In research facilities across the country, scientists have created mice whose brain cortexes are composed of nearly half human-derived cells — not as metaphor, but as functional biology. This achievement, known as xenocortication, opens new windows into the human neurological conditions that have long resisted study, by giving researchers a living system that mirrors the cellular architecture of the human brain. Yet as science extends its reach into this hybrid territory, it arrives ahead of the ethical and regulatory frameworks meant to guide it, leaving humanity to reckon with questions abou