Session 6: From Prokaryotes to Multicellular Organisms
Transcript of Part 2: Evolution - Why it Matters
00:00:16;05 Hi, my name is Ken Miller, and I want to talk to you today about 00:00:21;01 why evolution matters to biology, not just biology, but all of science. 00:00:25;07 I've got to start right up front by telling you that I'm not an evolutionary biologist. 00:00:29;19 I don't dig for fossils. I'm actually a cell biologist, 00:00:32;07 and most of my career has been spent working on the structure of biological membranes, 00:00:37;28 especially the photosynthetic membrane. 00:00:40;13 I use the electron microscope; that’s where my training is. 00:00:43;06 I've used a technique called freeze etching to look inside those membranes, 00:00:47;00 and I've also used image analysis and reconstruction to develop things like 00:00:51;14 a 3-dimensional model of a photosynthetic membrane. This ended up on the cover of Nature. 00:00:56;12 And more recently my laboratory has also worked on the translocon, 00:01:00;12 which is a little channel by which proteins leave the ribosome and enter the rough endoplasmic reticulum. 00:01:06;07 So how does a nice cell biologist get interested in evolution? 00:01:09;18 There are actually two answers to that. 00:01:11;29 The first answer came from a student. 00:01:14;05 When I first began to teach at Brown University, where I still am, 00:01:18;11 a student came to me in the spring of 1981 and he challenged me. 00:01:22;21 He asked me if I wanted to debate a scientific creationist. 00:01:28;03 I had actually never heard of scientific creationism before 00:01:32;01 and the more I looked into it, the more I thought, "Yeah, I might like to go ahead and do this." 00:01:35;27 So the students ended up establishing and setting up a debate at my university. 00:01:41;04 To my amazement, an enormous crowd bought tickets to this event, 00:01:45;29 so many that we had to put it in the largest room on our campus 00:01:49;03 which was the ice hockey rink, believe it or not. 00:01:51;21 And I participated that year in another debate as well. 00:01:54;29 And in fact, in the two debates, in that year (1981), more than 3000 people showed up in aggregate. 00:02:02;21 I'd given scientific talks before, but I'd never attracted a crowd even close to that or seen that level of interest. 00:02:09;19 That made an impression on me. 00:02:11;11 That told me this was an important issue; one that people care about in the general public. 00:02:16;01 And also, I was appalled by the amount of scientific distortion 00:02:20;08 and misinformation that was garnished in the name of scientific creationism. 00:02:25;17 A second thing happened. Pretty much the same year, and that is, when the debates were over, 00:02:32;18 a former student of mine came to me with what I thought was an outlandish idea. 00:02:37;14 And that is: how about you and I get together and write a high school biology textbook? 00:02:42;19 Well, after a few debates, I decided that was over. 00:02:45;17 I sat down with my friend Joe Levine, 00:02:48;00 and Joe and I published a series of biology textbooks designed for high school students 00:02:53;25 that have been very successful and have been used through all parts of the country. 00:02:57;19 That's the second part of the story as to how I came to be interested in evolution. 00:03:02;28 Our books, being cutting edge biology, had a very strong treatment of the theory of evolution. 00:03:09;08 In some school districts, they were banned. 00:03:11;28 In other school districts chapters were cut out, 00:03:14;13 and in one, very important school district, a warning label, 00:03:18;06 which you can see right here, was actually placed on the surface of the textbook, 00:03:22;10 warning students that evolution was a theory and not a fact. 00:03:26;08 That brought me, in a way, 00:03:27;27 right back into the issue of whether evolution should be taught as part of mainstream biology. 00:03:33;25 Now a lot of my scientific colleagues ask me from time to time, 00:03:37;21 "Didn't we settle all this in 1925 during the Scopes so-called monkey trial?" 00:03:43;04 And unfortunately, I'm afraid, that what they're thinking of when they talk about this 00:03:47;05 is in fact the movie, Inherit the Wind, which is loosely based on the Scopes trial. 00:03:52;07 The reality is that when William Jennings Bryan and Clarence Darrow squared off 00:03:58;02 in that Tennessee court room, John Scopes was convicted, 00:04:01;27 and evolution basically disappeared from science textbooks in the United States for almost 50 years. 00:04:08;19 It's an extraordinary thing. 00:04:10;08 And even today, the anti-evolution movement in this country is thriving. 00:04:14;26 TIME magazine, several years ago, had a cover story on it. They called it the evolution wars. 00:04:20;16 Books, pamphlets, movies and even a museum have been opened to support the idea 00:04:27;15 that evolution is fundamentally wrong and that evolutionary science is completely mistaken. 