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Steve: Welcome to Science Talk, the podcast of Scientific American for the seven days starting June 14th. I am Steve Mirsky.This week on the podcast: an evolution update. We will talk to freelance reporter, Beth Baldwin, who recently attended a big Molecular Biology and Evolution meeting and Scientific American's paleontology and anthropology expert, Kate Wong will talk about some new wrinkles in human evolution that she found out about at another conference.Plus, we'll test your knowledge about some recent science in the news.First up, Beth Baldwin. She is an attorney, which may give her a special insight into evolution seeing as how Darwin called his presentation of the case "one long argument." Baldwin also closely follows evolution news. I met her at the Dover intelligent design trial and she reports on the subject for radio. I called her at her home in Erie, Pa.
Steve: Hi Beth, how are you?
Beth: I am good Steve. How are you?
Steve: I am fine. Good to talk to you. So, you just returned recently from the annual meeting of the Society for Molecular Biology and Evolution and the specific conference was called Genomes, Evolution, and Bioinformatics, right.
Beth: That's right.
Steve: What really stood out for you at the meeting?
Beth: Well, there were a number of keynote addresses that were very interesting, but [the] first one was given by a recent contributor to Scientific American. He is actually a physicist, not a biologist. His name is László Barabási and he discussed biological networks. Biological network is a very hot topic because if you know the sequences of multiple genomes have just generated a huge amount of information and the amount of information that you can really manage at this point. So, in order to mind the data to make it usable, computer scientists and information scientists really need to corroborate with molecular biologists and evolutionary biologists and see if they can generate anything that anybody can do anything with.
Steve: So, it's just a way to try to deal with the massive amounts of data that the current technology enables you to generate.
Beth: You know, that's right and it's a specific way of dealing with it. Could you picture the difference if you can between a plain old roadmap that you see in any Rand McNally atlas and what you see at the back of an insight magazine where, you know, airlines show their routes, you really do see a hub-and-spokes kind of visual image in terms of, you know, Chicago or Dallas or Atlanta. It's just having a whole lot of connection—and some put out, you know, in the middle of the boondocks like Erie, Pa, you know, it doesn't have a lot of connections to it—and the nonrandomness of connections in those kinds of networks Barabási and others have analogized to the protein interaction that happens in biological system. So, there is a preferential connection between important proteins and those important proteins just are involved in as many papillaries.
Steve: That's really interesting. So, what's the connection between that and evolution?
Beth: That's a great question because really when you think about it, they are very intimately related. Single-cell wise is the master of metabolism. There are so many different ways that unicellular life forms make their living—everything from, you know, hydrogen sulfide metabolism to ammonia metabolism to, you know, ferrous iron metabolism. Multicellular life doesn't do that. If metabolism is very conserved that is not really the variety, but what necessary [thing] the life learned to do is to manage information and that's why network biology and biological networks is such a hot point now, because being able to manage genetic information within a cell so that off and on [is] when it needs to be turned off and on to develop, you know, the several hundred cell-type organism that we are is how necessary the life has being just naked DNA with the physiology that makes multicellular life cell-diverse and interesting.
Steve: That's great. What else jumped at you from the meeting that you saw there?
Beth: Well, Sean Carroll, a geneticist, who is both a professor at the University of Wisconsin–Madison and an investigator for the Howard Hughes Medical Institute; and for him I think regulatory changes as opposed to protein changes in DNA solve a big problem in biology and that is you may have, you know, heard the phrase the complexity catastrophe and that's the problem that happens when you have genes that have multiple effects. We all know that genes do play trophic effects, epistatic effects where genes interact with one another. How do you change protein sequence and not have it make huge problems throughout an organism if one gene is having many effects? It's sort of like how do you remodel 747 in flight? You are going to have problems. One of the ways to sort of circumvent that problem is the concept that's really hot now of regulatory evolution, but they are noncoding sequences that happen.
Steve: Let's explain: a coding sequence would be a stretch of DNA that actually codes directly for a protein for example and a noncoding sequence would be another stretch of DNA that in some way is involved in whether or not that other protein is going to get made.
