It would be sick if they somehow reference the war between the pilots and predators in the movie.
I think the general consensus online is that the pilots bio-engineered the aliens as some sort of ultimate weapon to use against the predators (and any other species that got in their way) and subsequently used them during a civil war on their planet which all went horribly wrong.
At least thats what I can gather from poking around on the internet, although if anyone has better information I would be interested to hear it.
The definitive evidence that video games turn people into mass murderers