Steve:          Welcome to a special two-part Best of Thanksgiving edition of the weekly Scientific American podcast. For Science Talk, I am Steve Mirsky. In part one, we'll hear from Turkey scientist Rich Buchholz of the University of Mississippi in an interview that originally [aired] on November 22nd, 2006. I asked Rich Buchholz what he will be eating on Thanksgiving.

Buchholz:          I am going to eat a nice Butterball turkey. I'm not going to eat a wild turkey, they're too scrawny anyway; and I will enjoy him.

Steve:          Now the Butterball turkey is a domesticated version of the same species?

Buchholz:          Yeah, in fact the turkeys we eat today are really sort of a genetically engineered construct, and, I don't mean that in a technological way; it's not as though you actually physically removed DNA and moved it around.

Steve:          Right.

Buchholz:          But through selective breeding, they've created a turkey that has gargantuan breast tissue, because everybody wants some of the white meat; and something that will grow very quickly in captivity. And it's really nothing at all like a wild turkey, and in [fact] really different from the turkeys that Americans ate only 50 years ago.

Steve:          Really. So the turkeys that are in Norman Rockwell paintings were unknown before about 50 years ago.

Buchholz:          Yes, today's turkeys, for instance, can only reproduce through artificial insemination. They do not breed naturally. They cannot produce offspring by mating with one another. One reason they don't even try is because we've basically selected that trait out of them, females don't solicit copulation from males. But the original reason is the breast is so big that he is physically unable to do the balancing act of walking up onto the female's back and then trying to get his tail under her tail for insemination. So what's really different about these turkeys is that, and also the fact that they grow so quickly. And the heritage breeds of turkeys, the turkeys that Americans used to eat, were normally grown slowly, they were grown outside on pasture; and that changed dramatically with these modern sort, of, engineered breeds of turkeys.

Steve:          So they're big enough for dinner before they're sexually mature or even, you know, we're mixing things up, because they're not going to be interested anyway, but…

Buchholz:          That's right.

Steve:          It's a tough life for a domestic turkey.

Buchholz:          Yeah…

Steve:          It doesn't end well.

Buchholz:          No.

Steve:          But it tastes good.

Buchholz:          Yeah…

Steve:          If it's cooked right.

Buchholz:          Well, I am told that the heritage breeds of turkeys have more nuanced flavors and, of course, they have less white meat. But it seems to be a very popular trend for people to purchase pasture-raised, heritage breeds of turkey.

Steve:          Interesting.

Buchholz:          Well they're expensive. Supermarkets, of course, create great deals for us for the domestic white turkeys that are available so that we'll go there and buy other things for Thanksgiving, and the heritage breeds of turkey, the pasture raised ones, are considerably more expensive.

Steve:          So the dollar-a-pound turkey is a loss leader for the supermarkets?

Buchholz:          That's what I am told.

Steve:          Next we talked about his actual research.

Buchholz:          I am a full-time animal behaviorist who focuses on the behavior of turkeys.

Steve:          The behavior of turkeys. So are the turkeys behaving?

Buchholz:          They are behaving. They are a little nervous this time of year, but they are behaving.

Steve:          Well, that's certainly understandable. So, tell me about your current turkey research.

Buchholz:          Well, a long-term interest of mine has been whether the ornaments that are sexually selected in turkeys, that are involved in mate assessment, indicate something to female turkeys that might help them raise more offspring; and specifically the idea that those ornaments are dependent on the parasite load of the male that has them. So, that is, a female who chooses the male with larger, brighter ornaments can be assured that that male grew to look prettier to her because he has fewer parasites; and she is unlikely to get these parasites during mating. So, it's not an issue of her possibly becoming infected by these parasites, but because there is usually a genetic basis for parasite resistance, she may be looking for good genes for her offspring to survive better.

Steve:          Right, so that the offspring would have a lower susceptibility toward getting the parasitic load in the first place.

Buchholz:          Right, yeah. I mean, male turkeys don't provide any paternal care. They don't help the female incubate the eggs. They don't feed her. They don't protect their young. So, all she is getting from him are sperm, so that she has a matching set of genes for her offspring. And so she is going to only get that from a male. She should choose carefully and parasites are an important part of turkey life history. So, finding a resistant male and giving his resistance gene to her offspring is probably evolutionarily a good idea.

Steve:          Right, and she doesn't realize that's what she is doing. She has just been programmed to be most attracted to the turkeys that have the brightest colors, and those brightest colors are a marker for the health of the turkey.

Buchholz:          Well, usually in animal behavior studies we don't make any assumptions about the individual animal's thought processes, per se.

Steve:          Good idea.

Buchholz:          So, turkeys don't have a good reputation for being smart. I would say, they have been around for a very long time, so they are smart [at] being wild turkeys; but yeah, she doesn't necessarily have to walk around and say, "Oh, by mating with this guy I am going to have more surviving offspring." All that has to happen is the genes that make her be choosier about this have to survive better till the next generation by showing up in babies that survive better because of their resistance [to parasites].

Steve:          So, I saw on your Web site some research related to the ultraviolet reflection of the feathers. What's that all about?

Buchholz:          Well, it turns out that turkeys can see wavelengths of light that we can't see, and those are wavelengths in the ultraviolet spectrum. So, we normally think about ultraviolet as harmful; that it causes melanoma, skin cancer, and that sort of thing. But the near-ultraviolet is actually used by some organisms—some birds, lots of insects—and it turns out that turkeys are one of the bird species that can see ultraviolet light. So, I was curious about whether turkeys could see changes in feather reflectance, the colors coming off the feathers, when they are parasitized, that we can't notice. And by collaborating with colleagues at Auburn University, we are able to show that the turkeys that I experimentally infected with parasites actually showed less UV reflectance from their shiny feathers on their breasts and their wings compared to turkeys that had never been infected.

Steve:          Well, so, a parasitized turkey looks completely different to another turkey than a non-parasitized one and in ways that we can't really appreciate.

Buchholz:          Exactly, yeah. So, because we can't sense ultraviolet light with our visual pigments, we can't even pick up on the cues that turkeys are probably using. And now that I know that this is changing, the next step is to find out whether females actually care about this change. We don't know whether there is a behavioral response to turkeys being different in their ultraviolet reflections. We do know that domestic turkeys prefer to be in poultry houses where the lighting includes the ultraviolet wavelength.

Steve:          Interesting, because without the UV they keep looking around saying, "Nothing looks right to me."

Buchholz:          That's right. Imagine the UV as whole other color in the spectrum. What it looks like, how turkeys perceive it, we don't know, but that sort of equivalent of beyond violet, ultraviolet, a whole other sort of color.

Steve:          So, it's like if we were in a dark room where we just couldn't make out certain colors.

Buchholz:          Exactly.

Steve:          Interesting, Dr. Buchholz, very interesting. Thanks very much.

Buchholz:          Thank you, Steve.

Steve:          That's part 1, tune back in for part 2 of our Thanksgiving edition where we'll talk about the great tradition of the entire holiday season that goes along with turkey. And that is of course stuffing … your face.