December 13, 2024: Scientists narrow down exactly when humans and Neandertals interbred. Plus, e-scooter injuries are on the rise, and this is how many drones fly U.S. skies. —Andrea Gawrylewski, Chief Newsletter Editor | | | Joel Papalini/Getty Images | | | • We fact-checked a list of sleep tips that emerged on social media in 2024. Here is science-backed advice for snoozing better. | 4 min read | | | • Atmospheric rivers, which cause intense rain or snowfall, can be hard to predict. New storm-hunting aircraft are improving forecasts. |4 min read | | | For a study published this week, scientists sequenced the genomes of six individuals who lived between 49,000 and 42,000 years ago in Germany and the Czech Republic (some of the oldest modern human genomes ever sequenced) to try to pinpoint when humans and Neandertals interbred. Another study examined ancient genomes from dozens of humans who lived between 45,000 and 2,200 years ago. Both studies concluded that Neandertal and human genes intermixed during a single surge of interbreeding that occurred between 45,000 and 49,000 years ago.
Why this is interesting: Present-day humans outside of Africa owe 2 to 3 percent of their genome to Neandertal ancestors. The two species coexisted for tens of thousands of years, but exactly when they interbred had remained cloudy for paleoanthropologists.
What the experts say: Within about 100 generations of the interbreeding, the human genome evolved to closely resemble its modern form. Neandertal genes may have either boosted survival and reproduction to become permanently incorporated, or they caused harm and disappeared, says Joshua Akey, a Princeton University genomicist. | | | Emergency department visits involving e-bikes and e-scooters tripled in the U.S. between 2019 and 2022, according to a new study. Men were more likely than women to be injured, and of those injured, children and teenagers were most likely to be under the influence of drugs or alcohol. E-scooter injuries showed the most dramatic rise, from 521 in 2019 to 1,362 in 2022.
How this happened: Despite the growing popularity of so-called electric micromobility machines, infrastructure and safety regulations have not kept up. Early and mid-teenagers who drink and ride may be particularly vulnerable to crashes and head injury.
What the experts say: Not enough riders wear helmets, experts say. "Public safety campaigns and local regulations encouraging helmet use could greatly mitigate these risks," says Akshaya Bhagavathula, an associate professor of epidemiology at North Dakota State University. | | | Amanda Montañez; Source: "Alcohol-Related Injuries from E-scooter and E-bike Use in the US (2019–2022): A Retrospective Study," by Edwin Akomaning et al., in Injury Prevention. Published online December 9, 2024 (data) | | | If you're enjoying all the science we cover in this newsletter, dive deeper with a subscription to Scientific American. You'll have access to all our articles and will be supporting crucial science journalism. | | | • Last year, the American Library Association documented more than 1,200 cases of efforts to ban library books. Petitioners targeted more than 4,200 books for removal from schools and libraries, including works by authors Toni Morrison, Margaret Atwood and Judy Blume, as well as books on topics like climate change, health and evolution. Such bans rob young people of "opportunities to think critically, explore ideas and learn about experiences different from their own," write the editors of Scientific American, in this month's issue. "Book bans are antithetical to free speech and free thought. They are antidemocratic, antiscience and antievidence. ... We must stop the censoring of books." | 4 min read | | | Show off your science smarts with this week's science quiz. Also, take a break to play today's Spellements puzzle. Remember to send any science words that are missing from the puzzle to games@sciam.com. Yesterday, sharp-eyed players Peter, Paul, Louisa, Susan and John all found biome, which is a large geographical region with a particular climate and plant and animal life. A crucial science word! | | | MOST POPULAR STORIES OF THE WEEK | | | • What Are the Mystery Drones Reported over New York State and New Jersey? | 3 min read | • Google's Quantum Computer Makes a Major Breakthrough in Error Correction | 5 min read | • Luigi Mangione Said He Had Spondylolisthesis: What Is It? | 2 min read | | | • The experience of "being on the same wavelength" as another person is real, and it is visible in the activity of the brain. When people think, feel and act in response to others, patterns in their brain activity align, called interbrain synchrony. The extent of the sync indicates the strength of the relationship--brain waves between close friends match up the closest. | 16 min read | | | I'm gathering some end-of-year feedback from you, dear readers. If you could describe this newsletter in ONE WORD, what would it be? Send me your responses and I'll list what the rest of the community says next week. | Thank you for reading Today in Science this week. I welcome your feedback, suggestions, and thoughts: newsletters@sciam.com. Have a great weekend! | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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