How many neurons are in the average human brain?
For decades, textbooks repeated a round figure for the number of neurons in the brain without much hard evidence behind it. In 2009, a neuroscientist actually dissolved whole brains into a uniform 'soup' and counted neuron nuclei directly. Guess how many neurons she found.
Reveal the answer
About 86 billion, roughly 14 billion fewer than the long-repeated figure of 100 billion. The count came from Suzana Herculano-Houzel's 'brain soup' method, which gave the first direct, empirically counted total for the human brain rather than an extrapolated estimate.