WEBVTT - Ep82 "Why Do Your 30 Trillion Cells Feel Like a Self?" Part 1 0:00:05.400 --> 0:00:09.440 Although every cell in your body changes such that you 0:00:09.520 --> 0:00:14.440 are never again the same person physically, and your neural 0:00:14.480 --> 0:00:17.680 networks change every hour of your life as you absorb 0:00:17.760 --> 0:00:23.240 new experiences. Why do you have an illusion of consistency, 0:00:23.360 --> 0:00:26.880 as though you're the same person you were a week 0:00:26.880 --> 0:00:29.800 ago or a year ago. What does this have to 0:00:29.840 --> 0:00:34.640 do with the mythical watercraft of the Greek demigod Theseus? 0:00:35.360 --> 0:00:39.360 What is the end of history illusion? And why do 0:00:39.440 --> 0:00:43.000 you go through so much trouble to make things comfortable 0:00:43.159 --> 0:00:46.879 for your future self even though you don't know that 0:00:47.000 --> 0:00:50.159 person and you can be guaranteed that that person is 0:00:50.200 --> 0:00:52.640 not going to feel the same way you do now. 0:00:53.440 --> 0:00:57.400 And if there were an afterlife, what age would your 0:00:57.480 --> 0:01:04.920 deity dial you to for living out eternity? Welcome to 0:01:04.959 --> 0:01:08.360 Inner Cosmos with me David Eagleman. I'm a neuroscientist and 0:01:08.400 --> 0:01:12.160 an author at Stanford and in these episodes we dive 0:01:12.240 --> 0:01:15.600 deeply into our three pound universe to uncover some of 0:01:15.640 --> 0:01:30.080 the most surprising aspects of our lives. Today, we're going 0:01:30.120 --> 0:01:33.440 to talk about the notion of having a self and 0:01:33.600 --> 0:01:36.520 what that has to do with our memory. And this 0:01:36.600 --> 0:01:38.280 is a big topic, so we're going to do this 0:01:38.400 --> 0:01:41.920 in two parts. Today, we're going to talk about how 0:01:42.000 --> 0:01:45.680 and why we think of ourselves as lasting through time 0:01:46.120 --> 0:01:48.560 and what that has to do with our memories. And 0:01:48.800 --> 0:01:51.560 in next week's episode, part two, I'm going to talk 0:01:51.600 --> 0:01:55.320 with my colleague, neuroscientist Michael Levin, one of the most 0:01:55.520 --> 0:01:58.600 energized and original thinkers in the field, and I'm going 0:01:58.640 --> 0:02:01.040 to talk with him about the way which memories can 0:02:01.120 --> 0:02:04.440 be thought of like little creatures of their own that 0:02:04.640 --> 0:02:08.440 carry messages in a bottle from one version of you 0:02:08.720 --> 0:02:13.280 to the next. So for today, let's start in ancient Greece, 0:02:13.440 --> 0:02:17.480 where the historian Bluetarch wrote about a tough puzzle that 0:02:17.520 --> 0:02:20.960 had been floating around in the Greek philosopher circles, and 0:02:21.000 --> 0:02:24.639 they were all arguing about it. The puzzle was this, 0:02:25.320 --> 0:02:30.240 imagine the ship of Theseus. Theseus was the hero in 0:02:30.280 --> 0:02:33.160 Greek mythology who slayed the minotaur. The idea is that 0:02:33.360 --> 0:02:37.520 Theseus and his crew of Athenians sail back from Crete 0:02:37.560 --> 0:02:41.760 and dock his wonderful ship. But then the ship sits 0:02:41.800 --> 0:02:44.760 in harbor for a long time and one of the 0:02:44.800 --> 0:02:48.919 planks starts to rot, so it gets replaced with new 0:02:49.000 --> 0:02:52.359 and stronger timber, and then that happens with another plank 0:02:52.440 --> 0:02:56.240 on the ship, and another, and eventually, with enough time, 0:02:56.720 --> 0:03:01.280 the entire ship gets replaced, meaning that a single plank 0:03:01.680 --> 0:03:04.079 is the same as what it was when the ship 0:03:04.400 --> 0:03:08.000 first docked. And the question is is it the same 0:03:08.400 --> 0:03:11.800 ship of Theseus or is it not his ship anymore? 