Our favorite science news stories of 2021 (non–COVID-19 edition) | Science

If you’re a fan of weird animals and exotic concepts, we’ve got a top 10 list for you. From wombats that poop cubes to hypothetical power plants fueled by black holes, our annual end-of-the-year list includes staff favorites and some of our most popular stories of the year. You won’t find any COVID-19 news here (for that, check out our Breakthrough of the Year). But if you want some fun in your science—and don’t mind a bit of scatology—read on!

Barnyard breakthrough: Researchers successfully potty train cows

Scientists in Germany have achieved what many biologists (and farmers) thought impossible: They’ve toilet trained cows. The advance doesn’t just give our bovine pals more cognitive credit—it could help put a serious dent in the toxic chemicals and greenhouse gases produced by farm animal waste.

Two people collect DNA samples from mud
Luis Valentin-Alvarado (left) and Basem Al-Shayeb (right) collect DNA-filled soil samples from what was a temporary springtime pond.JILL BANFIELD

Mysterious DNA sequences, known as ‘Borgs,’ recovered from California mud

In the mud of her backyard, a researcher discovered a strange linear chromosome that included genes from a variety of microbes—a new type of genetic material that her Trekkie son proposed naming “Borgs” (after the Next Generation baddies). Are they part of a viral genome? Strange bacteria? Whatever Borgs are, one expert says, the find is “pretty exciting.” And who can resist a good Star Trek reference?

Researcher looking at brain waves on monitor
Researchers analyzed the brain signals and eye and facial movements of people engaged in lucid dreaming “conversations.”K. KONKOLY

Scientists entered people’s dreams and got them ‘talking’

Speaking of science fiction, one story this year brought us a bit closer to the fantastical world of the movie Inception, in which humans enter the dreams of others. For the first time, researchers have had “conversations” with people in the dream state, including getting them to answer yes-or-no questions and solve math problems. The work could help people better deal with anxiety and depression, and perhaps even gain new skills—all while catching some zzzs.

Dark flecks in a diamond
Imperfections such as the inclusions (dark flecks) in this diamond reveal that tectonic slabs can carry water deep into Earth’s mantle.EVAN SMITH/© 2021 GIA

Giant diamonds may hold the key to superdeep earthquakes

Let’s go deep again, this time 300 kilometers below Earth’s surface. Earthquakes shouldn’t occur here, yet they commonly do—a phenomenon that has mystified seismologists for decades. Something appears to be releasing water at these depths, weakening nearby rocks. The answer, according to this study, could be the same as what to get that special someone this holiday season: giant, fist-size diamonds.

Grizzly bears
Grizzly bears in the central coastal region of British ColumbiaMICHELLE VALBERG

‘Mind blowing’: Grizzly bear DNA maps onto Indigenous language families

Bears and Indigenous humans of coastal British Columbia have more in common than meets the eye. Grizzlies in this region form three distinct genetic groups that closely align with the region’s three Indigenous language families, perhaps because the bears clustered in the same regions favored by humans. One expert calls the find a “really shocking” observation that could reveal that the fate of humans and wildlife is even more intertwined than we thought.

artist’s impression of a Dyson sphere surrounding a star
An artist’s impression of a Dyson sphere surrounding a starDOTTED YETI/SHUTTERSTOCK

Black holes surrounded by massive, energy-harvesting structures could power alien civilizations

Another far-out idea, this time from a galaxy far, far away. Researchers have shown that highly advanced alien civilizations could theoretically build megastructures called Dyson spheres around black holes to harness their energy, which can be 100,000 times that of our Sun. Even better for us humans, if such technology is at work, there may be a way to spot it.

square wombat poop
A single cubic wombat dropping positioned by researchers on top of a rockYANG ET AL. 2021

How do wombats poop cubes? Scientists get to the bottom of the mystery

Only one animal on earth poops cubes: a furry Australian marsupial known as the bare-nosed wombat. But how do they do it? Researchers get to the bottom of the mystery in this scatological story. Now, they just have to figure out why the animals evolved cubic poop in the first place, though it may be to keep it from rolling off high perches.

This sea slug cut off its own head—and lived to tell the tale

It was “like a horror movie.” That’s how one scientist describes our creepiest video of the year, wherein a sea slug head wriggles around the bottom of an aquatic tank, seemingly searching for the rest of its body. Rather than die, the amazing noggin regrew the rest of its anatomy—a feat practically unheard of in complex animals.

robotic hand holding skull

Kinky and absurd: The first AI-written play isn’t Shakespeare—but it has its moments

When a conversation about euthanasia ends up in a fight about who has whose finger in whose anus, you know you’re not in for a typical day at the theater. But that’s what happens when a robot writes your play. In one of our most surreal stories of the year, artificial intelligence attempts to tell the story of a machine that ventures out into the world. Things don’t go as planned, as men become women, robots take over the world, and fingers … end up where they’re not supposed to be. The play wasn’t easy on the human performers either, a study author says. “One of the actresses told me it was the most challenging work of her career.”

artist reconstruction of dire wolves fighting gray wolves
Dire wolves (red) fight off gray wolves for dibs on a bison kill in this artist’s reconstruction.MAURICIO ANTÓN

The legendary dire wolf may not have been a wolf at all

Dire wolves are not what they seem. The first genetic analysis of the ice age carnivores finds that they are so different from other wolves, coyotes, and dogs that they don’t belong in the same genus as these animals. Instead, researchers argue, they need an entirely new scientific classification. This “fascinating” find was also our most read non–COVID-19 story of the year. Why so popular? Maybe people like wolves. Maybe they like ancient DNA. Or maybe there are just a ton of Game of Thrones fans out there.