Extraordinary claims require extraordinary evidence.
Monitor gas over the soil for radioactive CO 2 . Negative result, because even though CO 2 was generated, there was still the possibility that it was nonbiological. Repeating the experiment yielded no more CO 2 . Negative result, because although water added to the soil generated oxygen, it was realized that this could be nonbiological. So soil was heated to destroy any life, then the experiment run again, and more oxygen was generated.