0:03:11.840 --> 0:03:16.560 Because every single part has been replaced. Plutarch suggested that 0:03:16.800 --> 0:03:19.720 half the philosophers in Greece argue the ship is still 0:03:19.760 --> 0:03:23.880 the same ship because it retains its identity despite the 0:03:23.960 --> 0:03:27.160 changes to its parts, and the other half of philosophers, 0:03:27.200 --> 0:03:30.320 he suggested, argued that the ship is not the same 0:03:30.360 --> 0:03:33.360 ship because no part of it is the same. So 0:03:33.960 --> 0:03:37.680 for thousands of years, the Ship of Theseus has been 0:03:37.720 --> 0:03:42.640 a thought experiment that surfaces these tough questions about identity 0:03:42.760 --> 0:03:46.160 and change. By the way, there are lots of variants 0:03:46.200 --> 0:03:49.200 on this. My father had an axe in the garage, 0:03:49.440 --> 0:03:51.160 and he would always hold it up and tell me 0:03:51.760 --> 0:03:56.040 this was actually George Washington's axe. Oh, but the handle 0:03:56.080 --> 0:03:58.920 has been replaced twelve times and the axe head has 0:03:58.960 --> 0:04:02.600 been replaced for times. It was obviously a joke, but 0:04:02.640 --> 0:04:05.440 it got me thinking from a young age about the 0:04:05.520 --> 0:04:09.760 nature of identity in the face of change. Does something 0:04:09.840 --> 0:04:14.400 retain its identity if all departs change? Now, why would 0:04:14.440 --> 0:04:18.279 a neuroscience podcast care about the Ship of Theseus or 0:04:18.480 --> 0:04:23.599 George Washington's acts. It's because that kind of wholesale replacement 0:04:23.760 --> 0:04:28.279 is precisely what's happening to your brain and your entire body. 0:04:28.960 --> 0:04:32.039 A big part of the mystery of selfhood has to 0:04:32.080 --> 0:04:34.600 do with the fact that all the pieces and parts 0:04:34.640 --> 0:04:40.360 that make up you are constantly turning over. Your body 0:04:40.400 --> 0:04:43.880 is built out of thirty trillion cells, and this is 0:04:43.960 --> 0:04:49.080 just cellular stuff. Every bit of the cells has a lifetime. 0:04:49.560 --> 0:04:52.599 Most of the cells die or subdivide at some point. 0:04:52.680 --> 0:04:55.440 But even those cells that stick around your whole life 0:04:55.480 --> 0:04:59.280 and don't divide, like your neurons, they're totally different every 0:04:59.320 --> 0:05:03.120 few years. Why because brain cells aren't made out of 0:05:03.120 --> 0:05:06.960 something stable like metal or cement. Instead, they're made out 0:05:07.000 --> 0:05:10.960 of the basic proteins and lipids and other molecules that 0:05:11.080 --> 0:05:13.599 make up any cell in the body, and those things 0:05:13.680 --> 0:05:18.360 aren't particularly stable. So every single neuron and every cell 0:05:18.360 --> 0:05:22.320 in your body is like the Ship of Theseus. Every 0:05:22.360 --> 0:05:25.600 part of it is getting rebuilt all the time, one 0:05:25.720 --> 0:05:28.640 planket a time, or in this case one molecule at 0:05:28.680 --> 0:05:32.359 a time. The pieces and parts of the cell have 0:05:32.520 --> 0:05:36.200 no meaningful stability, and so a big part of all 0:05:36.279 --> 0:05:41.200 that cellular machinery is simply building and rebuilding and rebuilding, 0:05:41.760 --> 0:05:45.680 and in this way everything gets replaced. So who you 0:05:45.839 --> 0:05:49.800 are physically changes all the time, and the question is 0:05:50.240 --> 0:05:55.520 how does your self stay intact over this changing substrate. 0:05:56.279 --> 0:06:00.720 The answer is it's not clear that it does. But 0:06:00.880 --> 0:06:07.520 cognitively you have this illusion of stability. You are one being. 0:06:07.680 --> 0:06:10.560 You've spent your whole life with a fixed history, as in, 0:06:11.000 --> 0:06:14.680 I grew up here, here's my name, this was my hometown, 0:06:14.839 --> 0:06:18.000 these are my parents. This is how my trajectory in 0:06:18.040 --> 0:06:20.760 life has unfolded, leading me from here to there to there. 