly I shifted mental gears, but I’m certainly familiar with the emotional effect that music can have.

In fact, music might be one of the more common mood-altering substances around. Who hasn’t played lively music to get through a boring job, or sunny music to pull out of a brief emotional slump? Who doesn’t have some favorite vacation music that echoes the freedom you feel driving down the road, or rainy night music or comfort music? The music festival where I started thinking about art and thinking meat was full of rollicking danceable music that spread happiness to everyone within earshot. Poetry has a similar range of applications, and perhaps the other arts do as well, but I suspect words and music might be among the most accessible on an everyday level. Much has been written about the Mozart effect, which I consider to be overhyped psychobabble for the most part, but music can certainly change an attitude or an emotion and we use it that way all the time.

I’d love to say that my mind is no longer troubled in the least by the difficulties that were making me so miserable when I stumbled into the soothing effects of that piece by Handel recently. Art doesn’t make being thinking meat easy, however; it just makes it easier. It gives us some tools that can help us get through the bad parts with more grace than we might otherwise be able to muster. That’s enough, though. I’m happy about any gift of grace that I can find.

Joy, mortality, and music

This evening I went to an excellent performance of Mahler’s Symphony #2, “Resurrection”. It was a red-letter evening: gorgeous, emotionally intense music, skillfully performed and incorporating deeply meaningful words. (I don’t believe in a supernatural resurrection awaiting any of us, but I do believe we can bloom again after life’s barren times.) I spend a lot of time thinking about the long road that lead to where we are: the slow story of evolution, the contingencies that led to our capacities for language and music, and the way our use of language and music has grown and changed over human history. Our awareness of our own mortality, which sets us apart from other living creatures, is one of the more difficult aspects of being thinking meat, but on the other hand it leads to some of the most creative and poignant acts we humans are capable of, including this particular symphony. As I sat there in the concert hall surrounded by the soaring music of the last movement, I had to marvel at being able to listen to several hundred musicians bringing to life something so beautiful that originated in the brain of someone now gone. It made me feel very lucky to be here.

No links today, no news stories. I’m still basking in the music.

Tool-using dolphins

Dolphins appear to be the first documented case of a marine mammal using tools. Bottlenose dolphins in Shark Bay, near Australia, apparently use sponges on their noses to protect them when looking for food in the sand of the ocean floor. Not only that, it looks like mother dolphins may teach this behavior to their offspring. Researchers investigated whether it could be an inherited behavior, but the evidence for genetic transmission doesn’t look promising. (The dolphins that know how to do it are all related to a recent common female ancestor, but not all the females in that family know how, which suggests that some mothers teach their young how to do it.) No one has seen any signs of one dolphin teaching another this behavior, but I expect that’s one of the next things that these researchers will look for. Depending on how you define “thinking”, I guess you could say that some thinking meat swims in the sea, which is pretty cool. (I get this image of a scene from some Douglas Adams-style book where the dolphins explain what they’re really up to with those sponges, with some laughter about the weird mistaken ideas those humans have about what’s going on.)

http://www.nature.com/news/2005/050606/full/050606-2.html

Thoughts on gender and science

Here’s some follow-up from the Edge about the Pinker-Spelske debate on how differences in men’s and women’s brains might affect women’s participation in the sciences, which in itself was a follow-up to the uproar following some comments from Lawrence Summers of Harvard back in January. In this round, four academics react to points brought up in the Pinker/Spelske debate. I found Alison Gopnik’s description of how genes and environment interact to be particularly interesting. She suggests that one big environmental consideration that hampers women, the need for scientists to establish themselves in their careers during a woman’s prime reproductive years, could be changed by things like making part-time tenured positions available for both men and women who are raising children. This makes me curious about how the whole system got set up in the first place. I’m pretty sure that in mathematics, there is a perception that a person does his or her best work when young, and I wonder to what extent that perception is true, and whether or not it is true to any degree in the sciences as well.

