The article in this issue by Gitelson and Okladnikov provides a valuable summary of some of the work conducted at the Bios-3 project in Krasnoyarsk, Russia. As the title suggests, the focus is on humans and their role in a CELSS biosphere. I am aware of several translated reports and some recent articles by Dr. Gitelson and colleagues in which the Bios project is described, but this paper provides some information that I have not seen previously in an english article. Although the discussion is focused on bioregeneration, the authors state that complementary physicochemical technologies and some stowage may be needed in a CELSS. For example, animal protein foods were taken into the Bios-3 chamber, since, as the authors state, "products of animal origin would make the system considerably more complicated and energy inefficient."