0:06:20.800 --> 0:06:23.039 And so we tend to hold the impression that our 0:06:23.440 --> 0:06:27.800 identities are something very stable, but in fact who you 0:06:28.120 --> 0:06:31.680 are drifts in this light. It's always struck me as 0:06:31.720 --> 0:06:34.520 funny to think about the notion of an afterlife, because 0:06:34.880 --> 0:06:38.440 what age would you be Depending on when you get there, 0:06:38.480 --> 0:06:41.240 you might be a very different person than you were 0:06:41.360 --> 0:06:44.320 even five years before that. And so all this inspired 0:06:44.360 --> 0:06:47.200 me to write a short story that's published in my 0:06:47.240 --> 0:06:50.560 book Some sum and I'm going to read that story 0:06:50.839 --> 0:06:54.640 to illustrate the questions of this episode. The story is 0:06:54.680 --> 0:06:58.680 called Prism. God resolved at the outset that he wanted 0:06:58.800 --> 0:07:02.680 every human to partippaid in the afterlife, but the plans 0:07:03.040 --> 0:07:06.919 weren't thought out to completion, and immediately he began to 0:07:07.000 --> 0:07:11.720 run up against some confusion about age. How old should 0:07:11.760 --> 0:07:15.760 each person be in the afterlife. Should this grandmother exist 0:07:15.800 --> 0:07:19.040 here at her age of death, or should she be 0:07:19.080 --> 0:07:22.800 allowed to live as a young woman, recognizable to her 0:07:22.840 --> 0:07:26.600 first lover but not to her granddaughter. He decided it 0:07:26.680 --> 0:07:29.920 was unfair to keep people the age they were at 0:07:29.920 --> 0:07:32.920 the end of their lives, when much of their beauty 0:07:33.000 --> 0:07:36.840 and alacrity had been worn down. Allowing everyone to live 0:07:36.880 --> 0:07:41.320 as a young adult proved an unviable solution, because the 0:07:41.360 --> 0:07:46.560 afterlife quickly degenerated into unbounded sexual pursuits, and at middle 0:07:46.560 --> 0:07:50.119 ages they talked only about their children and mortgages, making 0:07:50.160 --> 0:07:55.080 conversations in the afterlife. Tedious God finally landed on an 0:07:55.280 --> 0:08:00.200 ingenious solution while watching light diffract through a prism. So 0:08:00.240 --> 0:08:03.600 when you arrive here, you are split into your multiple 0:08:03.680 --> 0:08:08.440 selves at all possible ages. The you that existed as 0:08:08.480 --> 0:08:13.520 a single identity is now all ages at once. These 0:08:13.680 --> 0:08:17.520 pieces of you no longer get old, but remain ageless 0:08:17.600 --> 0:08:23.000 into perpetuity. The ewes have transcended time. This takes them 0:08:23.000 --> 0:08:26.400 getting used to The different beams of you might run 0:08:26.400 --> 0:08:29.240 into each other at the grocery store, like separate people 0:08:29.280 --> 0:08:32.480 do in earth life. Your seventy six year old self 0:08:32.840 --> 0:08:36.560 may revisit his favorite creek and run into your eleven 0:08:36.640 --> 0:08:39.559 year old self. Your twenty eight year old self may 0:08:39.559 --> 0:08:42.120 break up with a lover and a diner and notice 0:08:42.160 --> 0:08:46.160 your thirty five year old self visiting that spot, lingering 0:08:46.320 --> 0:08:50.720 on the air of regret hanging over the empty seat. Typically, 0:08:51.120 --> 0:08:53.959 the different youws are happy to see each other because 0:08:54.200 --> 0:08:57.320 they possess the same name in a shared history. But 0:08:57.600 --> 0:09:00.480 the ewes are more critical of yourselves than they are 0:09:00.480 --> 0:09:05.160 of others, and so each you quickly identifies habits that 0:09:05.240 --> 0:09:08.559 get under your skin. It's a fact of the afterlife. 0:09:09.040 --> 0:09:13.319 Don't be surprised to discover that after decomposition into your 0:09:13.440 --> 0:09:18.960 different ages, the different us tend to drift apart. You 0:09:19.080 --> 0:09:22.600 discover that the you of eight years old has less 0:09:22.640 --> 0:09:25.320 than common than expected with the U of thirty two 0:09:25.760 --> 0:09:28.840 and the U of sixty four. The eighteen year old 0:09:28.880 --> 0:09:32.200 you finds more in common with other eighteen year olds 0:09:32.480 --> 0:09:35.760 than with your seventy three year old you. The seventy 0:09:35.800 --> 0:09:38.480 three year old you doesn't mind a bit seeking out 0:09:38.520 --> 0:09:44.079 meaningful conversations with others of the same generation. Beyond the name, 0:09:44.720 --> 0:09:48.920 the us have little else in common, but don't lose hope. 0:09:49.320 --> 0:09:54.400 The shared resume of life, parents, birthplace, hometown, school, years, 0:09:54.480 --> 0:09:58.839 first kiss has a magnetic nostalgic pull. So once in 0:09:58.920 --> 0:10:02.800 a while, the different yous organize a gathering like a 0:10:02.840 --> 0:10:07.800 family reunion, bringing together all your ages into a single room. 0:10:08.120 --> 0:10:11.520 At these reunions, the middle aged will delightedly pinch the 0:10:11.640 --> 0:10:15.160 cheeks of the young, and the teenagers will politely listen 0:10:15.240 --> 0:10:18.960 to the stories and advice of the elderly. These reunions 0:10:19.320 --> 0:10:23.960 reveal a group of individuals touchingly searching for a common theme. 