| Graham Cairns-smith |
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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 {Link without Title} . CLAY THEORY In simplified form, clay theory runs as follows: Clay s 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 has not been widely accepted. SEE ALSO REFERENCES
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