TERNATE, Indonesia -- Nearly 160 years ago, the naturalist and professional beetle-collector Alfred Russel Wallace dispatched a momentous letter from Ternate, then in the far-eastern reaches of the Dutch East Indies, now part of Indonesia. Its arrival three months later at Charles Darwin's residence in England was a bombshell for Darwin, who had been wrestling for decades with his theory of evolution.
Wallace's carefully argued five pages, "On the Tendency of Varieties to Depart Indefinitely From the Original Type," set out the answer to the conundrum: natural selection or survival of the fittest? His theory, arrived at in a malarial fever, explained why variants in offspring did not necessarily revert to their parents' form. Different species could emerge over time, always related to -- but distinct from -- an earlier species.