http://www.edge.org/discourse/science-gender.html

My undergrad degree is in astrophysics, but I chose not to go for a PhD and continue with a career in astronomy, in part because I had two young children and wasn’t willing to have my time with them subject to the long hours, financial uncertainty, and frequent relocations that are involved in establishing a career in astronomy. Do I ever miss astronomy? Sometimes. Would I make the same choice if I had it all to do again? Absolutely! Was there any way the experience of getting a PhD and going through post-docs and tenure-track positions could have been made more palatable to a woman with two small children? Perhaps; certainly at the time I railed against what I saw as the harsh demands of a career in science. But the kind of career you would have with a more family-friendly career path might be fairly different from what you would have otherwise, and so you would still have to make a choice, not between having a family and having a career, but a choice about what kind of career and what kind of family life you want to have. I think it would be good if men faced the same dilemmas as women here (i.e., if child-care responsibilities were shared as much as possible), but I think it genuinely is a dilemma. Having a family shouldn’t close off all other options for your life, for men or women, and I like the idea of family-friendly jobs, but raising children is an occupation itself, and it might simply be incompatible with some kinds of higher-powered careers (and not just in science). If more parenting-friendly options were available for scientists, and more women than men chose them, would there be complaints that the parenting-friendly options don’t provide as much opportunity (like complaints about the “Mommy track” in other occupations)? Quite possibly, but I don’t think gender bias would necessarily be involved. Sometimes you really do have to choose; that’s one of the challenges of being thinking meat. “There is never enough time to do or say all the things that we would wish.” (Charles Dickens)

Tempus fugit

One of the reasons you sometimes hear advice about living as if each day were your last is that that approach intensifies your appreciation for life. Here’s a press release from UC San Diego about research that produced some data on the emotional effects of a sense of limited time. Young people were asked about the feelings they thought they would experience in several different scenarios. The situations that involved time limits or an impending leavetaking of some sort evoked stronger and more complicated emotions. This certainly jibes with my experience.

http://ucsdnews.ucsd.edu/newsrel/soc/TeuscherTimeLimits.asp

I’ve heard people say that if we could live forever, we would lose the motivational spur of having limited time, and also a certain poignancy that gives meaning to our lives. I’ve always wondered about the motivational part. I’d like to think I would accomplish bigger things if I knew I had more time to complete them, but on the other hand, procrastination is a powerful force even when I know I won’t be here forever. But there is no denying the emotional impact of the brevity of our lives. In one of his books, Heinz Pagels quoted the following poem, which has haunted me ever since I first read it. (I just Googled “Dendid” and found that he is a deity of the Dinka in Sudan.)

In the time when Dendid created all things
He created the sun, and the sun is born, and dies, and comes again.
He created the moon, and the moon is born, and dies, and comes again.
He created the stars, and the stars are born, and die, and come again.
He created man, and man is born, and dies, and never comes again.

And all the while, the trees were balding

This is an intriguing story from Nature about another location in the brain, this one involved in metaphorical and abstract thinking. When the left angular gyrus, a small area in the cerebral cortex, is damaged, people lose the ability to extract a broader meaning from a figure ot speech. Such people tend to place a literal intepretation on sayings such as “reach for the stars” or “the grass is always greener on the other side.” The left angular gyrus is near parts of the cortex that process sight, sound, and tactile sensations, so maybe it is a place where synthesis of dissimilar sensory information can take place. Metaphor is fascinating to me, partly because I work in information technology and I’ve noticed that so many of the things we talk about in IT are more or less abstract or at least non-physical, and we talk about them in terms of analogies with more concrete things. (Just think for a minute about hotlinks, cookies, and bounced email, for starters.)

http://www.nature.com/news/2005/050523/full/050523-9.html

(The header for this post is a quote from Galatea 2.2 by Richard Powers; it comes from a part of the book where the narrator is describing the economy involved in this kind of metaphorical thinking. The AI program he has been working with has come up with a figure of speech for old age that involved leaves falling: trees were balding, the mind shed its leaves. “…the neurodes storing winter lent half their economical pattern to the neurodes signalling old age.” Fascinating stuff, metaphor, however—or wherever—it arises.)

