The American Astronomical Society does not regard any scientific theory as capable of rigorous proof or immune to possible revision in the light of new evidence. (aas.org)
Douglas Berg, a microbiologist at Washington University in St. Louis, while impressed by the new study, cautions, «Critical tests and rigorous proofs are difficult to obtain in their field of «microbial anthropology,» and some scientists will think that the authors rather overstated their case.» (scientificamerican.com)
No one has yet found a rigorous proof, so the idea still ranks as a conjecture. (showcase.casw.org)