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Zombie Ants

Do zombies really exist? They do... at least in the world of ants. Learn how some ants are made into zombies and find out what ants can do to avoid being zombified.

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A lot of people think we only use a small part of our brains, but this isn't true. While all of your brain is not active every second, most of us use 100% of our brains over the course of a day.

Question From: Tara
Grade Level: 7

Answered By: Patrick McGurrin
Expert’s Title:
Graduate Student

To learn more about how your brain works, visit What's Your Brain Doing?


Have a different answer or more to add to this one? Send it to us.

Images via Wikimedia Commons. Brain with lights by DARPA.

Tales of Termites

Termites are one of the planet's best recyclers. Yes, we usually think of these insects as something that destroy homes and need to be exterminated. It turns out that these critters are tiny 'green machines' that are critical to the planet. Dr. Biology learns about the history, social nature, and the important role termites have from entomologist, Barbara Thorn.

Content Info | Transcript

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Topic Time
Introduction. 00:00
Why do we talk about insects so much? 01:08
Why do you study termites? 01:40
Tropical rainforest termites. 02:24
Termites help aerate soil. 04:02
More reasons termites are important to study. 04:15
What happens when colonies of termites meet? 06:28
Evolution of termites. 08:13
Social insects and Darwin's natural selection. 09:08
Learning about science. 10:54
Think of science like a video game. 12:09
How did you start working on termites? 12:42
Did you know you'd stick with termites? 13:15
The benefits of basic research. 14:00
Science mixed with business. 14:42
How many patents do you have? 17:09
New ideas that turn into a societal benefit. 17:14
Explaining "eusocial." 17:54
Non-insect eusocial animals. 20:22
Are termites long-lived in the eusocial world? 21:15
Have respect for termites. 23:05
Three questions. 23:49
When did you know you wanted to be a biologist? 23:56
If you couldn't be a biologist, what would you be? 25:57
What advice would you have for a students looking to get into science? 27:42
Sign-off. 28:36

Transcript - (PDF)

Dr. Biology:  This episode of Ask a Biologist is being pulled from our special collections that have been stored in our secret vault. This is Ask a Biologist, a program about the living world, and I'm Dr. Biology.

Today we have a tale of the living dinosaurs, but not the type of dinosaurs that you might be thinking of. Instead, these are the dinosaurs of the termite world. A story of war, and change, colonies battling colonies, and workers changing into kings, sometimes queens and other times even a soldier.

Our guest today is Barbara Thorn, Professor and the Director of Biological Sciences graduate program at the University of Maryland. She's been studying termites and the really interesting world that they live in. Some of these colonies, when they meet each other, the battles begin. Barbara, I want to thank you for joining us on Ask A Biologist. It's wonderful having you here.

Barbara Thorn:  Thank you.

Dr. Biology:  For some of the regular listeners of Ask A Biologist, I know they're wondering, "Why is it they're always talking about insects? Why are they often social insects?" They just don't realize that we actually have one of the best social‑insect groups at Arizona State University.

The other reason is, well, there are a lot of insects out there. If you're going to study something in the living world, especially in the animal kingdom, this can be really cool stuff, right? That's one of the reasons why we have a lot of people that do this. You study termites. Now my question is, why termites?

Barbara:  Dr. Biology, I think you set that up really well. Why do people study insects and why do so many people study social insects? When you actually look at all the different insects in the world, it turns out that the social insects are a huge group of them. They dominate all the other types of insects.

Right there, social insects, there's something about that very interesting organization that has made them very, very successful and very diverse. They're in many different types of habitats and they're very important in those habitats. Termites, for example, are ultra‑cool because they are responsible for, say, tropical rain forests. You wouldn't think that, right?

Dr. Biology:  Tropical rain forests, termites. They wouldn't go side by side.

Barbara:  They don't go side by side. And yet, when you think about it...You think about a tropical rain forest, "Oh, how cool. There's monkeys in the trees, and there's great, big, tall trees. There's vines all around, and monkeys using those vines to swoop like Tarzan," and whatever.

All this just incredible diversity, and huge flowers. But all of that vegetation, all of that green stuff, the trees and the plants are sucking up nutrients from the soil. Even though you see a tropical rainforest looks really lush, in fact, it's hurting and the soil, the nutrients are gone.

They rely on the termites to recycle. The termites are the ace recyclers in the whole planet when it comes to plants.

Dr. Biology:  They're like the green machines out there.

Barbara:  They are. That's a great term. When a storm comes through and knocks down a big tree, poles vines, and all these drama from the plants and they die, but on the termites margin. The termites are able to digest dead wood or dead plants, of any type. That's rare. There aren't too many animals that can do that. Termites do it quickly, then all those nutrients from the plant are put back into the soil and new plants can grow.

Termites are really, really important for that. They're important where we live up her in the United States for aerating the soil that hang around in the soil there, digging around, and moving things around. That helps the roots of plants get oxygen so they grow better.

Anyway, for all sorts of reasons, termites are cool. Why do I study them? For those reasons and because they are important in our houses. We don't want them there. We want them in the tropical rainforest, we don't want them in our houses.

Another aspect of termites and why I got in to study them in the first place, is what you also talked about, that social insects are so common. Lots of people know about a honey bee, the honey bee queen flying off then swarms in the honey, the workers, the drones, and ants, they're all over, and wasps...Let's not talk about wasps too much. They sting but they're really intersecting insects.

Those are all cousins, they're closely related. They all have these amazing social systems with the queen and workers that hep the queen stay in the colony. There's another major group of insects that has that same kind of elaborate social organization, that's the termites.

The termites are a very, very different group of insects. This a is a case where we call it "convergent evolution. " The two very, very separate types of beasts, in this case, the ants, bees, and wasps, on one hand, and termites on the other hand have...For totally separate lineages, they've developed a very similar colony organization and life organization.

You have a queen termite, you have a queen honey bee, and you have lots and lots of workers with the termites and you have lots and lots of workers with the honey bees foraging for new food, and soldiers, and in the case of termites you got the king, really neat stuff.

That is engaging and as Biologists we always like to ask the big questions. Kids are always curious and it's great to ask questions. Don't worry about whether they're good questions or bad questions. If you're curious about it, that's a good thing, and ask the question. How these complex social systems evolve that are social insects, that's a big question.

Dr. Biology:  The interesting thing for you is you've been studying, what happens when two separate colonies of termites actually find each other. They bump into each other. They're on a tree, trees are really big. Been a long time not seeing each other but all of a sudden they come in contact and it's an interesting story.

It's that tale of battles and wars and the kings and the queens are ousted. You actually showed a really neat illustration. It was a chess board and I liked that. Can we talk a little bit about that? It illustrates what you were talking about.

Barbara:  It does. It's an amazing illustration, very clever. It was done by a National Science Foundation artist named Zina Deretsky. What it depicts is the two teams on a chess board. You've got the different players on the chess board and one of them is the queen.

The queen, she's moved to the other side of the board. When she gets there she is replaced by a pawn and the pawn becomes the new queen. That is what's happening in natural situations with termites. You start out with two teams, just like in chess, and the two colonies, two little termite families, when they meet the queen is assassinated.

Dr. Biology:  Whoa.

Barbara:  Drama, and then one or more of the workers in the termite colony, like the pawns in the chess game, they replace the queen. They become the new egg layers and do the duties that the queen did before she was assassinated. We've been looking at that as a model for what might have happened when termites first evolved, which was a long time ago, 130 or 140 million years ago.

Dr. Biology:  That's a million, with a big "M."

Barbara:  It is. If I had a time machine, that's where I'd be. Going back and seeing what was actually happening. I wish I could do that. Maybe in the future we'll be able to do that, but right now the best we can do is to look at the termites that are alive now, that have retained some of the characteristics of their ancient ancestors. That's what has sparked this study, is looking at the modern termites.

Dr. Biology:  I think you even called them "modern dinosaurs?"

Barbara:  Yeah, they're sort of the dinosaurs of living termites. That's how I think about them, but actually termites evolved a long time ago, the late Jurassic early Cretaceous. There were lots of dinosaurs around and probably ate termites.

Dr. Biology:  We know why you might be studying them, so we can answer some questions about evolution. In fact, this was something that Darwin was having a little bit of a problem with.

Barbara:  Absolutely. Darwin wrote his manuscript for his key book, "On the Origin of Species," including a section on social insects but it troubled him, because the kicker for Darwin was his whole theory was based on the theory of evolution by natural selection.

The winners in the evolutionary game are those who actually produce offspring for the next generation. He knew that honey bees were out there who didn't reproduce, that the worker honey bees were sterile. That was kind of a show stopper for him.

Instead of sweeping it under the rug he parked his whole big book manuscript in a drawer for close to 20 years. That was one of the reasons, he couldn't figure out the social insects. He wondered if they were an exception to his whole theory.

Dr. Biology:  Because there was a long delay between his travels on The Beagle, and actually publishing this manuscript.

Barbara:  That's right. One of the reasons that he delayed was the social insects, which we come back to asking big questions. This is something that still interests evolutionary biologists, is the evolution of sterile members of social‑insect colonies, which turns out to be most of the colony.

