The brains of birds may be small, says Herculano- Houzel, but they “pack surprisingly high numbers of neurons, really high, with densities at least akin to what we find in primates. And in corvids and parrots, the numbers are even higher.” Much depends on where the neurons are. Herculano-Houzel has shown that elephant brains have three times the number of neurons found in the human brain (257 billion to our average 86 billion). But 98 percent of them are in the elephant cerebellum, she says, where they may be involved in control of the trunk, a two-hundred-pound appendage with fine sensory and
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