In 1977, the identification of methanogens, a form of life dating back some 3.5 billion years, was reported by scientists at the University and Illinois. Microbiologist Carl R. Woese had long studied the evolutionary track of DNA and RNA. In 1976, he was approached by his colleague Ralph Wolfe, who presented a group of methane producing organisms. Woese studied their RNA and recognized their lack of the entire oligonucleotide sequences. He discovered the organisms were so different from bacteria, they deserved their own branch of the family tree as the third domain of life, Archaea. Methanogens are found in oxygen-deficient environments, and mostly obtain their energy by reducing carbon dioxide and oxidizing hydrogen, with the production of methane.