How did sterility evolve? It's still a very contentious subject. We'd love to hear Darwin's current opinion about it. I think he'd be very excited by all the work that's been done.

Dr. Biology:  It's the thing about science, it's always changing. We're learning more things. We re‑evaluate what we've learnt before. That's why we need more scientists.

Barbara:  Absolutely. A lot of people get intimidated by, "Oh, there's so much to learn," and "What if I make a mistake." Those fears are natural, but the cool thing about science is that, if you get interested in whatever, be it termites or outer space or microbes, and you really start learning about it, you become an expert pretty quickly.

You just pick one topic, of snakes or something, and you could learn a lot about them that the kid next door doesn't know. Already, you're an expert. That's really how, when you get serious about science, you dive into something and you don't worry about the mistakes, because we all make mistakes and we continue to make mistakes.

That's actually how you learn, by making a mistake and then you realize, "Oh, that's for this reason," and you get it. It does seem intimidating, there is a lot to learn, but it's also logical and it's fun. The super‑fun part is that you're making new discoveries.

Dr. Biology:  It's not unlike some of the very complex computer games today. If you start out at level 10, you'll never get anywhere, so you usually start out maybe a level before level one, that teaches you how the game works. Then you go one, two, three, and it gets more and more complex, not unlike science.

Barbara:  Yeah, that's a great analogy.

Dr. Biology:  Again, with games and science, if you like what you're doing, time goes by. It's amazing how fast you learn things and you learn techniques. How did you get started with termites?

Barbara:  I got excited about termites for the same reason that Darwin was interested in social insects. This whole idea of, "How did they evolve? What was the driving force that led to these complex societies?" There were lots and lots of people studying ants, bees, and wasps.

I thought, "Well, there's a lot of people on that level [laughs] and playing the game, and I'll just go back to the first level, but do termites, where there's fewer people, and yet it's a very exciting system."

Dr. Biology:  When you got started, did you figure that you're going to be doing research for this long on termites?

Barbara:  Honestly, I had a feeling I would. It was the kind of thing that felt like a good fit for me. But I have had the privilege of doing a wide variety of studies with termites. It hasn't just been one thing, which is another way to have a wonderful career in science.

What I've been able to do is to travel many different places in the world and work on a whole different variety of termite species, asking different questions about them, sometimes about their genetics, their evolution or their behavior. To me, that's been a great fit with interests and opportunities. I've loved it.

Dr. Biology:  All those things, when it fits in that realm, it's not uncommon for people to look at basic research, and if you're not in that game, if you're not playing that game, you don't always see why you'd want to play that game. Why are they doing that, what's the benefit? Many times, humans, we have a tendency to think everything has got to be all about us.

In this case, not only do you do the basic research but that basic research has actually turned into some very important things for us. This comes back to...You were talking earlier about why we like these termites, we need the termites. As a matter of fact, without termites we'd be in deep trouble, even if we'd be here. We don't necessarily want them in our house.

Barbara:  Absolutely.

Dr. Biology:  In this realm, you actually hold some patents, I've heard. With patents people think business. Have you seen your science and business crossing paths?

Barbara:  Yeah, and I think that's another avenue that science can take people, when they don't even expect it. In my case for example, it used to be that the way that people controlled termites around houses was to spray all sorts of nasty pesticide on them. That put pesticide around homes, and that was a very persistent pesticide, and so dangerous. That was taken off the market.

All of a sudden, there weren't the tools to protect homes from termites. We as humans, we build our houses out of termite food...wood. Of course, we want to keep the termites happy in the forest, in the desert or whatever their normal habitat, but not in our homes. That was at a point that I had begun my termite studies so that I really was learning about the biology of the insect.

When we now needed to create new ways to detect them, to manage them, to prevent them getting into houses, to control them...I won't say I could think like a termite, but I could psych out how they would behave in a certain situation, or foods they would like to eat, or types of homes they were more likely to infest.

Working with a colleague of mine, James Traniello at Boston University, our goal was to develop an approach for managing termites that would be less reliant on widely broadcast pesticide and specifically target the termites. We developed what is called a "termite bait," that is like a cookie that termites can't resist. If they bump into it they want to eat it.

We laced that cookie with a pesticide that really only the termites would eat because they're the ones that would encounter the cookie. There aren't too many things that eat the kind of cookies termites like, that are made out of dead wood.

The principle was that some of the termites in the colony would come and feed at the cookie, then pass along the pesticide to their friends in the colony. At least for once they were eating a house, they would then go away.

Dr. Biology:  How many patents do you have?

Barbara:  I have three termite ones, and one other one. It is a way that if you're developing new ideas as a scientist and potentially new technologies and there may be ways to apply it in ways you didn't even think of when you first started the study.

I think it's a good thing for all of scientists to do to, one, communicate their work, and learn how to tell people what they're doing that doesn't sound like just some narrow, narrow study of scales of snakes or whatever, and why is it important or what can you learn from that system that then you could apply to a different system.

Communicating is very, very important, explaining what you're doing. Also thinking about applications that might help people.

Dr. Biology:  When you were talking today, there was a word that you used. It was actually in your title. Although we don't use...This isn't a big word, it's not very long, but it's a word that a lot of people don't hear..."eusocial." Can you talk just a little bit about eusocial?

Barbara:  Eusocial, it basically means highly social. If you're just social, like humans, we're social, right? We do Facebook, we do...

Dr. Biology:  There's Twitter out there...

Barbara:  Love, being with each other, parties. You want to be alone at some points, but you like company. Monkeys, wolves, lions and many things are social in that the live in groups or families. Eusocial is amping it up one more notch, and a higher level of sociality.

It's a term that is restricted for extreme cases like the social insects, which any of them are not only social but eusocial. A honey bee for example, with the queen and the workers, there are three characteristics that if a group of animals has all three of them, they have to have all three of them, they are considered eusocial.

One of them is overlapping generations. The moms and the offspring have to be alive at the same time, or the grandmother and the mom and the offspring. The queen honey bee and her offspring are alive at the same time. That's overlapping generations. And then, something called "cooperative brood care" which means, they all help. They pitch in to help with the nursery to raise the offspring.

The final one is the big tough angle that not too many animals have. Again, it's this one coming back to Darwin, that was the tough spot for him, and that is what's called "reproductive division of labor", meaning that everybody in the colony does not reproduce, and then there can be a spectrum.

There are certain ones like the queen honey bee, she does the production. She produces all the eggs, for most of them. All the workers in the colony are for the most part sterile. That extreme difference called reproductive division of labor.

Dr. Biology:  Humans, we could say, we could do two out of the three, maybe?

Barbara:  Yeah. We might do two out of three. A lot of animals are in that boat, they did the two easy ones, well, easier. The really restrictive one, it limits it to a very few animals. Quite diverse animals, so in addition to the social insects that we always think of, there's a mammal called the naked mole rat that lives in Africa.

There are some really cool shrimp, snapping shrimp that live in the coast of Central America. Those are pretty diverse. Insects, mammals, shrimp, all of which have this organization of a queen and many workers that help out, but don't reproduce.

If Darwin had known about the shrimp and the naked mole rat, not much was known at that time, very exciting.

Dr. Biology:  When you were talking about the termites, you actually mention how long they live. 18 to 20 years is one of the links of time that was in my notes right now. When most insects, or a lot of insects are measured their lifespan in days, that seems like a really, really long time. Is that really long even for eusocial types of insects or eusocial types of animals?

Barbara:  That's a very good question. One feature of these highly social or eusocial insects, is that the reproductive, the queens for example, do tend to live a long time compared to most other insects. When you think of a butterfly for example, they hatch out of the egg, do their little caterpillar for a couple of weeks, they go into their pupa and they emerge from the chrysalis as a beautiful butterfly, they fly around, and mate, and eat, and then they die.

They're relatively short lived. Some social insect, workers maybe as well, we don't really know because it's hard to age them in the field. We do know that the reproductives, the queens and in the case of the termites, the kings too, lives for many years.

The example that you just mention, 18 to 20 years, those are known measurements that we did in our lab of termite royal pairs, the king and the queen that we put together. We find them again alive, healthy, thriving with their colony two decades later and potentially they could live even longer. Not all social insects and not all termites, even the queens live that long but that's on the extreme side.

Dr. Biology:  Still impressive to me.

Barbara:  Very impressive.

Dr. Biology:  I have a new respect for the termite.

Barbara:  Termites do get a bad rap, has a nasty reputation for eating houses. Remember, tropical rain forests would not exist without termites and they're interesting with their kings, and queens, and colony organizations.

Dr. Biology:  I would say for those who say, "What if we don't have tropical rain forests, we don't need those, no big deal," I want you to go out there and do some homework. Find out what would happen hypothetically, if we have no tropical rain forest.

You are going to find a very interesting story and one that maybe will get you thinking about, "These green machines, these termites, we really owe our lives to them." On Ask A Biologist, we always ask our guest three questions. The first question is, when did you first know you wanted to be a scientist or a biologist?

