Science Talk

Arachnophilia! And War...What Was It Good for (in Human Evolution)?

Spider expert Greta Binford, from Lewis & Clark College in Portland, Oregon, and her student MG Weber talk about the fascinating world of spiders. And economist Samuel Bowles, from the Santa Fe Institute, discusses the co-evolution of war and altruism. Plus, we'll test your knowledge of some recent science in the news. Web sites mentioned on this episode include

Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting February 27th, 2008. I'm Steve Mirsky and I've got a big frog in my throat. It's one of those Beelzebufo ampingas if you we were listening last week. Anyway, this week on the podcast, not frogs, but arachnids and altruism: spiders and struggles. We'll talk with spider expert Greta Binford about what makes spiders tick and we'll also hear from Samuel Bowles about how war and altruism probably had to evolve together for either to exist. Plus, we'll test your knowledge about some science in the news. First up, Greta Binford and her student, Marjorie Weber. Binford is a biology professor at Lewis & Clark College in Portland, Oregon. She studies spiders, especially the brown recluses and six-eyed sand spiders and she was a technical consultant for the movie, Spider-Man. We spoke after she talked to about 300 great school kids a couple of weeks ago at the annual meeting of the American Association for the Advancement of Science in Boston.

Steve: Hi to both of you.

Weber: Hi, Steve.

Binford: Hi, Steve. Thanks for having us.

Weber: Thank you.

Steve: Sure, good to talk about. We're going to talk about spiders, which are really endlessly fascinating.

Binford: Yes.

Weber: Absolutely!

Steve: Tell me, this may be a hard question to answer because regions of the country are so different, but I'll ask it anyway. How many spiders can you estimate I might have in my house?

Binford: In your house…

Steve: How many different species and how many different individuals would you think?

Binford: Oh! That's a tough question. You'd at least have, I'd say, 10 species, in the physical structure of your house, not in your yard.

Steve: Yes, inside.

Binford: Between five and 10, depending on how cluttered your basement is, so I think that would be one of the defining features, or your garage…

Steve: It's pretty cluttered.

Binford: Okay. Well, then I'd push you up to about 10 and it's going to depend on where, which part of the country you live in, but just as an anecdote in terms of numbers, they can go varying enormously depending on how, what the habitat is like and what species are in the area, but there is a family in Kansas that had a known population of brown recluse, but none of the individuals in the family had ever had a problem with those spiders, and so they allowed people to come in and trap them. They collected over 2,500 individual brown recluse from that single house and their family was delighted, you know, these were co-habitants of a rural house with a lot of wood debris outside and, you know, we create ideal habitat for a lot of these spiders with their clutter.

Steve: 2,500! Now, these are venomous spiders.

Binford: They are venomous, yes, but the key is that they are not aggressive; reclusive is exactly the right way to describe them. So they hide in crevices and cracks and accidents happen when people crush them in their clothing or roll over on them and it turns out that the reaction we have to brown recluse venom is one part due to the venom toxins themselves, but it's also an immune response. So people vary a lot in how severe the reaction is.

Steve: Tell me about the work you do, actually analyzing the venom of this family of spiders. Taxonomically is it family? Genus?

Binford: It's a genus.

Steve: Genus of spiders. Okay.

Binford: Yes. But the other genus in the family has the same toxin. They are the six-eyed sand spiders. So, that—the genus that includes the brown recluse has a hundred species. They're found natively in Africa, South America, and Central and North America, with 50 species in North America. So, what we are interested in is understanding how different the toxin is that causes lesions across all of these species, whether or not they all have it, whether or not they're capable of causing lesions, and whether or not a single treatment might work across the entire genus, and we do that by using comparative analyses, so we go out and we collect as much diversity as we can, we bring them back, and we figure out the relationships among species.

Steve: You are talking about a lesion; it causes some kind of a skin lesion.

