4 Great Science Stories | MinuteEarth Directors’ Picks

**Sanitized Transcript:**

This video was sponsored by KiwiCo.

Hi, this is Kate from MinuteEarth. Today, we’re doing something a little different. All of us on the MinuteEarth team have plenty of strong opinions, including how we feel about our own videos! So here, three of our writer-directors will each share one of their favorite MinuteEarth videos and explain why it’s at the top of their list—maybe it’s the awesome analogy, maybe it’s the storytelling style, or maybe it’s the particularly clever puns.

I’ll start: I LOVE “Why Poor Places are More Diverse,” the brainchild of our great writer Peter. It is totally counter-intuitive that greater numbers of species grow where soils are…well…dirt poor. But this video cleverly explains why poverty drives diversity not only in the natural world but elsewhere on our planet too. Take a look.

A soccer-field-sized patch of forest in frigid Alaska has about 40 different species of plants, compared with about 70 in temperate England and 300 in the Amazonian rainforest. These biodiversity differences hold true for entire countries too: England has 1500 plant species, while tropical Guyana has six times that many. The super-diversity of tropical rainforests is only equaled in one other type of ecosystem on Earth: scrubby fire-prone shrublands that grow in western Australia and southern Africa. These shrublands may not look as majestic as tropical rainforests, but in a given area, they’re home to similarly impressive numbers of species.

Which doesn’t necessarily mean that the rainforests and shrublands are easy places for plants to live. In fact, both ecosystems owe their enormous diversity, in part, to the fact that their soils have critically low supplies of nitrogen and especially phosphorus, nutrients plants need in order to grow. The plant world’s leading biodiversity hotspots are, quite literally, dirt poor. Logically, it seems like richer soils should support more species. But in nature, as in human society, ‘plenty of resources’ doesn’t necessarily translate into ‘everyone gets plenty.’ In meadows, forests, and wetlands around the world, we consistently find more or bigger plants but fewer species where soil nutrients are highest. The fastest-spreading species soak up most of the extra nutrients, which lets them keep growing rapidly, which lets their roots absorb so much water, and their leaves capture so much sunlight, that other, slower species actually get LESS of those resources than otherwise. So in rich soils, slower species die out while the fast-growers thrive.

On the other hand, poor soils don’t provide enough nutrient capital for fast-growing plants to build their massive infrastructures and take all the resources. So poor soils inhibit the greedy and allow everyone else to survive. We see this pattern in human society as well—there’s a far greater number of businesses, mostly small, in poor countries, while fewer larger companies dominate in rich countries. But poor soil isn’t the only thing that helps super high diversity flourish; for example, beaches, mountaintops, and other places frequently affected by harsh weather or catastrophic events have poor soils AND few plant species. The other major prerequisite for hyperdiversity is time. On most of the planet, glaciers regularly clear away ecosystems and grind up mineral-rich rock, creating new soil perfect for growth but not diversity. However, our high-diversity rainforests and shrublands have spent millions of years beyond the reach of the ice sheets, leaving their residents plenty of undisturbed time to evolve a wide variety of ingenious strategies for surviving nutrient poverty—strategies that have allowed for the development of tall, diverse rainforests in wet poor soils and scrubby, diverse shrublands in dry poor soils. The human landscape also seems to follow a similar pattern, with the highest cultural and linguistic diversity as well as the greatest number of businesses in climatically stable places where humans have been the longest and where economic resources are scarce. So in some ways, the poorest places on earth are actually the richest. That ending blows my mind every time. It’s incredible how similar the processes that shape the world around us are to those that shape who we are. But that’s enough philosophizing from me—here’s David with his pick.

Thanks, Kate! My favorite MinuteEarth videos are the ones that totally make me rethink the way I think about everyday stuff. And every time I go to the store, I think about this awesome video—also written by Peter—about the relationship between beer and biodiversity. Now, whenever I’m in the beer aisle and I look at a local microbrew, I think about it as a small plant trying to survive in a competitive environment filled with big breweries. Go watch the video, enjoy, and I’ll see you at the end.

