We are always changing. Literally. In a region of the brain called the hippocampus, about 3% of neurons are replaced each month. Red blood cells get a little overripe after a few months in service and are trashed in favor of new ones. Proteins have a shelf life, after which they are degraded and new copies are substituted. You'd be hard-pressed to find a single molecule in your body that was there at birth.
This unsettles me — the idea that the me sitting here is destined to be reconstituted with all new molecules. It would probably unsettle anyone. On a psychological level, we are all resistant to the inevitability of change, all biased to believe that what is, will always be. This isn't just an academic concern; it's pertinent to the new world dawning in a few weeks.
If you carry out a "longitudinal" study — follow your subjects for decades, as scientists have done — and, at various points, assess their personalities and values, you'll find that there's a steady rate of change throughout. We're all constantly evolving. Then try asking your subjects a retrospective question: How much has your personality changed in the last decade? What about your values? From teenagers to grandparents, people give relatively accurate assessments.
Now, instead, ask your subjects a prospective question: How much do you think your personality and values will change in the next decade? People systematically underestimate the extent. They believe that the person they are today is the person they will always be.
Belgian scientist Jordi Quoidbach and his colleagues first discovered this phenomenon. In a 2013 Science paper, they called it the "end-of-history illusion." People recognize the changes they've undergone but resist the idea that change will continue unabated into the future. Intellectually, history ends with the present.
This phenomenon is reflected in how we perceive our tastes and social patterns. Who was your best friend 10 years ago? Joe Blow from Outer Mongolia, to whom you haven't spoken in years. Who do you predict will be your best friend 10 years from now? Well, of course, my current BFF. It's hard to imagine that a relationship that so matters in your present could drift into irrelevance, as so many have in the past. What was your favorite band 10 years ago? Some flash-in-the-pan group you'd be embarrassed to be caught listening to today. And a decade from now? Well, your current favorite, of course — hey, this is music for the ages.
It makes intuitive sense that, while remembering specific changes from the past, people have trouble picturing specific changes in the future. How can we contemplate liking some new singer in a decade who probably is in middle school now? But this limitation evidently extends beyond specifics; we have trouble contemplating how much we will "change as a person."
Quoidbach and his colleagues found that this end-of-history illusion produces bad economic decisions. How much would you pay to go to a concert by that band you loved a decade ago? "Them? Two cents." How much would you pay for tickets to a concert in a decade by your current favorite? "Lots, they'll be even more awesome by then." There's no better example of the economic consequences of the end-of-history illusion than people paying to remove tattoos — who would have guessed that your opinion would change about those ink portraits of Pokeman characters?
We view our present selves as having finally arrived, finally evolved into the person we were always meant to be. We can recognize that we are the end-product of all those changes over the years. But no way will this slow evolution just keep going, we think.
The end-of-history illusion applies to issues larger than the wisdom of tattooing. Consider political scientist Francis Fukuyama's 1992 bestseller, "The End of History and the Last Man," which posited that earth had achieved its apex form of government — Western-style democracy — ushering in peaceful stability. Not so fast. Since then, we've had 9/11, the rise of those un-Western, undemocratic folks from Islamic States, plus some wars between functioning democracies. Or consider the (probably apocryphal) statement by the 19th century head of the U.S. Patent and Trademark Office., predicting its future irrelevance: "Everything that can be invented has been invented."
In various ways, then, we tend to find the present to be, well, so powerfully present, that it's hard to imagine that it will prove as fleeting as all those dimly remembered pasts. But — here's the conclusion to my long windup — we'll need to be more imaginative in the new year.
I feel as if we are in crisis like nothing in my lifetime, and I know I'm not alone. A demagogue, riding on lies and the bullying of underdogs, despite losing by more than 2 million votes, is about to take power; his Cabinet appointments suggest that things will be as bad as we feared. We have lost our country, and it seems like we will never recover it, or recover from this, that we are powerless — "the media are his lapdogs, he'll control both Houses, he's a master at punishing dissenters."
To fight this despair, I remind myself daily of the end-of-history illusion. I try to both think and feel the fact that the present about to cave in on us eventually will be the past. We can hasten that process if, as a New Year's resolution, we struggle against it every inch of the way.
Robert M. Sapolsky is a professor of neuroscience at Stanford University. He is a contributing writer to Opinion.