Barbara:  That's actually a good story with me. I absolutely did not want to be a scientist. I did not like science in elementary school, junior high, or high school. With the passion that I didn't like it so much, I went to a college that I chose because I wouldn't have to take science.

Got there, they made the very good point that to be an educated person you need to explore lots of different things and be exposed to, and learn how to think, and so forth, all sorts of knowledge. So, I took a couple of science courses just as exploratory and loved it.

The first course I took was called, "The Earth, Moon and Mars". The things that I loved about science were the logic and the precision, and then the excitement of new discovery. Once I was hooked, for various reasons, navigated to biology, and then into genetics, and bugs as systems to look at and then I read a book on insect societies and that got me hooked on social insects and termites.

Dr. Biology:  Was this the book by Ed Wilson?

Barbara:  It was. I say, I'm a case where I didn't know from early on that I wanted to be a scientist, but I hadn't really given it up a fair shot. Sometimes, all of us have had teachers that haven't very inspiring, and they were boring.

If you're out there and you're dealing with that kind of a situation where it hasn't got hooked on science, go read something you're interested in. Forget what the teacher is talking about, or your class is covering, volcanoes or something that does or doesn't interest you, just go and read about something that really is of interest to you. See if that makes it a little more exciting. Go in that direction.

Dr. Biology:  I know how you got started. I'm going to take it all away. You can't be a scientist of any kind and most of my scientists love teaching too. I want you to stretch. I'm going to take that away from you and I'm going to give you the gift of whatever you want to do, you get to do. It's not as if you think you'd be able to do it. What would you be or what would you do?

Barbara:  That's a very difficult question. If you asked me that about what other direction in science I'd want to go I could tell you, but for a field? I do like writing. Maybe I would have done that. To be fair, perhaps I didn't know about enough. I didn't give other fields a chance either, there are many directions to go. For me personally, the way I think, the way I like to discover new things, science is a very good fit for me.

Dr. Biology:  If you went into another field of science, I'll let you answer that one?

Barbara:  I think that what changes there is that there are new developments all the time, and new technologies. You can ask questions that you couldn't have asked years ago.

To me now, the field of genomics, looking at genes, really getting down in the dirt and actually seeing what we're all made of, and the variation there, how it's controlled, that's very exciting. I think many dimensions of neurobiology and all the connections now that are possible by merging different fields of science, biomechanics and computational biology.

Dr. Biology:  Bioformatics, large numbers. We have a whole new world that is just opening up to us.

Barbara:  There are no barriers any more, that's a good thing.

Dr. Biology:  My last question, what advice would you have for an up and coming scientist to be?

Barbara:  The big thing is, keep asking questions. Just ask question and don't think that's a stupid question or a dumb question, or it's obvious. Just keep thinking of new questions and follow things that are exciting to you, follow your passion.

The other advice I'd have is, be nice to people. Treat people well because your opportunities, to a large degree, are going to depend on people wanting to mentor you. If you're a classy, solid, honest, hardworking person, you're going to be getting lots of opportunities and people are going to want to invest in you.

Dr. Biology:  Barbara Thorn thanks again, I really appreciate you being on Ask A Biologist

Barbara:  Thanks, Dr. Biology.

Dr. Biology:  You've been listening to Ask A Biologist, and my guest has been Barbara Thorn, professor and director of The Biological Sciences graduate program at the University of Maryland.

The Ask A Biologist podcast, is produced on the campus of Arizona State University and is recorded in the Grassroots Studio. Housed in the School of Life Sciences, which is a division of the College of Liberal Arts and Sciences.

Remember, even though our program is not broadcast live, you can still send us your questions about biology using our companion website. The address is or you can just Google the words, ask a biologist. I'm Dr. Biology.

Transcription by CastingWords

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Tales of Termites

Audio editor: CJ Kazilek

What's a Biologist

Biologists study everything from tiny organisms to whole ecosystems. Let's take a closer look at what biologists do and how you can become a biologist.

>> Full Story

Learning from Darwin's Finches

The Galápagos Islands are home to some of the most amazing plants and animals. One group of animals, the Galapagos finches, have been the focus of biologists ever since Darwin wrote about them in his book, On the Origin of Species. Dr. Biology had the opportunity to sit down with Peter and Rosemary Grant to talk about the more than 30 years they spent studying what have come to be called Darwin’s finches. Don't miss listening to this Robinson Crusoe and Swiss Family Robinson adventure that includes the Grants' two children.

Content Info | Transcript

MP3 download | 15MB

You are missing some Flash content that should appear here! Perhaps your browser cannot display it, or maybe it did not initialize correctly.

Topic Time
Introduction. 00:00
How long did you spend researching finches in the Galapagos? 01:50
Which islands do you work on? 02:16
Daphne Island. 02:43
What's it like living on Daphne Island? 03:28
Misunderstandings of evolution. 05:06
Did you know you'd see evolution in action? 05:44
Observations on fast evolution. 06:18
What were you measuring? 07:09
Is "survival of the fittest" a good phrase to use? 07:54
What happens when the environment changes again? 09:14
Beak variation. 10:54
Darwin's finches in the Galapagos Islands. 11:50
How do you catch the finches and what do you measure? 12:49
How many birds have you captured? 13:48
Vampire...finches? 13:56
Other interesting finches. 15:02
Do you have a favorite finch? 16:15
How the finches learn certain behaviors. 17:40
Did your whole family collect data on the finches? 18:07
Choosing to grow up visiting the Galapagos. 18:38
Immersing the kids in nature and science. 19:14
Independence in science can make a big difference for kids. 20:03
Funny stories in the Galapagos. 20:16
Three questions. 22:15
Rosemary, when did you first know you wanted to be a biologist? 22:26
When Peter first knew he wanted to be a biologist. 23:36
Peter, if you couldn't do science or teach, what would you do? 24:46
Rosemary, if you couldn't do science or teach, what would you do? 26:22
Peter's advice to people interested in biology. 27:07
Rosemary's advice to people interested in biology. 29:19
Sign-off 30:28

Transcript - (PDF)

Dr. Biology:  This is "Ask A Biologist," a program about the living world, and I am Doctor Biology.

I can still remember my trip to the Galapagos Islands even without looking at the thousands of photographs I took during my stay. And even though my trip was short, I felt the same way as many visitors have felt. These Islands are unlike anything I have seen before.

As I visited each island, I wondered who was really watching whom? The animals, especially the Marine Iguanas, stacked alongside and on top of each other; as if in the bleachers of some stadium or seats of a theater watching the players Me, walk by, dressed in my colorful yet unmatched clothes, and wearing a large floppy hat to protect my head from the sun.

My stay at the Galapagos Islands might have been short, but my guests today, Peter and Rosemary Grant, have spent many lifetimes, that would be bird lifetimes, studying the famous Darwin Finches. Their research on the tiny island of Daphne Major has a touch of Robinson Crusoe and Swiss Family Robinson, especially with the Grants' two daughters being part of the story.

I'm not the first to feel this way, in fact, the two biologists are the subject of a Pulitzer Prize‑winning book The Beak of the Finch by Jonathan Weiner. The two scientists have added to their impressive list of honors, the Kyoto Prize in Basic Science.

For those that don't know what the Kyoto Prize is, it's a Japanese award similar to the Nobel prize recognizing outstanding work in the areas of Philosophy, Arts, Science and Technology. I want to welcome you, Peter and Rosemary Grant.

Rosemary Grant:  Thank you.

Peter Grant:  Thank you.

Dr. Biology:  How long did you really spend researching Darwin's Finches on the Galapagos?

Rosemary:  We started in 1973 and we've been back every year. We go back for about three months on average. Once it was as long as six months and it's usually never shorter than two months. Three or four months is usually the average time that we go there.

Dr. Biology:  Three or four months.

Rosemary:  Every year. Since 1973.

Dr. Biology:  Since 1973? Wow. When you say you go back, it's one of the tiny islands called Daphne Major?

Peter:  That's right, but we don't always go to Daphne Major. Sometimes we go to other islands as well. I don't think there's been ever a year when we've not gone to Daphne, but there have been years when we've scarcely visited the islands and spent much more time on another island on the northeastern part of the archipelago called Genovesa where we did a long term study on the Darwin Finches for eleven years.

Dr. Biology:  Daphne Island, when I read the description of it. It doesn't sound like much an island to me. I went to the map, and I hate to confess, but I couldn't find it on the map.

Peter:  On the maps that we use to illustrate the work that we've done, is no bigger than a dust speck. It's three quarters of a kilometer long, about half a kilometer wide, and a 120 meters high. It isn't a very big island. It's a very steep, sloped island with a crater in the middle and it's not the sort of an island that you would pick for a holiday.

Dr. Biology:  What does it look like?

Rosemary:  Somebody has written a poem about it and they described it as a barnacle. Really what it looks like is the top of a volcano just sitting above the surface of the sea.

Dr. Biology:  Just barely. What's it like to live there for three months. Do you have running water?

