Friday, 5 December 2014

Influences on Darwin and his theory

Alfred Wallace: a great man with a great beard

Darwin’s seminal ideas and insight did not appear as if in an intellectual vacuum. Darwin’s biological studies, and particularly his observations whilst a naturalist aboard HMS Beagle, had a major influence on his formulation of ‘evolutionary theory’. But this is not the whole story. Darwin was clearly influenced by the intellectual milieu of his time. Many of the intellectual strands important and having bearing upon the theory had been worked out by others. Darwin’s own direct observations together with ideas already established culminated in a coherent explanation of how species change with time. The synthesis, in one mind, was ultimately due to Darwin’s genius. That being the case it will be worthwhile  to examine the ideas available to Darwin in the mid 1800s  which helped to shape his most wondrous of theories. This is by necessity an abridged treatment, a complete consideration is beyond the scope and remit of a modest blog article. Therefore I have limited the discussion to just a few of the most important men and their ideas. Bugger nuts. 

Lamarck (1744-1829)
The kinship between animal species is obvious. But did individual immutable species exist from the start or did they emerge from pre-existing forms and change by some mechanism, unknown. If this was the case it was no longer acceptable to say, ‘God did it’. A causal naturalistic mechanism was demanded. Lamarck was the first serious minded scientist to actually propose a mechanism. In 1809 he published his work on acquired characteristics. According to Lamarck’s theory, overuse of a body part would enable the animal to become better adapted to its environment and this characteristic would be passed on to the offspring. The classic example generally quoted is the case of the giraffe. It was proposed that the primitive giraffe stretched its neck to reach higher leaves, this would lead to offspring with longer necks which would eventually evolve into the very longed necked giraffe of today. There is no explanation about giraffe blotches. Why giraffes have blotched bodies on the savannah is bothersome to me. I digress.  Lamarck’s ideas were ignored during his life time and were rejected not on scientific merit but on religious grounds; makes me sad and want to burn stuff.  Darwin, in his autobiography, acknowledges that Lamarck influenced his own theories.

Malthus (1766-1834)
Thomas Malthus had a profound influence on Darwin and his ideas. Although not a scientist, but an economist, Malthus appreciated that populations are limited by resource supply. Unchecked, populations would grow exponentially, but this never happens. Ultimately populations of any species are regulated by food supply.

Erasmus Darwin (1731-1802)
Charles' grandfather Erasmus, was certainly interested in evolutionary ideas and wrote a book on how adaptations result in speciation. For the most part he narrated his notions in verse. Undoubtedly this was a ploy to keep him falling foul of the religious authorities of his day. It is easy to forget the power of religion during the early and middle parts of the 19th century and it is down to great men, like the Darwins, that we attribute the triumph of reason and science over stolid religious dogma.

Charles Lyell (1797-1875)
Lyell was a prominent 19th geologist and through his observations on fossils he began to suspect that small adaptations accrued over time.

Alfred Wallace (1823 -1913)
It would be unfair not to mention Alfred Wallace in the context of evolutionary theory. Although he did not exert any direct influence on Darwin, he did propose his own theory of evolutionary theory independently, and at the same time. In fact when Darwin heard of Wallace's ideas it spurred him on to publish his own theory. To Darwin's credit, he published a joint paper with Wallace entitled: "On the tendency of species to form varieties; and species by natural means of selection (1858)." Unfortunately for Wallace, either by chance or design, he never received the just credit and due for his important contribution. Ain't dat the sad truth.

Clearly, the situation with regard to factors, personalities and available contemporary knowledge contributing to Darwin's theoretical principles is highly complex and cannot be exhaustively considered in this brief sketch, but it will have to do. I have not ventured into any consideration of the influence of Darwin's experiences whilst collecting data and biological samples from abroad.       

The scene is now set for the next stage in the saga, that is evolutionary theory; the exposition of the greatest show on earth......

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