10 November, 2006
Lamarck. Haeckel, Darwin and the giraffe actylic on canvas 600mm x 450mm.
The quote is from Sherlock Holmes, “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” Of course it appears improbable that three white-haired Victorians would find themselves sharing a drink with a giraffe in the Masai Mara, but not is not necessarily impossible…
Everyone is familiar with Darwins theory of natural selection as the driving force for evolution. Though he can hardly be described as the final word on evolution.
Jean-Baptiste Lamarck was a contemporary of Darwin’s and suggested that evolution occurred by the passing of traits developed during an animal’s lifetime from one generation to the next. One of his examples was that of the giraffe, which would stretch its neck to reach higher leaves, and therefore produce longer necked offspring. This theory, Lararckism, is generally ridiculed, since Mendelian genetics only supports the shuffling of genes during sexual selection, the occasional mutation and ‘survival of the fittest’.
Haeckel, of course, is the ‘ontogeny recapitulates phylogeny’ guy – the idea that the developing foetus expresses all of its evolutionary forbears sequentially during development. This was later proven to be an exaggeration, but that should not undermine his other achievements not only as a theoretician but also as a talented artist.
The emergent field of epigenetics posits a mechanism for the ‘turning on and off’ off genes within an individuals lifetime, and that these changes in gene expression can be passed on to future generations. Which is, in a way, Lamarckism in a different form. And where do these genes come from that can be switched on and off in such a way? Well, our genome, which aside from carrying instructions for building a human, also has a bunch of code from our evolutionary ancestors. Could it be possible that Haeckel was kinda right too?
All of them, no doubt, would have their own theory on how a creature as seemingly preposterous as the giraffe could come into being. And perhaps, to some extent, all three could be partially right.
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