00:04:33;06 This sort of activity led to a dramatic confrontation in 2005 in a federal court room 00:04:39;27 in the state of Pennsylvania after a town, Dover, Pennsylvania, decided to 00:04:45;08 order its teachers to prepare a curriculum on an anti-evolution idea called 'intelligent design'. 00:04:51;29 What followed was a dramatic and widely publicized seven week trial. 00:04:57;21 I had the honor, but I'm never sure if that's the right word, 00:05:00;22 of serving as the lead witness in that trial, 00:05:02;24 and what you see right here is actually the NBC TV court room sketch of my cross-examination 00:05:08;22 during the first days of that trial. 00:05:11;13 At the end of the seven weeks, what happened? 00:05:13;02 Well, the judge, actually a conservative republican, 00:05:16;09 appointed by George W. Bush, looked at the evidence and testimony and said, 00:05:20;27 "Intelligent design simply isn't science." 00:05:24;21 In my opinion, of course, exactly the right verdict. 00:05:27;22 And this was big news. It appeared on the nightly news on every one of the major networks, 00:05:32;03 front page of the New York Times, everywhere you can possibly imagine. 00:05:36;06 Now, despite this verdict as it turns out, or perhaps because of the verdict, 00:05:41;08 a lot of us who testified in the trial, and I was just one of several scientists who did that, 00:05:46;04 ended up with some very interesting requests when the trial was over. 00:05:49;21 I appeared on a couple of TV programs, here's a snapshot of one of them. 00:05:53;26 And those TV programs appeared on unlikely networks like Comedy Central. 00:05:58;16 And, yes, I actually appeared as a guest on the Colbert Report, 00:06:02;07 and if any of you listening to this would like to find a clip of that, it's really easy to do. 00:06:06;22 You just go to Google, and you type in my name and Colbert Report 00:06:10;24 and a couple of appearances on Colbert will come up. 00:06:13;14 It was an extraordinary thing. 00:06:15;10 It got, I think, the message of science across to an audience that normally wouldn't get it. 00:06:19;28 But something interesting comes out of that, 00:06:24;03 and that's one of the key points that I want to make. 00:06:26;10 All too many of my colleagues in the biological science community think that 00:06:31;11 evolution's just a story about the past, and therefore defending evolution is the job of 00:06:36;10 paleontologists and fossil hunters and that sort of stuff. 00:06:39;18 But the reality of science today is that evolution is everywhere. 00:06:44;13 It's even in our blood, and because it's in our blood, it's in our genome. 00:06:49;07 Now, what I've put up here is an image showing hemoglobin, 00:06:53;08 the red protein that carries oxygen in our blood stream. 00:06:56;28 We know the exact location of the genes for alpha and beta globin on the human chromosome, 00:07:02;14 and there's something very different and very interesting about their structure and organization. 00:07:08;12 We actually have five copies of the gene for beta globin. 00:07:13;22 We use this at different times in our life cycle. 00:07:16;03 They were all produced, any evolutionary biologist would tell you, 00:07:20;03 by the process of gene duplication, but here's what's really cool. 00:07:23;18 Right in the middle of this collection of genes, and you can see it right there, 00:07:28;14 is in fact a pseudogene. You can see the Greek letter psi above it. 00:07:32;08 That means it's a gene that is broken. Now why do I say it's broken? 00:07:36;26 It means that one of these multiple copies 00:07:39;02 accumulated so many mistakes that it couldn't work anymore. 00:07:43;01 What are the nature of the mistakes? You can see them here. 00:07:45;27 They involve altered control regions, frame shift mutations. 00:07:49;20 Even if this piece of DNA could be transcribed, 00:07:52;21 it could never be translated; it could never be made into a protein. 00:07:56;01 Now, why is all of that significant? It's significant for a very simple reason. 00:08:01;07 Mistakes are unique. They occur only once, and then they're propagated to 00:08:07;06 all of one's descendants, and that's what's happened with the beta globin pseudogene. 00:08:11;09 But, the interesting part is that we share not only the structure of this beta globin locus, 00:08:18;12 but we also share those mistakes with three other organisms. 00:08:23;29 Want to know who they are? 00:08:25;15 They're the gorilla, the chimpanzee and the orangutan. 00:08:28;29 And what does that mean? It means that all four of these species, 00:08:33;04 these three guys and us, share common ancestry. 00:08:36;06 And our genome is testament to that. But, there's even more. 00:08:40;21 As a cell biologist, I've worked prety much my entire career on organelles within cells. 00:08:46;10 Two of the most interesting are chloroplasts and mitochondria. 00:08:50;14 And my lab has done some research on both. 00:08:52;25 These are extraordinary organelles that are involved in the transduction of 00:08:56;28 either chemical or solar energy into a form that the cell can use. 00:09:01;29 Now there are some weird things about these two organelles. 