Which Came First - The Rain or the Rainforest?

Here's a question I'd never thought to ponder before: which came first, the rainforest or the rain? One would suppose there was rain before the rainforest appeared, but was it as much as a rainforest normally gets? MinuteEarth explains the cycle of water moving through a tropical forest, and what happened to kick start this cycle long ago. However, they also describe the damage mankind is doing to the rainforest and the weather cycle it supports. (via Viral Viral Videos)