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Bruce Chatwin – Songlines

Most evolutionists believe that climate is a motor of evolutionary change

Species, on the whole, are conservative and resistant to change.  They will go on and on like partners in a shaky marriage making minor adjustments here and there until they reach a bursting point beyond which they cannot cope. 

In a climate catastrophe, with its habitat fragmenting all around, a small breeding community may get hived off from its fellows and stranded in an isolated pocket, usually at the far end of its associated range, where it must transform itself or die out.

The ‘jump’ from one species to the next, when it does come, comes quickly and cleanly.  Suddenly the new arrivals no longer reply to old mating calls.  In fact, once these isolating mechanisms take hold, there can be no genetic backsliding, no loss of new features, no going back.  Sometimes the new species, invigorated by the change may recognise its former haunts and replace its predecessors.

The process of ‘jumping’ in isolation has been called ‘allopatric speciation’ and explains why, whereas biologists find countless variations within a species – in body size or pigmentation – no one has ever found an intermediate form between one species and the next.

Reflecting on the above I was struck by the similarity between allopatry and the Aboriginal Creation myths in which each totemic species is born, in isolation, at one particular point on the map and then spreads out in lines across the country