The hobbit is still Homo floresiensis

In 2003 Evolutionary Anthropology came crashing into popular culture with the discovery of Homo floresiensis, found – as the name might suggest – on the island of Flores. Affectionately nicknamed “the Hobbit” by the media, this diminutive creature stood at only 108 cm tall (~3′ 6”) and by virtue of this peculiarity managed to capture the public’s attention.

But being tiny is only scratching the surface of the bizarreness of H. floresiensis. The hobbit made tools on par with the humans of the time, despite having a brain 1/3 their size and lived during a time when all other hominins had died out (except H. sapiens).

Understanding the hobbit would revolutionise how we view human evolution, yet coming to terms with our miniature cousin is something we’ve yet to do. Why is it tiny? How could it make such complex tools? What species did it evolve from?

One persistent answer to the mystery surrounding the hobbit has been that it isn’t especially mysterious.  Almost as soon as it was categorised as a new species people were arguing that it wasn’t, that it’s actually just a Homo sapiens with some kind of condition.

Microcephaly – a condition in which a person’s head is signficantly smaller than average – was one of the first conditions proposed to explain H. floresiensis since it can produce individuals with a brain size on par with the hobbit. Although this typically greatly impairs intelligence, it would mean that there was a population of modern humans present who could produce the complex tools discovered.

Yet shortly after microcephaly was suggested it was refuted. Cranial scans of sufferers revealed that they had a significantly different brain shape than the hobbit did. Further, although victims of the condition have been known to be short, none have a skeleton similar to those found on Flores.

But that was not the end for those who dispute assigning the specimens from Flores to a unique species and in the intervening years they have suggested many other conditions which could explain the existence of the hobbit without drastically altering our understanding of human evolution.

The most recent pathological explanation for H. floresiensis is that they are “myxoedematous endemic cretins.” Now, I must confess that before I started researching this topic I only knew what 1/3 of those words meant: endemic (or “unique” to you lesser, non-sciency mortals).

Drat.

On top of that, even “endemic” has a different definition in the world of pathology.

Double drat.

So I guess it’s time to twirl my moustache and play “catch the definition.”

Which was surprisingly easy.

Clinically…[myxoedematous] cretins are usually distinguished by…extreme growth retardation, facial dysmorphism [differences], myxedema [insufficient amounts of thyroid] and less severe mental retardation

Further, clinical definitions typically come with a precise suite of features used to define the condition, allowing us to diagnose the specimens from Flores! Which is exactly what recent research has done, taking the extensive list of features used in the diagnosis of “cretinism” (I’m still not sure if I’m comfortable using that word) and applied them to the hobbits.

The comparison table is very long and the end result of this in-depth comparison? They aren’t alike at all. Other than the short stature, the only skeletal feature Homo floresiensis has with cretins is their humerus is twisted in a similar manner. Pretty much every other feature used to diagnose myxoedematous endemic cretinism is absent.

Rather hilariously, this includes having a normal sized brain! That’s right, the disease being used to explain why there were small-brained, small-bodied hominins on Flores does not result in small brains. Cretinism also results in differently shaped feet and hands, which the hobbit doesn’t have; it also means people keep their milk teeth, which the hobbit didn’t…

However, the hobbit skeleton doesn’t look as it would have when it was inside a person, having been altered and damaged by spending thousands of years in the dirt and during excavation. This introduces a potential source of error, since these specimens might only be different because they have been changed by such taphanomic (“after death”) processes.

Claiming that this is the case is one of the arguments put forwards by those suggesting the hobbit is just a cretin, suggesting that the skull size has been reduced hence the discord between the small-brained hobbits and the large-brained human cretins.

For example, they suggest that the skull used to be larger as there was cartilage between the bones, but this decayed and the bones came closer together, eventually fusing into a smaller sized skull.

Such alterations leave behind fingerprints on the bone, so to speak, which can allow this claim to be tested. As one might have guessed by now, it turns out those suggesting the hobbit is a cretin are wrong.

The areas which have undergone deformation don’t seem to align with where bones would merge if cartilage disappeared. On top of that, there are sections of the skull which aren’t deformed but should be if what the pro-cretin crowd say happened happened.

So, it would seem the hobbit is still the member of a unique species: Homo floresiensis. Which means the mystery is a mystery again.

For scientists, who love to investigate, this is good news. For those who just want easy answers well…

Triple drat.