00:09:05;24 One of them is: they both import proteins from the cytoplasm (the rest of the cell). 00:09:10;18 Now, that's not surprising, but they import them, take them inside, 00:09:14;28 and then re-export them into their own membranes. 00:09:18;08 It’s sort of a roundabout route. 00:09:19;27 It's like going to one side of the shopping center and then the other, 00:09:23;05 and then coming back in and then going back out again. 00:09:25;19 It makes very little sense. 00:09:27;20 It also turns out, they're both surrounded by two membranes. 00:09:31;12 Most organelles of the cell-only one. 00:09:33;29 How come two? It's a bit of a puzzle. 00:09:35;15 Another thing is they are not made by the cell from scratch. They're self-replicating. 00:09:42;00 In other words, they come only from the division of pre-existing mitochondria and chloroplasts. 00:09:46;26 In addition, the ribosomes, the protein synthesizing machines, within these are distinct. 00:09:52;13 They're very different from ribosomes from the rest of the cell. 00:09:55;14 Why should these guys have their own unique ribosomes? 00:09:59;00 And last but not least, they've got their own DNA. 00:10:01;26 They have their own genetic systems. 00:10:04;20 Why is all of this the case? 00:10:06;12 Well, the answer, from evolution, turns out to be very clear and very straightforward. 00:10:10;24 Mitochondria, there's very clear evidence, arose from primitive bacteria 00:10:15;29 that were then taken inside an early eukaryotic cell and then surrounded by a second membrane 00:10:21;11 and eventually formed into the organelles that today we call mitochondria. 00:10:26;15 Chloroplasts are pretty much the same thing, 00:10:28;17 except it was a cyanobacteria (a photosynthetic prokaryotic organism). 00:10:33;14 And once you understand this process, which is called evolution by endosymbiosis, 00:10:38;19 everything makes sense, protein import and re-export, the double membranes, 00:10:43;20 the self-replication and the unique ribosomes, and the fact that these organelles have their own DNA. 00:10:49;01 It all fits together, and it fits together quite beautifully. 00:10:52;03 Today, evolution itself is a research tool. 00:10:57;00 We use evolution to understand the relationships of proteins in the cytoskeleton, for example. 00:11:03;14 We also use evolution to understand the development of body plans 00:11:07;26 in the field of evolutionary developmental biology. 00:11:11;20 If you want to read up on this, pick up Sean Carroll's great book, "Endless Forms Most Beautiful". 00:11:17;29 And in this, Carroll explains the way in which the animal body is modular. 00:11:22;02 It's made up of repeating parts and these repeating parts 00:11:25;16 basically produce the forms and patterns that we look at and appreciate as biologists. 00:11:30;20 Now, one of the problems that I see as a scientist and an educator is 00:11:35;00 that evolution acceptance in this country is near the bottom of the industrialized world. 00:11:40;05 There were 29 countries polled in which a larger proportion of their citizens 00:11:45;17 accepted the theory of evolution than in the United States. 00:11:48;21 We're at the bottom of that list. The only country we beat out in Western Europe is Turkey. 00:11:53;20 Why is that? I think in large measure that's because 00:11:56;22 evolution is presented as a fearful doctrine, as something to be afraid of. 00:12:01;24 And that fear that characterizes, or the induction of fear that characterizes 00:12:06;12 the anti-evolution movement is dangerous. 00:12:09;01 Not just because it might cause people to reject evolution, 00:12:11;20 but rather because it might lead to us raising up a generation of young people 00:12:17;02 who have been taught that science is to be feared and distrusted. 00:12:21;03 And if we do that, this country will give up world scientific leadership, 00:12:25;14 something that we simply cannot afford to do. 00:12:28;03 In fact, in the current year, 2011, anti-evolution measures have actually 00:12:34;11 been introduced and attempted to be made law in no fewer than 7 state legislatures. 00:12:40;15 I'd like to pretend this is in the past, but it is in fact an ongoing problem. 00:12:45;07 So, what do we make of this? 00:12:46;18 Defending evolution is really defending the scientific method. 00:12:50;29 It isn't about Darwin anymore. It's about the science that we do today. 00:12:55;16 And I think every member of the scientific community 00:12:58;09 whether student, post-doctoral researcher, faculty level researcher or independent scientist, 00:13:05;02 owes it to themselves to defend evolution for two reasons. 00:13:08;14 One is, it is the unifying principle that makes sense of everything we do in biology. 00:13:13;14 And number two, acceptance of evolution means acceptance and embrace 00:13:17;28 of science and the scientific method. 00:13:20;08 Nothing could be more important for the scientific enterprise, 00:13:23;15 and in my opinion, nothing could be more important to our country. 00:13:27;05 Thanks for listening.
