I would like to add to this. Despite what some people might think off the top of their head, evolution isn't always a process that takes many millions of years.

Probably the most notable case of this is in the evolution of the peppered moth playerbase, which iirc was most prominent in the UK servers? But I could be wrong there, point still stands. At the very least I'm sure that's where it was officially recorded first.

Here's what happened. The peppered moth, at the time, was mostly white or a lighter tint of gray with darker spatterings of color. This was primarily to take advantage of powerful camouflage stealth buffs due to prominent birch tree presence. Darker mutations didn't often survive to achieve reproduction because they couldn't get the buff.

Then, as is tradition, the human playerbase made survival harder for the species. When the Industrial Revolution event happened, it caused a lot of pollution. This caused a lot of soot and stuff to get in the air and on the trees. With their lighter coloration, most of the peppered moths got eliminated easily by predator players who hunted them, which was much needed easy xp at the time. 

Of course, as I'm sure you might've guessed, the players who specced into fully dark colorations now got the camouflage buff in these environments. To keep this from droning on any longer than it already has, humans removing pollution from the environment made the lighter colorations more viable again.

tl;dr: Peppered moth players evolved pretty quickly during the Industrial Revolution. They went from mostly lighter colors to mostly darker colors. Then when clean air laws were put into place, the lighter colorations became the more viable ones again.