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October 15, 2025—One dishonest act primes you for another. Plus, the most efficient animal is a human on a bike, and our first potential glimpse of an exomoon. —Andrea Gawrylewski, Chief Newsletter Editor | | An artist's concept of the giant exoplanet WASP-39b and its host star. NASA, ESA, CSA, Joseph Olmsted (STScI) | | Supporting our work means amplifying science. Consider a subscription to Scientific American and back independent science journalism! Today in Science readers can get started for just $1. | | Even one small act of dishonesty can desensitize the brain and make it easier to keep doing wrong things. This is called a moral death spiral (not to be dramatic) and explains how people can escalate their wrongdoing gradually over time. In one study, participants inside fMRI scanners played a game in which they could enrich themselves by deceiving others. The more people lied to other players, the more exaggerated their lies were likely to be the next time around. These habitual liars also showed reduced activation in the brain's amygdala, which is involved in emotional arousal—and the lower their amygdala activation, the more flagrant their lies were in the next round of the game. Why this is interesting: Surprisingly, just as neural habituation can drive ethical collapse, it can also drive escalating spirals of virtue, in which one honest or brave action makes the next one easier to carry out. Gradual moral adaptation goes both ways, toward good and bad. What the experts say: "All the neural networks that we have are changeable," says clinical psychiatrist Christian Heim, who is affiliated with the University of Queensland. "If we use [them], they become stronger. If we don't use them, they become weaker." Once people understand how the brain gets accustomed to repeated behaviors, they can exercise more choice at the outset, asking themselves what kinds of actions they want to get comfortable with. | | | | |
For humans to move their bodies, it costs a lot of energy. We must first fight gravity, then propel ourselves forward. But on a bike, we move more like fish, which glide through water and have natural buoyancy that keeps them afloat. Bicycle wheels let us coast down streets, and the frame lets us sit as we move. Tyson Hedrick, a comparative physiologist at the University of North Carolina at Chapel Hill, calculates that velomobiles, which are slender vehicles with an aerodynamic shell, let us move with aquatic-esque efficiency. We've updated a classic graphic comparing different forms of animal locomotion (first published in the magazine in 1973) to include these new bicycle-cars. — Andrea Tamayo, Newsletter Writer | | DTAN Studio; Sources: "Energetic Cost of Locomotion in Animals," by Vance A. Tucker, in Comparative Biochemistry and Physiology, Vol. 34; June 15, 1970 (most data); chart by Dan Todd in "Bicycle Technology," by S. S. Wilson, in Scientific American, Vol. 228, No. 3; March 1973 (data for human on a bicycle); Tyson Hedrick/University of North Carolina at Chapel Hill (velomobile calculation) | | - Avoiding ultraprocessed foods entirely is impossible. | The Atlantic
- Media coverage of what humans die from doesn't reflect the actual numbers of deaths. | Our World in Data
- The ocean is a carbon toilet. Marine heat waves are clogging it. | Grist
- One of the longest ancient dinosaur trackways has been discovered in England (cool aerial videos at the link). | BBC News
| | The ancient Greek philosopher Aristotle wrote in his book Nicomachean Ethics in 350 B.C.E. that virtue is formed by habit: "We become just by doing just acts, temperate by doing temperate acts, brave by doing brave acts." Modern neuroscience backs up this early, wise take. Our brains are quick studies: they get better at whatever we practice. Each small act of honesty or compassion strengthens the next. In that sense, ethics isn't fixed—it's a habit we build, one choice at a time. | | Be good (if you choose to) and send any feedback about this newsletter to: newsletters@sciam.com. See you tomorrow! —Andrea Gawrylewski, Chief Newsletter Editor
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