Thursday, 28 October 2004

"Hobbits" in Indonesia

This week excavators announced they had found human ancestor remains on the Indonesian island of Flores in 2003 and dated them to 18,000 years ago. The adult female, nicknamed Hobbit, was about three feet tall and had a skull about the size of a grapefruit. The working theory is that it descended from homo erectus, which is known to have inhabited the region. News reports: Wired, ABC, Illawarra Mercury. Read on.

This is being hailed as the most exciting anthropological discovery in 50 years. It is fascinating: human ancestors this short and with such small brain cases were believed to have died off about 3 million years ago. This find shows how bizarre-seeming evolutionary effects can occur when an island separates from larger land masses and its ecosystem is "suddenly" isolated for a long time. Australia's marsupials teach the same lesson, but they have become cliché.

Despite the mistreatment I am sure this discovery will receive in the Bible Belt, it reinforces the theory of evolution and highlights one of the key shortcomings of creationism and intelligent design. Evolution describes a process of mutation, adaptation, and natural selection and does not, under any circumstances, predict what morphologies should result from isolating an ecosystem for a long time. Sometimes it can, however, predict what morphologies can result from this kind of isolation.

To the extent that evolutionary theory does predict the future or posdict the past, it does so by examining a known starting point, the constraints within which change is possible, and the relevant environmental pressures. Contrast this with creationism, which states its conclusion before hearing evidence from more than one source and leaves no room for new data. Intelligent design similarly states its conclusion in advance, but at least it attempts to predict and postdict. However, its predictions and postdictions have been, thus far, uniformly wrong.

Notice that the "hobbit" skeleton looks pretty much like what you would expect of a humanlike creature of small size. From what little of the remains we have to examine, its features appear to have generally humanlike proportions. As the theory of evolution would predict, the creature does not have wings, fins, gills, or other features radically different from its close evolutionary relatives. Nothing about this find suggests supernatural or alien influence. (Although archaeologist Peter Brown joked, "I would have been less surprised if my colleagues had found an alien spacecraft.") This creature is simply an animal that was genetically isolated from its closest relatives for a few hundred thousand years. As the Wired article explains, isolation on an island like Flores typically puts selective pressure on human-sized animals to grow smaller — which is exactly what appears to have occurred in this instance. The too-common refrain from the creationist camps that evolution fails to make falsifiable predictions is, again, demonstrably wrong.

Correction (29 Oct.): The remains have been dated to sometime between 12,000 and 18,000 years ago. I stated the latter as if it were firmly established. Fortunately, however, this gives me an excuse to link to more news and commentary coverage: Nature's Special Report, Tech Central Station, The Australian

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