A question about pond algae just won the Nobel Prize

Three scientists won the 2026 Nobel Prize in physiology or medicine for figuring out how to switch brain cells on with light, a technique that began with a question about pond algae. Karl Deisseroth of Stanford University, Peter Hegemann of Humboldt University of Berlin and Georg Nagel of the University of Wurzburg were honored for their work on optogenetics. Hegemann and Nagel started by asking how a single-celled alga called Chlamydomonas senses light and swims toward it. The answer was a protein, channelrhodopsin, that opens a tiny passage in the cell when light hits it. Deisseroth and the others realized the same protein, delivered into nerve cells by a harmless virus, could let researchers flip specific neurons on with a thin optical fibre. The method is now in early trials to restore some vision in people with retinal degeneration. It started with algae nobody expected to matter.