The hypothesis that life on earth evolved under
thermophilic conditions and then adapted at cooler temperatures
is based on the discovery, in the last decade, of organisms
growing optimally at temperatures near and above 100 °C,
termed “hyperthermophiles,” and on the rooted
phylogenetic trees based on 16S rRNA sequences proposed
by Woese and colleagues in which all branches leading to
hyperthermophiles are short and located at the base of
the tree. These observations led to the conclusion that
the common ancestor of all extant organisms (cenancestor)
was a hyperthermophile. This hypothesis, which implies
the fascinating opportunity of studying the origin of life
by investigating thermophilic organisms, is still the subject
of controversy and debate. In particular, considerable
opposition arose to the concept of the hyperthermophilic
origin of life and to the interpretation of the phylogenetic
and geological data. With this in mind, the collection
of papers written by selected speakers from the international
workshop Thermophiles: The keys to molecular evolution
and the origin of life contributes significantly to
the discussion by offering the opinions (some of them in
open conflict) of leading protagonists from a range of
disciplines. In fact, as the editors correctly point out,
the majority of researchers in the thermophile field have
backgrounds in biochemistry, microbiology, and genetics,
but the views of geochemists, oceanographers, and evolutionists
would also be of great interest. With this aim, the book
gives an opportunity to readers with different backgrounds
to approach such fundamental questions as to how life originated
and under what environmental conditions.