The Gist has been on a field trip in New York City this week, taking culinary detours into Italy, Korea, Lebanon, Ireland and the Sichuan province of China.
The Grand Sichuan International in Chinatown is a living-room-sized restaurant with an invisible kitchen, a dozen tables, and a soft-drink cooler wedged against one wall. Grand or not, it’s where I learned the meaning of ma la, the Chinese name for a soup made of dried chilies and Sichuan pepper. It arrived as a steaming tureen, set before us on a portable gas burner and filled with a bright-red bubbling liquid. Crispy dried chilies - perhaps 40 of them - bobbed in the waves like radioactive minnows, and we eventually fished them out to keep the soup from getting any hotter.
But the real draw were the small woody flecks of Sichuan pepper floating in the broth. At first, these gave the soup a random and alarming crunchiness. But moments later the taste developed into a citrusy buzzing and tingling over my mouth and tongue. As it went on, the feeling almost perfectly balanced the heat from the chilies, mellowing it and sweetening it in waves that sloshed across my mouth. That’s ma la: “numbing hot.”
The nearest equivalent is the tingling you get from eating orange or lemon zest (or perhaps, the weird taste/sense as your tongue comes back to life at the dentist’s). But for me, the sensation brought back precisely a visit to a south Georgia barrier island some 15 years ago. I had searched the back dunes for a tree in the genus Zanthoxylum. Sometimes called “toothache tree,” the leaves are supposed to make your mouth go numb. When I found it, it was a short, stout tree covered with immense thorns and sporting leathery dark-green leaves. At the time I was disappointed that my mouth didn’t go completely numb, but the sensation was identical to the lemony fizz of my Sichuan hot pot.
Back home, a little reading turned up why. Sichuan peppercorns (or huajiao) are the dried seed husks of a few Asian species of Zanthoxylum (one of many neat botanical holdovers from the days before the Atlantic Ocean stood between Eurasia and North America).
Fortunately for us, ma la and Sichuan pepper have not escaped the notice of chemists, and a 1999 paper in Brain Research suggests why the spice can make our tongues feel so many things at once. The lemony taste and tingling sensations come from a half-dozen volatile oils, the most peculiar being something called hydroxy-alpha-sanshool. When scientists tested this compound (on rats), they found it activated several different classes of neurons, including touch-sensitive, cool-sensitive, and cold-sensitive receptors.
Sichuan pepper is in the citrus family and is unrelated to white, black, or red peppers. Importing the spice to the U.S. only became legal in 2005 after fears eased about its potential for transporting a citrus disease. So, if I arm myself with some Zanthoxylum berries and the right cookbook, might I be able to recreate my hot pot - and make my taste buds do back flips again? After my nose stops running, I’m going to try.
(Image: the toothache tree of North America, Zanthoxylum clava-herculis; amyb/Flickr)
Behold the fearsome Manospondylus: one of the largest, fiercest predators the world has ever seen. With a skull the size of a wrecking ball and teeth like scimitars it terrorized the Cretaceous fens, eviscerating plump vegetarians and kicking around the skinny ones like discarded soda cans.
What’s that you say? Sounds an awful lot like a T. rex? That’s because Manospondylus was T. rex’s original name - coined in 1892 before the monster acquired its rather more striking name (in 1905) and started getting into showbusiness.
The mixup is an example of a very basic problem in paleontology: How many species of dinosaurs were there, and how do we know we haven’t named something twice? Scientists have named about 1,400 dinosaur species, but slightly fewer than half of those actually merited their classification upon closer inspection. Fortunately, a new study by British paleontologist Michael Benton suggests that we’re getting better at catching these mistakes.***
According to the study, the modern rate of discovering new dinosaur species is a breakneck 30 species per year, about double the previous peak of dinosaur-naming, in the so-called “Bone Wars” of the late nineteenth century. But because paleontologists have discovered very high quality fossil beds - especially in North America and Asia - they’re now working with much more complete material.
