system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why don't woodpeckers all suffer serious traumatic brain injury by later in life?
gpt
Three reasons,

1) Woodpeckers' brains are tightly encapsulated in their skulls, so the brains do not bash against the skulls with sudden accelerations as do human brains.

2) Humans have many ridges at the surface of their brains, and woodpeckers do not - their brains are more smooth.  This distributes the force of impact across a large surface area, meaning parts of the brain gets squished less.

3) Woodpeckers don't have any rotation in their heads when pecking, meaning the brains don't experience rotational stresses.  Rotational stress is a major factor in human brain injuries in cases like car accidents, etc.