Rosemary:  No. We take all our water with us. It's because if there is no water on the island, we take every drop of freshwater with us. We take all our food. We've got to be extremely careful to wash everything.

We live in tents so we've got to make absolutely sure that the tent is washed and all our clothes are washed, all our equipment is clean, because we must be very careful not to introduce any insects or any seeds, anything on the island. For example, we cannot take any fruit that has seeds in, because there's a possibility that those seeds will grow.

Dr. Biology:  Right, it would be an introduced or an un‑invasive species even.

Peter:  Boots have to be checked. Socks have to be checked, before we get off the boat and onto the island for exactly that reason.

Then when we have fresh vegetables and there is very little that we can take to the island, limes are one item that we are allowed to take onto the island. They go into the water when we arrive. Get washed, scrubbed, put in a bucket and carried up to the top of the slope.

Bananas are the same. We take half a head of bananas and dip that in the water, swish it around, get rid of all insects, if there are any. Typically there are none because the bananas have been washed back at the research station on the other island where we work.

Rosemary:  We should say that the limes have no seeds in them.

Peter:  Yes, that's right.

Rosemary:  Those are the ones that we're allowed to take.

Dr. Biology:  That would make sense and is it possibly because they have vitamin C or is it just because you like limes?

Rosemary:  No. It's just because it's the only fruit that we can take. There is no choice.

Dr. Biology:  That makes sense. We're going to be talking about evolution and this is in an area filled with wonder and in many cases misunderstanding. For example, most of us have been taught that it takes a really long time for evolutionary change to occur. I'm not talking about those long car trips when we were kids and it seemed like it took forever to get there.

What I'm talking about are things that take hundreds or thousands of years, even millions. Your research actually shows that evolution can happen in pretty short periods and that's if you can consider 20 or so years short. When you started your project did you have any idea that you'd be able to see evolution in action?

Peter:  No. We didn't. At least not on the magnitude, not on the scale that we have seen it. It's not that it was out of our minds.

I'm sure thinking back to 1973, we would have been speculating that maybe once in a while it is possible that there will be a very slight, small evolutionary change in the population, if weather changes and the food supply changes. We had no real conviction that this would happen on anything like the scale that it really has occurred over the last 30 plus years.

It occurs in a very short space of time. It's not a matter of evolution taking 20 years before it can be observed. Rather, when the weather changes and we have either a very wet year or a very dry year and the vegetation changes, the conditions for the birds alter.

Then when a drought sets in, after a period of production of seeds and insects and it becomes difficult for the birds to find enough food, that is the time, the crunch time when finches are subjected to pressures only few of which can withstand them and that is the time when natural selection occurs and evolution occurs in the following generation.

Really we're talking only in terms of about a year or maybe two at the most for evolution to take place on the scale where it can actually be measured.

Dr. Biology:  What were you measuring?

Rosemary:  The first time we measured it, there was drought, a very severe drought. More than 80 percent of the birds died on the island and there was a large variation in beak size.

On the island, in the soil on the ground there were large hard tribulus seeds [Tribulus terrestris]. The birds with the small beaks could not crack those tribulus seeds. They eventually stopped and died. The birds with the very biggest beak were able to crack those large, hard tribulus seeds and they were the ones that survived.

At the end of that drought, which took a year, there were a few birds left on the island and they were all the large birds with the large beaks.

Dr. Biology:  We saw them change or we saw those evolutionary change or survival of the fittest. Is that good time, because you hear that a lot and that's not necessarily correct?

Rosemary:  In some ways survival of the fittest is not a very good term because most people think that fit means, the ability to run around a racetrack or something like this. In biology it's more used, the ones that actually are capable of surviving. The next year, which was what happened in this case, those birds were able to breed and produce young and those young were large like their parents.

This is because often small parents will produce small children and very tall parents will produce very tall children. It's exactly the same with the birds. Those with large beaks will produce large young with large beaks and those with small beaks will produce small young with small beaks.

What we saw was this change in average beak size in the population, which is natural selection and the evolution was what happened the next year when the young grew up to be the same as their parents.

Dr. Biology:  Instead of the survival of the fittest, it's the survival of the ones with the best set of tools to survive.

Rosemary:  To survive, yes.

Dr. Biology:  It would be the beaks this time for these.

Rosemary:  Yes.

Dr. Biology:  Then the rains do come back as they do. What happens then?

Peter:  Then the survivors breed. They produce young as Rosemary just explained, that they're like themselves. The beak size of the finches is inherited. Their offspring, the children inherit factors or characteristics of the mothers and the fathers that produce them. They also are large.

The evolution that has taken place then is one of a shift in the average beak size from the parental generation before natural selection occurred, before any of the members of that population age group died, all the way through to the next generation. That is the measure of evolution.

Biologists use the definition that evolution is a change in genetic characteristics of a population from one generation to the next.

Dr. Biology:  It can go both ways there?

Rosemary:  It can go both ways and we actually have seen it go the other way too. Nothing really happened for many years, then we had an enormous El Nino year. That is a year when he had an enormous amount of rainfall. The rain lasted for eight months and the birds bred every month for eight months.

Those plants that were producing the large hard seeds got smothered and other plants grew up, which produced small soft seeds. Then after that, when the next drought came, we again had large numbers of birds die. Now in the ground were a lot of small, soft seeds and this time it was the large beaked birds that died and the small beaked birds that survived.

Dr. Biology:  We know that the small beaked birds are the ones that survive.

Rosemary:  When there were small soft, seeds.

Dr. Biology:  If I'm sitting in the classroom, and I'm getting this lesson from Rosemary and Peter Grant, I'm along with this ride in the Galapagos. It's great, but, if all the birds that had, in the first round, the small beaked ones died and I only had a large beaked ones, then the conditions changed. Where do you get the small beaked ones to start up again?

Peter:  Not all of the small beaked birds died, when the large beaked birds had the survival advantage in the first drought. There were still some small beaked birds left. They bred, and, gradually, their numbers increased in the population.

When the next drought occurred, and small beaked birds had an advantage over the big beaked birds, there were quite a number of small beaked birds, as well, of course, a large number of the large beaked birds.

Dr. Biology:  When we talk about Darwin, and if you read a little bit more about Darwin, when he went to the Galapagos, first of all, the whole trip he took was five years. The thing that really amazes me is he is basically seasick the whole time. I'm impressed that anybody could take good notes and do some good drawings, but he collected the finches. Even he didn't know what he had.

What got him to look at his specimens, when he returned?

Peter:  He handed his specimens over to an expert, at the British Museum, a man called John Gould, who compared them with a lot of other specimens of other birds collected in South America beforehand.

Then, he gave the verdict to Darwin in 1837 that they were all members of the same group and that they weren't, as Darwin had previously thought, in some cases related to blackbirds, in some cases, related to warblers, and, in other cases, related to finches. Nope. They were all of one group and that made Darwin really sit up and take notice.

Dr. Biology:  Wow. When you talk about your research, and there's so many years worth of research. I read a little bit in the book about going out and capturing the birds. As tame as I thought a lot of the animals were, especially the iguanas, the iguanas were amazing to me, but these finches some of them are pretty tough to get.

How do you capture your finches and when you capture them what are you measuring?

Rosemary:  We capture them in mist nets. These are nets made in Japan. We put those nets up very early in the morning, usually, just before it gets light. Then, we catch the birds. Then, we take the birds out immediately, when it's still cool, so that they aren't harmed at all.

Then, we measure them. We measure their bill length, their bill depth, their bill width. We measure the length of their legs, the length of their wing. We weigh them. We also take a tiny little bit of blood, and that's enough for us to get DNA out of that blood, so that we're able to do the genetics on the finches.

Dr. Biology:  How many birds have you done this with over the years?

Rosemary:  I can't tell you how many, but thousands.

Dr. Biology:  In one of the Ask a Biologist shows, we talked about bats, bones and biology. Of course, when you do a show like that, you have to include vampire bats. What I didn't know is there’re vampire finches?

Rosemary:  Yes. This, again, in the droughts in the dry years, and this bird ‑ it belongs to a member of a species, which is called the sharp beaked ground finch, and it occurs up on Wenman Island, during the drought, there were no seeds or very few seeds on the ground. There is very few nectar in the flowers that do flower during the drought like cactus.

What they do is they resort to jumping on the back of sea birds, pecking at the base of the feathers, pecking at the base of the tail, and drawing blood. We think that this habit probably arose, because they were pecking out little flies, Hippoboscidae flies, which suck blood from the seabirds. By going straight to the blood source, they are bypassing this.

Dr. Biology:  There's also one that's a vegetarian. I'm a vegetarian. There is one there I think is my favorite is the one that actually makes tools with its beak.

Rosemary:  Yes.

Dr. Biology:  Can you talk a little bit about that finch?

Peter:  The woodpecker finch makes his own tool for extracting the bee larvae that are inside a dead or rotting wood. What they do is, they pick either a twig or a cactus spine or even the long stalk of a leaf. They trim it down, whatever it is. They trim it down to a size about twice or three times the length of its own beak. They hold it slightly crosswise, but pointing forward and probe it into a hole to tease out the insect larvae on the inside.