0:10:24.600 --> 0:10:27.960 They appeal to your name as a unifying structure, but 0:10:28.040 --> 0:10:31.480 they come to realize that the name that existed on earth, 0:10:31.960 --> 0:10:36.400 the you that moved serially through these different identities, was 0:10:36.480 --> 0:10:40.400 like a bundle of sticks from different trees. They come 0:10:40.440 --> 0:10:45.840 to understand with awe the complexity of the compound identity 0:10:45.920 --> 0:10:49.360 that existed on the earth. They conclude with a shudder, 0:10:49.840 --> 0:10:55.559 that the earthly you is utterly lost, unpreserved in the afterlife. 0:10:55.600 --> 0:11:00.600 You were all these ages, they concede, and you were none. 0:11:15.280 --> 0:11:18.040 So we're changing all the time. But why is it 0:11:18.440 --> 0:11:21.960 hard to keep track of these changes. Obviously it's because 0:11:22.280 --> 0:11:26.479 everything in our lives and our biology changes so slowly. 0:11:27.000 --> 0:11:30.160 It's like the hour hand of a clock. You can 0:11:30.160 --> 0:11:32.720 see that it's moved, but you can't see it move. 0:11:33.440 --> 0:11:36.440 In general, we can see change most readily in the 0:11:36.480 --> 0:11:39.839 growth of our children. You look back at photographs from 0:11:39.880 --> 0:11:42.240 a year ago on your phone and you can't believe 0:11:42.280 --> 0:11:44.800 how much things have changed. But it's hard to keep 0:11:44.880 --> 0:11:48.800 track of the changes in yourself. A friend of my 0:11:48.920 --> 0:11:52.080 parents went to his high school reunion, which was taking 0:11:52.120 --> 0:11:54.400 place at a hotel, and he went around looking at 0:11:54.440 --> 0:11:57.440 the different conference rooms to figure out which one was 0:11:57.480 --> 0:12:00.160 the correct class, because they were divided up by decades, 0:12:00.559 --> 0:12:02.280 And he thought he found the right room, but he 0:12:02.320 --> 0:12:05.640 popped his head in and he realized that's completely not 0:12:05.720 --> 0:12:07.880 the right room. All of those are very old people. 0:12:08.200 --> 0:12:10.360 And then he stepped back and looked at the sign 0:12:10.760 --> 0:12:13.880 and realized that indeed this was the correct room, and 0:12:14.000 --> 0:12:17.800 he too must presumably look that old to others, even 0:12:17.880 --> 0:12:21.119 if he still thought of himself as young on the inside. 0:12:21.840 --> 0:12:24.120 So it's hard to keep track of our own changes 0:12:24.120 --> 0:12:29.640 because they happen slowly. But maybe the thing that binds 0:12:29.679 --> 0:12:34.760 your self together across the ever changing physical substrate is 0:12:34.800 --> 0:12:38.560 the one thing you have that remains constant, your memory. 0:12:39.240 --> 0:12:43.040 Memory ties all these versions of you together. Memory serves 0:12:43.080 --> 0:12:47.560 as the thread that weaves through all these transformations, anchoring 0:12:48.120 --> 0:12:50.599 a sense of self. So that sounds very nice, but 0:12:50.640 --> 0:12:53.880 there's a fundamental problem with this, which is that memory 0:12:53.960 --> 0:12:58.440 itself is not stable. It drifts, and I've talked about 0:12:58.440 --> 0:13:03.760 this in several episodes. Memory is not a faithful, unchanging 0:13:03.840 --> 0:13:07.920 record of the past. It's instead a fragile brain state, 0:13:08.000 --> 0:13:11.760 and it needs to be reactivated and reconstructed each time 0:13:11.880 --> 0:13:17.120 you recall it. And in this process, memories morph, So 0:13:17.120 --> 0:13:19.600 we can't really think of them as an archive. They're 0:13:19.600 --> 0:13:24.560 more of a story which we continually rewrite. And that 0:13:24.600 --> 0:13:27.320 would be fine