We are always changing. Literally. In a region of the brain called the hippocampus, about 3 percent 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 our 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 Pokemon 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.

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.

I feel as if we are in crisis like nothing in my lifetime, and I know I'm not alone.

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 we struggle against it every inch of the way.

Tribune News Service

每一天，一個全新的你

我們始終處于變化之中，這種變化實實在在。我們大腦中有個叫海馬體的區域，每個月都有3%的神經細胞會被替換掉。紅血細胞在為人體服務數月后會失去活力，然后會被新的紅血細胞取代。蛋白質也有保質期，過期后它們就會被分解，為新的所取代。你很難從身體里找到哪怕一個分子是自你出生就存在的。

這種想法讓我很不安——即現在坐在這里的我注定要被全新的分子重構。這也許會讓任何人都感到不安。心理上，我們都抗拒這種變化的必然性，我們都一廂情愿地相信，現狀會永遠繼續。這不僅僅是一個學術問題：它也關系到未來幾周后即將出現的新世界。

如果你從事一項“縱向”研究——像科學家那樣，追蹤受試者數十年，并在不同的時點評估他們的性格和價值觀，你會發現，自始至終他們的變化速率非常穩定。我們都在不斷進化。然后，你問你的受試者一個回顧性的問題：在過去10年中，你的性格改變了多少？價值觀改變了多少？從青少年到老人，他們都會給出相對準確的評估。

現在，你再問你的受試者一個預測性問題：你覺得未來10年自己的性格和價值觀會改變多少？人們通常會低估改變的程度。他們認為當下的自己會永遠如此。

比利時科學家若爾迪·霍爾迪巴克和他的同事首先發現了這一現象。在2013年《科學》雜志上發表的一篇論文中，他們將其稱為“歷史終結錯覺”。人們承認過去的變化，但拒絕接受未來也會同樣變化的道理。在人們的頭腦中，歷史終結于當下。

這種現象反映在我們對品味和社交模式的認知上。誰是10年前你最好的朋友？一個你已多年未曾聯系的來自蒙古的某個人。再預測一下，誰會是你10年后最好的朋友？那當然是我現在最好的朋友了。你很難想象現在對你如此重要的關系，會和過去很多關系一樣，逐漸淡化成毫不相關的事。10年前你最喜歡的樂隊是哪個？也許不過是某個曇花一現的組合，而現在你可能都羞于被別人發現在聽他們的音樂。那么10年后呢？當然是你現在最喜歡的樂隊——嘿，他們的音樂會經久不衰。

從直覺上說，這不無道理。人們雖然能記得過去具體的改變，卻很難想象未來的具體變化。我們怎么能夠預期自己喜歡10年后出現的新歌手？他沒準現在還在讀中學呢。但這種思維局限顯然不止于具體事情；我們很難預測自己“作為一個人會有多大改變”。

霍爾迪巴克和他的同事發現，這種歷史終結錯覺會讓人在經濟方面做出糟糕的決定。要是讓你現在去聽自己10年前喜歡的樂隊的演唱會，你打算付多少錢？“他們嗎？2美分吧。”要是讓你10年后去聽你現在最喜歡的樂隊的演唱會，你愿意付多少錢？“很多。到那時他們會更棒?！比藗兓ㄥX除掉紋身的例子，最能反映歷史終結錯覺的經濟行為后果——誰能想到你對“口袋妖怪”紋身的想法會發生改變？

我們認為當下的自己已經定型，最終演變成了我們應該成為的自己。我們會認為自己是過去所有變化的終極產物；在我們看來，這種緩慢的演變絕不會繼續發生。

在種種情形下，我們會發現當下如此真切強大，以至于我們很難想象，它會和那些我們只有朦朧記憶的過去一樣轉瞬即逝。但——這就是我鋪陳到此的結論——我們需要更具想象力。

我感覺我們就像身處一場空前的危機之中，而且我知道，有如此想法者不只我一人。

為了對抗這種絕望，我每天都提醒自己歷史終結錯覺的存在。

(本段的翻譯有獎征集中)

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