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Why have we domesticated some animals but not others? It comes down to four F's.

An entertaining video explains why we can't ride zebras or breed "war bears."

Photo credit: Canva

Horses were domesticated over 5,000 years ago. Zebras, never.

Humans have domesticated several kinds of animals over the millennia, from trusty horses and mules to livestock for milk and meat to our favorite furry companions. But why those specific animals and not others? What is it that led us to those particular choices? Why can we ride horses but not zebras? Why don't we purposefully breed "war bears" to fight for us?

That last question comes straight from the always-interesting and often-hilarious CGP Grey, whose YouTube videos explore all kinds of things we wonder about but don't necessarily take the time to research. In the video "Why Some Animals Can't Be Domesticated," Grey explains the four main elements that make an animal a good candidate for domestication, which excludes bears (and many others) from the list.

Grey alliterated the four elements to make them easier to remember: Friendly, Feedable, Fecund, and Family-Friendly. Let's dig into what those mean.

- YouTubewww.youtube.com

Domestication requirement #1: Friendly

This one is fairly self-explanatory, but basically an animal has to not post an inherent, immediate threat. We have to be able to catch them if we're going to domesticate them, so that eliminates all of the "carnivores whose day job is murder" as Grey puts it, as well as the large, nervous prey animals that are too afraid of us to let us get anywhere near them.

wild animals, domesticated animals, gazelleGood luck trying to catch a gazelle.Photo credit: Canva

Domestication requirement #2: Feedable

Every animals is feedable, of course, but that doesn't mean it's easy or cheap to feed them, especially in large numbers. This category pretty much eliminates pure carnivores and some omnivores, leaving mostly herbivores (and some unpicky omnivores) that are easy and cheap to feed. And that aren't dangerous (see #1).

wild animals, domesticated animals, chickens, chicken feedChickens will eat just about anything.Photo credit: Canva

Domestication requirement #3: Fecund

This requirement is all about breeding and babies. Some animals are extremely slow to breed, like pandas and elephants, making them undesirable candidates for domestication. Animals that have mate frequently and have relatively short gestation times and/or large litters are more suited to domesticated life. They also need to grow up quickly, which also takes elephants out of the pool.

However, as Grey points out, humans can still tame other animals like elephants. But taming is not the same as domesticating. The basic rule is: If it's on a farm, it's domesticated. If it's in a circus, it's tamed.

Domestication requirement #4: Family-friendly

This is where the horses and zebras question comes in. Horses were domesticated in Eurasia, but if humans started in Africa, why weren't zebras domesticated first? Grey explains that while horses tend to live in hierarchical herds, zebra are more independent with no family structure. Humans can capture the lead male horse and get the rest of the herd to fall in line. Zebra herds are more of a free-for-all and they're kind of jerks to even one another.

horses, zebras, domesticated animals, wild animalsThere's actually a big difference between horses and zebras besides just the stripes.Photo credit: Canva

Barnyard animals have inherent family structures that humans have figured out how to fit into. These animals learn to see the humans who own them as a lead cow or top chicken or whatever.

Way back in the hunter-gatherer age, when humans were just figuring out animal domestication, animals had to have all four of these requirements. Today, we have the ability and technology to domesticate more animals if we want to, but we also have less of a need to. Some breeds of foxes have recently been domesticated, bred to be friendly with humans. How fun would it be to have a pet fox?

- YouTubewww.youtube.com

Technically, a lot more animals could be domesticated if people really wanted to put in multiple human lifetimes of time and effort, but why?

You can follow CGP Grey on YouTube for more fun and informative videos.

This article originally appeared in April.

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'Last trace of magic': Americans are changing their backyards to save fireflies from extinction

Firefly lovers are taking action after scientists sound the alarm.

Photo credit: Canva

If you're thinking you don't see as many fireflies as you did when you were a kid, you're right.

There’s nothing quite like spending a summer night surrounded by a moving constellation of fireflies. Suddenly, those fae realms in stories of old feel like they very well could take shape in front of our eyes. It’s one of Mother Nature's most miraculous gifts for the way that it ignites the inner child in us all.

