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Science Talk

Phrasing a Coyne: Jerry Coyne on Why Evolution Is True

During a Scientific American cruise in the Caribbean, University of Chicago evolutionary biologist Jerry Coyne talks about his new book Why Evolution Is True. And we hear a brief example of what it's like to attend science lectures at sea. Plus, we'll test your knowlege of some recent science in the news. Web sites related to this episode include www.insightcruises.com; www.whyevolutionistrue.com

Podcast Transcription

Welcome to Science Talk, the weekly podcast of Scientific American, for the week of March 13th, 2009. I'm Steve Mirsky. And I'm just back from 11 days at sea on a Scientific American lecture cruise with InSight Cruises. Because this is Darwin's big anniversary year, the cruise featured a faculty of evolutionary biologists as well as cognitive scientists, who we'll hear from in future episodes. This week, though, we talked to Jerry Coyne, who gave a series of lectures on the ship. He is professor of ecology and evolution at the University of Chicago and the author of the New York Times bestseller Why Evolution Is True. We spoke on March 8th in his stateroom on the Holland America ship The Zuiderdam.

Steve: In the last chapter of the your book, you tell us the story at the beginning where you've just spoken to a group of businessmen and one of them comes up to you afterwards and says, "I thought you made a very convincing argument, all your evidence for evolution, but I still don't accept it."

Coyne: What he said was "I am not convinced." So, yeah, I mean, my reaction, of course, was somewhat dismayed because I'd gone giving evidence to these people and this guy said, you know, "I don't accept it", even though that was right there before his eyes. But you know, it's sort of understandable if people have religious predilection that's really, really strong, not to believe in it, then they are not going to you know how much evidence they see.

Steve: So given that why did you write this book?

Coyne: Well I didn't write for those kinds of people. I wrote it for, I mean, because lot of people are open-minded including religious people, I mean, not everybody adheres to literalistic interpretation of the Bible. So, you know, during my career I found that a number of people are on the fence, willing to be convinced if they see the evidence and that's sort of the people it's for. It's also for the large number of scientists that, sort of, accept evolution because it's the going thing in the field, but don't really know what the evidence is. Even a lot of evolutionary biologists, in fact, have never read On the Origin of Species or know, you know, all of the lines of evidence for evolution.

Steve: And there are, of course, many lines of evidence that Darwin didn't have a clue about when he wrote Origin of Species.

Coyne: Right, like fossil record, for one thing. He knew that if it was good it would document evolution, but they had a crappy fossil record at that time, and that's one of the new lines of evidence more or less; and also the molecular biology finding, for example, dead genes and pseudogenes and species were active in an ancestor and a relative, but are dead like our gene for making vitamin C, that's also new developments. So, you know, there have been a number of new lines of evidence, all of which just support the sort of propositions that [Darwin] laid out 150 years ago.

Steve: The dead gene thing is really interesting. Why don't you just take another minute or two and explain that in a little more detail?

Coyne: Well, in a lot of organisms including ourselves, in the DNA in our genome, there are genes called pseudogenes, which are genes that are not active; we can tell they are not active because the coding sequence of the gene is interrupted by something that prevents it from making its product, a protein; or there will be a mistake in the switch that will turn it on or off it. We can see directly whether a gene is active by seeing whether it makes the RNA product which leaves the production of a protein. So what we found from sequencing the DNA of ourselves and other species is that virtually every organism is loaded with pseudogenes. The most famous in our species is the gene for making vitamin C. And we have the complete pathway, but the last step, the genome involved in the last step of the process, is broken; it's dead because there is a part of the DNA sequence which has actually been removed or has been snipped out. And yet the gene is active in a lot of our relatives who use it to make vitamin C. Presumably humans don't need to do that because we have plenty of vitamin C in our diet and so the pathway was superfluous and it just sort of became inactivated by random mutation. So that's just one example of these pseudogenes, but every organism has them. The platypus which has no stomach has genes for producing stomach enzymes, which were broken, and the only thing you can conclude is that its ancestors had stomachs, which you can get from other molecular evidence or from fossil evidence; and platypus lacking the stomach simply, you know, kept the genetic information, but it became inactivated. So there is no other way to explain this unless you know if the creator was some kind of prankster that would put inactive genes indicating evolution in creatures except to say that creatures have genes descended from common ancestors.

Steve: And the genes become inactive because there is no longer any selection pressure to keep them around.

Coyne: Yeah, that's one reason; simply, you know, mutations are always happening, usually they are weeded out because they have lethal or deleterious effects, but in a dead gene, a gene that's no longer useful for the organism, mutation inactivates that is of no consequence; or sometimes it's actually useful to get our genes that you don't need anymore, so natural selection can actually inactivate genes such as those from making eyes in cave animals or wings in birds that don't need to fly, like on islands.