Binford: It causes a necrotic lesion; it causes your skin to die and that's the result of the immune system actually cutting off the blood flow to the bite site.

Steve: And the only treatment for that is to remove that patch of skin?

Binford: Yeah. That's the only post-bite treatment. There are anti-venoms that have been developed; there is one in Mexico and we are working through the process with the FDA to get it approved in the United States for use, but currently there is no direct treatment in the United States.

Steve: You collect these spiders and then you milk—Is it called milking as it is in snakes?

Binford: Exactly, yes. I give them an electrical shock; they give me venom and we analyze the venom for the toxic enzyme activity, but then we also try to isolate the gene that codes for that toxin and so we do that by removing the venom glands two days after we milk the venom and at a time when the spiders are making more of the toxin, so we actually capture what's called messenger RNA in the venom gland that gets turned into DNA.

Steve: The spider is still alive because that shock was a mild electric shock?

Binford: Exactly. So, we give them a mild shock. The spider survives that and then we extract the venom glands two days later.

Steve: Right, so you wait for a period when you know that there's a lot of the messenger RNA present, because the genes have been activated because that's the time to make this stuff.

Binford: Exactly. So, we're isolating the tissues where we know the toxin is being made and the genes are active. That's exactly the strategy.

Steve: And the ultimate idea here is to have treatments available?

Binford: Yeah. So, by understanding how different the toxin is across the species, then we can decide which sets of species in the group will be treatable by the same treatment, or create a cocktail that includes a treatment that will work across all species in the group. And the only way to do that is to understand the diversity represented in the group.

Steve: And you can even predict which treatments will be effective against species that you don't even know for sure what their venom is like?

Binford: Exactly, yeah. We use a logic called phylogenetic inference, where we try to understand what the ancestors must have looked like and then the simplest explanation is that if something is present in an ancestor it's going to be present in all of its descendants. So, even if we can't go to, you know, look under every rock in Namibia or Bolivia to get every single species, if we simply know where they fit in the tree of relationships, then we can predict that a toxin that will work on a close relative will also work on that species.

Steve: Your lab made a discovery, it was unknown before; you found it in your laboratory about this spider that traps sand.

Binford: Yes.

Steve: To camouflage itself.

Binford: Yes.

Steve: And you discovered these little, you call them hairlets.

Binford: Exactly, yes.

Steve: Let's talk about that and how that discovery was made and what possible uses that discovery may lead to.

Binford: Okay. So, the spiders you are referring to are called the six-eyed sand spiders. They are the closest relatives to the genus that includes the brown recluse and they also have the same toxin that a brown recluse has; so because of that we've been collecting them as well to understand how the toxin is, how different it is from the brown recluse. So we have in my laboratory many hundred live six-eyed sand spiders and they are beautiful spiders. They have hairs on their bodies that allow them to capture the sand particles from their native environment and that works amazingly for making them hard to see by, presumably, predators; so it makes them what we call cryptic. Now, nobody had looked at what the mechanism is that the spiders used to capture the sand, and so one of my students, Rebecca Duncan, simply took close-up photographs of the hairs on the surface of the body and discovered that on a single hair there were other little protrusions coming off of them, so small things we called hairlets and we actually were able to photograph sand sticking directly to those hairlets and so, we've been able to do some fun things like, you know, once the spider molts, meaning they shed their skin, they have no sand. So, if we put a freshly molted spider into, say, colored chalk, it will dust itself and become that color, so we've made blue spiders and pink spiders and yellow spiders and it stays for a long time. So, potential applications may be anything that requires capturing and retaining particles.

Steve: Right. So, we might have a better dust mop in the future from your research.

Binford: Yes. A spider-inspired Swiffer-like cleaning device, or a way to camouflage, you know, clothing that can capture particles and become the color of the background.

Steve: We're speaking on February 14th, it's Valentine's Day and everybody has heard some interesting spider mating stories. You have any that people might not know about? I mean the typical one is that, you know, the black widow where she kills him and eats him while he is still going at it.

