Nearby Galaxy Surprisingly Young

Pi_0's don't shower writes "The hubblesite is reporting that a galaxy discovered 70 years ago, I Zwicky 18, has been confirmed to be one of the youngest galaxies in the universe, at only 500 million years old. By contrast, our Milky Way, Andromeda, and most other nearby galaxies are 12 billion years old. This galaxy is the closest newly-formed galaxy, at only 45 million light years away, which has rather interesting implications for galaxy formation."

Galactic ignition

[Mark of THE CITY]

My understanding is that old galaxies had enough fuel in a small enough space to condense into masses that became stars by gravitational compression. Are young galaxies simply areas where this process took much longer, or is there more to it?

Experts only, not Trekkie wannabees! :)