Davis: In an ideal world, a man should kill something and eat it. He says that would give him all the nutrints he needs to survive in today's modern world. But we can't do that because there are too many animals left for us to get them from now on,. so we have to compensate with other sources of food such as fish or water - which is full of mercury. We're trying to mimic what humans should have been doing all along, davis says.