New work suggests that life could have arisen and survived a mere 15 million years after the Big Bang, when the microwave background radiation levels would have provided sufficient energy to keep almost all planets warm. Summary here, and actual article here. This is still very preliminary, but the possibility at some level is extremely frightening. It adds billions of years of time for intelligent life to have arisen that we don't see, and if anything suggests that the Great Filter is even more extreme than we thought.