If you’ve ever had trouble figuring out how many kinds of ducks you’re feeding at your local city park, you might relate to the problem paleontologists face. They’re usually trying to differentiate species based on characteristic bumps, fissures, and cavities they find on whichever bones someone has managed to dig up.
Imagine trying to tell a mallard from a pintail based only on the shape of its kneecap, and you get an idea what they’re up against. Manospondylus was named from two large but shattered vertebrae, while the first Tyrannosaurus was named, 13 years later, from a partial skeleton. It wasn’t until 1917 that the similarity between the vertebrae in the two separate finds was recognized.
As a result of the recent flurry of advances, Benton reports, we may be honing in on a guess of how many dinosaur species there really were. At the start of the nineties we guessed there might be 1,200 species, but after a decade of discoveries and some 300 new species, that figure has risen to perhaps 2,200. With only about 675 “valid” species on the books right now, that leaves some 1,500 entirely unknown dinosaur species to discover. Ladies and gentlemen, grab your rock hammers.****
***Kind of incredibly, Benton suggests that whatever naming mistakes might be happening nowadays are partly the fault of - you guessed it - the media. From the paper:
The aims of this study are to explore the recent burst of dinosaur work and to resolve whether the new phase is illusory or not. It could be that palaeontologists are producing poor-quality work, perhaps fuelled in part by excessive interest from museums and the media worldwide
****We also recommend obtaining a Ph.D. in paleontology.
This week we learned that dogs can catch yawns from people. And the evidence on this one is pretty solid. It comes from a controlled experiment conducted on 29 dogs of different breeds and posted this week in Biology Letters, the top-flight journal of the Royal Society of London.***
A stranger sat in a room with each dog for five minutes and either (a) started yawning (with sound effects) or (b) simply opened his mouth wide, but without moaning or even scrunching up his eyes. (The authors include a great photo-sequence of the two facial maneuvers [subscription required].)
The results came out clearer than a Higgs boson in a 17-mile Swiss tunnel. Not a single dog yawned when confronted with a simple open-and-close of the mouth. But on average, after watching just a minute and a half of real yawning (equal to about 4.5 yawns), the dogs opened wide. Only a few were totally immune to yawns, including a weimaraner, a shih tzu, a Jack Russell-corgi mix, and a great dane.
One dachsund resisted yawning, but he was offset by three others that yawned with aplomb. Prolific yawners included a lab and a Staffordshire bull terrier, with four yawns each. But the champion yawner? Big surprise: a border collie, the smartest dog in the world. He probably also had an opinion on which statistical analysis to use.
Here at the unofficial Gist Center for Animal Psychology we attempted to replicate the experiment on a Rhodesian ridgeback mutt (above). He took considerably longer than 1.5 minutes to start yawning, and then only because one experimenter was scratching him behind the ears, which he really likes.
***In the world of animal cognition, this actually is pretty neat research. Lots of animals yawn, but the only animals known to pass yawns from one to another are humans and chimpanzees. This finding suggests dogs really do empathize with humans to some extent - and in any case it says something pretty neat about the ways domestication has caused our evolutionary histories to become intertwined.
Turn the clock back 230 million years, and the land was covered with big, toothy reptiles.*** But as many a nine-year-old can tell you, not all of them were dinosaurs. Some were “crurotarsans,” a lineage that all but died out just as the dinosaurs were acheiving global domination. Today, the only crurotarsans are the crocodiles. But alas! It all could have been so different, according to research published in Science today by Stephen Brusatte, of Columbia University, and colleagues.
The Age of Dinosaurs may have been a matter of luck, they say: just a matter of which group was hit harder by a mass extinction 200 million years ago. Before then, for nearly 30 million years, dinosaurs and crurotarsans had vied for superiority in a classic Darwinian struggle.
