Where in Southeast Asia

The Wallace Line

I am on the Wallace Line!

by Charles Hirschman

The Wallace Line does not actually exist in reality. It is an imaginary line that intersects the Lombok Strait between the Indonesian islands of Bali and Lombok to the south, and extends north through the Makassar Strait between Kalimantan (Borneo) and Sulawesi.

Alfred Russell Wallace (1823-1913) is probably the most famous person that most people have never heard of.  He was a 19th century naturalist who, independently of Charles Darwin, “discovered” the theory of evolution.  Wallace’s hypothesis was based on observations from islands in the Indonesian archipelago.  He noted a distinct divide between the fauna of the western islands, with animals largely of Asian origin, and that of the eastern portion where animals were Australasian.  Today this dividing line bears his name: the “Wallace Line.”  From his observations, he began to discern a process of natural selection, as expressed in his autobiography:

“The problem then was not only how and why do species change, but how and why do they change into new and well defined species, distinguished from each other in so many ways; why and how they become so exactly adapted to distinct modes of life; and why do all the intermediate grades die out (as geology shows they have died out) and leave only clearly defined and well marked species, genera, and higher groups of animals?”

Darwin rushed his book, On the Origin of Species, into print in 1859 when he learned that Wallace was about to publish a work with the same ideas, but Wallace was never jealous that Darwin received all the credit.  The two men corresponded and exchanged scientific papers.

Although Wallace traveled to South America and other parts of the world, his longest period of fieldwork (eight years) was in the islands of Southeast Asia, where he observed flora and fauna, and collected specimens of insects, butterflies, birds, reptiles, and mammals. His two volume magnum opus The Malay Archipelago was published in 1869 and dedicated to Charles Darwin. The book has been reprinted many times and is even available online (http://papuaweb.org/dlib/bk/wallace/cover.html).  Wallace’s lively prose and detailed description of peoples and places as well of the natural world still speak to contemporary readers.