Learn about why some words are more memorable than others; how hair growth works; and how fish end up in landlocked lakes.
Learn about why some words are more memorable than others; how hair growth works; and how fish end up in landlocked lakes.
Brain study reveals why some words are more memorable than others by Kelsey Donk
Hair growth, explained by Steffie Drucker
Fish eggs migrate to landlocked lakes via bird poop by Grant Currin
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/why-some-words-are-more-memorable-how-hair-growth-works-and-how-fish-end-up-in-landlocked-lakes
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about why some words are more memorable than others; how hair growth works; and how fish end up in landlocked lakes.
CODY: Let’s satisfy some curiosity.
Some words are easier to remember than others, aren’t they? Like, I have a handful of words I can never remember. One of them is “invincible” — no joke, I had to Google the definition just to remember it for this story. So why does this happen with some words more than others? Well, a new study suggests that it comes down to a word’s relationship with other words.
During an epilepsy study at the National Institutes of Health, researchers had epilepsy patients look at pairs of words from a list of 300 common nouns — like "hand" and "apple." After a few seconds, they saw one of the words they’d just seen, like “hand,” and then had to remember what it was paired with. “Apple.”
In the end, the researchers found that, yeah, people recalled some words more successfully than others. Words like “tank,” “doll,” and “pond” were remembered more often than words like “street,” “couch,” and “cloud.” And it didn’t matter what other words they were paired with. When they tried the same test on 2,623 healthy volunteers, they saw the same thing.
But why? To find out, researchers analyzed the most memorable words in a bunch of different ways. Did they appear more often in the English language? Nope. Maybe concrete words were more memorable than abstract ones? That didn’t pan out either.
Instead, the more memorable words turned out to have more semantic relationships. In other words, they’re linked to more other words by their meaning. Like, the word “tank” can refer to a military vehicle, an aquarium, clothing, a prison cell, or failure. The word “street,” on the other hand, almost always refers to a thoroughfare. The more other concepts a word is linked to, the more likely a person will be able to come up with a cue that helps them remember that word.
Electrodes in the epilepsy patients’ brains showed the researchers how this worked. The brain remembers past experiences, faces, and words using something that resembles an airport terminal map — or the internet. More memorable words represent the most trafficked ‘hubs’ in the brain’s memory network. They have more meaning attached to them, and they’re connected to other words with similar meanings. Those more memorable words are bigger on the brain’s map. As a result, the patients’ brains recalled those words faster and more easily than words in less-trafficked hubs.
Basically, your brain is like Google. When you start searching for a word, it pulls up a list of relevant terms based on what else you’ve looked for. Since “invincible” just has the one meaning, it tanks my ability to remember it.
This far into quarantine, you might be feeling a bit like Rapunzel. Hair cuts are SO 2019. But actually, with so many people letting their flowing locks flourish, why don’t we all have floor-length hair? Well, because your body tells it when to stop growing, and some strands stop earlier than others.
Let’s get into the details. Hair grows in three stages, which are conveniently in alphabetical order. First is the active growth, or anagen phase, where stem cells quickly divide to form the root of the hair. As they reach the skin’s surface, these cells die and leave behind a protein called keratin, which holds the strand together. Since the hair we see is already dead, it doesn’t hurt to cut or shave it.
Next is the catagen phase. The follicle’s blood supply cuts off to stop cell division. Then, the follicle shrinks and pushes the hair up & out like a Play-Doh mold.
Finally there’s the resting, or telogen phase, where the hair just kinda sits there for anywhere between a few weeks to a few months. Then the follicle starts up the anagen phase again, and the old hair falls out. You actually shed between 25 and 100 hairs every day!
But why can our head hair grow for what seems like forever but our, say, eyebrow hair stays short? It’s all about the length of each phase. About 100,000 of your five million hair follicles are on your scalp. These hairs grow about half an inch or 1 centimeter a month during the anagen phase, which can last from 2 to 7 years. For our eyebrows, that same growth stage only lasts about a month, but the rest stage is longer. That’s why your brows never grow long enough to cover your eyes.
Still, other mammals have fur all over. What’s up with our long head hair and the barely-there body hair? We don’t know for sure, but the leading theory comes down to dissipating heat. Our ancestors had hair everywhere to keep warm in the forest. As trees gave way to grassy savannas, those early humans shed most of their hair so they could hunt in the heat of the day.
Our hair stayed in only the most important places. Head hair protected us from direct sunlight while walking upright, eyebrows and eyelashes kept rain and debris out of our eyes, and underarm and pubic hair stayed around to help us attract mates and protect those bits during mating.
So the bottom line is that your head hairs grow long because they spend more time in the growth phase, and that’s probably for your protection. As for me? I spend about 2 minutes every morning in a fourth phase, when I put in my hair gel and carefully sculpt my ‘do into the meticulously groomed piece of artistry that you see on the Curiosity Daily podcast logo. I call it: the “Night Rider” phase. [Kevin Murphy]
Here’s a headscratcher: when a new lake forms, how do fish move in? I mean, they don’t just hop out of the ocean and walk over to landlocked lakes, right? And lakes have been forming and fish have been living in them since way before humans were around to help. So what gives? Well, new research has revealed an exquisitely gross answer: poop! From waterbirds, to be exact. Yes, fish eggs migrate to landlocked lakes via bird poop.
Believe it or not, ncientists already had a word to describe the dispersal of offspring through poo: endozoochory [EN-doh-ZOH-uh-KORE-ee]. It’s an important part of reproduction for a lot of plants and some insects. But fish eggs aren’t as tough as, say, a fruit seed, so researchers were skeptical they could survive the entire journey from mouth to bird butt and beyond. They thought eggs probably traveled on the outside of birds by hitching a ride on their feet, or beaks, or feathers. And these new results don’t mean that never happens, though there isn’t any scientific evidence that it does.
The first evidence for fish endozoochory [EN-doh-ZOH-uh-KORE-ee] came just last year, when researchers reported finding viable killifish [KILL-uh-fish] eggs in swan droppings. It was definitely an interesting finding, but some biologists thought it was an exception to the rule. That’s because desert-dwelling killifish are notoriously tough. I mean, their eggs can hibernate for months in a dry lake bed until a rainshower turns it back into a pond.
This new scatological science project involved two species of carp, which are fish with wide-ranging habitats and soft eggs that are more typical of other fish species. Researchers fed carp eggs to some mallard ducks — and the ducks had quite a feast. Each of the eight birds chowed down on about 500 eggs.
Then, the researchers waited.
Most of the eggs made their entire, you know, journey in the first hour, though some took quite a bit longer.
When the researchers examined the ducks’ excrement, they only found 18 of the original 4,000 eggs. Twelve of those eggs were viable, but only three hatched. Those might sound like pretty terrible odds until you find out that a common carp can lay up to 1.5 million eggs when it spawns. And when fish are spawning, some waterbirds eat nothing but eggs. Researchers once found a glaucous gull that was carrying more than 63,000 eggs in its belly.
With all those birds eating all those eggs, even 1-in-500 odds aren’t too shabby. And get this: there was one slowpoke egg that survived inside the bird for as long as six hours. According to the researchers, that means it could have traveled 220 miles in the wild. New lake? One fish-egg delivery, comin’ up!
Let’s recap what we learned today to wrap up. Starting with
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CODY: Today’s stories were written by Kelsey Donk, Steffie Drucker, and Grant Currin, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was produced and edited by Cody Gough.
CODY: Join us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!