In the local shop, next to major beer brands, you might find microbrews with unique names. While the big brands run ads featuring adventurous individuals, their small competitors have to fight for attention on the store shelf. That’s because, much like a small shrub or fern beneath the tall trees in a forest, microbreweries live in the shadows of their larger corporate competitors. Surprisingly, many species and businesses that manage to survive in the shadows of giants employ similar strategies to succeed in their respective competitive environments.

The winners of this competition in the forest or beer business, as defined by sheer volume, are those that capture the most resources—sunlight in one case and consumers’ dollars in the other. The mechanics differ—big trees capture sunlight by being tall, while large brewers earn profits by having a broad reach, attracting customers with low prices and extensive marketing. The outcome is the same, though—by capturing the most valuable resources before they reach others, dominant trees and companies exclude weaker competitors who employ the same tactics. But there are trade-offs to any strategy, and being the best on average rarely works in all cases and conditions.

That’s how understory ferns and microbreweries can succeed—by specializing in conditions the “big guys” are not so good at: the so-called empty niches. In deep shade, a fern can make a modest living by avoiding direct competition and investing prudently in just enough photosynthetic machinery to make a profit from the faint sunlight reaching the forest floor—leftover light not worth the extra effort for the big trees to capture above. Ferns can even thrive on a photosynthetic income that’s inadequate for the small offspring of many tall trees, and thus the humble fern coexists with the tall timber above by competing on its own terms. Similarly, microbrews, which invest in being unique and strongly flavored, can persevere by attracting enthusiasts not swayed by the marketing and lower prices of larger breweries. Sure, fewer people fall into this category, just as fewer beams of sunlight fall through the canopy onto the forest floor, but where there are resources, there’s potential to survive. And survival is the goal of both ferns and firms, so it’s not really that surprising that both nature and the economy, driven by the same kinds of competition, give rise to niches and diversification, to canopy and understory in the forest and in the supermarket aisle!

Have you guys ever noticed that “canopy” sounds like “can of pee”? At any rate, I’m off to try to find some unique brews. Julián, you’re up next!

Thanks, David! One of my favorite videos is Kate’s “How We Evolved To Browse The Web.” We humans think we’re all that—and from the perspective of our command of global resources, we certainly are—but as this video points out, some of the things we do that seem uniquely human, like searching for memes on the internet, are not so different from how our fellow animals behave. Kate did an excellent job of looking at human behavior through a zoological lens; check it out.

Hi, this is Kate from MinuteEarth. Let’s find some cat memes! This site looks good—yeah, there’s some funny cats and some great content on here! But, well, hmm…the pickings are definitely getting slimmer. Maybe we should try another site? But that means we have to FIND another site! And we’re already here… so, should we stay or should we go? Well, it turns out that online, we forage for information just as, say, a chickadee forages for fruit; it has to choose which tree to visit and decide how long to stay there before moving on to find another. Ecologists have all sorts of models to describe how animals forage. And it turns out that one of these models, which explains how animals move between patches of food, also predicts how humans move between websites: both you and the chickadee will forage in one place until the rate of reward you’re getting there drops below what you think you’re likely to get elsewhere. This calculation is subconscious, of course—you’ll just notice the tree is getting bare and move on. It’s a matter of spending your time and energy in a way that gets you as much reward as possible…and that’s something foraging animals—and humans—do all the time.

For instance, we’ve found that chipmunks that take longer seed-gathering trips bring back bigger hauls than those that take short ones. That makes sense: it’s only worth spending lots of resources if you can score big. And a study of more than 400 robberies in the Netherlands found that the farther burglars travel to commit their crimes, the more valuable their loot tends to be. Researchers have even found that the longer we search for a romantic partner, the more likely that relationship is to last; perhaps a bigger investment leads to a better payoff. We probably optimize like animals because we are animals, and in fact, we share critical decision-making circuitry. For instance, monkeys have special neurons that seem to track the rate of reward the monkey is getting in a patch—when it drops too low, the neurons send a signal to the monkey, who switches to a new patch. We also have these neurons—and there’s evidence to suggest that lots of other animals do too; they were likely so critical to making good food-finding tradeoffs in the distant past that they were passed on over many generations. This kind of shared machinery may help explain why we behave like our non-human kin.

