A few years ago, a Brazilian neuroscientist, Suzana Herculano-Houzel, tried to figure out who originally estimated that the human brain contained 100 billion neurons. Turned out, nobody knew. The figure—a round, easy-to-remember number, astounding without seeming implausible—simply ossified into fact over time. She figured out a way to verify it. She ground down the exhumed brains of animals using a “brain blender,” a Tarantino-esque device that sounds just as macabre as it is. Herculano-Houzel devised a method to count the neurons in her homogenized brain soup.
