2. Hypotheses for where Life Originated
    1. Vent Hypothesis: Chemosynthetic, external source of energy for earliest (anaerobic) autotrophs were chemical reactions (not sun).
    2. Tidal Pool Hypothesis: Hot tidal pools of seawater concentrated chemicals and provided energy for origin of amino acids and DNA.
    3. Panspermia: Life originated on Mars, and rode to Earth in meteorites.Image source: http://library.thinkquest.org