A billion years ago, the Earth was an exceptionally unpleasant place. Temperatures were unbearable and the air was unbreathable, with carbon dioxide comprising about one-third of the atmosphere. Then a tiny new life form entered the picture and changed everything. Known as microalgae, these single-celled organisms evolved from the primordial soup, absorbing atmospheric gasses and reducing CO2 levels to a fraction of a percent, fostering an environment in which higher […]