Page 19 - RD (English) - Sample

the orIgIn of SpecIeS 11

puzzled by the geographical distribution of species. That the Galapagos
alone hosted many distinct yet obviously related species of plants and
animals scattered over a few small islands sowed in his mind the seeds
of the idea of organic evolution. He wrote in his journal, “It is the cir-
cumstance, that several of the islands possess their own species of the
tortoise, mocking-thrush, finches, and numerous plants, these species
having the same general habits, occupying analogous situations, and
obviously filling the same place in the natural economy of this archi-
2
pelago, that strikes me with wonder.”
If species had been created separately, then why had God created
different yet very similar species for each of the small islands, the
smallest of which were, in Darwin’s words, barely more than “points of
rock”? It would have made more sense if completely different species
inhabited each island. This phenomenon, something Darwin began to
notice everywhere he traveled, led him to think that perhaps the species
had not been created separately at all but had evolved from a common
ancestor in the distant past.
When Darwin returned to England in 1836 he continued to ponder
the issue and gradually became convinced of organic evolution. In 1844
he wrote a friend, “At last gleams of light have come, and I am almost
convinced (quite contrary to the opinion I started with) that species are
not (it is like confessing a murder) immutable.”
3
As other naturalists of Darwin’s time also observed the geographi-
cal distribution of species, they too became convinced of evolution.
One such naturalist was Alfred Russel Wallace (1823–1913), a young
correspondent of Darwin’s who now and then sent Darwin plant and
animal specimens from his travels in Borneo. Wallace shares with
Darwin the honor of having proposed the theory of evolution, because
while Darwin had written down his thoughts privately, he had never
published his theory. Wallace had found the time to spell out his ideas
on evolution through natural selection while he was bedridden with
malaria in Borneo. He detailed his thoughts in a paper he sent to
Darwin, asking him to send on both the letter and the paper to Charles
Lyell, whom Wallace did not know. It is said that Darwin was dismayed