We think one of the interesting things about that peculiar, unique behavior is the question still not satisfactorily answered, whether there is any genetic predisposition of some to feed like this and others not to. Because it is known that in some times of the year, in some places, it's much easier to see the tool using habit than in other places on the same island.

Dr. Biology:  I picked my favorite finch. Do either of you or both of you have your favorite finch?

Peter:  We're not allowed to have favorites.


Peter:  From time to time, Rosemary has had favorite individuals. One was called perfect. It was called perfect, because, in some ways, it was a beautifully designed finch, for feeding in a variety of ways.

I think one of the extra reasons for calling it perfect was that it seemed to have a very good understanding of when I was around, and it would avoid me. When Rosemary was around alone, it would come up to her. There have been lots of other birds with funny habits.

For example, one year, we saw two cactus finches, only two of them, pecking at the tail of lizards. A lizard if it's attacked at the tail end will wriggle its tail very fast, break his tail off and run away, very good defense. Better to lose the tail than to lose the life.

Two finches decided, somehow or other, they managed to discover that the tails could be gained from the lizards by grabbing hold of them and then, eating them. There are lots of other idiosyncratic behavioral tricks that these finches get up to, and, if we have any favorites at all, it's those individuals that display these unusual behaviors.

Dr. Biology:  You just wish you could see them learning. What was the trigger you'd love to see that or have you ever seen that?

Rosemary:  Actually, yes. You do see them going around together, especially young ones. It's usually the young ones, after they've finished being fed by the parents. Then, they go around, sometimes in groups, and there they copy each other doing things. One would do something, and they'll copy it. There's a lot of copying and trial and error learning that goes on.

Dr. Biology:  Was the process of collecting data in the Galapagos a family affair and two daughters went along?

Rosemary:  Yes and also we've home‑schooled them, on the islands too. When they first came in, they were six and eight‑years‑old. Then right up to University. Even when they were at the University, they would decide they wanted to come down with us.

They did do their own project. Thalia worked on the dolphin. Nicola worked on the mocking bird. They both worked very well on that and got a publication out of it.

Dr. Biology:  You answered my question, but I still am amazed that they decided to go back every year, and I could understand when they were younger but, as they got older...

Rosemary:  I know.

Dr. Biology: would think that, "Oh, no. I'm going to go off to ‑‑ it's not the Riviera, it's not something really posh.

Rosemary:  There's no television.

Dr. Biology:  No television.

Peter:  No distractions.

Rosemary:  No friends.

Dr. Biology:  No video games, because...

Rosemary. No.

Dr. Biology:  Did you have any electricity?

Rosemary:  No. Wait. Not then.

Peter:  Not at that time.

Rosemary:  Now, we take solar panels, which we use just for charging up batteries and things like that.

Peter:  They also had a lot of freedom to read and make observations and do whatever they wanted to do in the way of immersing themselves, as naturalists on that island.

Your earlier question was, "What did they do? Did they help you?" and the answer was, "Yes, they did help us." Putting up nets, for example, requires help. They engage themselves in those activities, but that was a minor component of their total daily activity. They were often doing their own thing. If they weren't doing schoolwork, they were doing their own thing.

Rosemary:  I should say that, we didn't force them to, because every year I would say to them, "You don't have to come down with us." No, No, they definitely wanted to come down. Now, they're grown up and have children of their own, and they now say that this is one of the best things that ever happened.

Dr. Biology:  You stumbled upon what I think is probably the reason they kept coming back is they weren't doing your work.

Rosemary:  No. They were doing...

Dr. Biology:  They had their own projects.

Rosemary:  Yes.

Dr. Biology:  That really is a big difference.

Rosemary:  It's very big difference, yes, yes.

Dr. Biology:  With over 30 years of experience on the Galapagos and many people have never been there but if you look to the list of where people would like to go that's got to be very high. Is there a story or an event that the two of you can think of that's...

Rosemary:  So many. There’s one. This is on the island of Genovesa. This is an island up in the northeast of the archipelago. It is very isolated. You can't see another island from it.

We had two students, who were working on the island. We weren't there, actually, at the time. We had been there. We left, and we left the two students to follow on the work. They were sitting in camp one day, and not a boat to be seen. All of a sudden, a man walks into the camp, carrying a briefcase and a rolled umbrella.

Dr. Biology:  This is out in middle of nowhere, right?

Rosemary:  This is out in the middle of the nowhere, an uninhabited island, no boats anywhere. They couldn't see anything, and in he walks, with a road umbrella. What had happened was that he was in a lone boat, traveling around the world, in a little lone sailboat. He'd gone to sleep, and the boat had crashed, on the other side of the island.

He had taken his little bag, which had all his precious passport and various things in, and, for some reason or other, he also had his umbrella. He walked around the island. The island is quite large. It's about five miles in diameter.

He walked around and, fortunately, for him, he found students on the island, because they were able to feed him and give him water. He was able to stay there, until a boat came, and they could take him off the island. [laughs]

Dr. Biology:  That's a very lucky man and a very interesting one there. I can see this vision. They must have thought they were hallucinating.

Rosemary:  Yes.

Dr. Biology:  On Ask A Biologist, my scientists never get out of here without answering three questions, and I have the two of you. We'll just trade off here. The first one, pretty simple, to get you warmed up, when did you first know you wanted to be a scientist or a biologist? I'll start with Rosemary.

Rosemary:  Before I even knew the word biologist, I was brought up in a small village, in the Lake District, and it's a wonderful little village. It's on the coast. It has carboniferous limestone cliffs, with lots of fossils. Then, behind those cliffs were fells with rare plants and butterflies. I grew up with my mother, hunting for fossils and looking at plants and butterflies. I was always curious about the diversity of animals and plants.

When I got a little bit older, my father suggested that I should read Darwin's Origin of the Species and then, when I was a teenager, I thought that studying genetics would be fundamental to this. I wanted to go to Edinburgh University and study genetics at Edinburgh University. I was one of these weird people who knew, from the very beginning, that I was really interested in plants and animals and the diversity.

Peter:  Rosemary married another weird person.

Dr. Biology:  Besides you.

Rosemary:  [laughs]

Peter:  I don't know. I am very weird, in exactly the same way, in that my own interest started at a very early age. My earliest recollection actually is, smelling flowers and catching butterflies with my hand. I was fascinated by natural history, I would call it, as I was growing up and interested in a lot of other things as well.

In fact, I did better in my exam as a 16‑year‑old at school there, in a couple of other subjects ‑‑ mathematics was one, and English literature and language was another ‑‑ than I did in biology, but my passion was for biology. When I went to university, I started zoology, botany, and two other subjects, which I had to do. Organic chemistry was one and geology was another.

I didn't know whether I was going to become a scientist until I went to graduate school, became a graduate student. There I learned that one could do research on the topic of one's own choosing and teach. I thought my Gosh, these two activities are just what I love to do, and, if I am qualified to do it, they pay me for it. That's it. That's my career.

Dr. Biology:  That's your career. The next one is a little tougher. I'm going to take it all away from you. You have such a great career. I know this is very, very difficult, but I am going all your science away from you, and I am going to take academia away from you. It takes the teaching away, because I know my scientists like to go to the mode of teaching, which is great. I want to stretch you a little bit. I'm going to start with Peter this time.

What would you be or what would you do if you couldn't be a biologist or a scientist? What would you do?

Peter:  I'll be a cricketer.

Dr. Biology:  Really?

Peter:  I had two passions, as a schoolboy. One was biology, as I told you, and the other one was sport. I was almost ‑‑ you might say ‑‑ keen on anything with the ball running around, tennis, cricket, grass hockey, and soccer. All of those, but the ones in which I did best of all were cricket and grass hockey, and I could have pursued those for a while.

Now at my tender age, I would not be a professional sportsman, but if I'd been thwarted in trying to become a scientist, that's the direction I probably would have taken. I don't know how long I would've lasted that way. Then what I would've done, when I had to retire from sport, gone into something else. Rosemary jokes that it would be acting, because that's the only other thing I can do.


Dr. Biology:  All right. I do enjoy that. Cricket. I have to admit that I'm really terrible. I watch the game but I don't get it.

Rosemary:  It's so boring. Isn't it?

Dr. Biology:  I'm not saying that.

Peter:  I did tell you I was a weird person.

Dr. Biology:  Rosemary, what were you going to be or what were you going to do?

Rosemary:  Mine would either be dancing, which I loved to do, when I was a child or music, some form of music. If you also gave me the ability, it might be music. I'm fond of all sorts of music. It would be either playing an instrument, violin, piano, cello.

Dr. Biology:  Very good. You're my first ballet dancer.

Rosemary:  [laughs]

Peter:  First cricketer.

Dr. Biology:  Absolutely, but not the first sportsman. We have quite a few of them would be play second base for some team or others that would be a surfer or a snowboarder professional. That's amazing to me.

The last question is to help those, and I used to say a young person that wants to get into science. In this day and age there are people that decide, I'm not interested in what I'm doing anymore and I have always enjoyed biology. What would your advice be for them? What would you say to them?

