system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What causes someone to be ticklish? Why are some people ticklish and not others?
gpt
I believe certain parts of our bodies are ticklish so that we learn to protect those most sensitive parts quickly and automatically. It would be an evolutionary advantage to have an instinctive reaction to protect your throat or stomach. That trait has become less relevant to humans as our society has evolved, so now it's just one of those things that some people have and others don't.