The Brain

★The frontal lobe is the last brain region to fully mature — not until around age 25. This is why teenagers take more risks: their impulse-control hardware is still under construction.

★Albert Einstein's parietal lobes were 15% wider than average — the region responsible for mathematical and spatial reasoning. His brain was removed and studied without his family's permission when he died.

★Damage to a specific area of the right temporal lobe can cause prosopagnosia — the inability to recognize faces, including your own in a mirror. Sufferers use voice, gait, and hairstyle to identify people instead.

★About 30% of the human cerebral cortex is devoted to vision — more than any other sense. You don't actually see with your eyes; your eyes just collect light. All seeing happens in the occipital lobe.

★In 1848, railway worker Phineas Gage survived an iron rod blasting through his prefrontal cortex. He physically recovered — but his personality changed completely. He became impulsive, profane, and unreliable. His case proved the PFC controls personality.

★London taxi drivers, who must memorize thousands of streets, have measurably larger hippocampi than average. When GPS removed the need to memorize routes, the effect disappeared in newer drivers.

★The amygdala can hijack the brain before the conscious mind is even aware of a threat — responding to danger in ~12 milliseconds, far faster than conscious thought (~300ms). This is why you jump before you realize you saw a snake.

★The hypothalamus is about the size of a pea but controls nearly all of the body's survival drives. It directly links the nervous system to the endocrine system — making it the master regulator of homeostasis.

★The thalamus acts as the brain's switchboard — processing roughly 40 million nerve signals per second. During sleep, it partially disconnects from the cortex, which is why external sounds don't wake you unless they are personally significant.

★When neurosurgeon Roger Sperry severed the corpus callosum in epilepsy patients, each hemisphere effectively became a separate mind with different knowledge and perceptions. Sperry won the Nobel Prize for this split-brain research in 1981.

★The basal ganglia is why you can drive a familiar route on autopilot while your mind wanders. Once a behavior is sufficiently practiced, the basal ganglia takes over — freeing the cortex to think about something else entirely.

★The cerebellum contains only 10% of the brain's volume but over 50% of its total neurons. People born without a cerebellum can lead near-normal lives — the brain rewires itself — but movement and coordination are significantly impaired.

★The brainstem is the most evolutionarily ancient part of the brain — sometimes called the 'reptilian brain.' It keeps you alive without any conscious effort. Damage to it is almost always fatal or results in a persistent vegetative state.

★The medulla is about 3 cm long and keeps you alive every second of your life. It's the target of many lethal poisons and drugs — opioid overdose kills by suppressing the medulla's drive to breathe.