Beth: That's exactly right. For example, a protein that makes melanin and does make pigmentation in a fruit's life versus that part of the DNA sequence that is pretty close to it, it may be, you know, hundred to thousands of nucleotide bases, but it's on the same chromosome. There are areas upstream and downstream is the lingo of gene where these regulatory regions lie and they are actually five to 10 bases long and they are bind inside. They are grooved sort of in the DNA where proteins known as transcription factors in certain cells [are found] and their presence, some people think it causes the DNA—the bands and loop and coil around—[OK? NOT REALLY SURE HOW TO DEAL WITH THIS PHRASE]so that the promoter sequences that actually start gene transcription get activated. This regulatory system is they are the couple from the protein sequences themselves. You get a lot of sort of combinatorial power. You can change a regulatory sequence that might control whether the protein itself, the melanin is expressed in a vein spot or in the veins that are outflow veins or the edge of a vein without changing the actual gene product.
Steve: You can have big evolutionary change without having massive genomic change because you can just turn on or turn off the genes for certain things, you know, just by analyzing the genome that only gives you so much info. There is a lot of other stuff going on in how the genome gets used.
Beth: That's exactly right. You probably heard the famous quote from Barbara McClintock. She won the Nobel Prize for her work on transposon[s]—those jumping genes. Her quote is that 'if you give me a fertilized male egg and I can control the timing, when genes are turned off and on, I can make an elephant,' you know—that's translation, but that's the concept.
Steve: I never heard that. That's great.
Beth: Yeah. The animal genome, the protein coding part of metazoan genome, is amazingly conserved and that it is featuring with when and where genes are turned off and on, but that's where we get the amazing morphological diversity that we see.
Steve: Beth thanks very much. Pleasure talking to you.
Beth: I really enjoyed it. Thanks so much, Steve.
Steve: The Barabási article for SciAm that Baldwin talked about was in our May 2003 issue. It's available at www.sciamdigital.com Baldwin told me that [at] the end of Sean Carroll's talk he put up a slide to illustrate the power of regulatory change. The slide featured this "give me one example that proves evolution, one example—you can't." The next slide then had the attribution for the quote "Tom Delay, House majority leader." The next slide then made the kind of tiny regulatory change that has major ramifications. It just added the letters "e," "x" so that Delay was now, which he is: the ex-House majority leader. Minor change big effect. Yes, it's ironic Delay famously said "our school systems teach the children, [that][OK?] they are nothing but glorified apes who are evolutionized out of some primordial soup." What's ironic is that Delay was an exterminator before joining Congress. He might have helped evolutionize pesticide-resistant insects. We'll be right back.
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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: A genetic predisposition for becoming an entrepreneur. A study with identical twins shows that if one twin has a freelance-type career, the other has a significantly greater chance of also freelancing.
Story number 2: By using sounds decoded by the brain's higher learning centers, a new cell phone ring tone can only be heard by people with IQs over about a 120.
Story number 3: Another cell phone item: high cell phone usage among teenagers may be a sign of depression or anxiety.
Story number 4: Most millipedes don't really come close to the thousand legs their name implies, but a species of millipede with almost 800 legs has been rediscovered after not being seen for 80 years.
We'll be back with the answer, but first, Kate Wong. She is the editorial director of Scientific American.com and she is the magazine's resident paleo and anthropology expert. We talked at our offices in Manhattan.
Steve: Hey Kate, how are you doing?
Kate: I am doing well, Steve. Thanks.
Steve: And you just got back from a big meeting in Puerto Rico.
Kate: That's right. I was attending the annual meeting of the Paleoanthropology Society in San Juan.
Steve: What really jumped out at you at that meeting?
Kate: Well, one of the most exciting discoveries in recent years has been a set of fossils from a site called Dmanisi in the Republic of Georgia, and this is where the oldest human remains outside of Africa have turned up and they are not at all what researchers expected to find.
