Explore our planet’s largest, and most biodiverse archipelago with Jesse Lewis, Rainforest Trust’s Education Coordinator, as he leads a study abroad trip across Indonesia and blogs about the journey in this eight part series.

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Our homestay village of Kedungmiri in central Java feels idyllic. About 170 families live in this rural hamlet nestled in a dramatic river valley. Lush rice fields frame a small collection of homes with a blue-green mosque standing prominently at its center. Scattered throughout the streets and alleyways are tethered cows and goats, prancing chickens and giggling children.

As our class gathers on rattan mats under the leafy shade of a village courtyard I unroll a large map of the Malay Archipelago for a lesson. I want to talk about Indonesia’s natural history today, but making sense of this complicated world of islands is challenging. It requires a discussion of biogeography: the distribution of plants and animals across space and time. And any discussion of biogeography must include my favorite science hero – the British naturalist explorer Alfred Russel Wallace.

Beginning in 1854, Wallace began an eight-year journey that took him 14,000 miles around the Malay Archipelago. Visiting every major island at least once Wallace discovered an invisible species boundary separating the faunas of Asia from Australia, known today as the Wallace Line. Animals, like tigers, live on the Asian side of Wallace’s Line and look much different than animals living on the Australian side, like marsupial kangaroos.

At the lines’ narrowest point, between Bali and Lombok, only 22 miles separate radically different groups of plants and animals.

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Scientists now know that Wallace’s Line corresponds with a deep water trench that acted as a barrier to animal migrations when sea levels were much lower during previous ice ages. The trench separated islands from one another and shaped distinct groups of plants and animals on each side.

Wallace’s passion for studying and collecting species was instrumental to understanding this boundary and contributed to the theory of evolution. In 1858, while bedridden with malaria on the remote island of Halmahera in North Maluku, Wallace wrote a letter to his friend, Charles Darwin. His letter described how evolution proceeds through natural-selection. Darwin had arrived at the same conclusion and hastened to publish his seminal work, On the Origin of Species. While both men are credited with the theory of evolution by natural selection, Wallace’s contributions are far less remembered.

As I wrap up my lesson on Wallace and biogeography I can’t help feeling wonder at the rich, intact natural world he must have seen and the pioneering discoveries he made in the name of science.

Today, Wallace would likely be horrified by the extent to which agriculture, commercial logging, and oil palm plantations have transformed much of Indonesia. Though humans have inhabited these islands for 40,000 years, most habitat destruction has taken place during the last century.

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Looking around the farming village of Kedungmiri, all is tranquil and harmonious. However, this domesticity is deceiving as it has come at the expense of the wildlife that once existed across Java and many other parts of Indonesia. The dense human landscape of farms and villages has replaced rainforests, along with many of the species that called them home. Over 350 of Indonesia’s vertebrate species are now threatened with extinction, and several species, like the Javan Tiger, have already gone extinct.

Yet, there are still places where one can catch a glimpse of the world Wallace knew. In the dense rainforests of Borneo and Sumatra and on remote mountaintops and isolated islands, Indonesia’s wildlife still thrives. Just as Wallace is the “other Darwin”, the Indonesian archipelago is “the other Galapagos” – an enchanting living laboratory to observe evolution and be amazed.

Stay tuned for our next post as my class journeys to Sulawesi, staying in the Bajau village of Sampela and exploring Indonesia’s “rainforests of the sea”.

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