Learn about why animals keep evolving into crabs in a principle called “carcinization,” whether water is actually wet, and if there’s any truth behind the old adage "feed a cold, starve a fever."
Learn about why animals keep evolving into crabs in a principle called “carcinization,” whether water is actually wet, and if there’s any truth behind the old adage "feed a cold, starve a fever."
Animals keep evolving into crabs by Grant Currin
Is Water Wet? Listener question answered by Ashley Hamer and Cody Gough
Is There Any Truth Behind the Old Adage "Feed a Cold, Starve a Fever"? by Joanie Faletto
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/why-animals-keep-evolving-into-crabs
[MUSIC PLAYING] ASHLEY HAMER: Hi. You're about to get smarter in just a few minutes with Curiosity Daily from curiosity.com. I'm Ashley Hamer.
NATALIA REAGAN: And I'm Natalia Reagan. Today, you'll learn why animals keep evolving into crabs, whether water is actually wet, and if there's any truth behind the old adage, "Feed a cold, starve a fever".
ASHLEY HAMER: Let's feed some curiosity.
[SWOOSH]
NATALIA REAGAN: If you follow science news sites, you may have seen this viral headline going around, "Animals Keep Evolving into Crabs", which is somewhat disturbing. What the heck are they talking about? Well, it's called carcinization. And it's a fascinating example of a principle called convergent evolution. Crustaceans with 10 legs have been crawling Earth's sea floors for about 365 million years. These ancient crustaceans looked more like lobsters than crabs.
But as the generations passed, some of their descendants slowly evolved their way into a new crabbier body shape. Their tails got way shorter. And the upper part of their body, called the carapace, got wider. Presumably, this new shape made it easier for them to pass on their genes. That's natural selection. And it's a driving force behind evolutionary change.
Anyway, this evolution into crab look-alikes continued for about 100 million years until, wait for it, the first true crabs emerged. Finally, the real deal. All of those knockoffs. But that was just the start. Over the past 250 million years, tons of crustaceans that looked like shrimp or lobsters evolved to look more like well, crabs. We're talking king crabs, blue crabs, fiddler crabs, coconut crabs, horseshoe crabs, porcelain crabs, Mr. crabs, and thousands of other species.
It's important to note that not every animal we think of as a crab is what scientists call a true crab. That distinction is based on a species precise evolutionary history. What matters for us today is that all of them started off looking like one thing, and then evolved in a crab-wardly direction. But why does this keep happening? It's hard to say for sure. But biologists think the answer is simple.
A crab-like body makes it easier to survive and reproduce in the environments where crab-like animals live. It's not hard to imagine why. Their wide, short bodies make it pretty easy to move around. Their shells make it harder for predators to eat them. Their claws are a pretty effective way of getting food. But carcinization isn't just shell deep.
Crab-like creatures have strong similarities in the structures of their brains and circulatory systems too. Like I said, carcinization is an example of something called convergent evolution. That's what researchers call it when many different species evolve the same trait usually, to deal with similar problems and adapt to similar environments. Like think about how birds, bats and many insects all evolved the ability to fly separately. From the fact that so many species have evolved flight, we can assume that flight is a super helpful trait. Apparently, so is looking like a crab.
[SWOOSH]
ASHLEY HAMER: Usually, we save our listener questions for Fridays. But we thought we'd make an exception for today's throwback Thursday clip. This one first aired in July of 2018. And it's just a really fun question with a surprisingly interesting answer. Enjoy.
[SWOOSH]
CODY GOUGH: We got this email from Kristi in Pennsylvania. And she wrote, "Love your podcast. Please resolve this ongoing controversy in my family. Is water itself actually wet?" So I told Ashley this happened. And you just sent me the definition like, the Webster's definition of water.
ASHLEY HAMER: I did.
CODY GOUGH: And you're like, "They're solved."
[LAUGHS]
ASHLEY HAMER: I did it.
CODY GOUGH: Well, I didn't do that. I did a quick Google search. And the results spoke to me.
ASHLEY HAMER: Did they?
CODY GOUGH: It really did. It took me down a rabbit hole. I did not expect to go down, ever.
[LAUGHS]
Because there's just so much here. I found this question on debate.org, is water wet? And it has a practically even split, with 49% saying yes, and 51% saying no.
ASHLEY HAMER: Wow!
CODY GOUGH: Yeah. Now, I don't know if I'll have a super satisfying answer that will resolve the ongoing controversy in your family, Kristy, but I will do my best. According to UCSB Science Line, it depends on how you define the term wet. There's a few different ways to do this. If we define wet as, the condition of a liquid sticking to a solid surface like, water wetting our skin, then no, water is not wet by itself. Because it takes a liquid and a solid to define the term wet.
Now, if we define wet as a sensation that we get when a liquid comes into contact with us, then the answer is a conditional relative, yes, water is wet to us. And if we define wet as made of liquid or moisture, then yes, water is definitely wet. Because it's made of liquid. So all liquids are wet. Because they are all made of liquids. You see where I'm going with that.
So there's three completely different answers, depending on how you define the word wet. And the definition I actually found was literally--
ASHLEY HAMER: The literal definition is covered or saturated with water or another liquid.
CODY GOUGH: Not really the most helpful definition. So I did some digging. And I found a 2011 study out of the University of Southern California titled, Water's surface not all wet: Some water molecules split the difference between gas and liquid. That's the name of the paper. The summary reads, "At any one time, one quarter of water molecules in the uppermost layer have one hydrogen atom in water, and the other vibrating freely above. Such molecules straddle gas and liquid phases according to a new study that bears on atmospheric chemistry. And raises the question of how exactly to define the air water boundary."