Infinite diversity in infinite combinations

It takes all kinds, my father would say when I was growing up. It took me awhile to realize that this is literally true for living things. Look at the different kinds of plants and animals there are, each adapted reasonably well to its local environment, and thriving there while other creatures exploit other niches. Living things have different tool-kits, shaped by the conditions under which they evolved, that allow them to thrive. Think of the quicksilver brilliance of a hummingbird on the wing, the aggression of an ostrich protecting a nest, the graceful swoop of a pelican and the ungainly waddle of a well-insulated penguin, the raucous clamor of crows. Which one is the best bird? Well, best for what? Each one is better than others at living in its own environment.

I wonder sometimes if there’s a metaphor there for human personality traits. Personality traits are like different tools that are distributed across the population, and each one offers advantages and disadvantages depending on the situation. It really does take all kinds.

Are there any truly bad personality traits? Perhaps not. (There are truly negative behaviors, but that’s not the same thing, although traits obviously predispose us toward certain behaviors.) Maybe there are unhealthy extremes for each trait, but by and large each one helps you sometimes and hurts you at others. I think we call the same trait by either a positive or a negative name depending on who has it, whether we’re finding it useful or annoying in the current situation, and to some degree our history of interacting with people who have that particular trait.

The art of building successful families or workplaces or teams of any kind has a lot to do with finding a way to use the strengths of a variety of personality types, not trying to make everyone match some ideal. Think about going to the video store with friends. If everyone’s really opinionated, you might never find something everyone can agree on. On the other hand, an easy-going crowd can drift for a long time saying, “Well, that would be nice” or “Whatever you want” until you all leave the store, irritated, with a movie that no one really wanted to see but everyone thought someone else wanted to see.

This is obvious, of course, but there are areas these days where we sometimes think in terms of ideals that we should all try to reach. For example, psychopharmacology is probably going to continue to come up with new ways to tinker with our selves; some biochemical interventions are obviously beneficial, but if we move toward shaping personality rather than curing illness, we will at some point need to realize that there isn’t any one ideal personality that will be happy and productive in all situations. Psychiatry and related sciences seem bent on describing variations from normal as syndromes or disorders, ignoring the possibility that there is no such thing as normal. Since each trait, and each constellation of traits that makes up a personality, has its good and bad points, none is trouble-free and probably none is completely negative.

Another area where this comes into play is genetics. When people talk about the potential for genetic manipulation that will allow us to select particular features of our children, they tend to assume that there is one desirable set of characteristics that everyone will want his or her children to have. But when you think about it, this might turn out to be remarkably hard to do. First, I don’t know if it’s ever going to be possible to figure out how to select for something as broad and subjectively identified as personality characteristics. Even something like intelligence comes in many flavors and possesses many components, and is not determined by a single gene or even a simple combination of genes. Leaving that aside, how on earth would we choose what kinds of humans to produce, given the chance?

Would we favor extroverts over introverts? The practical over the innovative? The builders or the dreamers? The cautious or the daring? I wouldn’t want to be responsible for choosing any one of these over the others, because I think every personality trait is a mixed blessing. And if people did want to choose, they would choose differently. There certainly are dumb things we can and maybe will do if we start trying to engineer personalities, either through pharmaceuticals or through genetics, but I don’t think we’ll create a uniform race of superpeople. Even if we could agree on their attributes, and even if we could figure out how to create them, they’d struggle with the downside of their strengths the same as the rest of us.

In short, there is no ideal and maybe not even a normal. We vary in the traits we possess and the strength of each one. The environments we’re raised in shape our inborn tendencies in different ways. And that’s as it should be. The diverse combinations that result can be a source of strength, not a liability.

The challenge is to find the strengths in our diversity. We often feel that life might be easier if everyone were just like us. You think how many mistakes could be avoided if everyone paid careful attention to details like you do, or you wish other people would try to get the big picture and stop harassing you with those little details. It’s usually easy to appreciate your own traits, and harder to appreciate those of others.

Obviously our traits are more malleable than the bright plumage of the hummingbird or the caw of the crow. We live in a complicated environment that requires different things from us at different times. We can learn how to flex, how to be the best of who we are and still work around our weak spots, sometimes borrowing insight from those who are not like us.

