The Wallace Line - by Tre

I've given up on funny titles. When you're writing this much, you get to a point where all the puns and funny sayings are used up, so we'll just stick with what it is: a post about The Wallace Line.

Let's start with the line's namesake, Alfred Wallace, an often overlooked historical figure.

Alfred Russel Wallace was a British explorer and scientist, who traveled through the Indonesian Archipelago and gathered over 126,000 specimens, several thousand of which were new to science. We actually got to visit one of the places he stayed in Indonesia while we were on a hike to see birds of paradise. It was a tiny raised shack that wasn't even big enough to stand in. He spent six weeks there, collecting birds of paradise specimens and probably swatting lot of mosquitos.

Not only was Wallace an accomplished explorer, he was also a biologist to rival Charles Darwin. While he was traveling in the Indonesian Archipelago, Wallace came up with the Theory of Evolution Through Natural Selection completely separate from Darwin. In fact, Darwin had come up with the theory twenty years earlier but hadn't published it. The two scientists corresponded on their theories, and eventually collaborated on a paper discussing their findings. The theory was unpopular at first, but Darwin expanded on it in his best-selling book, Origin of the Species. The book's popularity led to Darwin's name being associated with the theory, but he always recognized the role that Alfred Wallace had played in its development. The two colleagues became friends, and Wallace even dedicated his book, The Malay Archipelago, a memoir of his travels in what are now Indonesia and Malaysia, to Darwin. The book has been quite popular, originally published in 1869 and has never gone out of print.

Another discovery Wallace had while he was traveling in the Malay Archipelago (Basically Indonesia plus Malaysia) was a phenomenon where animal and plant species could only be found on either the east or west side of the archipelago. It was almost like a line ran North-South through the whole archipelago going between Borneo and Sulawesi and through the Lombok Straight. Nowadays, we call this phenomenon the Wallace Line, which marks a deep water straight that cuts through the otherwise shallower waters, dividing the archipelago into two zones.

Although animals and plants have differing levels of observation of the line, the majority of plants and animals stay on either one side or the other. Many birds won't even fly over narrow sections of water to the other side of the line. A few exceptions to the Wallace Line are some species of bats and the long-tailed macaque (aka the crab eating macaque, a small monkey species), both of which we saw while exploring the Bornean Jungles.

Before the time of the Wallace Line, Australia is believed to have been connected to Antarctica. When Australia broke off and started drifting northward, it opened up the Antarctic Circumpolar Current, which now plays a major role in keeping the earth's climate cool. It also caused the animals and plants of Australia to adapt to a cool and dry climate. Eventually the Australian plate collided with the Asian one, forcing the seafloor between them upward and creating a whole bunch of islands, which are now the Malay Archipelago. The plants and animals of Asia were already adapted to a tropical continent, so they were ready to move into the newly formed tropical islands. However, the Australian flora and fauna were used to a cool, dry climate, so they were unprepared to move into these new tropical islands that were now their neighbors. Eventually, Australian animals crossed into some of the islands nearer Australia, like Papua. But, many animals and plants of both Australian and Asian descent were prevented from island hopping further by a deep water trench that ran through the Archipelago. Sound familiar? This deep water trench was the origin of the Wallace Line. Animals and plants on their respective sides of the line adapted to their own environments. Eventually, the Wallace Line became a major biogeographical divide that only a few species were able to cross.

Now, old Alfred Wallace already had his very own line named after him, but we didn't think that was enough, did we? No, he also got a bunch of islands named after him, too. Bordering the Wallace Line are Sulawesi, Lombok, Flores, Timor, Halmahera, Sumbawa, Sumba, and many other islands, that are now collectively known as Wallacea. These islands are like the gray area of the Wallace Line, where certain species from both sides mix, even creating some hybrid species. Wallacea encompasses approximately 347,000 square kilometers.

And that my friends, is the Wallace Line. See you next time!