Everything about Graham Cairns-smith totally explained
Alexander Graham Cairns-Smith (born 1931) is an organic chemist and molecular biologist at the
University of Glasgow, most famous for his controversial 1985 book,
Seven Clues to the Origin of Life. The book popularized a theory he'd developed since the mid-1960s, that a simple intermediate step between dormant matter and organic life might be provided by the self-replication of clay crystals in solution. He was disenchanted with the other ideas about
chemical evolution including the
Miller-Urey experiment and the
RNA World.
Cairns-Smith has also published on the evolution of consciousness, in
Evolving the Mind (1996), favoring a role for
quantum mechanics in human thought, a book respected but disputed by the philosopher
Daniel Dennett.
Clay theory
In simplified form, clay theory runs as follows:
Clays form naturally from
silicates in solution. Clay crystals, as other
crystals, preserve their external
formal arrangement as they grow, snap and grow further. Masses of clay crystals of a particular external form may happen to affect their
environment in ways which affect their chances of further replication — for example, a 'stickier' clay crystal is more likely to
silt a stream bed, creating an environment conducive to further
sedimentation. It is conceivable that such effects could extend to the creation of flat areas likely to be exposed to air, dry and turn to wind-borne dust, which could fall at random in other streams. Thus by simple, inorganic, physical processes, a selection environment might exist for the reproduction of clay crystals of the 'stickier' shape.
There follows a process of natural selection for clay crystals which trap certain forms of
molecules to their surfaces (those which enhance their replication potential). Quite complex proto-organic molecules can be
catalysed by the surface properties of
silicates. The final step occurs when these complex molecules perform a 'Genetic Takeover' from their clay 'vehicle', becoming an independent locus of replication - an evolutionary moment that might be understood as the first
exaptation.
Despite its frequent citation as a useful model of the
kind of process that might have been involved in the prehistory of
DNA, the 'clay theory' of
abiogenesis hasn't been widely accepted.
Richard Dawkins uses it as an example in his 1986 book
The Blind Watchmaker -- it was current and fashionable at that time.
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