Human brain has 14 billion less neurons than previously thought

Human brain actually has 86 billion neurons, not 100 billion, as previously thought, according to a Brazilian neuroscientist.

With the help of colleagues, Dr. Suzana Herculano-Houzel 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.

Dr. Suzana Herculano-Houzel told Nature: “We found that on average the human brain has 86billion neurons. And not one that we looked at so far has the 100 billion.

“Even though it may sound like a small difference the 14 billion neurons amount to pretty much the number of neurons that a baboon brain has or almost half the number of neurons in the gorilla brain. So that’s a pretty large difference actually.”

The figure came as a surprise because most textbooks and articles about neurons, which are nerve cells that carry messages around, agree that there are 100 billion of them in a human brain.

Dr. Suzana Herculano-Houzel, however, was unable to find out where this figure had come from.

Her study represents a leap forward for neuroscience, but it only came about after she had come to terms with making “brain soup”.

Dr. Suzana Herculano-Houzel told Nature: “It took me a couple of months to make peace with this idea that I was going to take somebody’s brain or an animal’s brain and turn it into soup. But the thing is we have been learning so much by this method we’ve been getting numbers that people had not been able to get.

“It’s really just one more method that’s not any worse than just chopping your brain into little pieces.”

Although her results mean our brain power has been downgraded, we still have superior minds to other primates because we have more neurons in the brain that are devoted to cognition – mental processes – and behavior as a whole.