1) von Waechterhausen (or -er?) and Cairns-Smith
have produced interesting (and highly debated) proposals
as to how the primoridal biomolecules were able to
stick together before the formation of cells. If you
have not read these (and some of the debate on them),
2) The most likely reason that the Viking landers found no
signs of _extant_ life is that Mars is bone-dry. However,
Viking was not equipped to look for micro-fossils. It is
also possible that life does still exist there, but only in
very limited regions (and not at the Viking landing sites).
Future missions to the Martian surface should answer some
of these questions.
Department of Cellular & Developmental Biology
Department of Genetics / HHMI
robison at biosun.harvard.edu