James Lovelock (born 1919), British environmentalist and author of the 'Gaia Hypothesis', speaking during the 'Seeking Signs of Life' Symposium, celebrating 50 Years of Exobiology and Astrobiology at NASA. Lovelock's proposition is that the biosphere is a self-regulating system, in many respects similar to an organism, but on a global scale. Photographed at the Lockheed Martin Global Vision Center, Arlington, Virginia, USA, on 14th October 2010.