And yet, there have been recent claims that soon, the gentle twinkling of these universally loved insects—also known as lightning bugs for those of us from the South—might soon become a fairy tale in its own right. According to a 2024 study in Science of The Total Environment, firefly populations in North America are declining.

There are four major reasons for this (and surprisingly, they all have to do with human interference):

@ricoexplains Fireflies — those glowing icons of summer nights — are quietly vanishing. And artificial light might be their biggest threat. This short video explains the real science behind why fireflies are disappearing, and what we can do to help. Sources: – Lewis, S. et al. (2020). A global perspective on firefly extinction threats. BioScience, 70(2), 157–167. – Firefly Conservation & Research. Xerces Society. – International Dark-Sky Association. #fireflies #lightpollution #biodiversity #scienceexplained #shorts #ricoexplains ♬ original sound - ricoexplains

Habitat loss: Paved streets and urban environments have replaced much of the moist environments like wetlands, marshes, and damp woodlands where fireflies thrive.

Light pollution: This is an even bigger threat than habitat loss, studies have found. While the glow of fireflies delights human audiences, its main function is a mating ritual. However, the exposure to artificial light from streetlights, billboards, etc., disrupts not only the mating cycle, but also the larval stage.

Pesticides: Certain commonly used chemicals kill not only fireflies directly, but snails and slugs, which firefly larvae consume. Not to mention they also contaminate their water source.

Climate change: Warmer temperatures also disrupt mating cycles and changed precipitation levels further contributes to unstable habitats.

Understandably, people are heartbroken to hear this news. Across social media, folks have noted that indeed, they see a lot less of these bioluminescent bugs compared to years prior, and shared their sadness that future generations might not get to experience such natural beauty.

@aliyah.noels midsummer fireflies in Appalachia 🕯️#fireflies #midsummer #solctice #appalachia #appalachianmountains #fairycore #fairy ♬ A Quick One Before the Eternal Worm Devours Appalachia - Lizard in the Spring

“I know that losing the bees would be the death of us all, but it would be somehow worse to lose the fireflies. Like killing the last trace of magic in the world.”

“This explains a lot. I wondered what happened to them, used to see them all the time when I was a kid…now where I'm at, they're basically non-existent.”

“I remember when I was little in the 90s fire flies would be EVERYWHERE at night and now you're lucky to see them at all. I miss that.”

“I wondered why I didn’t see fireflies or salamanders as an adult. I had so many excuses and eventually learned it’s our fault they’re all dying. It was magical finding salamanders under logs with my mom and catching lightning bugs in a jar.. kids these days don’t get that. They get tablets.”

“Fireflies bring me back to a time with less technology and more peace.”

Still, it’s not all doom and gloom. Several also shared how they do their part to help revive firefly populations, particularly by removing toxic pesticides from their yard maintenance.

As one person wrote, “a few years ago I stopped treating my yard. Last year I let part of it over grow and I had an abundance of fireflies and dragonflies. It's absolutely beautiful to watch at night.”

According to the study, we can also mitigate light pollution by incorporating dark-sky-friendly lights. This of course doesn’t offset the light pollution brought by street lights and other city fixtures (as with most conversation efforts, it takes both individual contribution and systemic change) but regardless, small actions add up.

One last helpful note: Ben Pfeiffer, founder of Firefly Conservation and Research and Texas-certified master naturalist shared that “while fireflies are disappearing in many areas, mainly due to habitat loss from residential, commercial, and industrial development. They are doing well in places [where] they are protected.”

“We won’t be the last generation to see fireflies,” he affirmed. What is actually threatened, he noted, is the “biodiversity” of previous firefly generations. “What these species get replaced with is the common firefly Photinus pyralis [which] is more of a habitat generalist and can tolerate more habitat types.”

fireflies, fireflies extinct, firefly conservation, environment friendly pesticides, where to see fireflies, Every child should get to experience this. Photo credit: Canva

So, while we haven’t necessarily seen the last of these magical insects, it is nonetheless a wake up call if we want to continue basking in their glow.

