- Half a million neurons form every minute during the first five months in the womb.
- The brain of a medium-sized dog weighs around 3 ounces (80 g), the same as a small kiwifruit.
- A one-year-old child's brain weighs about 2 pounds (950 g), ten times the size of the average dog's brain.
- The primate cortex is so large that it has to be folded to fit inside the skull. That's why the surface of the brain is wrinkly.
- Plants have no nerves and no brain.
- Some animals, like earthworms, snails, and spiders, have nerves but not actual brains.
- The nervous system runs on electricity, but the levels are low. Brain signals involve less than one-tenth the voltage of an ordinary flashlight battery.
- Some messages shoot through the nervous system faster than others. When you pet a fluffy dog, one signal races from your fingertip to your brain in 10 to 20 milliseconds, letting you know she is soft. Another signal reaches your brain a few milliseconds later, telling you she is warm.
- The longest neuron in the animal kingdom goes all the way down the giraffe's neck.