The Download: Neuralink's AI boost, and Trump's tariffs

Is this the end of animal testing? Animal studies are notoriously bad at identifying human treatments. Around 95% of the drugs developed through animal research fail in people, but until recently there was no other option. Now organs on chips, also known as microphysiological systems, may offer a truly viable alternative. They're triumphs of bioengineering, intricate constructions furrowed with tiny channels that are lined with living human tissues that expand and contract with the flow of fluid and air, mimicking key organ functions like breathing, blood flow, and peristalsis, the muscular contractions of the digestive system.