The Download: mice with part-human brains and climate tech innovators

Plus: US and Chinese experts have proposed nuclear-style AI safeguards. Multiple cameras tracked a mouse as it wandered around a small arena. The reason to watch this rodent so carefully? Nearly half its brain volume had been replaced with human cells. A team at Stanford has revealed the effort to mix brain tissues of distant species this week. They previously showed that human brain organoids could survive, and even function, after being injected into the heads of baby rodents.