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Ocean Wise
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Sustainability

Amazing ocean facts you never learned in school

Not even Captain Ahab knew this much about marine life.

Photo by Milos Prelevic on Unsplash
brown fish beside coral under body of water

The ocean covers more than 70 percent of our planet—yet there’s so much about it that we don’t yet know. Experts, in fact, believe we’ve only explored about five percent of the ocean so far—meaning that most of it remains completely unseen and undiscovered.

What we do know, however, is that the ocean is truly wise. Not only does it sustain all human and animal life on the planet, the creatures under the sea continue to give scientists insight that can transform human lives as well (just read about the amazing axolotl below to see what we mean).

A happy ocean makes for happy, healthy human beings (not to mention a healthy planet)—so this summer we’re helping our friends at Ocean Wise spread the word that no action is too small—holding a cleanup on a local shoreline, for instance. Learning about our ocean and all its wonders is another step anyone can take for conservation, so buckle in and prepare for a tidal wave of info that will blow your mind.

1. Playing music—specifically, recordings of healthy reef soundscapes—can help grow coral reef populations.

live coralsPhoto by QUI NGUYEN on Unsplash

Healthy coral reef populations are filled with diverse sounds, thanks to the fish, snapping shrimp, and other marine life that live there. Scientists have found that playing recorded sounds of healthy reefs actually attract coral larvae, since the sounds indicate a healthy, vibrant habitat. Using this knowledge, scientists have taken recorded reef sounds, played them near degraded reefs, and in doing so, have increased the settlement rates of coral larvae, helping the coral reefs regenerate.

2. Dolphins like to party with pufferfish.

Photo by Talia Cohen on Unsplash

How’s this for a good time? Dolphins, particularly younger ones, have been known to seek out pufferfish to play games with them, chewing on them and passing them back and forth between each other like a hacky sack. Not only is this entertainment for the dolphins, scientists theorize that they may intentionally be trying to get the pufferfish to give off a neurotoxin called tetrodotoxin (TTX)–which is a chemical they release when threatened. This chemical is highly toxic in large doses–but in small quantities, experts think that it might induce a mild, pleasurable effect in the dolphins, similar to a narcotic. Party on.

3. Male humpback whales are total crooners.

A male humpback whale breaches the water.

Photo by Thomas Kelley on Unsplash

All humpback whales can vocalize, but male humpback whales actually sing.

During mating season, scientists have observed male humpback whales making sounds that are distinctly different from other humpback calls. Unlike other sounds, these songs have a clear structure, and use small, repetitive “phrases” organized in a specific sequence—in the same way humans sing different verses during a song. Even more amazing? Male humpbacks all sing the same song together in “choruses,” in sessions that last from five minutes to several hours.

4. Axolotls have superpowers (and scientists think it could benefit humans one day).

a couple of animals that are in some waterPhoto by T K on Unsplash

Among biologists, axolotls are known for their ability to regrow lost or damaged tissue. When an adult axolotl loses a limb, they can actually grow it back in just a few months time, thanks to a substance they produce called retinoic acid, which plays a large role in regenerating skin cells. (If the name sounds familiar, it’s because retinoic acid is a derivative of Vitamin A, and it’s commonly found in skin creams.) While we already know that retinoic can make our skin look fabulous, scientists are currently studying whether it could someday help human limbs regrow, similar to the axolotl’s.

5. A healthy ocean can help reverse climate change

green algae underwater photographyPhoto by Brian Yurasits on Unsplash

The ocean generates half of the oxygen we breathe and absorbs nearly a third of the world’s carbon emissions. Phytoplankton, the microscopic algae that float near the ocean’s surface, are a big part of the reason why. But there’s another unsung hero—kelp. Unlike phytoplankton, kelp are large seaweeds that grow in dense underwater forests along coastlines, absorbing CO2 and supporting ecosystems. Ocean Wise is helping bring back these powerful carbon sinks one kelp forest at a time.