to keep rewriting a story, except that 0:13:27.320 --> 0:13:30.440 we assume at all times that our memories form the 0:13:30.600 --> 0:13:34.120 core of a stable identity. So let me give an 0:13:34.160 --> 0:13:37.720 example of how memories change Imagine that you and two 0:13:37.800 --> 0:13:41.040 friends were at some rooftop party and you were best 0:13:41.040 --> 0:13:43.760 friends since college, and the night was full of jokes 0:13:43.760 --> 0:13:47.320 and old stories, and you remember feeling grateful for this 0:13:47.440 --> 0:13:49.959 bond that you shared, and you can still picture the 0:13:50.000 --> 0:13:53.360 three of you by the fireplace, vowing to never let 0:13:53.400 --> 0:13:57.439 life pull you apart. But now, a year later, everything 0:13:57.440 --> 0:14:00.720 has changed. Those two guys are now enemies. It all 0:14:00.800 --> 0:14:02.920 fell apart because one of them had an affair with 0:14:02.960 --> 0:14:05.920 the other's girlfriend. So now when you think back on 0:14:05.960 --> 0:14:09.360 that rooftop party, you wonder was there something in the 0:14:09.400 --> 0:14:13.880 way he and the other guy's girlfriend exchanged glances across 0:14:13.920 --> 0:14:17.240 the room? You now think you sort of remember there 0:14:17.280 --> 0:14:20.960 were little stolen looks, there was some subtle tension in 0:14:21.000 --> 0:14:24.200 the air. Did your other friends sense that something was funny? 0:14:24.400 --> 0:14:28.000 Even then, the memory that once felt warm and comforting 0:14:28.040 --> 0:14:31.080 now feels different, like a scene in a movie that 0:14:31.120 --> 0:14:34.520 you're watching for the second time but noticing new things now. 0:14:34.640 --> 0:14:38.040 The past hasn't changed, but your present knowledge of what 0:14:38.200 --> 0:14:42.640 came after that party colors the memory and reshapes it, 0:14:42.680 --> 0:14:44.600 and it makes you question what was really there and 0:14:44.640 --> 0:14:49.760 what you've unconsciously added. Memory is slippery, like that, the 0:14:49.760 --> 0:14:53.440 more you revisit it, the more it shifts and blurs, 0:14:53.960 --> 0:14:56.960 which reminds me of a great quotation from Sigmund Freud 0:14:57.040 --> 0:14:59.600 on this topic. In eighteen ninety six, he wrote a 0:14:59.640 --> 0:15:03.320 letter to to a colleague about quote, the material present 0:15:03.480 --> 0:15:08.160 in the form of memory traces being subjected from time 0:15:08.200 --> 0:15:13.120 to time to a rearrangement in accordance with fresh circumstances, 0:15:13.160 --> 0:15:17.600 to a retranscription. And there's another quotation that I cite 0:15:17.720 --> 0:15:21.080 often from a writer named John Dufresny, who once wrote 0:15:21.120 --> 0:15:25.200 that quote, Memory is a myth making machine. What we 0:15:25.280 --> 0:15:29.440 do is keep revising our past to keep it consistent 0:15:29.880 --> 0:15:33.120 with who we think we are. So here's where we 0:15:33.200 --> 0:15:36.320 are so far. Our biology is always changing, and so 0:15:36.440 --> 0:15:39.600 the thing that crosses time is our memory. But even 0:15:39.640 --> 0:15:43.600 that changes all the time, drifting or warping or disintegrating altogether. 0:15:44.040 --> 0:15:47.560 And as a result, who you are is always on 0:15:47.640 --> 0:15:50.800 the move. Now, I've been speaking as though we're not 0:15:51.080 --> 0:15:54.320 always aware of so much change happening over time, But 0:15:54.360 --> 0:15:56.080 of course we can come to be aware of this 0:15:56.160 --> 0:15:59.280 in some circumstances. For example, when you look back at 0:15:59.320 --> 0:16:02.320 a diary entry that you wrote some years ago, it's 0:16:02.360 --> 0:16:06.240 often surprising how much you've changed, how much the person 0:16:06.280 --> 0:16:09.640 who held that pen is a bit different than who 0:16:09.720 --> 0:16:13.520 you are now. So we do confront this sometimes. But 0:16:13.640 --> 0:16:17.280 what's weird is despite the massive changes that happen in 0:16:17.320 --> 0:16:20.880 our past, we always think that there will be little 0:16:21.000 --> 0:16:24.760 change in the future. We've changed a lot up until now, 0:16:24.800 --> 0:16:27.720 but now we've settled into place and there won't be 0:16:27.840 --> 0:16:31.560 much change from here. And this is a cognitive illusion 0:16:31.720 --> 0:16:35.640 known as the end of history illusion. In other words, 0:16:35.840 --> 0:16:39.160 we can recognize significant changes in ourselves when we think 0:16:39.200 --> 0:16:42.440 about our past, but we underestimate how much we're going 0:16:42.480 --> 0:16:46.120 to change in the future. We acknowledge that we've grown 0:16:46.200 --> 0:16:50.040 or evolved, but we incorrectly assume that who we are 0:16:50.160 --> 0:16:54.200 right now is pretty close to our final or mature 0:16:54.400 --> 0:16:58.960 version of ourselves. This end of history illusion was first 0:16:58.960 --> 0:17:02.160 studied by psychology just like Daniel Gilbert and his colleagues, 0:17:02.400 --> 0:17:05.800 and they surveyed people on their values and their preferences, 0:17:05.840 --> 0:17:09.159 their personality traits, their life goals, and across the board. 0:17:09.200 --> 0:17:13.840 They found that people consistently believe that they've undergone more 0:17:13.960 --> 0:17:15.919 change in the past than they will in the future. 0:17:16.240 --> 0:17:20.359 But of course it's an illusion because change is a 0:17:20.440 --> 0:17:24.280 continuous process. In other words, if I ask you now 0:17:24.600 --> 0:17:28.000 if you've essentially finished changing in life, if you're likes 0:17:28.000 --> 0:17:30.520 and personality have settled, you'll say yeah. But if I 0:17:30.640 --> 0:17:33.719 track you down and ask you again in five years, 0:17:33.800 --> 0:17:37.600 you'll say, actually, the past five years did hold a 0:17:37.640 --> 0:17:41.080 lot of change for me, but now I've finally arrived 0:17:41.080 --> 0:17:43.560 at my stable self. And it's the same story if 0:17:43.560 --> 0:17:46.119 I survey you five years after that. And this is 0:17:46.200 --> 0:17:50.440 problematic because, for example, we're always trying to predict our 0:17:50.480 --> 0:17:54.360 future emotions. You think, oh, if I get that job promotion, 0:17:54.680 --> 0:17:57.800 or if I'm in this relationship, or if I have kids, 0:17:57.840 --> 0:18:00.520 or if I don't have kids, this will make me happy. 0:18:00.600 --> 0:18:02.520 Or if I lose this job and I have to 0:18:02.560 --> 0:18:04.440 find a new one, that's going to make me miserable. 0:18:04.560 --> 0:18:09.320 This is what psychologists call affective forecasting, where we project 0:18:09.400 --> 0:18:11.960 how we think we're going to feel, but it's based 0:18:11.960 --> 0:18:15.280 on your current limited knowledge about the world, and that 0:18:15.359 --> 0:18:18.119 might change. So why do we have an end of 0:18:18.200 --> 0:18:21.679 history illusion. Well, presumably it's because it's easier for us 0:18:21.720 --> 0:18:25.040 to see the past changes because we have memories and 0:18:25.080 --> 0:18:30.280 experiences to draw from, but future changes are hidden in 0:18:30.320 --> 0:18:32.800 the mists of the future. We don't know what they are, 0:18:33.280 --> 0:18:36.080 so let me give you some concrete examples of this. 0:18:36.480 --> 0:18:40.160 Think about the way we have our career goals. As 0:18:40.200 --> 0:18:42.399 a thirty year old, you might look back and realize 0:18:42.440 --> 0:18:46.760 your career aspirations have changed, maybe significantly, from the time 0:18:46.800 --> 0:18:49.480 you were twenty, but you might assume that your current 0:18:49.560 --> 0:18:52.720 career goals are unlikely to change much in the next 0:18:52.720 --> 0:18:55.440 ten years, even though lots of people shift career paths 0:18:55.520 --> 0:18:58.800 or professional interests throughout life. Or think about your music 0:18:58.960 --> 0:19:02.600 preferences you are older. You may recognize that your taste 0:19:02.600 --> 0:19:06.080 in music has evolved since your teenage years. Maybe you 0:19:06.119 --> 0:19:10.480 went from popper rock to maybe jazz or classical. But 0:19:10.720 --> 0:19:13.480 despite that, you're likely to believe that your current musical 0:19:13.520 --> 0:19:16.359 preferences are going to remain stable for the rest of 0:19:16.400 --> 0:19:18.679 your life, even though your musical tastes are going to 0:19:18.800 --> 0:19:23.280 keep evolving with exposure to new genres and bands and 0:19:23.400 --> 0:19:27.000 instruments that don't even exist yet. We're thinking about friendships. 