Counting brain cells helps scientists explain how humans differ from other animals, but until recently, enumerating billions of cells by species was too onerous a task to tackle. That changed with the work of a Brazilian researcher who pioneered a technique that is both fast and accurate.

“We’re looking at the most basic properties of brain tissue,” said Suzana Herculano-Houzel, who developed the approach. “What is it made of, what are the rules of putting a brain together and how does the human brain compare to other brains?”

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