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These are excerpts and elaborations from my book "The Nature of Consciousness"
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Life And Heat Whatever the mechanism that
created it, the progenitor of all terrestrial life, four billion yeas ago, was
able to tolerate the extreme heat conditions of the time (a few hundred degrees
or even a thousand). As a matter of
fact, if we walk backwards up the phylogenetic tree (the tree of species), we
find that genetically older organisms can survive at higher and higher
temperatures. Thermophiles (the
microbes that live at temperatures of 70-80 degrees) are living relics of the
beginnings of life on Earth. Based on such a phylogenetic
tree, the US biologist Carl Woeseproposed a classification of
living creatures in which thermophiles (or "archaea", first
discovered in 1964 by the US biologist Thomas Brock) are different both from eukaryotes (in which DNA is held by a
nucleus) and prokaryotes (in which DNA floats free in the cells of bacteria):
in thermophiles, DNA floats free (like in prokaryotes) but resembles the DNA of
eukaryotes. Thermophiles can be found
underground: some have been retrieved from 3 km beneath earth. An archaea has about two million base pairs
of DNA (a human cell has about three billion). The Australian physicist
Paul Daviesretraced the history of life on Earth and concluded that it began
inside the Earth, with microbes that lived several kilometers under the crust
of the Earth. His reasoning was that the surface of the Earth and the oceans
were just too unstable and dangerous for life to appear and survive. Furthermore,
the record of genes seems to prove that the ancestor of all life forms lived
underneath the Earths surface at very high temperatures. Surprisingly, very little
has been made so far of a discovery due to the French chemist Louis Pasteurin the 19th century:
that living systems prefer molecules with a certain handedness (all proteins
are made of L-aminoacids and genetic material is made of D-sugars). This
molecular asymmetry is, actually, the only difference between the chemistry of
living and of inanimate matter. Back to the beginning of the chapter "The Evolution of Life: Of Designers and Design" | Back to the index of all chapters |
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