system
Given the following post, respond as if you're commenting on Reddit:
human
How quickly did life on Earth become planet-wide?

Basically, how much time did it take for life to spread out from ground zero and become widespread across the entire Earth? By now it'd be pretty hard to find a square kilometer of the surface without life.
gpt
We don’t really know. Different phases in the colonization of earth probably took different amounts of time i.e. land couldn’t be colonized until algae evolved into dry-ground plant life. Even today, there are  technically places on earth where life doesn’t exist.