The Tongue Map Myth

Four years ago in a psychology graduate seminar, my professor mentioned an odd benchmark for determining whether a psych textbook is legit.  He says he thumbs through the pages to see if it includes a tongue map.  Apparently, the tongue map is to taste researchers what phrenology is to neuroscientists.  Total pseudoscience.  And I’d had no idea.

This morning the AIR message board greeted me with a request for hoax-themed story pitches for an  April Fools Day edition of the chemistry podcast Distillations.  Today’s unexpected snowfall ruined my dreams of taking the day off and exploring the Chinatown in Queens.   Instead I ended up finding myself surprisingly entertained with research for this pitch:

“Remember the tongue map?  Many science students today still learn that we taste sweet chemicals at the tip of our tongue, bitter in the back of our tongue, and salty and sour on the sides.  Sorry kids, not only is Pluto not a planet and brontosauruses aren’t real, but the tongue map is a total myth.  Thousands of students are totally getting hoaxed!

The whole idea for the tongue map came from one pretty unscientific study done by a German PhD student in 1901.  His test subjects showed only slight differences in taste perception between different areas of their tongue, but Herr PhD made this data into a real nice graph for his thesis–a graph without any scale markers.  The graph suggested his subjects could only perceive certain tastes on certain parts of their tongue.  Other researchers liked this story.  In 1942 a Harvard scientist decided to make the graph more accessible to the public.  He oversimplified the 1901 results to make a tongue “map”.  For over 35 years taste scientists have published studies disputing the tongue map. They keep trying to tell us that receptors for every kind of taste compound are scattered all over our tongue. Yet for some reason the tongue map still persists in many schools’ science curriculum.

I’d start out this piece with a scene of school-aged kids tasting different foods and trying to see if they can sense any kind of taste map on their own tongues.  Then I’d talk with a taste researcher about how he or she is working to dispel the tongue map myth.  I’ve found one of the original tongue map naysayers working a couple hours away from me at Yale, so he’d be my first pick to interview.  I’d also like to visit with an educator to get his or her perspective on why the myth still gets perpetuated.”

Have you seen or heard anything about the tongue map recently?

A Fish Tale

Photo courtesy of WildlifeDirect.org

This woman just might be the best scientist-storyteller I’ve ever met. Enjoy.

Listen Here Running time 6:47

This is the story of one sick little fish. It’s completely colorless. And blind. You won’t see it swimming along with the other fishies, nope. This fish is only seen dead, on the banks of the Lower Congo River. Pathetic, right?

But our story starts with someone way classier, a New York scientist. Melanie Stiassny’s curator of fishes at the American Museum of Natural History.  Dr. Stiassny’s got this thing for the Congo River.

“Oh it’s just the most incredible system,” she gushes. “Particularly for an ichthyologist-”

A what?

“An icthyologist, someone who studies fish. The Congo is just like, oh my goodness, it’s just like a magical place. It’s very rich in species, but it’s extremely poorly known.”

Right. Most of Dr. Stiassny knowledge about the Lower Congo River came from just one expedition done decades ago. It was carried out by two American ichthyologists in the early 70’s, Roberts and Stewart.

“They found some very extraordinary things in the Lower Congo River,” she explains.

Basically, Roberts and Stewart found a crazy number of new fish species there. Which was cool, but weird. Because the Lower Congo River has a few nice areas of rapids, but for the most part it looks like a normal river. At that point, nobody could really explain what was causing it to be such an evolutionary hotspot. Roberts and Stewart just didn’t really have a good explanation for all the new species there.

Their trip also turned up a second mystery, which involves that weird little fish I mentioned earlier. That one with no eyes, and no pigmentation. It’s about the size of you little finger and shaped like a torpedo. They’d really only seen two of them. And that’s if you count the second one, which they found stuck to the bottom of one of their shoes.

It turns out Dr. Stiassny’s kind of a sucker for weird fish stories. She made her own trip out to the Lower Congo River in 2007, and she made a big point of seeing if these fish really existed. Surprisingly, the local fisherman knew exactly what fish she was talking about.

“But the more extraordinary thing,” says Dr. Stiassny, “was that they said they found it dead. And that didn’t make any sense. We asked, ‘Where does it come from?’ They said they don’t know, they don’t know where it comes from , they just find it dead occasionally.”

“So no fishermen ever found it in their nets alive, or anything?” I asked her.

“Nope, no. They would just find it as they were kind of going up and down the river, along the river bank in their wooden canoes.”

At that point Dr. Stiassny was still kind of skeptical. Like “Really, this fish can only be found dead?” But sure enough the locals pointed out the odd fish bodies on the shore. And Dr. Stiassny searched and searched the waters but couldn’t find any of these fish alive.

“After another couple of days,” she recalls, “one of the fisherman actually came with a specimen that was just alive, and he handed it to me, and actually as I examined this poor little thing it died in my hands, which was sad but it was also an extraordinary moment because having this very very moribund animal in my hand I could see that its skin was full of air bubbles. There were huge bubbles of air all along its back, all in its gills. This animal looked very much as if it had died from decompression, it had de-gassed.”

She explained that would be the equivalent of a fish having the bends, like a scuba diver who’s come up too fast from the bottom of the ocean.

“And the only way that we could think that could have happened,” she continues, “was that it was living at depth, and it could have just suddenly risen to the surface, and with such a rapid change in pressure it had degassed. Now that was a very kind of eureka moment. Because that made us think suddenly, well could this river be deep? Could there be depth involved here?”

