Humans: 14 Billion Neurons Short of a Full Load?

Published: February 28, 2012

New research finds we probably don’t have as many neurons as once thought.

A Brazilian scientist has determined that the long-held assumption that the human brain has about 100 billion neurons is wrong, and that the average brain has probably something closer to 86 billion. Dr. Suzana Herculano-Houzel says she wanted to find out whether the 100-billion-neuron notion held any water, and as she discovered, she couldn’t find any previous research that arrived at that number. So, she took it upon herself to turn the brains of four recently deceased men into a soupy mixture that she could sift through to determine how many neurons – or brain cells – each of the men had. After the brains had been liquefied (every writer dreams of writing that clause), she took samples from the soup and counted the number of neuron nuclei in the sample. Those samples led her to conclude that the average brain has somewhere around 86 billion neurons, which is far higher than any other mammal but not quite as large as we had previously thought. Herculano-Houzel says that 14-billion-neuron difference might not seem too big, but that’s the equivalent of one baboon’s brain. Considering we’re about one baboon-brain dumber than previously thought, we might have the inklings of an explanation for the sudden popularity of Rick Santorum.