This is often easier said than done. Sometimes when you’re dealing with people who are bafflingly or annoyingly different, it’s tempting to shrug and give up on understanding, much less learning from, their take on the world. But if we’re smart and charitable, we try to figure out how the world looks to them rather than just assuming they’re malicious or crazy. On the other hand, sometimes we don’t think they’re crazy; sometimes we admire them and wish we were more like them. Either way, we have to stretch to learn other ways of experiencing the world.

My friend Jean suggests that one way to do this with people close to you is to try to find positive or at least neutral terms to describe the other person. You know how this naming of characteristics goes. For example, we have the courage of our convictions. Those other guys are stubborn or even downright pigheaded. I value good living; he’s a spendthrift. I’m thrifty; she’s a tightwad. I’m meticulous about details; you’re a fussbudget. This is something of a parlor game that you can use to translate personal ads and resumes. My friend’s idea is, for example, to try not to think of your partner or child or friend as flaky, and to ask them to reconsider their claim that you’re timid. “Spontaneous” and “prudent,” respectively, are much more generous assessments of each other’s characters.

Of course, different personality types tend to favor certain values and behaviors, and you need to negotiate the ground rules for behavior within a relationship, no matter what kind of personalities are involved. The whole process is easier, though, if you can shift your perspective somewhat, and one way to begin is to change the labels you put on things.

Note that I’m not talking about a fuzzy-headed effort at enhancing self-esteem by never saying anything bad about other people. For starters, there are some behaviors that are in my opinion required of everyone, and I’m not trying to whitewash misbehavior by blaming it on the personality someone was blessed and burdened with. I’m talking about balance. You probably already have some negative words for the things that irritate you about other people. The best way to learn how to accommodate the inevitable differences in people is to try to understand how it looks from the other side. Maybe this will ease the friction in a family or at work, and at its best, it can give you a glimpse of another way of seeing and evaluating the world, something more or less foreign to you but still understandable if you make the effort.

Of course, we’re sometimes attracted by someone’s spontaneity and then frustrated by his or her flakiness. This is another place where the alternate names for a single trait come into play. A charming playfulness turns into airheadedness; a protective streak comes to seem controlling; someone with a strong sense of responsibility winds up looking like a fuddy-duddy. Again, the good and the bad are opposite sides of the same thing. If you want a mate who is willing to take over paying the bills, you’re going to have to put up with times when he or she looks to you like a killjoy. I think one of the richest experiences of growing older is to learn to accept things and people as wholes, in all their complexity.

In some cases, I wonder if there are biological underpinnings to particular characteristics, so that the pluses and minuses reflect an inevitable trade-off. You may have read the recent news story about the gonopodia of mosquitofish: larger ones attract the ladies, and thus enhance reproductive success, but they also make it harder to evade predators. You can’t be both a babe-magnet and the speediest swimmer. Or to take a human example, I’m fairly sensitive to emotional and other stimuli, so it takes me awhile to adapt to new situations. While I enjoy traveling and seeing new places, I have to do so carefully, because the discomfort of strange surroundings can wipe out the joy of discovery. I might dream of adventures, but I have to accept that, like the Mole in The Wind in the Willows, I am by and large a creature of the garden-plot. On the other hand, I can derive a great deal of enjoyment from the most everyday things. I don’t need to spend a lot of money or go to exotic places to find joy and pleasure in the mundane. (And as Mole realizes, the pleasant places that surrounded him “held adventure enough, in their way, to last for a lifetime.”) I don’t know if there is a physiological basis for this sensitivity to stimuli, but I do think that the good and the bad aspects are linked and I probably can’t have one without the other.

