Monday, April 15, 2013

Much ado about little extinct people

Once again, it is time for a time warp post from the beginning of my bloggering days in 2005. This time, I go back to my enthusiasm about the discovery of Homo floresiensis, thinking them to be a good candidate for the legends of three foot tall human-like creatures called the Ebu Gogo. (Alas, hobbits are still fictional.)
` It is certainly true that H. floresiensis outlived the Neandertals, but were they alive recently enough to have been remembered in the Nage people's legends? Or, more likely, could the inhabitants of Flores living thousands of years ago have come across fresher remains than what has been found in modern times?
` At the time, I had been hit with the bug of thinking about such exciting possibilities -- probably because I had read such articles as this one from Nature News.

I apologize in advance for the 'white highlighter' effect on the text, which I didn't know about until I published the post, and have no idea what to do about it. I did, however, "deblathify" the first of these for your reading pleasure:

Richard Roberts and the Little People (deblathified)

Despite the title, it doesn't actually have much to do with the archaeologist Richard Roberts, although the second one was about him and a certain Teuku Jacob, who claimed that the H. floresiensis bones were merely a deformed modern human.
` Unfortunately, that post disappeared -- I don't recall how -- which leaves us with this one:

Richard Roberts, Little People, and Snits

At the time, television interview transcripts were one of very few sources of information I could find about the kerfuffle over Jacob hiding the H. floresiensis remains (apparently from people who didn't agree that they were  modern humans).
` Three months later, he returned the bones, with serious damage apparently caused by making casts. According to this BBC article:
The damage included long, deep cuts marking the lower edge of the Hobbit's jaw on both sides, said to be caused by a knife used to cut away the rubber mould. 
In addition, the chin of a second Hobbit jaw was snapped off and glued back together. Whoever was responsible misaligned the pieces and put them at an incorrect angle. 
The pelvis was smashed, destroying details that reveal body shape, gait and evolutionary history.
Way to go, Team Jacob! Then, presumably to further stop anyone from disproving Indonesia's "king of paleontology", the Indonesian government blocked scientists from the dig site until Jacob's death in 2007. Yes, really.

Originally, I was going to go on to say that there is no longer any doubt about H. floresiensis being a new species because more remains, including another skull, were found on a separate island. However, I was surprised to find absolutely no mention of this anywhere on the internet, not even as a hoax.
` I don't know how I could have gotten such a false impression, but it happens from time to time, and this is why I generally check my facts before spouting them to the whole world. So, what did I find?

First of all, showing that H. floresiensis really is its own species and not a diseased human is possible without finding a second skull. For one thing, there are two different jawbones that "match", so the second jawbone probably went to a skull that is similar to the first.
` Also, there are many different bits of other individuals that similarly "match" the near-complete skeleton, which is called LB1. If LB1 was surrounded by so many others that looked like her, as far as we can tell, then who's to say that she's a mutated freak with a deformed skull?

Nevertheless, many scientists have tried to show that Homo floresiensis is a modern human, which is a good thing, because that's how you rule out all the ideas that don't make sense.
` For example, LB1 has been speculated to have an interesting genetic condition called Laron Syndrome, a type of dwarfism caused by a mutation that affects growth hormone receptors. However, the skulls of such people are widest toward the top of the head, with a protruding forehead and an abnormally small face.
` This is exactly the opposite sort of 'deviation' from LB1's skull: It is broadest at the base, with a backswept, sloping forehead, and a disproportionately large face. With such contradictory evidence, it's no wonder this idea has been discredited.
` Despite the small size of the braincase, the brain was similarly shaped to that of a modern human, with large temporal and frontal lobes, and other advancements that modern humans don't have. This is not the case for humans with microcephaly, which has also been suggested as an explanation for the skull and skeletal deformations of the Liang Bua individuals.
` Even without a normal-sized brain, various features of a microcephalic's skull fit within the range of normal human head measurements, whereas the LB1 skull does not, and the same can be said of the rest of the skeleton.
` Another speculation is that these little people are just 'cretins', that is, they aren't getting enough thyroid hormone, as some Flores natives do today. Such deformities also don't match, although they could have helped to inspire legends of the Ebu Gogo.

If Homo floresiensis isn't a deformed modern human, then what is it? As I talked about in the first article, it seems to be a dwarfed version of something like a Homo erectus. However, the brains of modern human pygmies are less reduced in size compared to their bodies, whereas the brains of H. floresiensis are instead shrunken far more than H. erectus.
` A similarly disproportionate brain size reduction has also happened among the extinct Balearic Islands Cave Goat, and on the UK's Natural History Museum website, I found a page with a video that discusses the dwarfism of extinct Madagascar hippopotamuses having a similar brain size reduction as H. floresiensis.

Due to a spotty fossil record for early Homo species, it is not known whether they share many of H. floresiensis' other skeletal characteristics, such as long arms and short legs, and Australopithecus-like wrist bones. Other such "primitive" characteristics include long foot bones with no medial arch, curved toes, and a short 'big' toe.
` Unlike what I had thought at first, H. floresiensis tools were similar to the first stone tools in the archaeological record, and were found among evidence of the use of fire for cooking and the butchered bones of the dwarf Stegodon elephants.
` These tools were found in strata as old as 94,000 years ago, and no later than 12,000, although this is just one snapshot in time -- they may have lived long after this.

For your further reading enjoyment, I found this fully-referenced Nature Education article, Making Sense of the Small-Bodied Hominin Fossils from Flores -- although I should note that the bones are not technically fossilized.
` As a bonus, I found a video on YouTube that shows what happens when your little cretin goes untreated for 28 years -- now that's bizarre! Also, here's a really cute microcephalic boy who is now learning to speak, thanks to surgery that allows him to move his tongue more normally.
` Somehow, I think that even people with milder versions of these disorders would have a more difficult time than the rest when it comes to surviving 30 years in a jungle full of lethal hazards. After all, you have to be on top of your game when your way of life involves killing Stegodons and defending the meat from enormous, infectious bitey lizards.

Those Ebu Gogo, or whatever they were -- they had small brains, but they were tough and smart for their size. It is thought that a volcanic eruption that killed off many species also decimated H. floresiensis. My bet is that if it weren't for their confinement to a volcanic island, we may have heard about H. floresiensis long before now.

[Note: I don't know what the deal is with the white background, so if anyone knows how to fix it...]

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