A researcher in Brazil has found that the number of neurons a human brain contains is not 100 billion as previously thought.
Humans actually have 86 billion - according to neuroscientist Suzana Herculano-Houzel, the Daily Mail reported Friday.
She found out the true figure in a rather grisly manner - by turning four brains into "brain soup" and counting the number of cell nuclei belonging to neurons.
The brains belonged to four adult males aged 50, 51, 54 and 71 who donated them to science - and none had died of a neurological disease.
Herculano-Houzel told Nature: "We found that on average the human brain has 86 billion neurons. And not one that we looked at so far has the 100 billion."