Peter:  If the person is at school, high school let's say, and being encouraged to go in one direction but really deep down wants to become a scientist, being encouraged may be to go into politics by parents or what else we say, even sport, it's difficult to advise that person to go against parental wishes.

In general, our philosophy is when anybody asks us, I really would like to become a biologist, but I'm just not sure whether I should or not. Our general advice is, go with your heart, go with what ever really motivates you exceedingly strongly.

If you have a passion for studying plants or viruses or anything that is living and you want to become a biologist, then just take whatever course you can at school and at university, as far as you can until the doors come down, and it no longer become possible to pursue that a career option but just go with your passion, go with where your feelings are really strongest. That's my general attitude.

Dr. Biology:  Marvelous and the parents won't be upset, I don't think.

Peter:  Some are. We've know some parents who've stressed that the budding paleontologist that we had been teaching really should go into law, because that's where the action is.

Thinking of the parents, who are directing their child in one direction, and the child really wants to go in another one, the advice that I would give and again a very general one and not specific to very young people is, "Don't be put off by adversity. Try not to be discouraged, when it does not seem possible or easy to follow one's heart, but to keep persisting, if that is the decision on where the person really wants to go."

Rosemary:  Following your passion is the most important, but once you have done that, then I think I would have a few pieces of advice. One would be to get to know a system really well and to read widely around that system. So that what you're reading you can apply to your system.

Then, the other thing which my father used to drive home to me, was always value your exceptions. When you are actually doing an experiment or anything like that, don't come to conclusions too quickly. Try and be your own devil's advocate and say, "What would it take for me to disprove this and to do this?"

Then the other thing is that when you are doing an experiment or you are following some observation and you see something which doesn't fit, then don't discard it, but follow that has, with us, led us down some very interesting paths and to new discoveries. Value your exceptions is something that I would say as well.

Dr. Biology:  On that note, I want to thank you both Professors Peter and Rosemary Grant for being in Ask A Biologist.

Peter:  Thank you.

Rosemary:  Thank you very much.

Dr. Biology:  You've been listening to Ask a Biologist and my guests had been biologist Peter and Rosemary Grant, two emeritus faculty from Princeton University. The Ask A Biologist podcast is produced on the campus of Arizona State University, and it is recorded in the Grass Roots Studio housed in the School of Life Sciences, which is a unit of the College of Liberal Arts and Sciences.

Remember even though our program is not broadcast live, you can still send us your questions about biology using our companion website. The address is or you can just Google the words, Ask A Biologist. I'm Dr. Biology.

Transcription by CastingWords

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Learning from Darwin's Finches

Audio editor: Eric Moody

Metamorphosis Bits

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Metamorphosis Bits

By Carole Flores

show/hide words to know

  • Adult: fully grown.
  • Complete metamorphosis: a change in body form with four stages: egg, larva, pupa, and adult.
  • Egg: a female gamete, which keeps all the parts of a cell after fusing with a sperm.
  • Exoskeleton: hard body covering... more
  • Incomplete metamorphosis: a change in body form with three stages: egg, nymph, and adult.
  • Larva: the second, "worm-like" stage in the life cycle of insects that undergo complete metamorphosis (like caterpillars).
  • Metamorphosis: dramatic change in body form... more
  • Pupa: resting stage during which tissues are reorganized from larval form to adult form. The pupa is the third body form in the life cycle of insects that undergo complete metamorphosis (like caterpillars).

Flashcard facts and information about metamorphosis

Biology Bits stories are a great way for you to learn about biology a little bit at a time. We’ve broken down information into pieces that are very tiny—bite-sized biology cards. Cutting out the cards will let you organize them however you want, or use them as flashcards while you read.

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You're right, GMOs have been in the news more often lately, probably because more people are starting to question what GMOs are and whether or not they are safe to eat.

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Grade Level: 10

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Cute Colorful Poison Dart Frogs and Their Mimics

They might be colorful. They might be cute to some people. But don’t let that fool you. These bright colored frogs are poisonous. Dr. Biology talks with biologist Molly Cummings to learn about her work with some frogs that advertise to predators to stay away and other frogs that take advantage of this signal by copying the colors of their poisonous cousins.

Content Info | Transcript

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Topic Time
Introduction. 00:00
Poison dart frogs. 01:24
Don't touch these frogs. 01:48
Why are there different colored frogs of the same species? 02:08
Three frog mimicry system. 02:51
Mimicry system: chicken behavior experiment. 03:50
Predators learning to avoid colors. 04:29
Evolution of different colors. 04:44
What can drive this change in color? 05:13
Can color vision affect evolution of color? 05:41
Sexual selection affects color. 06:22
How brightness and color are related. 06:50
Sexual selection vs. natural selection. 07:38
What colors do the frogs see? 08:01
Day vs. night vision. 09:08
Night vision and color vision. 10:04
Why poison dart frogs? 10:54
How to catch poison dart frogs. 11:25
Are these frogs active at night? 12:08
Is there a more popular color among these frogs? 12:26
Do different colored frogs mate with each other? 13:50
Do you travel often for your research? 14:15
Revisiting the three frog mimicry system. 14:51
More on chicken behavior experiments. 16:17
Scarab beetle research. 17:34
Scarab beetles and Avatar. 18:13
Polarized light. 19:03
Beetles and polarized light. 20:29
The early days of stereo images. 22:13
Three questions. 23:06
When did you first know you wanted to be a biologist? 23:16
What would you do if you couldn't be a scientist or teacher? 24:25
What advice do you have for someone who wants to be a scientist? 25:21
What's your math background and how do you use math? 26:12
Sign-off 27:49

Transcript - (PDF)

Dr. Biology:  This is "Ask a Biologist," a program about the living world. I am Dr. Biology. For today's show I want to start out by us thinking about bright reds, screaming yellows, brilliant blues and gloriously intense greens.

If you've placed those colors in your mind, now think about some tiny tropical frogs that use these colors as warning signs. They're signals to other animals that they might not want to take a bite out of them, because...well, you might croak. I know, I know. Sorry, I couldn't pass up the pun.

What is also interesting is these colors have been copied by other frogs that are, actually, quite tasty. These frogs use the colors to keep predators away. They're what we call mimics.

My guest today is Molly Cummings, Professor from the School of Biological Sciences, at the University of Texas Austin. She's been studying a particular type of poison dart frog. The strawberry poison frog and has found out that there's more to the story than just bright colors.

She's also been working with a brightly colored beetle called a scarab beetle, and I've been told these beetles have a connection to the movie "Avatar." Let's take a moment to learn about colorful poison frogs and beetles and the story they are telling us about one part of life. Welcome to the show, Molly, and thank you for visiting with me today.

Molly Cummings:  Thank you very much, Dr. Biology. I'm happy to be here.

Dr. Biology:  Let's start by talking about your cute study subjects. I'm actually looking at them here, and they're amazing. Why don't you talk a little about this colorful, cool and, in this case, sometimes dangerous animal?

Molly:  They're very attractive, which is kind of unusual for something that's trying to tell other animals to stay away from it. When we see these colors, they're bright and beautiful and we think, "Wow, how gorgeous, want to grab them."

That's actually a bad idea. If any of you go down to Costa Rica or Panama and see a brightly colored frog, do not grab it and, by all means, do not lick it, because that's exactly where they keep their poisons, on their back.

We were really interested by why this one species, species means groups of animals that can mate together and make more individuals, why they changed their colors. Some islands have red backs, some islands have yellow, some have green, some have blue. They're all considered the same species.

We wanted to understand why because, when it comes to using colors to advertise, it doesn't make sense to change your advertisement signal. When you're driving down the street and you see a McDonald's sign and you see that golden arch on the red background, you think McDonald's. If McDonald's constantly changed colors, you wouldn't always associate those arches with McDonald's. That's the mystery we were trying to solve.

Dr. Biology:  I'm looking at some pictures of your frogs. There are actually three frogs here, brightly colored backs, really bright red. Not being a poison dark frog connoisseur, they all look the same to me.

Molly:  That's actually another frog. That's a series of three different species that live in Ecuador. This particular story is a very interesting story because we didn't understand why this non‑toxic frog, this very juicy frog, was able to copy these two different types of nasty frogs, but when the frogs overlap, they only copied one of them.

That didn't make sense to us because the one frog that it would copy in this zone of overlap, where all the frogs were hanging out together was the frog that was the least toxic. It was almost close to palatable, tasty.

Dr. Biology:  Yeah, tasty.

Molly:  It was the least abundant. It didn't make a lot of sense. We ended up doing a behavior experiment where we got chickens involved. We trained some chickens to learn to avoid these two different types of nasty frogs. What we found is that when chickens learned on the less nasty frog, they only avoided that specific frog color.

When they learned on the more toxic or more nasty frog, they not only avoided that particular frog color but they also avoided new colors of frogs. That was really interesting to us. It made us wonder whether or not this was a way where frogs could develop new colors, warn predators, and not get in trouble for it, not get tasted.

