[our understanding of] The ‘hobbit’ is growing up!

Homo floresiensis, or the ‘hobbit’ in popular media, turned 10 years old last month. Well, it’s more accurate to say the study of the hobbit turned 10 years old. H. floresiensis was discovered in October of 2004 buried deep in a cave on the island of Flores in Indonesia. Much like the women on “I didn’t know I was pregnant”, scientists were shocked to find a small-bodied, weird-looking human. After studying the fossils and discovering the species was incredibly short with disproportionately long feet, it was aptly nicknamed ‘the hobbit.’

liang bua cave
Excavations at Liang Bua, Flores, Indonesia

While the majority of the scientific community has accepted H. floresiensis for what it is, a primitive species of hominin – H. sapiens’ cousin, some argue it is a pathological modern human. Over the last 10 years dozens of studies have been published about the hobbit suffering from any disease they could find in a medical dictionary including Down Syndrome, Laron syndrome, microcephaly, some even claimed it is a cretin, which sounds just as bad as it actually is. A lot of these studies base their claims on the short stature (~1m or 3ft 6in tall) and alleged excessive asymmetry (the left and right sides of the face don’t match up) for the individuals.

hobbit
Left: Homo floresiensis; Right: modern human

There are a lot of problems right off the bat with these claims. First, there is no evidence of these specific diseases on the fossils, but there is lots of evidence that H. floresiensis had enough distinct features to be a unique species. If you can look past that, many other fossil hominins were quite short; the famous Lucy (Australopithecus afarensis) was also about 1m tall. Moreover, many modern human populations have shrunken down in different ecological conditions. These pygmies aren’t diseased, and their skeletons look exactly like any other modern human.

But the hardest claim to shake is the alleged asymmetry in the face of the only H. floresiensis skull. Even researchers who believe it is a distinct species have to admit that the skull is really asymmetrical. Unfortunately for paleoanthropologists, not developing symmetrically tends to happen in modern human individuals that are either sick or suffer from poor nutritional conditions as kids. Because of this, it has been hard for scientists to definitively prove H. floresiensis is in fact a valid species.

Until now. Last semester I had to do a class project on some member of the genus Homo. I decided to tackle this enigmatic fossil and find explanations for the asymmetry that wouldn’t include a dramatic pathology. I collected 3D coordinate points from a cast of the fossil skull along with 134 modern human actual skulls from the collections at the American Museum of Natural History. I chose a variety of individuals from all around the world: Europe, Asia, Africa, and the Americas; people from continents and islands big and small; populations from hot tropical forests to cold snowy tundra. I thought that I may find a pattern of asymmetry increasing on islands since H. floresiensis is found on a small island where resources are low.

To separate my study from others, I omitted points on the skull that were damaged or reconstructed. A lot happens to a skull before it is found as a fossil. First, the skull is a part of a living animal that dies. Death can be a damaging process. Afterwards, this dead animal needs to be buried quickly in an environment good for preservation. Think of what happened to your favorite childhood toy you buried in the yard for fun, and how your mom needed to throw it away when you dug it up a few days later. Now think of digging it up 20,000 years later. Once this fossil was finally settling in to its hole in the ground some guy came at it with a shovel. All these things that happen to a bone after death are part of a whole category of scientific study called taphonomy. Long story short, this fossil has a lot of areas that have been distorted. I figured some of the measured asymmetry might be from damaged areas and not actually represent how the fossil would have looked when it was alive- or at least right after it died.

When I took out the problematic points I was surprised to find that H. floresiensis was not asymmetrical at all. In fact, it was more symmetrical than the average modern human in my sample – awkward. Furthermore, the patterns of asymmetry in the modern humans did not match the predictions. Humans were not more likely to be asymmetrical on small islands or in harsher conditions. Instead, it seemed to be more closely predicted by relatedness where populations closer together were more likely to have similar degrees of asymmetry even if they lived in different environments – doubly awkward.

But I can only imaging H. floresiensis would be happy about my results. She has gone 10 years of people calling her ugly, or at best funny-looking. At least now she can blame it on the really bad 20,000 years she’s had.

party

You can read more about the fossil discovery here:
http://www.bbc.com/news/science-environment-29665829

http://www.nature.com/news/the-discovery-of-homo-floresiensis-tales-of-the-hobbit-1.16197

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