“Just sitting quietly, doing nothing at all, your brain churns through more information in thirty seconds than the Hubble Space Telescope has processed in thirty years. A morsel of cortex one cubic millimeter in size—about the size of a grain of sand—could hold two thousand terabytes of information, enough to store all the movies ever made, trailers included, or about 1.2 billion copies of this book. Altogether, the human brain is estimated to hold something on the order of two hundred exabytes of information, roughly equal to “the entire digital content of today’s world,†according to Nature Neuroscience.* For all its powers, nothing about your brain is distinctively human. We use exactly the same components—neurons, axons, ganglia, and so on—as a dog or hamster. Whales and elephants have much larger brains than we have, though of course they also have much larger bodies. The main strand of a neuron is called an axon. At its terminal end, it splits into branch-like extensions called dendrites, as many as 400,000 of them. The tiny space between nerve cell endings is called a synapse. Each neuron connects with thousands of other neurons, giving trillions and trillions of connections—as many connections “in a single cubic centimeter of brain tissue as there are stars in the Milky Way,†to quote the neuroscientist David Eagleman. It is in all that complex synaptic entanglement that our intelligence lies, not in the number of neurons, The brain is wrinkled by deep fissures known as sulci and ridges called gyri, which give it more surface area. The exact pattern of grooves and ridges in brains is distinctive to each individual—as distinctive as your fingerprints—but whether it has anything to do with your intelligence or temperament or anything else that defines you is unknown. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill (2019-10-14T23:58:59). The Body . Knopf Doubleday Publishing Group. Kindle Edition. ”