0:19:27.520 --> 0:19:30.560 In your early twenties, you might reflect on how your 0:19:30.600 --> 0:19:34.160 circle of friends has changed from high school to college. 0:19:34.280 --> 0:19:36.880 There's a big shift in relationships there, but you might 0:19:36.920 --> 0:19:40.280 simultaneously feel certain that the college friends you have now 0:19:40.800 --> 0:19:43.800 are going to be your closest companions for life. That's 0:19:43.840 --> 0:19:49.520 a totally understandable position, but it underestimates how friendships shift 0:19:49.640 --> 0:19:52.600 as you enter different life stages, like when you start 0:19:52.640 --> 0:19:54.919 a family or you move to a new city. The 0:19:55.000 --> 0:19:58.600 same reasoning applies to everything, So take hobbies and interest 0:19:58.680 --> 0:20:01.800 When you're in your fish, you notice that you've taken 0:20:01.920 --> 0:20:04.720 up new hobbies and given up old ones over the years, 0:20:04.720 --> 0:20:08.040 but you'll generally believe that your current interests will remain 0:20:08.160 --> 0:20:11.800 consistent for the coming decades, when in fact, new hobbies 0:20:11.800 --> 0:20:14.760 and interests will still emerge. You just can't see that 0:20:14.880 --> 0:20:18.880 because they're ensconced in the dark forest of the future. 0:20:19.440 --> 0:20:22.680 Possibly there's some new technology that you're going to be 0:20:22.720 --> 0:20:26.600 obsessed with that hasn't even been invented or named yet. Okay, 0:20:26.640 --> 0:20:29.280 And the one that's really hard for us to admit 0:20:29.359 --> 0:20:35.120 to is future changes in our political values and social beliefs, 0:20:35.160 --> 0:20:38.840 and possibly religious beliefs. When you look back on any 0:20:38.880 --> 0:20:41.840 of your beliefs from a decade ago, you can sometimes 0:20:41.880 --> 0:20:44.520 see there have been some changes. But again, we tend 0:20:44.560 --> 0:20:46.960 to assume that our current values are now locked into 0:20:46.960 --> 0:20:50.200 place for the rest of our lives. We all fail 0:20:50.320 --> 0:20:54.119 to anticipate that our worldview is going to continue to 0:20:54.160 --> 0:20:59.600 get reshaped by life experiences, by new information, by changing 0:20:59.640 --> 0:21:04.520 social contexts. In a decade, we might not be precisely 0:21:04.600 --> 0:21:23.520 who we are right now. Now, this whole end of 0:21:23.600 --> 0:21:27.320 history illusion wouldn't really matter for our lives, except that 0:21:27.359 --> 0:21:30.760 it affects how we make decisions. Because so much of 0:21:30.760 --> 0:21:36.120 what you do is in service to the assumed future you. 0:21:36.119 --> 0:21:40.280 You suffer through courses and trainings now to make things 0:21:40.359 --> 0:21:44.440 better for your future you. You sweat through a workout 0:21:44.520 --> 0:21:47.679 so your future you will have a better body. You 0:21:47.720 --> 0:21:50.639 put your money into retirement plans to make sure that 0:21:50.680 --> 0:21:54.919 the future you has the resources that you predict that 0:21:54.960 --> 0:21:58.840 stranger will need. The difficulty simply is that we're not 0:21:59.000 --> 0:22:02.040 good predictors. You don't really know who that person is. 0:22:02.880 --> 0:22:06.320 That person shares your name and your history, but the 0:22:06.400 --> 0:22:09.919 fact is that person might be very different than the 0:22:10.040 --> 0:22:14.280 current you. So you're donating your retirement money for this 0:22:14.440 --> 0:22:18.919 future person that you can essentially guarantee will be not 0:22:19.200 --> 0:22:22.960 who you currently believe. That person might vote for the 0:22:23.160 --> 0:22:25.880 other political party, the what you would never vote for 0:22:26.119 --> 0:22:29.320 and yet you're slaving away and handing over all your 0:22:29.480 --> 0:22:33.080 money to that maniac. And you also do stuff assuming 0:22:33.600 --> 0:22:36.679 the best about your future self, but sometimes that's not 0:22:36.880 --> 0:22:39.680 useful either. We tend to assume that our future self 0:22:39.720 --> 0:22:43.880 will be more motivated or disciplined than we are today. 