Steve: Because then they can save a lot of metabolic resources.

Coyne: Yeah, flight is a tremendously expensive, and by expensive meaning, you know, if you could get rid of it, you can probably have a lot more offspring; and so birds that tend to live in areas without predators over millions of years tend to lose their wings because they don't need to fly.

Steve: You tell a great story in the book. There is evidence that people might be familiar with or at least the kinds of evidence that they have seen before, but there was something in the book about using coral reefs to gauge the length of the day or the number of days in the year, that I had never seen before that was really fascinating and kind of beautiful and elegant. You want to talk about that?

Coyne: Yeah, just briefly. I am not sure I can recall the details, but the fact is that due to motion of the tides, the earth's rotation has been slowing down overtime, so a day used to be a lot shorter than it is now. But a the day is the time it takes the earth to go around in its axis once, so if it has been slowing down then days are getting longer over time, which means that a year, which is the time that takes the earth to go around the sun once, which doesn't change and would consist of more days in the past than it does now. So we can actually calculate from the rate of tidal friction, how fast the earth is slowing down, make calculations with that. And then you can use it to predict how long days were in the past and there is another way to check that out too—and this is what Jonathan Wells did at Cornell it's a really elegant experiment. He looked at fossil corals in which they deposit both daily and annual growth rings and you can tell by looking at how many daily rings separated [an] annual ring how many days there were in a year. And they lived, I believe, about 400 million years ago in the Devonian; so he calculated that back in that time, a day would have to be about 22 hours long instead of 24. And then when we looked at the growth rings of the corals and calculated how long they would have to be to make that many growth rings for a year; it was 21.9 hours, so it was bingo, right on the [money]. So that's, you know, a good way of not only dating organisms but showing that a) the earth is really old, b) it's been slowing down over time, and c) these corals lived a long time ago.

Steve: [It's] beautiful piece of work.

Coyne: Yeah that really was a quite elegant and it's not very well known; I am surprised that it isn't.

Steve: This is Jonathan Wells at Cornell. Isn't there a Jonathan Wells at the Discovery Institute?

Coyne: The one at the Discovery Institute [who] we won't talk about. He's just a straight intelligent design creationism.

Steve: So it's not the same Jonathan, well.

Coyne: No, no, not at all.

Steve: Okay.

Coyne: This is many years ago; I think it was in the '60s that this guy at Cornell did the experiment.

Steve: Another thing you have in the book is the example that the intelligent design people try to trot out about the clotting factors and how there's no way that we can have a cascade of clotting factors that would be part of our current set up of clotting factors and have it work. And it's kind of good that the Discovery Institute people, the intelligent design people, set up these challenges because then the evolutionary biologists know where to look for some interesting new piece of data and seem to have always been able to find it pretty quickly.

Coyne: Yeah, that's because things evolve. I mean, yeah that was in fact, you know, the stuff about blood clotting and the flagellum were pretty much in the literature before the Discovery Institute, it's just th[at] people [didn't] think to look [at] them as evidence for, you know, to refute creationists, who said that this couldn't have evolved. So that was part of the decisive evidence at Dover—as you well know—that, I mean, the evolutionary immune system and the blood clotting system, huge [stacks] of literature were placed on the witness stand in front of Michael Behe to show him that there was all this speculation. So, the blood clotting system is a good one, because it's very complex and as creationists assert that they could not have evolved in the Darwinian stepwise fashion, but, you know, we now have a pretty good speculative scenario about how that happened; and we've been able to find some of the proteins having other functions in other organisms like sea cucumbers; so it's clear that like in any other complex biochemical pathway, blood clotting has been sort of [jury-rigged] from proteins and appropriated from various biochemical pathways in our ancestors.

Steve: What was the most interesting new thing that you learned while you were writing the book?

Coyne: I suppose, well, two things, I guess: the fossil evidence, which I sort of knew vaguely—but as a working evolutionist, you don't spend your time reading, you know, elementary disquisitions on where whales came from—but really looking at it, especially the new stuff on the origins of birds and whales was quite fascinating, and just to see it all fit into place. Also the molecular stuff, the evolution of pseudogenes are something I didn't know much about, and that's all coming in, retroviruses that we share the same insertion points in our chromosomes as apes of these now dead viruses, that's all pretty fascinating stuff.

Steve: Yeah, I just saw Ken Miller give the talk [in] which he talked about the beta-globulin pseudogene that we share with chimps and gorillas as a pseudogene. So it's inactive in all three species, which means that the common ancestor had it inactivated a long, long time ago.

