"Did Life First Appear on Alien Worlds 12-13 Billion Years Ago?"
This means that planets that could potentially have supported life may have formed eight, ten, maybe even twelve billion years ago. Surveys do detect a decrease in the number of planet-hosting stars with decreasing metallicity, but this drop is much shallower for terrestrial planets than it is for gas giants. Of course, the presence of some heavy elements during the planet-building phases is required, but the minimum level has not yet been determined. The raw materials for building terrestrial planets were available very soon after the Big Bang, raising the possibility that there could be life in the Universe far older than ours. Perhaps they reside around long-lived red dwarf stars, or have moved on from their home system after their star expired. Or, perhaps, we really are the first, which means that if life has happened just once throughout the entire history of the Universe, our existence must be a fluke and our planet very, very special indeed. Journal reference: Nature