“Had you even considered that before?” I asked.

“We’d never, we’d never considered that before. We’d never thought for one moment that this was an unusual river besides having the rapids.”

So now it was looking like she didn’t just have a weird fish, she probably had a pretty crazy river out there. Dr. Stiassny got a project going to check out its depth and currents.

“What we were doing,” she says, “was really getting a fish’s eye view of the river. And it was so illuminating. I mean we’d always looked at the river the way a human does, I mean you just look at it and you think oh my, it’s just water, if you’re a fish you can swim around in it no problem.”

No problem? Turns out the Lower Congo River is the deepest river in the whole world. And deep down there, there’s ridiculously strong currents of water flowing in all different directions, even straight up.

So this pretty much solved the mystery of that weird little fish. Who needs pigment and eyes when you’re living too deep underwater for light to reach you? And the fish probably kept turning up dead because it’d get caught in a crazy upward current. Which would shoot it up to the surface way faster than it’s body could handle.

So, so far Dr. Stiassny’s got two pretty cool realizations. She’s discovered the lower Congo River is the deepest river in the world. And she’s figured out what’s going on with the dying fish. But that still leaves the mystery of why so many fish evolved there. Let’s go back to those super strong currents she discovered.

“So you imagine you’re a fish living on one side of the river,” says Dr. Stiassny. “You swim out, into water and then immediately you hit a column of water flowing incredibly fast in the opposite direction. It’s like a wall, you can’t swim across that river if you’re a small fish. So that immediately told us, hey, this is what’s happening. The river itself is clearly presenting a series of really intensive barriers. And that seems to be what’s driving speciation.”

When it comes down to it, this is really one of the oldest ideas behind evolutionary theory. Speciation through isolation—two different groups of a species get separated by some kind of barrier, and the populations on either side of the barrier start evolving different adaptations. Eventually, they become separate species.

Dr. Stiassny realized that a current running through the middle of the river could separate species just like a mountain range running through the middle of a continent. This was the first time anyone had suggested that that kind of evolution-driving-barrier could exist within the water itself.

“I think people haven’t tended to look at rivers in this way,” she explains. “We’ve tended to look at it from a very kind of land-centric way. We’ve assumed that rivers are pretty homogenous, it’s just a bunch of river, under water and fish could swim around. But we’ve never really considered that a river itself could be driving speciation in this way. So it’s kind of cool and very exciting. And it all comes down to that very odd, blind, de-pigmented fish.”

So maybe those little dying fish aren’t so pathetic, after all.

Switching it up

I’ve decided to change the way I use this website. I want to keep you, dear listeners, more up to date on what it is I’m actually working on. I’ll still put up my completed radio stories, but I’ll also use these posts to blog about my as-yet-unbroadcasted conversations with scientists.

As a pay-off for your patience over the last few months, I’m showing you here what 90% of my radio journalism work time actually looks like. And hey, check out that top knot, I’m totally blog-ready.

Work in progress…

I wanted to add a post since it’s been a little while since I updated my site.   In the meantime, I’ve been getting settled into my new life in Brooklyn.  I attended the Third Coast Conference in Chicago at the end of last month, a great source of guidance and inspiration for independent radio producers.  I’ve also been collecting contacts and ideas to produce new science radio stories.   Expect some new pieces to be posted soon!

Roadtrip

A less scientific, more personal piece–an audio postcard from my move across the country this September.  My boyfriend Bruce and I spent three weeks in a minivan traveling from Seattle, Washington to Brooklyn, New York.  I collected sounds along the way.

Listen Here Running time 3:45

Addendum: We got this real nice picture of us speeding driving in Maryland for the low price of one $40 ticket. Look, you can see our bikes! And, no, that’s definitely not me in the driver’s seat.

To the Moon!

What can we learn from studying the moon? And what’s the value of returning there?  I talk with a local researcher and a NASA scientist about the future of moon exploration.

Listen Here Running time 4:08

Aired on KBCS in Seattle on August 19th, 2010 and New Hampshire Public Radio on October 4th.   Also available on prx.org.

Once Upon A Crow…

Crows!  Legends!  Scientific explanations!

Listen Here Running time 5:37

Aired on KBCS Community Radio in Seattle on 7/1/10, as well as WILL Public Radio in Illinois and REMIX XM Satellite Radio in Cambridge, Massachusetts.  Also available on prx.org.

Pieces Featured on KUOW

Generics-First Policy For Anti-Psychotics Draws Controversy

Washington state needs to save money.  So they’re asking doctors to turn to generic drugs first when prescribing for Medicaid patients.  But critics say the state’s scrimping on the wrong group of people.

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Aired 5/6/10 on KUOW Seattle.




Reaching Seattle’s Hidden Population Of Meth Users

A new study by the Seattle Counseling Service finds that women are often overlooked in methamphetamine treatment programs.  The Service is trying to reach out a particularly ignored subset of meth users: lesbian, bisexual and transgender women.

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Aired 4/15/10




Seattle Sprouts Urban Farms

Seattle Mayor Mike McGinn calls 2010 “The Year of Urban Agriculture.”  What does farming in the city look like?

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Aired 4/12/10




Pesky Parasite Devastates Vancouver Island Bees

Bees are disappearing from their hives, and the varroa mite is a possible suspect.  How can beekeepers protect their honey-makers?

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Aired 3/16/10




Night Exhibit Closing

On the last week of Seattle Zoo’s Night Exhibit, zookeepers and the public pay their final respects.

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Aired 2/26/10