I think the key thing to realize is that everyone is trying to perfect a kind of balancing act, to live with the mixed bag of attributes that make up who he or she is. We are, I hope, never going to make humanity over into a uniform personality, and we need to learn to live with what we’ve got. The best way to look at it might be similar to the Vulcan idea from Star Trek of infinite diversity in infinite combinations, and, as Spock once said, the way our differences combine to create meaning and beauty. Think of the grace and tact of the wishy-washy among us, for example, or the strength and tenacity of the loudmouths. Remember the steady reliability of the worry-warts in your life, or the joie de vivre of the unpredictable. Even if there are some personality types that you simply can’t get along with in close quarters, be glad that there are people out there who are different from you and willing, even happy, to do all the jobs and fill all the roles that you can’t imagine yourself in. It’s not always an easy way to look at life, and maybe I’m dreaming to think we can manage it. But then, I do tend to be an idealist and a dreamer. You could call me a visionary, or you could call me impractical, or even a crackpot. I like the word “dreamer” though. It can go either way.

Memory as a bridge between your selves

Recently I came home from work with my head so full of the next day’s chores that I couldn’t relax until I had made a list of all I needed to do. The list was full of cryptic items like “foop email in boilers?”. Looking at the jotted notes, I thought that in five years, probably none of this would make sense to me any more; it would be as if the list had been written by someone else. In the end, this speculation about my five-years-from-now self was beside the point, because my next-morning self couldn’t find the list.

That incident neatly captures our uneasy relationship with future and previous selves. Years ago I had a friend who liked to think of his choices in terms of making his future self’s life easier, in part by keeping as many options open as possible (e.g., avoiding going deeply into debt). This is an optimistic take on the relationship with our future selves, although aside from the obvious things like enough money to live on, it’s sometimes hard to know what your future self will want. And sooner or later your options must narrow; even not choosing winds up being a choice. Montaigne recognized these other selves with a more rueful attitude when he wrote that “I now and I anon are two several persons; but whether better, I cannot determine. It were a fine thing to be old, if we only travelled towards improvement… .” Indeed.

Even more interesting, though, is the way our past selves can confound us. Last year when my younger son was preparing to move away from home for grad school in another state, he told me that he sometimes thinks his mission in life is to do things that will later baffle himself. As evidence, he produced a gallon milk jug full of sand that he had no recollection of ever acquiring. I know exactly what he’s talking about; the reason I speculated about that to-do list was that other lists had floated to the surface months or years after I wrote them, and sometimes it feels as if they were written by someone else. Last year I made the following list of words, evidently seeds for some essay or meditation that never saw the light of day: faith, stories, twilight, food, evening, street. An evocative list, perhaps, but as devoid of meaning as if the words had appeared at random during a Scrabble game (which they might have, for all I know to the contrary). I’m reminded of Robert Browning’s explication of one of his poems: “When I wrote that, God and I knew what it meant; now God alone knows.”

Some of our past actions puzzle us because the behavior wasn’t important enough to register very deeply in the first place. Several years ago I ran into my older son on campus and we came back to my apartment for something to eat. There we found a jar of peanut butter in the dishpan with a few dishes waiting to be washed. My son was amused (“I want some of whatever you were smoking”), but I was curious about how that peanut butter got there. I could remember having peanut butter on toast for breakfast, and it was a new jar of the kind of peanut butter that separates and needs to be stirred. It’s hard to stir it without dribbling some down the side, and I guess that I took the jar over to the dishpan to wipe it off with the dishcloth. Why I then set it down in the dishpan is anyone’s guess.

It’s not exactly that I forgot where I put the jar; I wasn’t really aware of it in the first place. It wasn’t very important, and I was on autopilot. There’s often confusion when the conscious mind demands an accounting from the unconscious, demanding “Where did I set those keys down?” In my experience, a big part of being organized is setting up your surroundings so that you can unconsciously and by habit do things that will make sense later.

Other things register in our consciousness but don’t warrant saving in long-term memory. There are plenty of things I do at work that fit into this category. I’m a technical writer, and the documents that we work on come with logs that tell you who worked on them when. Sometimes I wonder who made a particular change, or think of something that needs to be fixed and find that it’s already done, and am surprised to look in the log and find that it’s my own work. I edit hundreds of documents every year, and look at hundreds more that are edited by my co-workers, so it makes sense that much of my work resides in short-term memory and then gets flushed periodically. If I remembered every single edit I made, I wouldn’t have room in my brain for the important things, like my family’s birthdays and the dozen or so passwords that are required for my online existence, or the names of the half-dozen teams that the Indiana University men’s basketball team played on its way to the NCAA championship in 1987. You can’t possibly remember everything, and so we have to let some things go.