Of course, most of us humans now find ourselves evaluating how fruitful websites are much more often than how fruitful fruit trees are, and the stakes of wasting your time on trivial content are far lower than wasting your time searching for food. But it’s not just web surfing…at what point do you move on from a boring TV show, or ditch the long line at the DMV, or give up on a job—or even a relationship—that you’re not that into? It turns out that the constraints—and the underlying machinery—that guide us in these everyday scenarios are likely the same as those that guide animals…which means that deep inside, we’re all a little bird-brained. I’d like to personally thank your neurons for staying with us, and they chose wisely—here’s Henry with his choice.

Awesome, Julián. One of my favorites is “Why is it Hot Underground?” written and narrated by our former team member, the excellent Emily Elert. What I love about this video is it starts with a simple question, then takes us on a journey with lots of intriguing false turns and dead ends (including some that people STILL get confused by) and then culminates in a truly modern explanation of our planet’s thermodynamics (spoiler: it’s not like a baked potato).

Way back in the Middle Ages, miners began to notice that the deeper they dug into the earth, the warmer it got. Who knows what they made of the heat, but the physicist Lord Kelvin—of temperature fame, naturally—had a theory: Earth started off hot and has been cooling down ever since, like a baked potato pulled from the oven. What’s more, Kelvin was confident this idea would allow him to calculate the age of our planet. Imagine pulling two recently-baked potatoes out of a freezer—one that’s been in there for just one minute, the other for half an hour. The minute-old one would still feel warm, while the half-hour frozen spud would have cooled well below the skin—you’d have to poke all the way to the center to feel its residual warmth. And so in principle, you can tell how long ago a potato was cooked just by feeling how warm it is right beneath its surface. Which is exactly what Kelvin did—except with the earth. And scientific rigor. He took temperature measurements from the mines, put them into his calculations, and got…20 million years. Which is, of course, very, very wrong—somehow, the hot temperatures just under Earth’s surface made it seem, to Kelvin, that our planet was pretty much fresh out of its cosmic oven, when we now know that it’s four and a half billion years old.

Kelvin’s error is usually attributed to the fact that he didn’t know about radioactivity, which creates a lot of heat in Earth’s core and helps keep the planet warm. But heat from radioactive decay moves so slowly through solid rock that taking radioactivity into account only improves Kelvin’s estimate by…pretty much nothing. Kelvin’s real oversight was in thinking of the Earth like a baked potato—a solid lump through which heat slowly diffuses. Earth’s mantle—the thick layer between the crust and the core—is mostly solid, but it isn’t rigid. In fact, the rock closest to the molten outer regions of the core gets so hot that it becomes slightly more pliable, like warmed candle wax. And like the hot air above a candle, the warm rock rises in convection currents—over millions of years—spreading heat more evenly throughout the planet. This stirring carries tremendous amounts of heat from the core to the crust, fueling volcanoes, maybe helping to drive plate tectonics, and heating mineshafts to temperatures that make Earth seem like it’s fresh out of the cosmic oven. Even though it’s not.

Alright, thanks Kate, David, and Julián for the trip down memory lane. And stay tuned, our illustrators are going to be doing the same thing, coming up soon. Bye! Speaking of our favorite stuff, the MinuteEarth team are big fans of KiwiCrates—boxes that come right to your door each month with everything your kids need to do fantastic projects. David’s two little ones already have monthly subscriptions, and this month my kids got a chance to try them out. Let me tell you, over the last nine months it has not been easy to keep these kids occupied…but with their KoalaCrate and KiwiCrate, they were not only occupied for an entire hour—they were happy AND they were learning about STEAM, from rainforest ecology to what goes on in the deep sea. Now I’m thinking that they just might each get a subscription as a holiday gift, since it would be fantastic to have that glorious hour every single month. Check out KiwiCo.com/MinuteEarth50 or click the link in the description below for 50% off your first month of ANY crate. Thanks to KiwiCo from this happy mom and these happy kids! Thank you, KiwiCo!