So on a molecular level, if you have a surface of water, it is both wet and not wet at the same time, depending on the state of the atoms. And along the lines of this microscopic definition, chemist, Richard C. Kelly, told the [? Nautilus ?] that water is wet because of strong tetrahedral hydrogen bonding. You'll get a similar answer, by the way, if you ask your Amazon Echo device, if water is wet. Trust us. We tried.
ASHLEY HAMER: So long story short, this is really just one of those unanswerable questions. Like, how many roads must a man walk down before you can call him a man?
[SWOOSH]
We're officially entering cold and flu season. And that makes it the perfect time to debunk some old wives' tales about illness. You've probably heard the old adage, "Feed a cold, starve a fever". Well, is it true? Turns out, new research is suggesting that there might actually be something to it. The idea behind, "Feed a cold, starve a fever" can probably be traced back to a 1574 dictionary that noted, "Fasting is a great remedy of fever."
The idea here is that eating warms the body up to fight a cold. And avoiding food will cool you down to lower your fever. But feed a cold, feed of fever might be better advice. Although, loss of appetite is a common side effect of being under the weather. Eating gives your body calories that it then converts into energy. When you're battling illness, your body needs the energy to fight the good fight. Just don't go overboard in either direction.
Starving yourself isn't a good idea. But neither is forcing yourself to eat when you're not hungry. The real key to nursing yourself out of a cold or fever is hydration. Fevers dehydrate you. Because even a small rise in body temperature requires more water for metabolic reactions. But that may not be the whole story.
For a 2016 study published in the journal, Cell, scientists used mice to study the loss of appetite, that's a typical side effect of illness. The team infected the mice with either a bacteria or a virus. Then gave some a nutritionally balanced food formula, and the others pure glucose. Basically, the mouse version of drinking nothing but Gatorade. They found that the food was protective in the mice with viral infections. More than 75% of these mice lived, while more of the mice on the glucose diet died.
But it was the opposite for the mice with bacterial infections. More than half of the mice on the Gatorade style diet survived, while those with food didn't do so well. So as far as this research goes, it sounds like, "Feed a cold, starve a fever" is an oversimplification. Maybe a more accurate saying is, "Feed a virus, starve a bacteria".
[SWOOSH]
NATALIA REAGAN: Let's do a quick recap of what we learned today.
ASHLEY HAMER: Well, we learned that many animals had evolved crab-like traits for millions of years before true crabs even existed. And many animals since have evolved the same traits. Probably, because it helps them thrive in their environment. This is called convergent evolution, which is a lot like how birds and insects have independently evolved wings to fly.
NATALIA REAGAN: Is this why I'm so crabby lately, Ashley?
ASHLEY HAMER: You might be turning into a crab. I mean, it might just be evolution pushing you there.
NATALIA REAGAN: Well, I've always liked a firm exoskeleton. I feel like a good, nice exoskeleton will serve me well. It'll protect my soft underbelly get too sensitive.
ASHLEY HAMER: Absolutely. And I think having a claw is really good for reaching into small jars and picking things out.
NATALIA REAGAN: I like that. Yeah, like pickles and things like that. Because that's-- I think crabs survive a lot on pickles. That's the thing. I just have to watch out for mantis shrimp. That's all I have to watch out for.
ASHLEY HAMER: Do mantis shrimp attack crabs?
NATALIA REAGAN: Yeah, they'll attack anything. We also learned that water is both wet and not wet depending on your definition of wet, which I feel like is one of those answers that like, Oh, darn. Everything is based on your definition. It's all relative. So I don't know.
ASHLEY HAMER: Right, I remember doing this one. And I remember the exchange that Cody and I described in the clip. And I feel like I've changed so much since then. Because I think I was arrogant about some things in science. If we would get a listener question where I'm like, that answer is so simple. I would scoff at it.
And then over time, I kept looking into more and more of these listener questions. And realizing that no. When there's a listener question that seems really simple, sometimes it's like the best question. Because it's way more complicated than you ever imagined. So I am sorry for ever scoffing at anything. I know I was wrong. And I'm doing better.
[LAUGHS]
NATALIA REAGAN: That's OK. That's the thing. Science is a-- It's a verb, not a noun. And you're changing your theory on what seem like easy questions. Because I understand. You're like, Oh, yeah. No, that's no big deal. And then you're like, Oh, shoot. There's 15 different answers or possibilities.
ASHLEY HAMER: Exactly.
NATALIA REAGAN: We also learned that the old adage, "Feed a cold, starve a fever" might hold some weight. Although, the more accurate version would be, "Feed a virus, starve a bacteria". It doesn't really have the same ring. But that doesn't matter if it helps cure what ails you. But it's hard to tell if you have a virus or a bacteria, right? I mean, it's not necessarily written on your forehead when you're feeling crummy. No, it's a bacterial infection.
ASHLEY HAMER: We're getting tests for COVID these days. But usually, if you have just a stuffy nose and you're coughing, you don't really know whether that's a cold or a flu. I feel like just do what your body tells you to. And maybe see a doctor if stuff gets bad.
[SWOOSH]
NATALIA REAGAN: Today's stories were written by Grant Curran and Joni Foleto. And edited by Ashley Hamer, who's the managing editor for Curiosity Daily.
ASHLEY HAMER: Scriptwriting was by Natalia Reagan and Sonja Hodgen. Today's episode was edited by Jonathan McMichael. And our producer is Cody Gough.
NATALIA REAGAN: Against all odds, try not to be crabby. And join us again tomorrow to learn something new in just a few minutes.
ASHLEY HAMER: And until then, stay curious.
[MUSIC PLAYING]