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No. 1270:
Wallace's Line

Today, we cross Wallace's line. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Physiologist Jared Diamond makes a pilgrimage to Wallace's line -- an imaginary line separating Borneo and Java from the Celebes and other islands to the southeast. "[Crossing] that line," he says, "may have been what made our ancestors truly human."

Alfred Russel Wallace was the now-almost-forgotten co-discoverer of the theory of evolution. Darwin had pretty well formulated the theory when he learned that Wallace was about to publish a similar idea. When Wallace heard about Darwin, he politely stood aside and let Darwin publish first.

Among many contributions, Wallace identified the demarcation between species of southeast Asia and completely different species in Australia and New Guinea. There are other such regions. The Sahara is one. A band from northwest India through the Himalayas and Indochina forms another such zone of separation. But Wallace's line has special significance.

For a long time, we've known that modern humans evolved in Africa 100,000 years or so ago, and that they began making dramatic art and tools in Europe 30 or 40 thousand years ago. But we've paid scant attention to the world southeast of Wallace's line.

The so-called Java Ape Man fossils make it clear that ancestors of modern humans reached southeast Asia a million years ago. Java Man got as far as Borneo and Java over land links that existed before the glacial epochs. But those links ended there, and he couldn't get to New Guinea and Australia.

Yet modern humans have occupied Australia for 60,000 years. Somehow, modern humans appeared in Java Man's world, and they managed to go island-hopping all the way to Australia. There they practiced advanced art and technology that rivals what we find in the caves of central Europe. The catch is, they did so much earlier than the European Cro-Magnons.

And so, Jared Diamond observes, we were the one species that lived on both sides of Wallace's line. The crucible of human creativity might well have been Australia. He believes the art and technology of Australian aborigines slowly trickled back and eventually reached Europe. Diamond thinks that crossing Wallace's line was the giant step that made us into a technological species.

Eventually, the vast geography and resources of Europe and Asia allowed the aborigines' cousins to run ahead -- to invent writing and the wheel, to build canons and cathedrals. Eventually, when Dutch and English navigators found their way back to Australia, all they saw were shockingly primitive humans. They had no way to see the sophistication of their survival strategies.

And they had no idea they should be saying "Thank you" to their ancient teachers.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Diamond, J., Mr. Wallace's line. Discover, August, 1997, pp. 76-83.

See the Wikipedia article about Wallace's line.