Coyne: That's right, that's one of the things I did mention. The pseudogene evidence is not just that we harbor these dead genes but that the sequence of these dead genes don't make anything; they're just there, and the DNA is more similar between us and chimps than that[it] is between us and gorillas or between us and gibbons. You know, how do you get this pattern of ancestry of something that doesn't do anything unless it has been inherited in inactive form from a common ancestor? So there is lots of evidence along those lines.

Steve: What do you actually do as a working evolutionary biologist when you are not writing books for [a] general audience?

Coyne: Yeah, well, my day job is studying the origin of species in Drosophila, which as I talked about in the book, is an area that Darwin didn't make a lot of progress; and so, you know, most of the progress in that area has been made since the 1940s with Ernst Mayr and Theodosius Dobzhansky. So my particular interest is in the genetic changes that accompany the origin of new species. What kinds of genes change? How many changes are all there? [Does it] take a lot of genetic changes to make the new species or [a] little? [Are there] particular genes that are involved over and over again in this process? And which kinds of reproductive barriers are the most likely to evolve when a new species forms?

Steve: And of course, the fruit fly seems like it was almost made for evolutionary biologist[s] to work on.

Coyne: Yeah, it has short generation time, in my case 10 days from egg to [egg]; they're easy to rear in media that you can cook up in the basement; they have a lot of characters you can study; and you can cross them together in the laboratory—at least a lot of species, even species that live together in nature without crossing, you can do in laboratory, which is a prerequisite for genetic analysis. So it's an ideal organism to study speciation. And the problem is can we extrapolate what we find in fruit flies to other species like mammals and hominins and things like that. So, it's harder to [do the] cross[es] [amongst the great apes than it is amongst] drosophila.

Steve: Right, who has the time for it?

Coyne: Or the ethical allowance to do that, so?

Steve: Something I always ask fruit fly geneticists, fruit fly evolutionary biologists: Can you trace your lineage directly to Morgan in terms of your mentor and his mentor and her mentor [or] whatever it is?

Coyne: Oh Yeah. Easy, its just three steps. You must know there is a computer program [that] does this. So I am out of Lewontin, who is a student of Theodosius Dobzhansky, who was a student of Thomas Hunt Morgan, so [I'm] three steps [removed] from the great [man].

Steve: So you are Thomas Hunt Morgan's scientific great grandson?

Coyne: That's right, [and] proud of it.

Steve: I just want to give you a little flavor of what it is like to attend science lectures on a cruise ship in the midst of an otherwise academic setting can come interesting interruptions, not to mention seasickness. Here's University of California, Berkeley cognitive scientist, Tom Griffiths, trying to talk about artificial intelligence on a day when the weather started getting rough and the rather huge ship was tossed.

Griffiths: So what you do is you take this matrix. You sum this way, so you work out the frequency of those items, and then you divide the entries by the frequency, just like we were doing for the length matrix to do the exhibited pattern, right.

Shane: Good morning everyone, this is Shane, your cruise director speaking, and [I] hope you're enjoying this morning at sea. It's nice a day for you to just relax and enjoy this beautiful ship. Of course, you have the best crew on the high seas to take care of you today. Anywhere you go throughout the ship, whether you're going to [the] Lido Restaurant today, our dining room or into your staterooms [to interact with] our entertainment team, our fabulous beverage team or [friendly] front office team, you'll know how friendly they are and they never intrusive to you and they are what sets The Zuiderdam apart, they are [an] amazing crew, we're proud of them. So today I am going to give you brief run-[down] of some of the events happening around the ship this morning. You c[an] find [an] amazing variety of activities happening throughout the morning. This morning [a] fun session of Bingo starts, this one is called the Win-A-Cruise Bingo! The game starts at 11:15 today. This is your chance to win your next cruise vacation on the [Bubba Gump Shrimpo] Boat—no, I'm just kidding, of course, it's [on] Holland America Line. It all starts in the Vista lounge at 11 A.M. today; you can win your next cruise, so take a look. And at 11 A.M., it's another fun cooking demonstration sponsored by Food and Wine magazine. This one is Delicious Hors D'ouevreswith our chef, Troy and also our party planner, Kelly; [it] takes place in our Culinary Arts Center, that's on deck number 2 [midship]. And there's a lot happening today at the Greenhouse Spa. There is a free seminar at 10 A.M. for detox for health and weight loss, it's pretty interesting; and at noon today there's another free seminar, this one is called, Secrets to Flawless Skin, both in the Greenhouse Spa, Deck number 9 in front of the [boat]. And last of all there's a great seminar in the Ocean Bar today. It's all about Rembrandt and his famous etchings, it starts at 10:30 today—very informative about the Rembrandt collection here onboard The Zuiderdam and you can hear about the greatest etcher that ever lived and find out why the art world has been obsessed with his copper plate[s], [a story] over 300 years in the making, that starts at 10:30 in the Ocean Bar on deck number 3. That's all from me. Have a great day, and remember to take a look at your daily program that tells you every activity happening around the ship today. Have a wonderful day everyone and we will see you around The Zuiderdam. Bye for now.