John Locke proposed that our personal identity is based on our memories of ourselves: we are who we remember ourselves being. Strictly speaking, this doesn’t take into account the necessity for letting some things drop out of our memories as we accumulate more and more experiences. My identity doesn’t feel compromised by the fact that I can’t recall what I had for breakfast on this date six years ago. However, with the proviso that some forgetting is normal and even essential, I tend to agree with Locke. Some memories do seem tied up with my identity, and the loss of them does seem to diminish my sense of who I am.

I think sometimes we forget who we used to be because those previous selves are connected to states of mind that it’s hard to re-enter after they have passed. Who we are at a certain place and time—or maybe more accurately, what it feels like to be who we are—is dependent on things like who we were spending time with and talking to, what we were hearing about on the news, what the weather was like, what we were eating, the route we took to work every day. The matrix of thoughts and associations and conversations and routines is not our identity exactly, but it’s a very strong link to what our identity felt like to us. A complex interplay of biochemistry and emotions plays a major role in our actions, and these things really are a part of our identity. It can be hard to understand who we are, or were, without remembering these factors.

William James wrote about what it is that makes the stream of thought continuous in each of us so that we know we are the same person over time. In particular, he talks about the way we pick up the thread of consciousness again after sleep. Even if we know what was in someone else’s mind when he went to sleep, we can’t reconnect with his earlier thoughts the way we do with our own. James distinguishes between the two things by saying that we remember our own earlier state, while we can only conceive of another person’s: “Remembrance is like direct feeling; its object is suffused with a warmth and intimacy to which no object of mere conception ever attains.”

I have sometimes thought that some of my earlier selves might as well have been strangers for all I could remember of what they were thinking, but if James is right, that’s not quite true. We probably seldom feel about our own past exactly the way we would about a story that a stranger told us about his past. There’s probably at least a little bit of that warmer feeling even toward past events that we remember only imperfectly. Even that scrap of paper with the list of words is recognizably a part of me, simply because I know that I’m always jotting things down on scraps of paper and the backs of shopping lists.

But the strength of that warmth and immediacy lessens as time goes by and we forget the details of our circumstances. Or maybe we misremember how we felt at the time or what our rationale was for whatever mystifying decision we came to. A particular past self feels further and further away, until at some point we have lost a part of ourselves.

Of course, it’s not only past selves that we can lose. As we grow older, we realize there are some things we will never be or do. The future self that lives in Europe or has a PhD or knows how to speak five languages slowly fades away and one day we realize it’s lost. This is a foretaste of the eventual loss of all our future selves. Perhaps that’s why I protest against losing touch with my past selves. Or maybe it’s because I’m a writer, and I take to heart Christopher Buckley’s observation that “A writer’s life is his capital.” I value experience, and I don’t want to forget any of the experiences I’ve gathered so far. If we have to let some things go, it’s good to at least retain signposts to help us access some of them again.

Maybe this is why people hang onto old letters or ticket stubs or the keys to old cars. Just holding these physical objects in our hands can call to mind the situations in which they were new to us: the 22-cent stamp, the handwriting of a lost love, the heft of the key in our hand. Walking around an old neighborhood (assuming you are fortunate enough to have a pleasantly memorable old neighborhood that hasn’t been utterly transformed by intervening years) can let loose a flood of memories. Music and smells are also powerful stimuli to this kind of memory.

Maybe that’s why we keep journals, too. My older son recently gave me a practical example of how useful this can be: he keeps notes as he writes code, so that if he has to go back and revisit the code later, he doesn’t need to work through his whole problem-solving process again to figure out why he programmed something a particular way. Most of us can probably see the usefulness of this: immersed in a task, you hit upon some process that makes perfect sense at the time, but later you (and probably your co-workers) wonder what on earth it was all about. I can almost feel a click in my mind later when things fall into place and I remember the sequence of thoughts that led to a particular workaround or decision. A journal helps you to reach that state much more quickly. Diaries about our personal lives can have the same effect; they can help you take a step closer to that immediate connection with your earlier self that James talked about.

