What would falsify common descent?
Common descent is the theory that all life evolved from one common ancestor, or groups of ancestors (although it is slightly more complicated than the straw man version of “one day a cell appeared and everything is technically its descendent”). Morphological and, more recently, genetic evidence puts common descent pretty close to being outright proven, but there are still ways to falsify it. Common descent could easily be disproved (without even seriously challenging the theory of evolution) if we discovered a form of life that was not related to all the life we know – most simply, by finding life that does not use the nucleic acids (DNA and RNA) for information storage and retrieval as known biological life does. This would be exemplified in the situation of a second genesis, where two different forms of life began at two completely different points. Also, if we were ever to discover life elsewhere in the universe, the odds lean towards it not having a common ancestor with life on ear