Binford: Right and that story gives spiders in general a pretty bad rap, but there are some wonderful spider-mating stories going on commonly in people's backyard. There are some spiders called jumping spiders that are very visual and the males turn out to be brightly colored. We refer to them as the butterflies of the spider world sometimes, and they'll approach a female and start to dance and the dances include waving their legs, tapping their legs on the ground, sidling from side to side, sometimes slamming their bodies onto the ground like break dancing, sometimes they make noises called stridulation, where they have, like crickets, hard parts of their body that they rub together to make sand.

Steve: To make sound!

Binford: To make sound, yes. (laughs) I'm mixing my stories. But there's one, a wolf spider, that sounds a little bit like a Harley-Davidson when it is rubbing its body parts together.

Steve: How much do you have to amplify that sound to get the motorcycle effect, though?

Binford: That's a good question; I don't know the answer to it.

Steve: It's quiet; it's not that loud to get that kind of quality.

Binford: It's quiet. Yes, you wouldn't hear it unless you are magnifying it.

Steve: Why do you like spiders so much? What attracted you to spiders?

Binford: Fascination with biodiversity. I was learning to be a biologist at a time, when we were realizing that biodiversity is being lost very rapidly. I was in the rain forest, meeting species that had yet to be described, and realizing that these species were being lost before we knew anything about them, so that drove a real passion for learning as much as I can about biodiversity and how it's created and spiders are a fantastic way to do that because we know so little and they are ubiquitous, they are very common, yet they've been under explored.

Steve: So, Marjorie, you are a student at[of] Dr. Binford's and you went on a collecting trip to Peru. So, you know, it sounds very glamorous, (laughs) but you're really, you're scrounging around under rocks and in caves, what's all that like and what did you actually find when you were there?

Weber: Yeah. It does sound really glamorous to fly around to different parts of the world collecting spider diversity, and it's really fun if you are interested in arthropods and arthropod evolution, but what it basically entails is climbing into these caves that are pretty full of venomous spiders and really getting down on your hands and knees and kind of wiggling into these nooks and crannies and trying to capture as much diversity as you can, so it's not for the fainthearted (laughs), but I certainly enjoyed it.

Steve: And you've never been bitten though.

Weber: No. And no one in Dr. Binford's lab has ever been bitten. Like she mentioned, these spiders are really docile—and we don't handle them with our bare hands obviously—but they are really not up to bite you, they will only really bite if they are under a lot of stress and pressures; if you roll over on to them or put your hand on top of them and push down. So you're just careful, you know where you kneel and where you lie down.

Steve: Right. Tell me just real quick about your project [that] had to do with speciation, which is a really interesting subject, and how to tell one species from another in these closely-related species. So, you know, what's that about? How do you do that?

Weber: Yes, so it's really important to locate spider species boundaries because there is so much spider diversity that is unknown—there is an estimated over 70 percent of spider diversity in North America alone that's undescribed—so looking at these species boundaries and asking questions about them is really important. So, I was basically taking different types of characters that they are using, genetic characters, morphological characters, and behavioral characters like the spider mating behaviors that are really rich and combining those three and looking at what they could tell us about how different spider species are and where to draw those lines, so it's important, like, in my opinion.

Steve: It's really interesting. You can have two creatures that look identical and may be morphologically and may be the DNA is incredibly close, but their behavior, especially their mating behavior is so different that they are different species, because they can't mate with each other.

Weber: Absolutely, absolutely. And there's so little known about the mating behavior of so many of these species and it takes time to learn about them, but it's really just time and patience and it can give us a much fuller picture of the diversity that's out there.

Steve: Well, listen, it was really great talking to both of you and I appreciate your time, and good luck! Keep not getting bitten.

Weber: Thank you.

Binford: Thank you, we will.

