More important implications of Flores: fossil damage

It’s been a long day, more than a full work-day of fossils. Which is nice. Foolishly checking updates to Journal of Human Evolution instead of leaving to eat and relax, I find yet another paper about the Flores fossils. My interest in Flores has strongly declined since last year, yet I had to look. Too tired to read the paper, but rather skimming through the figures, I find out the following disappointing information:

An attempt was made to cast the LB1 mandible, which resulted in damage to surface bone. Filler was used to correct the visible damage, and external dimensions were altered due to the separation of cracks in the corpus and a corresponding increase in bigonial breadth. The deep cut marks now running along the lateral inferior corpus of the mandible are an artifact of the mold-making process (Fig. 5). The dimensions and morphology reported here were recorded prior to the LB1 mandible being removed from Jakarta, and are supported by CT scans, stereolithographic models, radiographs, and photographs.

During an attempt to cast this mandible, it was irreparably damaged. The symphysis was broken, the medial surface of the right ramus removed and poorly repaired (Fig. 16), and cut marks, glue, and filler are now a feature of the lateral corpus and ramus. This has altered the original arch dimensions, occlusion, and morphology of the symphysis and ramus. Data reported here are based on a limited number of dimensions and photographs recorded before LB6 left Jakarta, supplemented by measurements, photographs, radiographs, and CT scans recorded after the mandible was returned. Unfortunately, many of these observations can no longer be verified through reference to the original specimen.

Damage to fossils is a very unfortunate consequence of their study. I’m told that the Taung child (first Australopothecus africanus discovered) cannot be studied anymore, and that so many people have taken measuring calipers to the thing that its gross morphology is drastically and irreversibly altered. Fortunately, non-invasive methods of study, such as CT and laser scanning, are becoming more common. However, until scanning becomes cheaper and scans of fossils are made widely and easily available to all scientists, our fossils will continue to be subject to the abuses of study. Or they become unavailable. And one important criterion for research to be “Scientific” is for it to be reproducible. Reproducability is undermined by damage to fossils, witholding of fossils for fear of possible damage (or being data-greedy), and the inherent difficulties in making CT data easily available. Quite a shame.

I suppose I should end on a positive note. What I did like from my brief glimpse of the paper is that they published all their raw data. This is an important step to Scientific repeatability (although sometimes it is good to verify others’ work on your own).

Oh, and on a less positive note, there’s a principle components figure that is one of the worst things I have ever seen. The figure is supposed to demonstrate how modern humans, fossil humans, Australopithecus afarensis, and the LB1 and LB6 chins are distinguished base on their side-view outlines. Modern humans overlap every single group, including A. afarensis. So the significance of the Flores chins falling closest to some A. afarensis specimens is not so shocking: some modern and fossil humans fall closest to afarensis, too. Anyway, a terrible figure, which I refrain from posting here simply out of concern for copyright. But just imagine something painted by Jackson Pollock, or an explosion, or what Oreos look like inside your stomach.

Reference

Brown, P and Maeda, T. In press. Liang Bua Homo floresiensis mandibles and mandibular teeth: A contribution to the comparative morphology of a new hominin species. Journal of Human Evolution. doi:10.1016/j.jhevol.2009.06.002

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