It's worth noting that the reason races in Star Trek look alike is because an ancient "humanoid" race seeded all of those worlds with their own genetic code. Season 6: The Chase.
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Pretty glad I upgraded a couple weeks ago. ;)
They might have sold a ton of tech to a bunch of minor races in desperation. ~SDC~
I'd be willing to bet your planets are overpopulated. The closer they get to the max pop, the unhappier the people get. Load them up onto a colony ship and drop them off onto another planet. If you don't want to move them right now, focus on PQ improvements. That'll increase the max pop of the planet and reduce the overpopulation problem in the short term. ~SDC~