Krista Conger writes about a Stanford Medicine study showing the human brain consists of two distinct organs that evolved independently over hundreds of millions of years. The forebrain and midbrain arise from one progenitor cell, while the hindbrain (brain stem) arises from a completely separate one, overturning the long-held assumption that a single progenitor cell gives rise to the entire brain. The finding explains why scientists have struggled for decades to grow hindbrain neurons in the lab and opens new avenues for studying diseases like spinal muscular atrophy and ALS.
- Published in *Nature Neuroscience*; Kyle Loh is senior author, with graduate students Carolyn Dundes and Rayyan Jokhai as co-first authors
- The same two-origin pattern was identified in chickens, zebrafish, and acorn worms — tiny ocean-floor creatures that share a distant common ancestor with humans
- The hindbrain contains the hunger-regulating circuits targeted by weight-loss drugs like semaglutide
- Published in *Nature Neuroscience*; Kyle Loh is senior author, with graduate students Carolyn Dundes and Rayyan Jokhai as co-first authors
- The same two-origin pattern was identified in chickens, zebrafish, and acorn worms — tiny ocean-floor creatures that share a distant common ancestor with humans
- The hindbrain contains the hunger-regulating circuits targeted by weight-loss drugs like semaglutide