Help us #BeOceanWise by doing one small thing for ocean conservation in your community (because just one thing can start a huge wave of positive change). Visit ocean.orgfor tips and tricks to keep our oceans healthy because no action is too small.

Science

Massachusetts bans uber-bright aftermarket LED headlights and drivers couldn't be more thrilled

The details of the law are a little technical, but it's a good first step toward much tighter regulation.

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It's impossible to see the road, other cars, and pedestrians when you're staring into someone's LED headlights.

I used to love driving at night. I'd just hop in the car and pick a direction and go, blasting music with the windows down and clearing my head along the way. It was truly one of my great joys. A lot of things were different back then, though. I had fewer responsibilities, for starters, and had time to just aimlessly wander. Gas was way cheaper, too, making these adventures far more economical.

But one big thing that has contributed to me losing my passion for night driving is absolutely, without a doubt, the rising prevalence of LED headlights. If you've ever wondered why everyone's headlights seem to be insanely, dangerously bright these days, you're not alone. And you're not the only one who's pissed off about it. What good is it to illuminate the road in front of you so well that you, in fact, blind the other drivers traveling at high speeds in your direction? How is that making anyone safer?

Just look at how infuriatingly dangerous these can be in real-world conditions:

- YouTubewww.youtube.com

The state of Massachusetts has reignited the conversation around LED headlights with a surprising new piece of legislation.

Many new cars come equipped with LED headlights, up to 75% or more of new models, in fact. But even more LED lights are sold as aftermarket options or conversion kits, and these are poorly regulated. Many aftermarket lights are far too bright and/or suffer from misalignment that shoots the light beams directly at the eye level of oncoming traffic. They represent a large portion of the glare problems we experience out on the road.

Massachusetts is cracking down with a new law. It states that LED headlights that come equipped from the manufacturer are fine (for now), but there will now be far stricter regulations on simply swapping in an aftermarket LED bulb or conversion kit onto your vehicle. The legislation specifically cites coloration and positioning issues with LED headlights that haven't been tested as a "full unit," meaning including the housing and reflectors that are typically part of a headlight.

So you could still legally upgrade from halogen bulbs to LED, but you'd have to replace the entire headlight unit and not just the bulb.

Hefty fines will be implemented for drivers who are caught in violation of the new policies.

LED headlights offer a lot of benefits, in theory. So why do people hate them?

LED lights use less power, are brighter (duh), and last far longer than traditional halogen bulbs.

But there are a few problems with the technology that make them a huge hassle for other drivers. First, they're just too bright! They look even brighter in real-life because of the pure/cool white they emit, versus the yellow glow of halogen bulbs. Cool colors like white and blue are harsher on the eyes than more night-vision friendly warm colors such as red, yellow, and orange.

Second, especially in America, we love huge vehicles. More and more people are driving trucks and jeeps that sit high. Now those ultra-bright LEDs are shining directly into the poor sedan drivers' eyes.

Third, too many Americans choose to drive with their high beams on at night — all the time. They like the extra visibility they get by dousing the entire roadway in bright light and have little regard for how dangerous it is for others in their path (or they simply forget they have them on). While a lot of American cars have high beams that can switch off when another car is detected, other countries have better technology at play.

Did you know that many cars in Europe and Asia feature a technology called ADB (Adaptive Driving Beam) that allows LED lights to shape and direct their light pattern in very specific ways on the road, actively avoiding the eyes of other drivers? US cars, so far, are not allowed to enable this mode — though the regulations are in the works.

- YouTubewww.youtube.com

Even still, assuming good alignment and ADB technology, bright LED headlights are a dangerous problem. They're causing accidents all over the world, and especially in America.

The legislation in Massachusetts is a good step toward even greater action. Organizations like the Soft Lights Foundation continue to fight for even stricter regulation of LED lights — and not just in cars — or even outright banning them.

And the public outcry for lawmakers to do something about the problem continues to grow. People are sick of being blinded in dangerous, high-speed situations. Hopefully more states will follow suit, and we can continue to pressure auto manufacturers to turn down the damn brightness.

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