Wallace Line

I've written this post over the last week, since we were in Lombok because I needed to do some research. It's about the Wallace Line, one of the reasons Mum wanted to take me to Lombok and Bali. There's a lot to read, so you don't have to, I did it because it will help me remember this trip, and about the Theory or Evolution - natural selection. 

Alfred Russel Wallace

Alfred Russel Wallace didn’t come from money or education like Charles Darwin yet he lived at the same time –in the 1800s. Wallace was born in 1823, he left school when he was 13, but read and read. He was a naturalist with a passion for understanding how the different species developed. Wikipedia describes him as an naturalist, explorer, geographer, anthropologist and biologist. Others add that he was a poet and a spiritualist. He was a humble man.

Charles Darwin

A bit about Charles Darwin

Admiral Phillip Parker KING

Darwin left for South America (esp Patagonia) in 1831 on the HMS Beagle, which was under the command of Admiral Phillip Parker King (1791 – 1856) [the son of Australia’s 3^rd Governor, Governor Philip Gidley King  (1758 – 1808)]. Darwin’s mid-shipman was Admiral King’s son (also called Philip Gidley King (1817-1904) and Philip Gidley King’s illustrations were used by Darwin. It was on this voyage that Darwin began to form his theory of evolution. I write this because Governor King is my 7^th grandfather, Phillip Parker King is my 6^th, and Philip Gidley King is my 5^th. It’s the reason my name is Apsara May KING Lindeman!

Alfred Wallace was born in 1923 so he was younger when Darwin was on the HMS Beagle. Darwin returned to England in 1840 but didn’t publish anything because he was still wanting to document everything clearly so he had all the evidence to support his theory. At the same time, Wallace was exploring, observing, discovering, documenting and developing his own theories.

Back to Wallace

While Wallace was still an apprentice, and a building surveyor he loved to spend his time outdoors and reading books. Books in which he read were novels written by Darwin of his travels around the world! Wallace became inspired by Darwin’s travels, especially the Beagle voyage. Darwin was an inspiration to Wallace, and he managed to save enough money for an expedition of his own to South America. Wallace went to the Amazon when he was 21yo first and discovered new species, but on the way back to London his boat caught fire and he lost all his specimens and notes, four YEARS of his work was destroyed. BUT he didn’t give up, but decided to start again and he travelled to the Malay Archipelago and Indonesia. He didn’t have money backing him, so he funded his explorations by collecting animals and selling them to museums in London, but this time he also collected for himself.

The Malay archipelago - Wallace's map drawing

Wallace spent his days catching and shooting animals to observe in detail. He drew illustrations, notated them all, he measured and weighed the animals, he even skinned them and looked at their anatomy. He discovered species that were unlike any others discovered, and were truly intriguing to him so he wrote in a journal of all his observations. Mum has been reading Wallace’s book The Malay Archipelago which was printed in 1869. She’s been showing me relevant sections from the book.

When he was travelling through the Malay archipelago, he noticed there was a sharp distinction between the western parts and the eastern parts even though there was similar climate and terrain as they are both volcanic islands. 

Sumatra and Java were ecologically more like the Asian mainland, while Lombok, Sulawesi and New Guinea were more like Australia. He especially saw a great contrast between Bali and Lombok because they were so close. He saw marsupials like the tree kangaroo in Lombok which had only been seen in Australia. He saw the white crest cockatoo on Lombok.

He wrote a letter from Lombok in 1856, which said:

“The islands of Bali and Lombok, though of nearly the same size, of the same soil, aspect, elevation and climate, and within sight of each other, differ considerably in their animals. As an instance, I may mention the cockatoos, a group of birds confined to Australia and the Moluccas, but quite unknown in Java, Borneo, and Sumatra; one species (Plyctolophus sulphureus, the lesser sulfur crested cockatoo) is abundant in Lombok but is unknown in Bali. The island of Lombok appears to form the extreme western limit of the cockatoos range and that of the whole family. Many other species illustrate the same fact, and I am preparing a short account of them for publication”

Wallace noticed a pattern in the distribution of fauna in the islands. Wallace was the first to notice there was a biogeographic boundary across the Lombok Strait and there was a striking difference between animals of Indo-Malaysia and those from Australasia and that there was a distinct definition between the two regions. This boundary is now called the Wallace Line.

Wallace thought it was the depth of the Lombok Strait that kept animals on either side isolated from one another. When sea levels dropped during the Pleistocene Ice Age, the islands of Bali, Java and Sumatra were all connected to one another and to mainland Asia, so they were mostly Asian fauna. The Lombok Strait was very deep, so the islands (like Lombok, New Guinea, Sulawesi) were colonized by Australasian fauna.

He wrote:

“the wide expanse of sea which divides the islands of Java, Sumatra and Borneo from each other is so shallow that ships can anchor in any part of it since it rarely exceeds 40 fathoms in depth. And if we go as far as 100 fathoms we shall include the Philippine islands Bali, east of Java”

He also wrote:

“it is well known that the natural productions of Australia differ from those of Asia. Australia in fact stands alone, it possesses no apes or monkeys, no tigers, no elephant, no horse, no squirrel. Instead of these it has marsupials, only kangaroos, opossoms, wombats and the duck-billed platypus. In birds it is almost as peculiar. It has cockatoos, honeysuckers and the brush tongued lorries which are found nowhere else across the globe. All these striking peculiarities are found also in those islands”

“The great contrast between the two divisions of the archipelago is nowhere so abruptly exhibited as on passing from the island of Bali to that of Lombok where the two regions are in closest proximity. In Bali we have barbets, fruit thrushes, and woodpeckers; on passing over to Lombok these are seen no more but we have abundance of cockatoos, honey suckers and brush turkeys which are equally unknown in Bali or any island further west”

He also thought that species survived better in environments because of their genes, and these would reproduce more so the strong genes survived and adapted to the environment. The weaker ones died off. It was survival of the fittest. This was exactly what Darwin had discovered – the theory of evolution through natural selection.

Wallace sent his findings, with his observations, hypothesis and evidence, and an essay to Charles Darwin (who he admired and looked up to) in London to ask his opinion. When Darwin read Wallace’s theory he realized Wallace had the same one as his, but Darwin hadn’t published his yet. So Darwin used Wallace’s essay (Wallace collected over 120,000 specimens) and his own and presented a paper in 1858 – with both their names. Wallace wasn’t told about it, because he was still in Asia. In 1859 Darwin published On the Origin of Species, with just his name, and this is who history remembers.