Mazich: Just a brief housekeeping announcement. We do seem to be settling down but these are rough seas, and so, just a reminder—I know Neil mentioned it probably when we first met—this is the time to go to the front desk if you have the least suspicion that you are feeling motion sickness; start to take the Avomine or whatever they give you at the front desk before you're even to motion sick or when you first begin to suspect or wondering or starting to feel the effects, that's the time to take the medication; number 1. Number 2, this is the day, if you're feeling sensitive to the motion, to moderate your diet and avoid rich foods, dairy products, alcohol and things like that. And number 3 is you'll see [bowls], probably [if] this persists, [of] green apples around the ship [and we may offer you] ginger candy up in the Lido dining room, and this is a hint that the rough seas will continue, because those are the things that have low doses of substances that tend to soothe the motion sickness. So it does seem to be settling down, by the [look of the weather] report that we've been watching and Dr. Griffiths has been chatting and it does seem like [it will be] persisting into the [day], so just consider that as you eat. Here's Dr. Griffiths.

Griffiths: Okay, so this our problem, right, we've got this matrix. The question is how we are going to use this information.

Steve: That was MD Theresa Mazich talking about the rough seas. She and husband Neil Bauman run InSight Cruises. For info on future SciAm cruises, just visit www.insightcruises.com or look for their ads in Scientific American magazine. We'll feature an interview with Tom Griffiths about his work on an upcoming podcast.

Steve: Now it's time to play TOTALL....... Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL....... Y BOGUS.

Story number 1: The most widely cited source of wireless usage information in the U.S. is the Centers for Disease Control.

Story number 2: One of those CDC studies finds that California leads the nation in households that have gone completely cellular and no longer have a landline.

Story number 3: There's link between cat poop and schizophrenia.

And story number 4: Lithium batteries that can recharge in just seconds are in sight.

Times up.
Story number 4 is true. M.I.T. researchers have come up with lithium batteries that may be able to recharge in just a few seconds. The report is in the latest issue of the journal Nature. The quick charge is related to the internal structure of the battery which takes advantage of clumps of nanoparticles. So in a couple of years you might be able to fully charge a portable device while brushing your teeth. For more check out the March 11th article at www.SciAm.com called "A Better Battery: The Lithium Ion Cell Gets Supercharged".

Story number 3 is true. Cat feces may be linked on rare occasions to schizophrenia, but more broadly to other common mental conditions—I'm talking about in the people who own the cats. Toxoplasmosis is transmitted via cat feces. In immunosuppressed people, the infection can change the brain's levels of dopamine which means a link to Parkinson's, Tourette's, ADD and bipolar disorder in addition to schizophrenia. The research was done at the University of Leeds in England. It's estimated that 22 percent of the U.S. adult population carries the toxo parasite.

And story number 1 is true. The CDC has the best records of cell phone use in the country, because they do health surveys by randomly calling landlines and they realized that a few years back that a significant portion of the population was now off the landline grid. For more, check out the March 11th blog item on our Web site called "U.S. Wireless-Only Use Rising Complicating Government Health Surveying".

All of which means that story [number] 2 about California leading the nation in cell-phone only households is TOTALL....... Y BOGUS because a new study from the CDC finds that only 10 percent of California homes have given up land lines; Oklahoma and Utah lead the nation with a quarter of homes having no landline. Vermont is still living in the 20th century with only one home in 20 having gone wireless; and for good reason: I still can't get a Sprint signal at Ben & Jerry's in Waterbury.

Well that's it for this edition of Scientific American's Science Talk. Check out http://www.SciAm.com for the latest science news and our In-Depth Report on the Baby Nobel, the Intel science talent search for high schoolers. For Science Talk, I'm Steve Mirsky. Thanks for clicking on us.

Science Talk is a weekly podcast, subscribe here: RSS | iTunes

During a Scientific American cruise in the Caribbean, University of Chicago evolutionary biologist Jerry Coyne talks about his new book Why Evolution Is True. And we hear a brief example of what it's like to attend science classes at sea. Plus, we'll test your knowlege of some recent science in the news. Web sites related to this episode include www.insightcruises.com; www.whyevolutionistrue.com     

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