Fossils Revisited: New Methods Applied to Old Bones

homo-erectus-300pxRevisiting the Trinil Femur

As a historian of science, a paper in the March 2015 issue of the Journal of Human Evolution recently caught my eye. The study reexamined the Trinil femur discovered by Eugene Dubois in 1892, using computed tomography to reconstruct the bone and compare it to other Homo femurs. This application of new tools to fossils that have been studied since the 1890s makes my historian of science brain giddy.

Revisiting fossils is not a new thing in paleoanthropology. Fred Spoor and others recently published a reevaluation of the OH 7 Homo habilis cranium using new technologies. In fact, these reevaluations are becoming increasingly common, opening up old fossil collections to possibilities and new insights. Reevaluations are interesting to me as a historian of science because they show how the same fossil can take on different meanings over time.Screen Shot 2015-04-01 at 8.01.28 PM

Pithecanthropus erectus: History

Eugene Dubois was wanted to find the “missing link” between apes and humans. Inspired by Haeckel and others who believed the fossils of human ancestors would be found in Asia, Dubois joined the Dutch Army so he could hunt for bones in Indonesia. Dubois has been celebrated in history as the first man who deliberately went looking for human ancestor fossils–and found them! (Neandertals had been found previously, but accidentally).

407936766In one of the miracles in the history of science, in a river bed in Java, Dubois found his “missing link.” He discovered a skull cap, along with a stray tooth, that came to be known as Java man. A year later he found a femur nearby and decided it must have belonged to the same individual. He named his discovery Pithecanthropus erectus (meaning upright ape man). As is clear from his naming, the femur was crucial in Dubois’s characterization of his missing link: it was the femur that suggested, to Dubois, that this creature walked upright. However, the fact that the bones were so loosely associated was problematic for scientists from the beginning, and questions over whether it could have been even contemporaneous with the femur sparked a debate that has lasted over a century.

Trinil Femur in 2015

javaThe Java man cranium is now categorized under the species Homo erectus, while the femur still remains a mystery. While many paleoanthropologists believe it is very unlikely that the bone belonged to the same individual, the question has become: is the Trinil femur that of Homo erectus as well? And was it even contemporary with the skull? This is where the new study weighs in. While many anthropologists have explored this issue over the years, this new study is particularly interesting. The authors, led by Christopher Ruff at Johns Hopkins, argue the femur’s characteristics are unlike any other Homo erectus. Instead, they argue, the femur looks more like later ice age humans. This group is not the first to argue that the femur is not contemporary with the skull cap and I can’t help but wonder if this study will help settle the debate.

So what?

Interpretations of fossils change over time and a fossil’s story gets increasingly interesting when new methods are applied to its study. New approaches to studying old fossils provide unique insights into the history of paleoanthropology because we can trace how conceptions of a single fossil has changed. The Trinil femur is a great example because it was originally so central to Dubois’ idea of his upright ape, but now it seems his crucial femur belonged to a totally different creature from a more recent time.javman

These kinds of studies raise questions in my mind, for example, how might technology continue to contribute to paleoanthropology? And new advances help settle debates such as the possible bipedalidty of Sahelanthropus tchadensis, for example? In the meantime, those of us interested in history will continue to look backwards, marveling at the progress paleoanthropologists have made, and enjoying the missteps that inevitably occurred along the way.

Source: Ruff, C. B., Puymerail, L., Macchiarelli, R., Sipla, J., & Ciochon, R. L. (2015). Structure and composition of the Trinil femora: Functional and taxonomic implications. Journal of human evolution, 80, 147-158

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