Your big brain makes you human – count your neurons when you count your blessings
Here’s something new to consider being thankful for at Thanksgiving: the long evolutionary journey that gave you your big brain and your long life.
Courtesy of our primate ancestors that invented cooking over a million years ago , you are a member of the one species able to afford so many cortical neurons in its brain . With them come the extended childhood and the pushing century-long lifespan that together make human beings unique.
All these bequests of your bigger brain cortex mean you can gather four generations around a meal to exchange banter and gossip, turn information into knowledge and even practice the art of what-not-to-say-when.
You may even want to be thankful for another achievement of our neuron-crammed human cortices: all the technology that allows people spread over the globe to come together in person, on screens, or through words whispered directly into your ears long distance.
I know I am thankful. But then, I’m the one proposing that we humans revise the way we tell the story of how our species came to be.
Brains made of cells, but how many?
Back when I had just received my freshly minted Ph.D. in neuroscience and started working in science communication, I found out that 6 in 10 college-educated people believed they only used 10% of their brains . I’m glad to say that they’re wrong: We use all of it, just in different ways at different times.
The myth seemed to be supported by statements in serious textbooks and scientific articles that “the human brain is made of 100 billion neurons and 10 times as many supporting glial cells.” I wondered if those numbers were facts or guesses. Did anyone actually know that those were the numbers of cells in the human brain ?
No, they didn’t .
Neuroscientists did have a rough idea. Some estimates suggested 10 to 20 billion neurons for the human cerebral cortex, others some 60 to 80 billion in another region called the cerebellum. With the rest of the brain known to be fairly sparse in comparison, the number of neurons in the whole human brain was definitely closer to 100 billion than to just 10 billion (far too little) or 1 trillion (way too many).
But there we were, neuroscientists armed with fancy tools to modify genes and light up parts of the brain, still in the dark about what different brains were made of and how the human brain compared to others.
