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It
is perhaps remarkable that fifty years after Watson and Crick detailed the
structure of DNA and Stanley Miller performed the first bold experiments aimed
at producing self-replication biochemistry, there is little consensus on how
life started. This is sometimes referred to as the problem of ‘abiogenesis.’
Darwin’s advocates often present natural selection as a complete and satisfying
account of biology. Dawkins goes so far as to say it “solves the mystery of our
existence.” If we consider its potential application beyond biology to social contexts
through sociobiology it could theoretically explain a great deal more than our
existence. However, the power of natural selection only comes into the picture
once we have the twin components of replication and inheritance with variation.
But do these twin features arise inevitably? If not, their origin will need be
to be explained.
There
is still optimism that the problem will be solved, but at the moment it is hard
to predict how much will be attributed to chance. As with natural selection,
until we have some confidence as to the probabilities involved it is possible
to draw a wide range of conclusions. On the other hand, Manfred Eigen
considered our knowledge to be sufficiently detailed to declare life
“inevitable.”Biochemist George Wald shares this view, also concluding that “the universe
breeds life inevitably.”
In
recent years, Miller’s experiments have been refined and greatly enhanced, but
as Ruse puts it: “at the moment the hand of human design and intention hangs
over everything...” Stanley
Miller himself has become cautious: “the problem of the origin of life,” he
says, “has turned out to be much more difficult than I, and other people,
envisioned.”The difficulties have led no less an authority than James Watson to the
conclusion that it the origins of life should be considered “almost a miracle.”
Despite
the challenges, abiogenesis research has made laudable progress on several
fronts. Two facts have emerged: there are plausible scenarios for how several
amino acids were produced, and
there is evidence that complex life developed early on. For example there is
evidence that carbon from 3.8 billion years ago passed through photosynthesis
indicating the presence of complex plant-like organisms. This
means that life must have arisen on Earth almost soon as the Earth could
physically support it. This
fact suggests three possibilities: self-replicating molecules are likely to
form, life on Earth is due to incredible luck, or life originated somewhere
else (where the improbabilities are lessened through different physical
circumstances or the availability of time). Francis Crick and Fred Hoyle
advocated this third theory which they referred to as ‘Panspermia.’
The
lack of a detailed account of the origin of life means that it is too early to
say that evolution provides an answer to the mystery of our existence.
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| Feedback | Contributed by: Adrian Wyard
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