Alfred Wallace: a great man with a great beard |
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......
No comments:
Post a Comment