The nastiest feud in science: Princeton geologist Gerta Keller has endured decades of ridicule for arguing that the fifth extinction was caused not by an asteroid but by a series of colossal volcanic eruptions — but she’s reopened that debate. The world’s worst mass extinction should make you very nervous for our future. The insect apocalypse is here — what does it mean for the rest of life on Earth? Insects, biodiversity, and mass extinction: An alarming new study, explained. Biological annihilation: Subhankar Banerjee on a planet in loss mode. Climate change and the escalation of extinction: As the climate crisis intensifies, try this simple exercise — count how many animals you can’t see.

Escalator to extinction: How mountain species are imperiled by warming. Humans are exterminating animal species faster than evolution can keep up. Humans didn’t cause animal extinctions in Africa, study says. Meet the scientists bringing extinct species back from the dead: New gene-editing technology could revive everything from the passenger pigeon to the woolly mammoth — but should scientists be playing God?

Lewis A. Grossman (American): Life, Liberty, (and the Pursuit of Happiness): Medical Marijuana Regulation in Historical Context. It’s official: Wall Street is bad for your financial health. Here’s why closing the government actually costs taxpayers money. What if actually is a horrible website? Mexico’s new president promised a revolution — has it begun? What the president could do if he declares a state of emergency: From seizing control of the Internet to declaring martial law, President Trump may legally do all kinds of extraordinary things. Resist the lure of theological politics: Instead of applying religious certainty to public debates, Americans need to take a different lesson from their faith traditions.

Byron E. Shafer and Regina L. Wagner (Wisconsin): The Trump Presidency and the Structure of Modern American Politics. Noam Chomsky, Richard Dawkins, Martin Rees and others answer the question: What’s your utopia? Scott F. Aikin and Robert B. Talisse our polarization problem. Why does such a thinker as Ayn Rand persist in being taken seriously by otherwise smart people? What the fall of the Roman Republic can teach us about America. Can the language of the Vikings fight off the invasion of English? Why air service is so crucial for small cities: As airlines cut small-plane services and consolidate bigger cities, some communities are suffering.