In the latest work, Mikio Fukuhara of Tohoku University and colleagues in Japan and Canada propose that these lighter elements can also be produced deep inside the Earth. The inspiration for this idea comes from the evolution of Earth's atmosphere. As the researchers point out, the atmosphere is thought originally to have been made up almost exclusively of carbon dioxide. But its composition then changed radically, resulting in the dominance of nitrogen ?" which today accounts for about 78% of the molecules in the atmosphere ?" as well as large amounts of oxygen (some 21%), while car