Dr. Biology:  In this way, they weren't so specialized. It wasn't saying, only avoid red backed frogs. It could be that you learned that, "Hey, if it's a bright color, avoid it altogether."

Molly:  Yes.

Dr. Biology:  It's amazing to me that they're all the same species but they have developed to have different colors and they're still the same species. What's the story behind it? When you say they've learned to change, this is overtime. We're talking a lot of time, right?

Molly:  Yes, we're talking thousands of years, which actually is a short period of time for evolution. These different islands where the different colors arise have only been in existence for ten thousands of years. Getting back to the question of why there are different colors, there's really two big sources of where we think the variation. The change in color can come from. It can be predators, and it can be other frogs.

Let me take on the predators first. The animals who eat the frogs can be a number of different types of animals. They could be birds, they could be snakes, they could be crabs, they could even be spiders. There are actually stories out there, big nasty spiders eating small nasty frogs. [laughs]

Dr. Biology:  Wow, OK.

Molly:  All of these different animals I've mentioned have different types of eyes. In their eyes, they have different cells that can see the world differently than you and I. You and I can see the world in one way we see these frogs as beautiful, red, and yellow. But birds actually have more types of cells and see a broader part of the light spectrum then you and I see. And snakes, and crabs see it differently even from these birds.

It's quite possible, and that's one of the things we try to study, is whether or not the different eyes of these different predators are driving the changes in color.

You'd expect that from animals who use colors to warn predators, but what is less expected is that the females, the girls in this species, can have actually have some influence, some say, in the direction of the color. We've been asking the girl frogs whether or not they like the boy frogs who are brighter or a different color then their own local morph. And sure enough the girls tend to prefer brighter frogs on all the different islands, regardless of what color their specific island is.

How this relates to color is, that brightness and color are kind of related. You can become brighter by simply bouncing off more photons on that part of the rainbow, or you can become brighter by bouncing off more photons across the rainbow. By bouncing off more photons you might actually change your color from a deep dark red to an orange or to a yellow or to a green. And if the whole goal is just to be brighter along the way you might change your color.

These two processes I've been talking about have been referred to as natural selection, that where they try to survive being eaten, and something called sexual selection, which is trying to be attractive to a mate. We're finding that both of these processes might be producing the changes in color we're seeing between the islands.

Dr. Biology:  Right and it can be at opposites in the sense that if you get really attractive and bright which might be great for sexual selection, so the girl frogs like the boy frogs more, but now the boy frog is much more noticeable.

Molly:  Exactly.

Dr. Biology:  Is that a problem that, now they get eaten more.

Molly:  Right.

Dr. Biology:  So there's that trade off going on, but because they're using this different type of light. You brought it up so, we see what's called visible light. It's this rainbow of colors and on both sides there's either UV, which is ultra violet, and then there's infrared. You also mentioned that snakes, a lot of reptiles, are really good with infrared.

Molly:  Correct.

Dr. Biology:  And there are a lot of insects that are really amazing and they can see in the UV. So what we see and what they see are really different. So what are the frogs seeing then if they're not seeing the bright colors? Is it bright colors or is it ultra‑bright colors?

Molly:  These frogs, because they're active by day, actually have a visual system somewhat similar to you and I. They have these three types of cone classes in their eyes as do humans, most humans do. That's different from, let's say, birds that tend to have four cone classes and can go into the UV, that you mentioned, and can go farther into the red then we can.

The frogs themselves, and we've done experiments to make sure that they can see the difference in the brightness, as well as we've gone into the eye and evaluated whether or not they're likely to detect this brightness, and sure enough they can. These day frogs can see it.

Now if you compare the eyes of a frog that's active by day, to the eyes a frog that's active by night they're going to be very different. The eyes of the frogs at night have two different kinds of cells called rods, which are types of specialized cells to see under low light conditions, and what's really unique is that humans and most mammals only have one kind of rod, that's only sensitive to one portion of the rainbow.

These frogs that are active by night have two different classes of rods that are sensitive to different parts of the rainbow, and the hypothesis right now ‑‑ and some of you out there can go out test it someday ‑‑ is determine whether or not they use these two different kinds of rods to see color at night. That would be pretty cool, being able to see color in the dark, which is something we are not actually very good at unless we have street lights to help us.

Dr. Biology:  Right, and even if you think you're seeing color late at night it's because you just get enough of the light.

Molly:  Exactly.

Dr. Biology:  On a moonlit night you really don't see the color.

Molly:  That's right.

Dr. Biology:  We've got our rods, really good for night vision, and then we have our cones, which is great because it's a 'C' begins with color [laughter] all fits together, so the cones are the ones for color. We actually have on Ask A Biologist a nice story on seeing color. It talks about humans see color and wavelengths of light and actually how some animals, what they're seeing. Because a lot of people think animals, dogs and cats, are colorblind, and they're actually not.

Molly:  Correct.

Dr. Biology:  Which is interesting. Your cat for example, can see the same colors we can see, but not as strong. They live in what I call a "Pastel world." Back to your frogs, why poison dart frogs?

Molly:  They're beautiful. I've always been intrigued by all the different colors in this world. My first intrigue was all the different fish colors in the world. Whether or not, you can predict variation in color in this world. Poison dart frogs are one of the most colorful. Almost every color in the rainbow pops up in a poison dart frog. I was very drawn to understanding this variation out there.

How you catch these guys is you put on rubber gloves, and you literally chase them. Some of the really bright ones are so toxic that they're very bold. They have this, "How dare you even think about picking me up," attitude. It's easy to catch them because they are shocked. You're going to grab them. [laughs] The less colorful ones are less toxic, it ends up.

They're a little bit more shy and want to run away. You have to get crafty. It takes a little bit of practice, but you can track them down eventually, if they don't go hide underneath the log. We also use little rubber Tupperware containers to catch them, so that you don't squash them, and then we poke holes, so they can breathe.

Dr. Biology:  I can see that. You're doing this in the night time?

Molly:  No. They're active by day. They're one of the rare groups of frogs that are active by day. Most frogs are active by night. That's what's so neat. Their visual system, their eyes have changed to adapt to their daylight activities.

Dr. Biology:  Are there more of these species of frogs that are on a different islands? It probably depends on the size of the islands. Are there more reds than yellows, or more blues than greens?

Molly:  There're more reds and oranges. The thing is, mostly on the mainland, they're all red red‑backed. They're red‑backed and blue‑legged across Nicaragua, Panama and Costa Rica. Just off this one, what's called an archipelago, which is a small series of islands on the western side of Panama, you have this variation, this changes in the colors.

We have up to 15 different colors more. Over three countries, you have the one species having a red back with blue legs. Then, on this very small little area that expands maybe 10 miles in diameter, you have 15 different colors more, from the blues, oranges, greens, yellows and reds. Most of them are the orange‑red theme. That's probably because that's what they look like on the mainland.

The blue is somewhat rare. We actually are thinking this idea that different predators can lead to different colors. Where you find the blues is where you find crabs. Crabs visual system actually favors seeing blue as a conspicuous color, more so than it sees red. We think that that might be a factor.

Dr. Biology:  Do the different‑colored frogs mate with each other?

Molly:  Yes, they do. Females tend to prefer the colors that they grew up in. When you bring them together in captivity, they often do mate, when their offspring are a mixture of those colors.

Dr. Biology:  They are?

Molly:  Yes.

Dr. Biology:  Interesting.

Molly:  Yeah.

Dr. Biology:  A little bit of genetics, we'll get into another show.

Molly:  Yes. [laughs]

Dr. Biology:  Do you have to travel often for your research?

Molly:  Yes, I get to do a lot of traveling. I travel to Panama for my poison frog research. I get to travel to Mexico to collect fish for my sort tail research. I travel to the Coast of Texas to do some marine work on polarized light. I travel to Florida to do some marine work on polarized light as well. Being a scientist, one of the best perks is getting to travel.

Dr. Biology:  I've said that. Anybody listens to this program knows that I'm a big advocate. If you want to see the world and travel, become a biologist.

Molly:  I agree. [laughs]

Dr. Biology:  The other frog that you work with, I actually have a picture in front of me. It's bright red. There are actually three different types of them.

Molly:  Yes.

Dr. Biology:  The way I read about it, one is very toxic.

Molly:  Correct.

Dr. Biology:  One is kind of toxic, and one's tasty.

Molly:  That's correct.

Dr. Biology:  The interesting thing about it is I wouldn't know one from the other right off the bad. If I did some studying, I'll be able to tell. I can understand why you would want to be a mimic the one that's pretending to be the really toxic one. The one that was mimicking, either the very toxic or kind of toxic one, it did the kind of toxic one.

Molly:  Yes. The more toxic one lives in the northern part of the Amazonian Basin of Ecuador, a great place to visit. The less toxic one lives in the southern region. The tasty one that mimics these two lives in both of those regions. When it lives in the north, it looks just like the really toxic one. When it lives in the south, it looks just like the less toxic one.

Dr. Biology:  I get it.