0:22:44.359 --> 0:22:47.000 So because of that, you might sign up for an 0:22:47.040 --> 0:22:51.320 expensive gym membership believing that you'll be more committed in 0:22:51.320 --> 0:22:54.320 the future, but then you don't really follow through. Your 0:22:54.359 --> 0:22:58.040 future self isn't as on board with the plan as 0:22:58.080 --> 0:23:02.200 your past self believed it would be. As a related example, 0:23:02.440 --> 0:23:06.200 I'm chronically over committed because at every moment I assume 0:23:06.600 --> 0:23:09.439 that my future self is going to be less busy 0:23:09.520 --> 0:23:11.879 than I am now, and so I say yes to 0:23:11.960 --> 0:23:16.720 future invitations or obligations like taking on big new projects 0:23:16.800 --> 0:23:20.600 or attending multiple social events, And when the time arrives, 0:23:21.080 --> 0:23:25.120 my future me wishes that my past me hadn't over committed. 0:23:26.000 --> 0:23:30.760 And more generally, we fall victim to lots of planning fallacies. 0:23:30.800 --> 0:23:33.800 We underestimate how long it's going to take to complete 0:23:34.040 --> 0:23:37.159 some task. You might think cool, I can knock that 0:23:37.200 --> 0:23:38.960 thing out in a week, and then you find that 0:23:39.000 --> 0:23:42.200 it takes twice as long now. That happens because we 0:23:42.560 --> 0:23:47.040 typically fail to correctly predict all the possible setbacks and 0:23:47.119 --> 0:23:50.840 complexities that will run into in the future. My favorite 0:23:50.880 --> 0:23:54.920 example of a planning fallacy is with a gentleman named 0:23:55.000 --> 0:23:58.760 James Murray who in eighteen seventy eight set out to 0:23:58.880 --> 0:24:02.679 write the for the English Dictionary, and the idea was 0:24:02.720 --> 0:24:05.720 to capture all the words in the English speaking world 0:24:06.040 --> 0:24:10.159 and give definitions for all of their various shades of meaning. 0:24:10.760 --> 0:24:13.160 And this seemed like a big undertaking, but not big 0:24:13.280 --> 0:24:15.479 enough that he couldn't complete it in a few years. 0:24:16.200 --> 0:24:20.520 So he worked on this for thirty six years until 0:24:20.560 --> 0:24:23.919 he died, and then several editors took up the mantle 0:24:24.040 --> 0:24:27.560 after him, and the first edition of the Oxford English 0:24:27.640 --> 0:24:33.720 Dictionary was finally completed seventy years after he began. He 0:24:33.920 --> 0:24:38.439 totally misapprehended the size of the project, and if I 0:24:38.520 --> 0:24:41.840 were here, I presumably would have done the same. So 0:24:41.960 --> 0:24:45.560 as a result of this sort of planning fallacy, we're 0:24:45.600 --> 0:24:50.399 constantly making decisions that our future selves are going to 0:24:50.440 --> 0:24:54.440 regret or disagree with. Why. It's not because we're idiots now, 0:24:54.840 --> 0:24:58.719 but instead because our circumstances and our preferences and our 0:24:58.720 --> 0:25:02.879 priorities are to change over time. Okay, so let me 0:25:03.000 --> 0:25:05.840 zoom back out to the big picture. We are creatures 0:25:05.920 --> 0:25:09.600 who live and change through time, but we're yoked with 0:25:09.680 --> 0:25:13.640 this illusion that we are unchanging, and so we misremember 0:25:13.720 --> 0:25:17.200 our past and we work hard for future versions of 0:25:17.240 --> 0:25:20.480 ourselves who we assume will be like us, but they 0:25:20.520 --> 0:25:23.200 may not be. And by the way, there are all 0:25:23.320 --> 0:25:26.560 kinds of complex relationships between your future self and your 0:25:26.600 --> 0:25:29.680 past self through time, so it gets pretty crowded. Your 0:25:29.720 --> 0:25:32.359 past self says, oh, I'm not gonna worry about my 0:25:32.440 --> 0:25:35.159 future self, and your future self looks back and says, 0:25:35.400 --> 0:25:38.239 what a jerk like. When people make the decision in 0:25:38.320 --> 0:25:42.639