Steve: You can find spider videos and photos on a New Yorker profile of Greta Binford by Googling Binford and spider. There's a great video of the six-eyed sand spider hiding in the sand at YouTube. Just search for six-eyed spider there. By the way, the unusual thing about the six-eyed spiders is not that they have so many eyes but that they have so few – most spiders have eight eyes. Also, I mentioned that Binford had just spoken to 300 grade school kids when we talked. Just to give you an idea what that was like, here's the AAAS' Bob Hirshon, warming up the crowd with a spider quiz.

(children's voices)

Hirshon: Calm down, calm down. I know it's exciting, but calm down. All the spiders spin their web by spinning the silk, how many types of silk can the spider spin?


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 Florida Marlins baseball team is auditioning fat guys for a new cheerleading squad called the Manatees.

Story number2: Scientists can detect molecules indicative of cancer and other diseases by examining your breath with laser light.

Story number 3: The Hillary Clinton campaign spent $1,200 on cough syrup for campaign workers in January.

And story number 4: A study finds that fishing nets can drive the evolution of fish to be smaller and slower growing.

We'll be back with the answer, but first, I attended a talk by Samuel Bowles at the AAAS Conference in Boston called, 'The Evolution of a Moral Species'. It was part of a session that looked at the evolution and psychology of moral judgment. Bowles is professor emeritus of economics at the University of Massachusetts Amherst and is currently the director of the behavioral sciences program at the Santa Fe Institute. In his talk, he mentioned a recent paper he had in the journal, Science, about the co-evolution of altruism and war. We spoke just after his presentation.

Bowles: What we found through computer simulations and other kinds of modeling is that it's highly unlikely that human generosity and civic mindedness could have evolved in the absence of conflicts, which among humans were quite lethal among our distant ancestors. It's also true that warfare itself was facilitated by the altruistic nature of early humans: that is, their willingness to fight on behalf of their group members. We think that the war-like aspects of humanity, as well as it's generosity and civic mindedness, therefore, have the same provenance. However, the fact that they originated together or that they may have originated together 50,000 years ago, it does mean that that's part of our legacy, but it does not mean that that's our destiny, because we have seen over and over again that humans are immensely susceptible to teaching and to culture. We may have originated as a war-like species, but we've overcome those tendencies again and again as is witnessed by the tremendous solidarity that people feel for members of the human race whenever there is a natural disaster.

Steve: Is it possible that this co-evolution actually began in a common ancestor? Is it older than 50,000 or 100,000 years ago?

Bowles: The most intriguing hypothesis about the co-evolution of war and altruism is that learning how to cooperate in opposition to other groups or in competition with other groups is the distinctive characteristic that accounts for the huge success of this tiny band of our ancestors, the ancestors of the entire world, who spread out from the upper Rift Valley in Africa and populated the entire globe. If they were the ones who figured out how to cooperate in conflict with other groups, they would have done very well when groups met as they must often have done in conflictual situations and that could account for their success.

Steve: Can you give me just a little bit of detail about why the two things seem to have co-evolved.

Bowles: The evolution of altruism is highly dependent on group survival, depending on there being a large fraction of altruists in the group. The conditions under which their group survival may depend on altruists are quite general, it could be environmental crisis, climatic crisis, but obviously one of the most important of such challenges would be military challenges or political challenges from other groups. So, the frequency of warfare contributes to the success of the altruism by favoring groups with lots of altruists. That's one part of the story, but it's also true that warfare would not have become a common element in human history and would not have become as lethal were it not that so many of us are ready to take up arms and kill people as long as they are called the other.

Steve: Or die for our buddy?

Bowles: Die for our buddy – take the risk of our own mortality on behalf of the group. So, both of those aspects I think, we see them in the world today, but we also see humans overcoming the war likeness repeatedly and in many different ways. We know there are sentiments in favor of the group, whether it be a race or religion are easily overwritten and sometimes even reversed. They are invented often in a matter of one generation and they can also be eliminated quite quickly.

