Welcome back to The Sunday Morning Post, this newsletter’s weekly rundown of the most interesting and important stuff I’m seeing in science, technology, economics, and beyond. Comments are open. Leave tips, papers, studies, tweets, posts, questions, and graphs in the comments, if you think they’ll serve for future editions.
We’re Never Going to Invent a Drug That’s Better Than Exercise
Euan Ashley has claimed that exercise is the “single most potent medical invention” ever—more broadly effective than any medicine discovered in the natural world or devised in a laboratory. In 2025, this is the sort of rah-rah sentiment about working out that one might associate with a Make America Healthy Again ambassador rather than, say, the chair of medicine at Stanford University. So, what makes Ashley’s claim significant is that he is the chair of medicine at Stanford University.
Last year, Ashley and a large team of scientists conducted an elaborate experiment on the effects of exercise on the mammalian body. In one test, Ashley put rats on tiny treadmills, worked them out for weeks, and cut into them to investigate how their organs and vessels responded to the workout compared to a control group of more sedentary rodents. The results were spectacular. Exercise transformed just about every tissue and molecular system that Ashley and his co-authors studied—not just the muscles and heart, but also the liver, adrenal glands, fat, and immune system.
When I asked Ashley if it was possible to design a drug that mimicked the observed effects of exercise, he was emphatic that, no, this was not possible. The benefits of exercise seem too broad for any one therapy to mimic. To a best approximation, aerobic fitness and weight-training seem to increase our metabolism, improve mitochondrial function, fortify our immune system, reduce inflammation, improve tissue-specific adaptations, and protect against disease.
The latest entry in the Exercise Is Magic file comes from the New England Journal of Medicine. In a recent study, 900 cancer patients who had undergone surgery on their advanced colon cancer were randomly assigned to two groups. One group got a “structured exercise program.” They went to behavioral support sessions and attended supervised exercise classes every few weeks for several years. The other group received only basic information about diet and health.
Compared to the control group, the exercise group saw “significantly” more years without cancer, a 7 percentage point increase in the overall survival rate after 8 years, and a dramatic reduction in new primary cancers. Exercise, it seems, doesn’t just prevent disease; it can also save your life after you get sick.
The author Daniel Lieberman has put it well: Exercise is healthy and rewarding even though it’s something we never evolved to do. To adapt to the physical ease of the modern world, people invented a variety of weight-resistant devices and bodily movements that allow today’s population to simulate the arduous tasks that were once necessary to make it through a life, and this strange pantomime of physical stress seems to do more for us at a molecular level than any therapy or intervention in the history of medicine.
How to Save 100 Million Lives
Soon after overseeing cuts to more than 80 percent of programs at the United States Agency for International Development, Secretary of State Marco Rubio said in remarks in July that USAID “has little to show since the end of the Cold War.” In the field of global health, this analysis may be off by about 100 million.
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