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Some people say the human brain is the most amazing structure on Earth. Our brain is so complex that it took about 700 million years to develop! The human being started out as a wormlike creature that used one end of its body to move forward. Over millions of years, a bunch of nerves began developing at that one end — the head. This helped the creature sense food, light, and danger as soon as possible. That bunch of nerves became a brain. Next, the creature grew a spinal cord that carried messages between the brain and the rest of the body. Eventually, the creature became a fish with a very simple nose, eyes, and ears. Now the brain could receive messages containing sights, sounds, and smells. Over time, the fish grew arms and legs so it could move around on land. For this, it developed a bigger and more complex brain. Millions of years passed, and the creature became a monkey. The parts of the brain for seeing and being social became very strong. Finally, it became human, with a brain highly capable of reason, emotion, creativity, memory, and the ability to judge right from wrong.
Believe it or not, people used to think of the brain as useless stuffing. Now we know that the brain is our control centre. The surface of the brain, known as the cerebral cortex, is the part of the brain that makes us so smart. The cerebral cortex has four parts, called lobes. The front lobe is where much of our thinking and feeling happens. The top lobe processes information coming from our skin, muscles, and joints. The side lobe plays an important role in hearing, speech, and long-term memories. The back lobe processes images from our eyes.
Which do you think is more powerful: your brain or a supercomputer? You might be surprised to learn that the world’s best supercomputer is only about as powerful as half a mouse brain! Your brain is packed with 100 billion brain cells called neurons. Neurons send information to your body telling it what to do, and they receive information from your body about what you are seeing, smelling, tasting, hearing, and feeling. Your spinal cord, which is found down the centre of your back, is the highway the information uses to travel to and from your other body parts. As the information travels from neuron to neuron, pathways are created. When you think about or practice something over and over, those pathways get stronger. That’s how the brain learns and remembers. You were born with most of the neurons you have now, but when you were a baby, you didn’t have many pathways to connect them. As an adult, you now have more than 125 trillion connections between your neurons. No computer on Earth can compete with the speed of your brain and how much information it can hold.
Yet the human brain is still very mysterious. Why do our brains need sleep? Why do we dream? What does it mean to be smart? Do we really have a self, or is the self an illusion? There is a lot about the brain that we do not know. Even so, the facts scientists have discovered so far can be very helpful in our daily lives. This book is like a user guide for your brain based on what we do know. It will help you take charge of your ability to learn and grow in the ways that matter most to you.
Scans of a brain