Steve: They can be completely changed in a 10-week boot camp at Parris Island.

Bowles: Exactly. Or if you look at the emergence of ethnic nationalism in the former Soviet Union, I spent a lot of time in the Soviet Union when it was still the Soviet Union, traveling, and I was astounded at the speed with which these ethnic hostilities emerged during that period. And it's also true that you can have a transformation of attitudes, for example, as it's going on right now about the question of race in America where people of European descent are markedly less racially prejudiced than they were when I was growing up.

Steve: So, you have some good news and some bad news for us.

Bowles: That's right.

Steve: Thanks very much for talking to me.

Bowles: Okay thank you.

Steve: For more on Bowles including the outline of his AAAS talk and a do-it-yourself simulation of his war/altruism modeling, just go to his Santa Fe Institute page at

Now it's time to see which story was TOTALL……. Y BOGUS. Let's review.

Story number 1: Fat guys as Manatee cheerleaders

Story number 2: Laser in your breath to find disease

Story number 3: Clinton campaign spent $1,200 on cough syrup in January.

Story number 4: Fishing nets can lead to smaller, slower growing fish.

Time is up.

Story number 1 is true. The Florida Marlins are auditioning overweight men with the intention of creating a male cheerleader squad called the Manatees. Actual manatees, of course, are both male and female and can weigh up to about 1,200 pounds. The Marlins' female cheerleaders are called the Mermaids, which is kind of ironic as some historians think that Manatee sightings are the source of Mermaid legends, a mistake not likely to happen again at any Marlins games.

Story number 2 is true. Researchers at the National Institute of Standards and Technology and the University of Colorado at Boulder have used lasers to detect molecules that may be markers for diseases that are in breath. The technique hasn't been tested in clinical trials yet, but it could offer a quick diagnostic tool. The work appeared in the February 18th online edition of the journal Optics Express.

And story number 4 is true. A study using two varieties of trout found that nets preferentially caught bigger faster growing fish, leaving more small, slow-growing fish behind to dominate the gene pool. There is not a much stronger selection pressure than getting caught and eaten. For more check out the February 26th episode of the daily SciAm podcast 60-Second Science.

All of which means that story number 3 about the Clinton campaign spending $1,200 on cough syrup for sick campaign workers in January is TOTALL……. Y BOGUS. But what is true is that the Clinton campaign did spend $1,200 at Dunkin' Donuts in January. The only reason I'm talking about this is because I think it's a good example of how critical thinking and a scientific mindset can be really valuable. And it's not important that it was the Clinton campaign; it could have been any other candidate's. This past Sunday, two New York Times columnists mentioned the seemingly huge Dunkin' Donuts January $1,200 bill as some kind of sign that the campaign was off the tracks, and Chris Matthews on television reported it as $1,300, which he thought was absolutely hilarious, and maybe it is, but I need more information. Was January unusual? How much did the campaign spend at Dunkin' Donuts in December? How many people work on the campaign? Was the money spent on doughnuts or on coffee at Dunkin' Donuts? Let's say there are hundred people working on the campaign, which is almost surely a very low estimate, right? And there are 31 days in January and all those people are working incredibly long hours away from home, basically existing on coffee, so a ballpark calculation: one cup of coffee per day per person at a dollar a cup equals $3,100. My conclusion, the Clinton campaign isn't spending enough money at Dunkin' Donuts, and more important, mainstream media pundits should be more critical in their analyses and the only one who spent $1,200 on cough syrup is me, I'm afraid.

Well, that's it for this edition of the weekly SciAm podcast. You can write to us at and check out numerous features at including science news, blogs and free content from Scientific American magazine. For Science Talk, the weekly podcast of Scientific American, I'm Steve Mirsky. Thanks for clicking on us.

(song plays)
Say war, hoo…
Good god, yo!
What is it good for?
Absolutely nothing!
Say it again!
(song ends)

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