4.1 Alive or Not?
45
sibly also among galaxies, by space dust, meteoroids, and even alien space ships, as
imagined by none other than the famous discoverer of the structure of genetic code
(Crick and Orgel, 1973). This, of course, only pushes the hard question back, redirecting it to the original source. In an extreme interpretation, it would presuppose
the unity of life, with the same chemical constituents all over the Universe, notwithstanding dissimilar environments on countless planets that may support life, perhaps
based on totally different chemistry, as speculated by biologists, astronomers, and
science fiction writers. There is, nevertheless, a persistent interest in a search for
traces of life in meteorites, and it is quite certain that microorganisms are capable of
surviving in a cosmic environment for a very long time.
The mainstream approach remains, however, earthbound. Charles Darwin imagined a warm little pond, with all sorts of ammonia and phosphoric salts, lights,
heat, electricity, etc. present. Alexander Oparin (1924), then in his twenties in the
still innovative Soviet Union, suggested that gradual evolution of organic chemicals in the Earth’s “primordial soup”, similar to Darwin’s, in an atmosphere rich in
methane, ammonia, hydrogen, and water vapor, may have led inadvertently to the
emergence of life. He was seconded by John Haldane and John Bernal, both, perhaps
not accidentally, communist sympathizers. There was quite some excitement when
Stanley Miller (1953) demonstrated spontaneous synthesis of amino acids within a
sealed glass flask filled with warm water and a gaseous mixture imitating what was
believed at the time to be the early Earth atmosphere, fired by sparks imitating lightning bolts. This supported Oparin’s opinion that there was no fundamental barrier
between organic chemistry and life.
The question of the actual mechanism of the emergence of life remains nevertheless open to this day, and the “warm little pond” scenario is no longer a leading
candidate. Even if the amino acids in Miller’s experiment polymerized by chance,
forming a clumsy semblance of a protein molecule, this is still a very long way from
sustainable life. A complex molecule emerging by a fleeting whim of chemistry will
disintegrate in response to another whim, unless it is capable of reproducing itself.
Life is a self-organizing process; its elements must join into a structure capable of
building and enhancing itself by joining into new elements.
We should expect it to be harder to uncover the origin of life than to understand
the way the Universe came into being: we see the distant past of the Universe by
observing its far reaches in spacetime much more clearly than we see the past of
our Earth, hidden in geology and in the genetics of extant organisms. Moreover,
even in the case of a brilliant success, the picture we would see would be merely
parochial. Life, at least primitive life, certainly exists on a great many planets, and
the particular circumstances of a transition from their various chemistries to their
various life forms will not necessarily conform to whatever happened here.
45
sibly also among galaxies, by space dust, meteoroids, and even alien space ships, as
imagined by none other than the famous discoverer of the structure of genetic code
(Crick and Orgel, 1973). This, of course, only pushes the hard question back, redirecting it to the original source. In an extreme interpretation, it would presuppose
the unity of life, with the same chemical constituents all over the Universe, notwithstanding dissimilar environments on countless planets that may support life, perhaps
based on totally different chemistry, as speculated by biologists, astronomers, and
science fiction writers. There is, nevertheless, a persistent interest in a search for
traces of life in meteorites, and it is quite certain that microorganisms are capable of
surviving in a cosmic environment for a very long time.
The mainstream approach remains, however, earthbound. Charles Darwin imagined a warm little pond, with all sorts of ammonia and phosphoric salts, lights,
heat, electricity, etc. present. Alexander Oparin (1924), then in his twenties in the
still innovative Soviet Union, suggested that gradual evolution of organic chemicals in the Earth’s “primordial soup”, similar to Darwin’s, in an atmosphere rich in
methane, ammonia, hydrogen, and water vapor, may have led inadvertently to the
emergence of life. He was seconded by John Haldane and John Bernal, both, perhaps
not accidentally, communist sympathizers. There was quite some excitement when
Stanley Miller (1953) demonstrated spontaneous synthesis of amino acids within a
sealed glass flask filled with warm water and a gaseous mixture imitating what was
believed at the time to be the early Earth atmosphere, fired by sparks imitating lightning bolts. This supported Oparin’s opinion that there was no fundamental barrier
between organic chemistry and life.
The question of the actual mechanism of the emergence of life remains nevertheless open to this day, and the “warm little pond” scenario is no longer a leading
candidate. Even if the amino acids in Miller’s experiment polymerized by chance,
forming a clumsy semblance of a protein molecule, this is still a very long way from
sustainable life. A complex molecule emerging by a fleeting whim of chemistry will
disintegrate in response to another whim, unless it is capable of reproducing itself.
Life is a self-organizing process; its elements must join into a structure capable of
building and enhancing itself by joining into new elements.
We should expect it to be harder to uncover the origin of life than to understand
the way the Universe came into being: we see the distant past of the Universe by
observing its far reaches in spacetime much more clearly than we see the past of
our Earth, hidden in geology and in the genetics of extant organisms. Moreover,
even in the case of a brilliant success, the picture we would see would be merely
parochial. Life, at least primitive life, certainly exists on a great many planets, and
the particular circumstances of a transition from their various chemistries to their
various life forms will not necessarily conform to whatever happened here.