Molly:  In this area, the small geographic region, you get the two toxic species living together. The tasty one also overlaps in its own. It's in the net zone, where it only mimics the less toxic frog. That's completely what I would call "Counterintuitive." It doesn't make sense. We did these behavior experiments, where we trained chickens to learn to avoid the more toxic one.

We trained another set of chickens to learn to avoid the less toxic one. Sure enough, they learned to avoid both frogs. We asked the chickens, "What would you do when we gave you the new‑colored frog?" When we asked the chickens that learned on the less toxic frog, they saw this new frog, and they thought, "Something tasty." They went, and tried to eat it.

When we asked the chickens that have learned on the more toxic frog, they would do with the new‑colored frog. They looked at it, and they got scared. They didn't want to eat it. We thought, "This makes sense because now, any of the tasty frogs, the mimic frogs that look like the less toxic frog now get 100 percent protection."

Because they're protected from any predator who is familiar with the less toxic frog, because it will avoid something that looks just like it. They get protection from any predator who is familiar with the more toxic frog, because they avoid new‑colored frogs. It's a clever way to avoid being eaten. It's a little complicated, but it's clever. Often, biology is like that.

Dr. Biology:  Besides the cool colorful and dangerous frogs, you've been working with some beetles. We've seen some cool beetles in some of the work we've been doing. You've been working with the scarab beetles. I actually describe them as almost like colorful, chrome‑plated beetles. Very jewel‑like. There is an article that you wrote with another scientist. It deals in particular with these scarab beetles and the movie "Avatar." Let's talk a little bit about scarab beetles in Avatar.

Molly:  What is the connection? The connection between these scarab beetles and Avatar is the material they have on their carapace, the back of their shiny backs, is the same kind of material that is in place for filters to see 3D.

What these filters do in the carapace of the beetles is they do something, and this is a very science term, but it's called "They face‑shift the light." Polarized light is something that our eyes absorb. When you go out and look on a lake, or river on a bright, sunny day or the ocean, you see what we call "glare" that's bouncing off at a certain angle, up and very bright into our eyes. That is actually something called "Polarized Light." Polarized light is simply when the vibrational plane of light, so light acts like a wave.


Dr. Biology:  Like water or anything else?

Molly:  That's right. Light from the sun has waves that are coming in all different types of directions. When these waves, when the light particle hit specific materials, such as water vapor in the sky, it favors certain directions of the traveling of those waves.

When light hits the water surface, a lot of the vibrational plane, the waves that the light want to go off in a certain direction right alongside of the water surface. That's polarized light. There are a lot of animals out there that not only can their eyes absorb polarized light, they can discriminate the particular direction of polarized light. This is something none of us humans can do. It's really needed.

In fact, a lot of insects use to navigate through the sky. Because as light comes into our atmosphere, it gets polarized, relative to the direction of the sun. It's a great way to navigate, when you can't see the sun directly. You can always follow the polarized light fields. It's common amongst insects to have polarized sensitivity in their eyes.

Not common amongst, we, humans, but somewhat common amongst other vertebrates, such as fish and some birds. These beetles are very unique. The fellow scientist, Perch Brady, was a PhD student in the Physics Department over in University of Texas. He came to me one day, and he showed me these beetles. He showed me these beetles with different filters.

When I looked at these beetles with a naked eye and unaided eye, they were this beautiful, chrome green that you were referring to. When I looked at these beetles with a linear polarizer, they were also beautiful metallic green. When I looked at these beetles with a right circular polarizing filter, they were green. When I looked at these beetles with a left circular polarizer filter, they turned black.

I threw in a couple of terms there that I forgot to explain to you. That was left and right circular polarized light. It's not something terribly common on land. That is even fancier form of light, and that's when the polarized vibrational plane gets slightly fey‑shifted, such that it starts moving in a circle, a rotation. That rotation will either go clockwise or counterclockwise, left or right‑handed direction.

This usually only happens with specialized surfaces, like the back of these scarab beetles, or underwater at the surface of the air and water interface. We're expecting to see more of this interesting, signaling or camouflage behavior using circular polarized light, when we explore underwater.

Dr. Biology:  It's like secret codes.

Molly:  It's like having the special flashlight that no one else can see. You can turn it on and off to your friends, and the teacher can't see.

Dr. Biology:  Today, when 3D is so popular in stereo images, one of the earlier ways of doing it was using polarized lenses on glasses. Very easily, what it did is you polarize the wavelengths of the light in one direction for one eye, and another direction for the other eye.

Then, you did the same thing for two different projectors that would be superimposed on each other. Because they were in this particular polarized wave in one eye, your left eye can only see the same corresponding wavelength of light, and your other eye can only see the other wavelength. You can get that nice 3D that you wanted to have.

Molly:  Exactly.

Dr. Biology:  A lot of people have also used sunglasses that are polarized. When you get to that glare, it makes the image much clearer in basically dealing with that polarization of light. On "Ask a Biologist," before I let my scientist get out of here, I always have three questions. These are the real telling‑tales of their life. The first one is, when did you first know you wanted to be a scientist or biologist? Was there that "uh‑huh" moment?

Molly:  According to my mom, she knew I was going to be a biologist before I did, because I kept bringing in dead animals into her kitchen, when I was four or five, [laughs] such as dead rabbits that I've found, bees, or fish when we lived on a lake. I've always been drawn to animals.

The uh‑huh moment was when I took a class in college, and the way this class worked is our beginning class, the morning class, we got to be underwater, scuba diving. The entire class period meant looking at animals underwater, and our teaching assistant had a slate with all the scientific names of the animals and plants.

We'd point to a cool organism, and he or she would point to the name of that organism underwater. I fell in love with the world underwater. I knew at that point, I want to work with fish. Since then, I moved on to land. I began as a marine biologist.

Dr. Biology:  What do you call the ocean? I have to say that's one of the more popular questions I come to ask a biologist. The next one is a tougher one. I have to take away your teaching, because a lot of people that are scientist also like to teach.

I'm going to take away all your science. You can no longer be a biologist or scientist. You're not going to be able to teach. This is your opportunity to do something you've always wanted to do. If you couldn't be a biologist or scientist, what would you be, or what would you do?

Molly:  Wow. I've never really thought about that. When I was younger, I worried about World War III a lot. When I was very young, I thought I'd become a diplomat. We feared the Russians, so I started to learn Russian in college. Right now would be a good time for more diplomacy. Maybe I'll be a diplomat. I'm not sure I'll be very good at it. [laughs]

Dr. Biology:  If you can go out there and chase down pores and dart frogs, it's good start.


Molly:  There you go, facing danger.

Dr. Biology:  Handling things gently with care. The last one is, what advice would you have for a young scientist or someone? Not all people get into science early in life. Someone that decides, "I really want to be a scientist." What advice?

Molly:  I would advise that you make sure you love your questions. Because in science, as in most places in academia, no one's making you get up in the morning. Your questions have to make sure you get up in the morning, and get you in the lab.

If it's in the field or out in your books, reading about your problem, and you have to be incredibly passionate about the question you're trying to answer. That's my biggest advice because if you're not motivated to find those answers, you're probably not going to find them and not do a good a job of it. You need to be motivated.

Dr. Biology:  Find that thing you're really curios about, and that's the one you go towards.

Molly:  Absolutely.

Dr. Biology:  Excellent. Just for a side note, another question that comes through with our students deals with math. How are you in math in school?

Molly:  I was quite good at math, as a youngster and in high school. In college, I took the basic math, and didn't push myself much beyond that. That was fine. I did fine for that. However, I got farther into math and got excited by math, when I went into biology as a graduate student because, then the application came to life for me.

I write my own codes now. I write my own statistics, and put them in the code. Once you get excited about a problem in math and have an application for math, it's right there at your fingertips. It's incredibly powerful. I use math in my models all the time to make predictions about how animals are going to behave. Without math, you are very limited as a scientist.

Math isn't that hard. You can make it hard, but it's really not that difficult. I want to encourage all boys and girls to continue on with math, but particularly girls. For some reason, we end up taking less math than our boy counterparts. That's not going to help us later on.

Dr. Biology:  As you said, it becomes a fun tool to learn what you are interested in. If you're curious about a particular animal or ecosystem, it's really great because then, you'll have a type of math, not all math. We don't use all math.

Molly:  Correct.

Dr. Biology:  That's great. Professor Cummings, thank you for visiting with me.

Molly:  Thank you so much, Dr. Biology. This is superb.

Dr. Biology:  You've been listening to Ask a Biologist. My guest has been Professor Molly Cummings, visiting ASU from the School of Biological Sciences at University of Texas, Austin. The Ask a Biologist Podcast is produced on the Campus of Arizona State University, and recorded in the Grassroots Studio, House in the School of Life Sciences, which is a division of the College of Liberal Arts and Sciences.

Remember, even though our program is not broadcast live, you can still send us your questions about biology using our company website. The address is, or you can just Google the words "Ask a Biologist." I'm Dr. Biology...


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Cute Colorful Poison Dart Frogs and Their Mimics

Audio editor: CJ Kazilek

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