RENEE MONTAGNE, HOST:
Few places on earth can rival the astonishing diversity of plant and animal life found in Indonesia, that collection of tropical islands stretched across a vast crescent. The abundance inspired British nationalist Alfred Russel Wallace to pen the first scientific paper arguing the theory of evolution with his far more famous co-author, Charles Darwin.
Wallace died 100 years ago this year. NPR's Anthony Kuhn takes us to the island of Sulawesi where the scientist made some of his most profound observations.
ANTHONY KUHN, BYLINE: Wallace arrived here more 150 years ago in what was then the Dutch East Indies. During his eight year expedition, he would collect over 100,000 plant and animals species. Tony Whitten with the British-based Flora and Fauna International says that on his journey, Wallace was constantly battling tropical disease and bad weather, but his mind was on other things.
TONY WHITTEN: When he was working, he would have just forgotten about the pain and the damp and the wet and the mold and he was just totally absorbed in what he was doing and just found life around him amazing.
KUHN: When Wallace landed here on Sulawesi in 1859, he had already co-authored his paper with Darwin, but he was still refining his ideas about evolution and he was fascinated to be on an island where most of the animals existed no place else on earth. Today, Sulawesi's natural abundance has been severely depleted. Many of its unique species are close to extinction in the wild.
You can only find them in nature preserves like this one. Here we have a sign board. This is the Bogani Nani Wartabone National Park. I'm looking for a bird called the maleo. Wallace's search for this bird was the high point of his explorations on Sulawesi. OK, so we're going to have to be really quiet when we approach the maleo, otherwise they're going to bolt.
We're just going to have to talk very quietly. Well, we're walking through sort of highland forest and we're lucky to be here on a day where it's very cool and misty with a light rain coming down. Wallace's observations about the maleo helped to build his understanding of evolution, but they also captured this man's limitless curiosity.
Wallace wrote that we should never be content to look at a living thing and say, oh, that's just the way it is. We should always be inquiring about how it got that way and how it's related to its environment.
MAX LELA: It's hard to find the maleo.
KUHN: With me, is park ranger Max Lela. I ask him, what does the maleo's call sound like.
LELA: (Through Translator) Maleo (unintelligible) comes in a couple. The male maleo will sound like (makes sound). Female maleo will sound like (makes sound).
KUHN: I've lost it now.
LELA: Victory, first branch.
KUHN: There they are, two male maleo's perching in a tree calling to their mates. Their size is somewhere between a chicken and a turkey, with black feathers and a salmon-colored breast. Wallace observed that maleos have adapted so perfectly to their environment that they even use Sulawesi's geology to survive. Instead of sitting on their eggs like hens, maleos use geothermal energy to incubate them.
They dig into the earth, which is heated by hot springs. They can sense where the temperature is between 86 to 97 degrees. That's where they lay their eggs. Those two in stereo, a very animated conversation. Now, we're at the park's hatchery and Lela is showing us a two-day old maleo chick. He's putting the downy little bird in my hand and this gives us a chance to see how its body has adapted to its environment.
Touching the feathers on the back of the little maleo's neck and they're very soft and downy. The maleo's feet that we're looking at right now, the legs are straight and the claws, it's got four fingers with webbing in between two of them and that's their shovel. That's what they use to dig. Lela says that after eight weeks, the buried eggs hatch.
It takes the maleo chicks about three days to struggle up through two or three feet of dirt - pecking, flapping and kicking their way out. They're able to fly away almost as soon as they reach the surface and that keeps them safe from predators.
LELA: Anthony, you can release.
KUHN: Off you go. Yes. So that bird sort of wobbled a bit on my right hand and then with a push and shove, off it flew and roosted on a tree branch. Very impressive for a three-day old bird. On Sulawesi, Wallace noticed something unusual and that is that the maleo is related to species found in Australia and the Western Pacific hundreds or thousands of miles away, but not in Asia, not even on the island of Borneo just a few miles to the west.
So Tony Whitten says Wallace drew a line on the map to separate what seemed to him to be distinct regions with different kinds of animals. That line is now called the Wallace Line and the region around it is called Wallacea.
WHITTEN: It was clearly this sort of transition between the Asian world and the Australian world. And so came the thought of this line that could be drawn between Borneo and Sulawesi that would separate the Asian fauna from the Australian fauna.
KUHN: Wallace didn't know it at the time, but his line is actually the divide between two continental shelves. Really, Wallace was just asking a simple question. Why do we find this animal in this place? At the Tasikoki Wildlife Rescue and Education Center, we meet up with local naturalist John Tasirin. And Tasirin says that you can see that process happening right here on Sulawesi.
JOHN TASIRIN: You can see the movement of the animals and then when they move, then suddenly they become new species. Well, not suddenly. After, I don't know, 3,000 - 6,000 years later.
KUHN: Even as Wallace's eyes observed life around him, his mind roamed millions of years back in time to imagine the birth of islands and continents. He also peered into the future. Wallace foretold today's situation in which Sulawesi's unique animals face extinction. He wrote that we have it within our power to save these creatures and not let them, as he put it, perish irrecoverably from the face of the earth uncared for and unknown.
Anthony Kuhn, NPR News.
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