Steve: And how are they not like what researchers expected?
Kate: Well, [the] fossil record indicates that humans evolved in Africa as many as seven million years ago and prior to the Dmanisi discovery, it looked as though hominids didn't make it out until around a million years ago. So, the conventional wisdom about this lengthy departure delay was that before humans could leave Africa, they needed to evolve long striding limbs and also invent relatively more sophisticated stone tools.
Steve: Because you got to walk and you got to do things on the way.
Kate: Right, need to butcher. So, the Georgian fossils—and these are representatives of the species Homo erectus,—they show that the migration actually began much earlier than that because they are around 1.8 million years old and they show that these first pioneers were in fact smaller and had more primitive tools than previously thought.
Steve: Primitive tools so they couldn't butcher necessarily or they were just good enough to butcher, but not good enough for anything else?
Kate: They were as good at butchering as the people who came later, who had fancier tools.
Steve: So, what is all this, tell us what's the new current picture of the picture long ago?
Kate: Well, all of this begs a question of, what finally enabled our ancestors to leave their native land and begin spreading across the globe? And at the meeting Marc Meyer of the University of Pennsylvania gave a talk that suggested language was the key.
Steve: Because if a bunch of people are on the move they need to be able to say to each other, "Hey, get over here. We are going that way."
Kate: Maybe. (laughs) So, researchers thought that Homo erectus lacked the ability to speak because it possessed a spinal cord that was too small to control, with sufficient precision, the muscles involved in the speech production. And this conclusion was based on what there, for a long time, [was] the only known Homo erectus vertebrae. These were found in the famous Kenyan fossil known as Turkana boy, and the vertebral canals—and we are talking about the holes in the vertebrae through which the spinal cord passes. The vertebral canals from this specimen were very constricted, indicating that the Turkana boy had a spinal cord that was really only about the size of a chimp's. But Meyer's analysis of the Dmanisi vertebrae and the Turkana one's showed that the Dmanisi people had vertebral canals that were just about as large as those of modern humans and this suggest[s] that they had moderate spinal cords that would have enabled precise control of the diaphragm, the abdominals and other muscles involved in the speaking. So, Meyer's work doesn't prove that Homo erectus communicated a decent language, but it raises the possibility that these guys could have and if so, maybe that's what allowed this species to become the trailblazer.
Steve: Right. So, the size of your vertebral opening down in your lower back is going to be related to your ability to construct the sentences that we are using right now.
Kate: That's right and that doesn't say anything about whether Homo erectus had this sort of symbolic capacities that modern humans have. So, we are only talking about whether they had the physical ability to produce speech.
Steve: So, the specimen with small openings in the vertebra, is that an anomaly? Is that a diseased individual? What do people think that was?
Kate: Well, Meyer thinks that the Turkana boy had a disease that constricted his spinal cord and so therefore he doesn't represent the norm for Homo erectus. What's additionally interesting about that is that the disease may have posed chronic health and locomotor difficulties in this individual that actually got worse as he aged and these problems could have included a spastic gait, numbness and weakness in his extremities and abnormalities in his reflexes. So, the fact that he survived beyond childhood with this debilitation hints that maybe other members of his group protected and provided for him and, interestingly enough, [is] another example of what possibly it could have been compassion that comes from that same Georgian site Dmanisi where last year excavators unearthed a skull of a very old individual who had lost all of his teeth while he was still alive. So, he may have had to rely on others for help processing food, just so that he could have enough to eat. So, Homo erectus was altruistic as these findings would suggest and that too may have helped facilitate that first migration out of Africa.
Steve: So, the physical evidence also gives you some clues about whole social relationships.
Steve: Interesting. There's also been, this wasn't at our meeting, but there was a big or a small new dinosaur discovery. What's the story on this new dinosaur that has been found?
Kate: That's right. Some paleontologists working in Germany found the remains of what appears to be a very small sauropod. Sauropods were the long-necked dinosaurs that include some of the largest animals ever to walk the earth: things like brachiosaurus that was 25 meters long and Europesaurus. This new find, it appears to have only been little more than six meters long.
