Microplastics on the Mind, Superstrong Shrimp and Bird Flu Transmission
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Let's kick off the week by catching up on some of the science news you may have missed.

First, a quick bird flu update. If you're a regular listener, you already know that H5N1 bird flu has been circulating in U.S. cattle for almost a year. That's been thanks to a type called B3.13. Now, a different variant of H5N1 that had been circulating in birds, known as the D1.1 genotype, has shown up in six herds in Nevada. This suggests that our current outbreak involved more than one spillover event, or an instance when a bird transmitted H5N1 to a cow.

We don't know when the D1.1 variant hopped over to cattle or how widely it's circulating. People have previously been infected with D1.1, including two severe cases, and NPR reports that scientists have speculated that this genotype might be more dangerous to humans. D1.1 was also responsible for the first U.S. death from H5N1 flu, when someone in Louisiana caught it from backyard flocks.

Let's move on to some other health news. Last Monday, a study in Nature Medicine reported surprisingly high amounts of microplastic in human brain tissue. Researchers looked at tissue samples from the brains, kidneys, and livers of 52 cadavers and found that the brains contained 7 to 30 times higher concentrations of microplastics than those other organs. They also noted that the average concentration of microplastics in the brain rose by 50% from 2016 to 2024.

The scientists found that the average amount of microplastics in the brains of individuals who died last year was roughly equivalent to the weight of a plastic spoon, according to the Washington Post. We don't yet know exactly how microplastics impact our brains, but I'm going to really go out on a limb and say the effects probably aren't great.

And speaking of brains, a new observational study suggests that people generally feel their best, at least mentally, in the morning. Based on data from a multi-year study that followed nearly 50,000 people, researchers publishing in BMJ Mental Health last Tuesday noted that in the morning, individuals tended to report higher levels of happiness, satisfaction with life, and feelings that life was worthwhile, as well as lower amounts of negative feelings like anxiety and loneliness.

People typically felt their worst around midnight. Unsurprisingly, winter was also relatively rough compared to other seasons, especially summer. So don't be too hard on yourself if you're not feeling chipper and ready to conquer the world on this cold Monday morning. The researchers also emphasized that they need more data to really understand how seasons and time of day affect our moods.

Regardless of the hour, if you find yourself struggling with something, you might be able to get a hand from a surprising ally: a bonobo. A study published last Monday in the Proceedings of the National Academy of Sciences explores whether our close primate relatives have what's known as "theory of mind," or the ability to imagine the mental states of others.

To test that, researchers set up an experiment where a human tester sat with a bonobo while another person hid a grape under one of three cups. The tester would then spend about 10 seconds making a show of being unsure which cup the grape was under. When the bonobo had seen the tester watch their colleague place the grape, the animal was slower to point out the tree's location and did so less often. But when the tester was blocked from watching the grape be placed,

the bonobo were more likely to point out where the fruit was and do so more quickly. In other words, the animal could seemingly comprehend that their human companion didn't have the information needed to complete the task and sought to help them out.

In other wild animal news, a study published last Friday in Science looked into the superpowers of the mantis shrimp. These aquatic creatures are known for packing pretty powerful punches. Some can swing their appendages so fast that the impact rivals that of a .22 caliber bullet shattering mollusk shells or even aquarium glass.

This new study aimed to figure out how these shrimps stay in one piece in the wake of the awesome shock waves they create. Apparently, the mantis shrimp's mighty hammer, or dactyl club, has layers of intricate patterns that help protect the small crustaceans. The part of the club that hits its target is covered in mineralized fibers that form something like a herringbone pattern that gives the club structural integrity when hammer time comes around.

But beneath that are twisted fiber bundles that rotate from one layer to the next. Researchers say this design filters out certain frequencies, dampening the stress of the impact and protecting the shrimp from facing the consequences of its actions. In addition to just being really cool, the researchers say, this natural design could help inform the creation of better soundproofing materials and perhaps even protective gear for athletes and soldiers.

On the topic of big blasts, new research suggests that each dramatic event could be to blame for two massive canyons on the moon. Vallis-Schrodinger and Vallis-Planck are roughly 1.7 and 2.2 miles deep, respectively, putting our own planet's Grand Canyon to shame with its mere 1.2 mile depth.

But while plate tectonics and erosion shaped our beloved Southwest landmark over millions of years, analysis of images and data from NASA's Lunar Reconnaissance Orbiter suggests things happened much more quickly for Schrodinger and Planck. Instead of gradually shifting Earth and a river of water, fast-moving streams of rock that resulted from a dramatic cosmic impact carved these lunar pits around 3.8 billion years ago.

The scientists behind the study, published last Tuesday in Nature Communications, estimate that the debris ejected in the impact reached speeds of up to about 2,800 miles per hour, hitting the lunar surface with a huge amount of energy and chiseling out the massive canyons in as little as 10 minutes. I guess we're just no match for lunar efficiency.

That's all for today's News Roundup. If you're wondering why we didn't talk about that asteroid that has a very small chance of colliding with Earth in like a decade, don't worry. We're going to give you the full 411 on Wednesday.

Science Quickly is produced by me, Rachel Faltman, along with Fondam Wanki, Kelso Harper, Madison Goldberg, Naeem Amarsi, and Jeff Daldusio. Shaina Posis and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news. For Scientific American, this is Rachel Faltman. Have a great week!