In the months before my first marriage, I carried around a spiral-bound notebook full of to-do lists for the wedding, notes about tux rentals and caterers and music, notes about the plans that my first husband Andy and I had for setting up a household together, and a sort of a crude day planner. This thing was lost to my sight for the better part of 20 years, and when it resurfaced 5 or 6 years ago, I was curious about what glimpses it would offer of my earlier self, who by then appeared somewhat puzzling to me.

I was 17 when I decided to venture into marriage, child-rearing, and what turned out to be a brief stint at back-to-the-land idealism. I thought I remembered the facts well enough, but I couldn’t really get inside the head of that naive teenager. What on earth made me think that I could live among the cows and chickens when I had never lived outside the city and didn’t even enjoy camping all that much, for example? I opened the notebook with high hopes for reconnecting with that earlier self; I found a fascinating blend of nostalgia and bemusement.

Some of the things in the notebooks were bewildering at first but ultimately understandable. Amidst all the flowers and white satin, I found a note to myself to buy a box of chocolate-covered cherries and a snorkel. This had me scratching my head for a moment, but I realized these were undoubtedly usher gifts for my younger brothers, one of whom is fond of chocolate-covered cherries. The note “Chicken Little Day” for a day in July made me pause for a moment, but I remembered that it was a reference to the day of Skylab’s fiery return to Earth.

(On the other hand, some things are utterly opaque to me now. I have a list that is headed “To add to Andy’s mother’s guest list” but instead of containing names, the list contains only the single baffling entry “wicker basket (instead of serving bowl)”. Maybe some parts of our earlier selves really are strangers to us. Luckily that’s not a very important part.)

There were more important hints of my earlier self, though. For example, I had the idea that I had been becoming more and more of a worry-wart as I got older as an unfortunate reaction to the inevitable ups and downs of life. In the notebook, however, I can see that I had an impressively detailed “Wedding worries” list that ran to no fewer than 14 addenda, and this for a simple low-budget wedding (no sit-down dinner, no alcohol, no limousines, no swans). So maybe I was this much of a worry-wart all along.

I had forgotten the tremendous enthusiasm with which I tackled my new life, the lists I made of the skills Andy and I would need to acquire and the things we hoped to do. I had also forgotten that I had planned to move out of my parents’ house before the wedding and live on my own, for reasons that I considered so obvious at 17 that I didn’t write them down, which makes them hard to reconstruct now. (Diaries have their limits, after all.) This planned move was a surprise to me; it never happened and I had forgotten that it was even contemplated. Maybe I was trying to prove my maturity to my parents, but I guess it’s just as well I didn’t carry it too far. I can’t imagine now what I would have lived on in a place of my own, since I was in college and working half-time. My list of assets was touchingly optimistic: $800 (with $800 crossed out and $605 written instead; even in 1979 this was not a lot of money), a bicycle, a record player, a sewing machine, two plants (one hanging). After all my notes about the apartment search, I wrote: “When you unpack, remember, the unicorn comes first!” I had totally forgotten a small glass unicorn that Andy had given me, but it was a precious object to me at the time.

The notebook did provide a portal through which I could catch a glimpse of my younger self. I could see that I had been willing to brave the cows and the chickens because I believed in giving myself wholeheartedly to a cause I thought was good and a relationship that I cherished. This is not news from nowhere, of course; I can see that same passion for throwing myself into things at work in my life now. Over time, however, it’s easy to forget the connection, to think you’ve changed more than you have. I may describe myself differently over the years, but the underlying traits are not that different in my younger and older selves. In short, reading that notebook re-introduced me to another and very different time of my life, and helped me to understand myself a bit better. Past experiences that had been growing misty are sharper in my mind now. I’m glad my all-those-years-ago self carefully put the notebook away in a box so that a later self could learn from it.