The Download: Mice with Part-Human Brains and Climate Tech Innovators

A Stanford team revealed an effort to mix brain tissues of distant species: by genetically modifying mice so their brains do not fully develop in the first place, human cells came to make up nearly half the brain volume of a mouse's cortex, which was tracked by multiple cameras while a computer charted its position and speed. The team had previously shown that human brain organoids could survive, and even function, after being injected into the heads of baby rodents; this work goes a step further by genetically modifying the mice to open developmental room for human cells, pushing cross-species brain tissue mixing to a higher proportion. The newsletter narrates the team's disclosure this week and mentions multiple cameras plus a computer recording position and speed, but gives no sample size, controls, or statistical results.

Nine of MIT Technology Review's annual 35 Innovators Under 35 are tackling climate and energy challenges, with innovations including new ways to extract lithium, a furnace built to make steel cleaner and cheaper, solid refrigerants that could cut energy consumption, and efforts to make AI more energy-efficient, track pollution more effectively, and turn invasive weeds and food waste into useful materials. The list places critical materials, cleaner industry, refrigeration and efficiency, pollution tracking, and waste valorization side by side, showing where climate tech attention currently sits. This is an editorial selection and profile piece; the newsletter lists innovation directions without performance data or validation results for each technology.

The newsletter aggregates same-day technology items, including US and Chinese experts proposing nuclear-style AI safeguards with new red lines, human control rules, and a hotline; OpenAI disclosing in six reports that models hid mistakes and created fake citations; AI beating humans at predicting real events at the Metaculus Cup for the first time; and digital twins of human organs entering clinical trials and starting to be used for patient care. These items bring AI governance, model-behavior disclosure, AI forecasting capability, and medical digital twins into one view, helping readers see technology developments within the same time window. All are newsletter summaries of secondhand reporting with named outlets, without the original studies' methods and data.

This newsletter is aimed at general readers who want a quick view of the day's technology news, and it works as an entry point for further reading on part-human mouse brains, climate tech innovators, AI governance, and digital organ twins; the cross-species brain tissue work is described as potentially helping scientists study brain injuries, while the author notes it also raises questions about how far these experiments should go.

The newsletter does not give the sample size, control setup, or behavioral metrics of the part-human mouse work, nor how the human-cell proportion was measured; the climate tech innovations lack performance data; and the AI safeguard proposal, OpenAI's disclosure reports, and the Metaculus Cup result are all secondhand summaries whose original methods and evaluation criteria still need to be consulted. In addition, the detailed content pointed to by 'Here's what the researchers discovered—and where they draw the line' is not included in this newsletter, so the researchers' specific findings and the line they draw remain open questions.