Learn about why lockdown has made us need nature more than ever; why plants are green; and how microbes and parasites might actually make us healthier.
Learn about why lockdown has made us need nature more than ever; why plants are green; and how microbes and parasites might actually make us healthier.
Why lockdown has made us need exposure to nature more than ever by Kelsey Donk
This is why plants are green by Cameron Duke
How microbes and parasites might actually make us healthier by Cameron Duke
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/the-need-for-nature-during-lockdown-why-plants-are-green-and-how-microbes-and-parasites-might-make-us-healthier
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 lockdown has made us need nature more than ever; why plants are green; and how microbes and parasites might actually make us healthier.
CODY: Let’s satisfy some curiosity.
If you’re like a lot of people, something funny may be happening to you during lockdown. No, I’m not talking about the overwhelming urge to bake bread. It’s that you’re feeling the pull of nature. Maybe you’re just watching more birds or squirrels from your window, or maybe you’re going on more hikes than usual. Nature is becoming so popular that many areas even closed down public parks because of crowding. And that makes sense. Exposure to nature has immeasurable benefits to our mental and physical health, and lockdown has made us need nature more than ever.
In 2005, author Richard Louv [LOO-v] coined the term "Nature-Deficit Disorder" to describe the human costs of alienation from nature. The term isn’t meant to be a medical diagnosis, but a way to talk about what Louv saw as a growing problem. He says that technology, urbanization, traffic, and parental fear have all accelerated our disconnection from the natural world. As a result, our activity levels have dropped, we’re finding it harder to focus, and our mental health is suffering.
Since then, more than a thousand studies have been done to find the impact of natural experiences on human development — especially the benefits. And it turns out that there are a lot of benefits. In children, it's been shown to decrease aggression and symptoms of attention deficit hyperactivity disorder. In adults, it can lower blood pressure and stress hormone levels, reduce nervous system arousal, enhance immune system function, increase self-esteem, reduce anxiety, and improve mood.
In a 2018 study, a group of psychiatric unit researchers found that being in nature helped patients feel calmer, less isolated, and just better overall. And in 2015, a British study found that more exposure to nature led to more community cohesion and lower crime rates.
The problem is that there’s a gap between who does and doesn’t have access to nature, and nature deficits often hit low-income areas and minority groups hardest. But a little is better than nothing. You don't need to live near a forest to reap these benefits — walking in a tree-lined neighborhood could help, but so could looking at trees through the window or bringing flowers into your home.
Louv suggests that people stuck in cities take walks in the neighborhood, watch live streams of nature, tell nature stories, or even set up a ‘world watching window’ where you can look at the clouds or spot birds and other urban wildlife.
If you’ve been indoors throughout lockdown and you’re feeling isolated and anxious, going outside or bringing the outdoors in could help. Connecting with nature might just be one of the few things we can still enjoy when everything else is closed.
Leaves are green, but have you ever wondered why? Like, yeah, green is the color of chlorophyll, which plants need to for photosynthesis. But what’s special about green? The most likely answer is kind of counterintuitive: it’s probably to avoid taking in too much energy from the sun.
Photosynthesis uses light from the sun. The sun gives off a full spectrum of color, so it looks white — you can plainly see that when sunlight hits a prism. But even though it contains every visible color, the sun doesn’t emit all colors equally. It actually gives off most of its energy as green light. That’s good news for plants, right? They’re green, and most sunlight is green. Problem solved.
Well, not exactly. Leaves are green because they reflect green light. That means they take the most energy-rich portion of available sunlight and punt it away as soon as it arrives.
How does that make any sense? Why would an organism that survives on sunlight just toss out the most powerful section of that sunlight?
Well, maybe because it’s too powerful. Being green might be a form of protection. This is because absorbing green light may actually oversaturate plants with energy. Just like drinking from a water fountain will quench your thirst but drinking from a firehose will break your glasses, sunlight can give too much of a good thing. If plants absorb too much energy, it might break down the chemical bonds that hold chlorophyll and other pigments together, which could lead to DNA damage. This is similar to what happens to your skin when you get a sunburn. Plants have adapted to balance their need for both energy and protection by using chlorophyll. Even though there’s less energy in the blue and red parts of the spectrum, it’s safer to use them.
But here’s a twist: photosynthetic organisms weren’t always green. In fact, early photosynthetic bacteria likely used a purple pigment called retinal [RET-tin-al, like “pal”], which absorbs that plentiful green light. These retinal-rich bacteria would’ve hogged all the space at the surface of the ocean, so the organisms down below would have been left with whatever wavelengths hadn’t been absorbed by seawater and other bacteria — which means there wasn’t much green light to work with. This is where chlorophyll photosynthesis probably evolved. Chlorophyll ended up being way more efficient than retinal, which is probably why it eventually became the dominant photosynthetic pigment.
It turns out that Kermit was wrong. It’s actually pretty easy being green.
If you’re listening to this, then congratulations! You are one of the luckiest humans to have ever lived. You and I get to live in a world where technologies like medicine and sanitation will allow us to live twice as long as many of our ancestors, on average. But that doesn’t mean that we’re automatically healthier. In fact, we have more problems with autoimmune and inflammatory conditions than our ancestors ever did. So what gives? It may come down to something called the hygiene hypothesis.
This problem relates to the fact that our bodies house huge microbial ecosystems, known as the microbiome. The microbiome does lots of great things for us, like synthesizing vitamins and helping out with digestion and immunity. The organisms in our microbiomes evolved with us, and together we become a cohesive unit.
But we have a problem. According to the hygiene hypothesis, a side effect of making our lifestyles so squeaky-clean is that we’ve killed off large swaths of the organisms we evolved with. And we’ve come to rely on many of these microbes. Experiments have shown that clearing out a mouse’s gut microbes basically kneecaps its immune system. Our microbes aren’t freeloaders, and their absence can turn our immune systems into glitchy messes that freak out at benign things like pollen — or worse, our own tissues, which is what happens in autoimmune disorders.
So if being clean is the problem, is getting dirty the answer? Well, it’s not that simple. In fact, some researchers take issue with the term “hygiene hypothesis” because of that misconception, opting for “biome depletion” instead. See, our damaged microbiomes are kind of like puzzles with some pieces missing — so, random microbes and parasites won’t fit in those spaces. Finding and replacing those missing bugs is a more promising answer. For example, there’s mounting evidence that gut parasites called helminths, which include tapeworms and hookworms, actually play a role in regulating the immune system. Helminth infections were so common in human evolutionary history that our immune systems seem to have evolved with the assumption they would simply always be there. In fact, some researchers are actively considering infecting people with helminths as a treatment for multiple sclerosis.
Although there may be no way to replace the species that our diets and sanitation have pushed to extinction, there are some things that may help. Eating a high-fiber, plant-based diet that’s low in processed food is a good start. Probiotics may help as well, though there’s less evidence for their benefits. Getting outside and exercising doesn’t hurt, either. But don’t stop washing your hands or cleaning your house. Your microbiome is picky, and not any old germs will do.
ASHLEY: Let’s review today’s takeaways, starting with the fact that
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CODY: Today’s stories were written by Kelsey Donk and Cameron Duke, 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!