 Watson and his students have subsequently developed "a priori" models for the regulation of atmospheric composition through geological time.He has applied the weak Anthropic Principle to evolution on Earth, suggesting that long-term regulation of the Earth’s temperature and environment may be a necessary pre-requisite to allow sufficient time for the evolution of complex life and intelligence, rather than an intrinsic property of the biosphere as Lovelock proposed.While at the Marine Biological Association and Plymouth Marine Laboratory in the 1980s, he developed techniques for tracking ocean water bodies using tracers such as sulphur hexafluoride and perfluorodecalin.