Live Science's best of 2021: Writers' choice

This drawing shows how the dinosaur Psittacosaurus may have used its cloacal vent (aka butthole) for signalling during courtship.

(Image credit: Bob Nicholls/Paleocreations.com 2020)

What makes a science news story stand out? At Live Science, our reporters and editors cover a broad range of topics, and each year brings plenty of opportunities for each of us to share some of the strangest, most unexpected and most interesting science around.

Of the many hundreds of stories that we wrote about in 2021, some were truly unforgettable. From an immortal bee army to a dinosaur's perfectly preserved butthole, here are the stories that Live Science's writers just couldn't stop thinking about.

My favorite story to write this year was a case study on a 23-year-old student in Germany who can directly control his pupils like a muscle, something that was previously thought to be impossible. It was previously known that some people could change their pupil size when they wanted to but by using indirect methods, such as by thinking about the sun. But it was thought to be impossible that someone could control the pupils directly like a muscle, just by concentrating on the eye. The student, referred to in the study by his initials D.W., told the researchers he could feel gripping when his pupils were constricting, and relaxing when they were dilating.

Nicoletta Lanese, Staff Writer: My favorite story this year delved into the neuroscience of movement, which I'm a huge nerd about, and also featured one of my favorite Olympic events: gymnastics. Gymnast Simone Biles, the certified G.O.A.T., made headlines during this year's Olympics when she came down with a case of the "twisties," meaning she lost sense of where she was in the air during a trick. Other athletes have reported a similar disconnect between brain and body, called the "yips," where they suddenly can't execute the skills they honed in practice. I spoke with experts about the complex motor learning that goes into training these skills in the first place, and what likely goes wrong when an athlete gets the twisties or yips.

Jeanna Bryner, Editor-in-Chief: When a person accidentally stumbles upon what ends up being a huge discovery, reporters like me take notice. And this year, the serendipitous find was giant in many ways: A park ranger who was ambling through a forest in California uncovered what ended up being a petrified forest chock-full of the fossilized remains of dozens of prehistoric behemoths, including a stunningly preserved mastodon skull, an extinct camel, rhinos, giant tortoises and even a monstrous 400-pound (181 kilograms) salmon ancestor.

Greg Francek first noticed a wood-like structure poking from the ground; upon closer inspection, he realized the smooth protrusion was one end of a petrified tree. After finding a second, third, fourth and more of these tree remains, Francek realized he was in the middle of a petrified forest. I would’ve loved to have been there when he spotted the stunning window into the area’s past. His finding opened up a treasure trove for paleontologists and geologists. Over the past year, these scientists have unearthed hundreds of animal fossils representing dozens of species. These animals would have lived some 10 million years ago when the area was covered by an oak forest on the outskirts of the sea.

Patrick Pester, Staff Writer: My favorite science story this year was about plateau pikas eating poop to survive Tibetan winters. The small, rabbit-like animals can't hibernate and don't migrate so scientists set out to understand how they cope with winters on high-altitude meadows in Asia, where temperatures fall to minus 22 degrees Fahrenheit (minus 30 degrees Celsius). The 2021 study found pikas slow their metabolism and, in some cases, eat domestic yak poop. Chowing down poop may help pikas spend less energy than they would foraging their own food and access water and nutrients that are scarce in winter.

Tia Ghose, Assistant Managing Editor: My favorite story of the year was about a 3.3 billion-light-year arc across the cosmos that is so big, it shouldn't exist. The structure, aptly named the Giant Arc, spans a 15th of the observable universe, and yet we only discovered it this year. The cosmic behemoth's sheer size challenges the cosmological principle, a long-held assumption stating that at large scales, matter is uniformly distributed. (According to this principle, there are limits to how big a structure can get.)

Astronomers spotted this gargantuan structure serendipitously, while they were constructing a cosmic map using light from quasars, or ultrabright galactic cores that beam radio waves. I love this story because it highlights the vastness of the universe and shows that even some truly big discoveries are hiding in plain sight. It reminds me there are likely infinitely more strange and mysterious objects lurking in the universe just waiting to be found.

The butterflies used tiny claws on their feet (yes, butterflies have claws) to scratch wounds in caterpillars' bodies, and then lapped up the liquid that oozed out. What fascinated me about this was why the butterflies were doing it: because caterpillars are basically stuffed full of full of chewed-up milkweed residue, and butterflies are attracted to certain compounds in milkweed as protection against predators and for producing pheromones that attract females. Caterpillars are brimming with milkweed goodness, and that makes them an irresistible (if somewhat gruesome) snack.

Laura Geggel, Editor: I've covered a lot of dinosaur news — the discovery of new species and investigations into how dinosaurs grew and behaved — but never have I written about a fossilized butthole. Scientifically, it's known as a cloacal vent — a multipurpose "backdoor" opening used for pooping, peeing, breeding and egg laying. This is the first preserved dinosaur nether region on record, and the researchers apparently struck gold because it's not like any other known to science. "It's its own cloaca, shaped in its perfect, unique way," study lead researcher Jakob Vinther, a paleobiologist at the University of Bristol in the United Kingdom, told Live Science.

That's why my favorite story this year was about the star system GW Orionis (or GW Ori) – located 1,300 light-years from Earth at the tip of the Orion constellation's nose. The star system looks like a giant orange bullseye made of three wobbly, concentric rings of space dust. At the center of those rings are two stars tightly orbiting one another; a little further out, a third star orbits that binary pair. Triple-star solar systems aren't unheard of, but GW Ori is special because scientists are pretty certain that there is an enormous, Jupiter-sized planet lurking in one of the system's dusty rings – the only triple-sun (or "circumtriple") planet in the known universe.

Ben Turner, Staff Writer: Looking back into the history of the natural world, it’s always tempting to view the process of evolution through the lens of the apparent perfection it creates. Take the biomechanical clockwork of the human eye; or the sculpting of a hummingbird’s beak to drink the nectar from the thinnest flower; or the apparent artist’s mania that not only finesses a butterfly mimic’s wings to appear as a leaf, but even adds markings to resemble caterpillar-chomped holes.

The bees ended up developing all kinds of weird and sneaky strategies, from hatching plots to insert their clones into positions of power to completely taking over other hives with their entitled, layabout offspring. It plays out like an all-bee version of "Game of Thrones," and, given the insects’ complete lack of genetic diversity and consequent susceptibility to disease, the finale is likely to be just as disastrous.

Mindy Weisberger is a science journalist and author of "Rise of the Zombie Bugs: The Surprising Science of Parasitic Mind-Control" (Hopkins Press). She formerly edited for Scholastic and was a channel editor and senior writer for Live Science. She has reported on general science, covering climate change, paleontology, biology and space. Mindy studied film at Columbia University; prior to LS, she produced, wrote and directed media for the American Museum of Natural History in NYC. Her videos about dinosaurs, astrophysics, biodiversity and evolution appear in museums and science centers worldwide, earning awards such as the CINE Golden Eagle and the Communicator Award of Excellence. Her writing has also appeared in Scientific American, The Washington Post, How It Works Magazine and CNN.

Live Science's best of 2021: Writers' choice

Pupil 'flex'

Twisties and yips

Ancient beasts in a garden

Poop-eating plateau pikas

So big, it shouldn't exist

Caterpillar-drinking butterflies

Mysterious Mexican mangroves

The 'perfect' and 'unique,' dinosaur butthole

The ultra-rare planet in Orion's nose

Bee creates immortal 'clone army'