And the crurotarsans should have won, the scientists argue. After analyzing the fossils of 64 species, they found the beasts had a greater variety of body plans - and evolved new species at about the same rate - as dinosaurs. They take this as evidence that dinosaurs weren’t innately superior creatures (otherwise, the reasoning goes, more dinosaur species would have evolved as they usurped the crurotarsans). In the race for supremacy, it wasn’t that the dinosaurs outpaced the crurotarsans - it’s more like the crurotarsans were felled in the home stretch by a calamity.
But hang on a second. I’m all for exciting new theories that offer explanations no one’s thought of before (i.e., prairie-stalking pterosaurs). But this logic sounds wonky in a few places. Does a lack of species divergence have to mean an ecological stalemate was going on? Or could it mean that the species in existence at that time were doing phenomenally well on their own? For that matter, might the rapid appearance of new species signal a sputtering lineage, dying out in a flash of ill-fated new forms?
More problematically, how does a mass extinction kill nearly all the members of one group (crurotarsans) without destroying a similar number of the other (dinosaurs)? That doesn’t sound like the luck of the draw; it sounds like one of those groups had a competitive advantage - what the regular person might call “superiority.”
Full disclosure: I’m not a paleontologist. Perhaps these are well-thought-through ideas that the authors lacked the room to explain in their paper. (If so, I’d love it if a real paleontologist would write in and educate me.) Maybe the authors imagine that a different kind of mass extinction (meteoric fireball vs. global warming, for instance) could easily have switched the tables and led to an Age of Crurotarsans.
But then, the crocodiles did survive, apparently content to hide out in the swamps for 200 million years while the dinosaurs enjoyed their 135 million years of fame - and then died out. Come to think of it, maybe the crurotarsans are superior after all.
(Image: the crocodile, last of the crurotarsans, Wikipedia)
***To be fair, there were also plenty of small and medium sized reptiles, some with rather ordinary teeth.
After 26 years of listening for radio transmissions from deep space, we learn this week that aliens - at least the really smart ones - could have been trying to contact us by a totally different method: manipulating the brightness of stars using stupendously powerful blasts of neutrinos. Or so say University of Hawaii physicist John Learned and his colleagues in a recent article on the physics forum arXiv.
It’s simple, writes Learned: aim your neutrino beam at a pulsating Cepheid star, and with enough energy input you can change the frequency of the pulsations - a kind of binary signal that any old sentient being equipped with eyes and a modicum of curiosity could pick up on. I mean (and you can almost hear the exasperation in his words), even humans have been watching Cepheids since the late sixteenth century.
Learned calls the technique “star tickling” and suggests that star-tickling aliens could even now be waiting for us to clue in and start deciphering the oscillations. He suggests that data could be transferred over immense distances this way, giving us a sort of “galactic internet.” You’ve got to give him credit for thinking big.
Still, you wouldn’t want to swap too many vacation photos on this system. With data rates of roughly 180 bits per year, according to Nature News, that 100 kB picture of you eating a fried twinkie at the fair would take a bit more than 4,500 years to download.
So it’s really more of a galactic telegram system. Also, you could run into trouble on your power bill. Each neutrino blast needs to contain roughly 1 millionth of the star’s energy before the Cepheid starts feeling ticklish.
But I like this expansive thinking. Whenever I get to talk with physicists, I always come away thinking how marvelous it must be to spend so much of your life being mostly correct and nearly insane all at the same time. And if you’re going to spend your time thinking of ways that aliens could be calling to us, you might as well cover all the possibilities.
Best of all, Learned keeps his suggestions practical, stopping well short of the ludicrous:
“In another context, the use of the cosmic microwave background to reach everyone in the universe was also considered [5] but as far as we know that is not within the capability of any inhabitants of the universe.”
At least with Cepheid stars, we have 100 years of observations to fall back on. A graduate student given a laptop and enough Code Red could have the answer in a few months. (Although, their optimism notwithstanding, it does appear that Learned and colleagues opted to publish their paper before running that analysis.)
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