Steve: And there is reason the folks who have found this new dinosaur, they think they know why it's so small relatively.
Kate: Right, they suspect that this animal evolved a small size because it lived on an island and the islands that it inhabited may not have been large enough to provide enough food for very large-bodied sauropods, so it's the dwarfism evident in this creature [that] appears to have been an adaptive response to limited food resources in its environment.
Steve: Well, thanks for the update, Kate.
Kate: You're welcome, Steve, any time.
Steve: For more on this small sauropod, check out Kate Wong's entry at our blog—that's blog.sciam.com—and Kate has an article on the Georgia research in a special human evolution anthology edition of Scientific American coming out in a couple of weeks. The issue is called "Becoming Human." We'll be right back.
Male Voice: Novartis, committed to making innovative medicines for a world of patients and their families, online at www.novartis.com.
Novartis… think what's possible.
Steve: Now it's time to see which story was TOTALL.......Y BOGUS. Let's review:
Story number 1: Genetic predisposition toward becoming an entrepreneur.
Story number 2: New cell phone ring tone only heard by people with high IQs.
Story number 3: Lots of cell phone used by teens may be a sign of depression.
Story number 4: Long-lost millipede found.
And your time is up.
Story number 1 is true. Studies with identical twins show that if one twin has a freelance-type career the other has a greater chance of also having such a lifestyle. The study was done at the Twin Research Unit of St. Thomas' Hospital in London.
Story number 4 is true. The many-legged millipede called Illacme plenipes—which translates to plentiful feet—has been rediscovered in San Benito County in California, although possibly the leggiest of all millipedes it hasn't been seen since it was first identified in 1926. In large part because frankly no one was really looking for it and it's probably really, really fast.
That leaves out two cell phone stories, lots of use by teens being associated with depression or [a] new ring tone only audible by smart people. To clear up the mystery, here is a sample of that ring tone. [silence] Relax. You're smart, I am yanking. I didn't really play anything. The true story is that a study presented at the American Psychiatric Association meeting in May found a correlation between very high cell phone use by high school students and higher scores on tests for depression and anxiety, but even the lead author of the study thinks that perhaps the teens are just experiencing 'teenanxed,' which means that the ring tones only audible to smart people is TOTALL.......Y BOGUS. What's true, however, is that there is a new ring tone called teen buzz supposedly inaudible to most adults who lose the ability to hear very high frequency sounds, whereas many teenagers can still hear the sounds. The buzz was actually originally created to drive kids away from places that wanted an adult clientele, but kids have taken the sounds and co-opted it for their own purposes, allowing them to buzz each other in classrooms with the teacher usually remaining oblivious, said one student. Who can argue with that? We'll be right back.
Male Voice: For breaking news about science and technology, visit www.sciam.com/news today.
Steve: Couple of corrections. On the May 31st podcast I said that Jupiter's Great Red Spot is as wide as an earth diameter. Podcast listener, Tom Bassua—he is actually an old friend of mine—he wrote to point out that it's actually two earth diameters across. Thanks Tom. And, on the June 7th podcast we talked about the lack of any census of breeding bird pairs in Central Park. Marie Winn, who was on the June 7th program, wrote into say that there was in fact such a census done in the mid-90s and that although it sounds like there are thousands of robins in the park, there are probably only hundreds of breeding pairs, which is not surprising, since it's very expensive to find a place to live with a view of Central Park.
Well that's it for this edition of the Scientific American podcast. Our e-mail address is firstname.lastname@example.org, and also remember that science news [is] updated daily on the Scientific American Web site, www.sciam.com. For Science Talk, the podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.
Organizations and Web sites mentioned on this podcast include the Society for Molecular Biology and Evolution, http://www.smbe.org; the conference page, http://www.smbe.org/geb; the Paleoanthropology Society, http://www.paleoanthro.org; the Scientific American blog, blog.sciam.com; the Scientific American Digital Archive, http://www.sciamdigital.com