The brain — the central “control unit” of our bodies, repository of memories and emotions. Throughout history, philosophers have believed that the brain may even house that intangible essence that makes us human: the soul. What should we know about our brains?
In a poem written around 1892, American poet Emily Dickinson described the wonder of the human brain.
Her verses express a sense of awe, considering the brain’s marvellous capacities of thought and creativity.
Musing on how this fascinating organ is able to encompass so much information about the self and the world, she wrote:
“The Brain — is wider than the Sky —
For — put them side by side —
The one the other will contain
With ease — and You — beside”
The main organ of the human nervous system, the brain manages most of our bodies’ activities and processes information received from both outside and inside the body and is the very seat of our emotions and cognitive abilities, including thought, long- and short-term memory, and decision-making.
The first mention of this organ was recorded in an Ancient Egyptian medical treatise known as the “Edwin Smith surgical papyrus,” after the man who discovered this document in the 1800s.
Since then, our understanding of the brain has expanded immeasurably, although still we contend with many mysteries surrounding this key organ.
In this Spotlight, we look at some of the most important facts we have uncovered about the brain — and some aspects that remain to be understood.
1. How big are our brains?
Brain size varies widely, depending largely on age, sex, and overall body mass. However, studies have suggested that the adult male brain weighs, on average, about 1,336 grams, whereas the adult female brain weighs around 1,198 grams.
In terms of dimensions, the human brain isn’t the largest. Of all mammals, the sperm whale — an underwater denizen weighing an impressive 35–45 tons — is known to have the biggest brain.
But, of all the animals on Earth, human brains have the largest number of neurons, which are specialized cells that store and transmit information by electrical and chemical signals.
Traditionally, it has been said that the human brain contains approximately 100 billion neurons, but recent investigations have questioned the veracity of that number.
Instead, Brazilian neuroscientist Suzana Herculano-Houzel has discovered — by using a method that required liquefying donated human brains and turning them into a clear solution — that the number is closer to 86 billion neurons.
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