‘Hobbit’ Humans Much Older Than Previously Thought

I do love a good scientific controversy. I don’t mean the false kind of controversy peddled by climate change deniers and creationists, I’m talking about genuine arguments going on between real scientists at the cutting edge of human knowledge. Science is frequently portrayed as a close minded, dogmatic exercise in back slapping and reaffirming of existing doctrines. Scientists merely set out to confirm one another’s findings only to then laud it over the ignorant.

Nothing could be further from the truth. Science is very much a dog eat dog world where only those who produce results can survive. There are a lot of big egos in the field and a lot of time and effort is put into trying to prove rivals wrong.

If you want to look into a genuine scientific controversy then read up on what intelligence is and how to properly measure it, or what the first living organism was and how it came to be, or whether or not there are parallel universes. Believe it or not the question of what killed the dinosaurs is still an active debate though the meteorite impact hypothesis has gained ground in the public consciousness. And, of course, amongst academics it is generally accepted that there is no evidence, outside of the bible, that there was ever a dude called Jesus proclaiming himself the son of god 2,000 years ago. He almost certainly didn’t exist.

skull
Image courtesy of Ryan Somma

A more recent scientific controversy is the one surrounding the so-called hobbit people of the island of Flores in Indonesia. Located about 1,000 km north of Australia, 10 years ago a team of archaeologists discovered what turned out to be a highly contentious set of bones. They were clearly ancient and the team that discovered them contested that they had unearthed a completely new species of human, Homo floresiensis. The reason that they were so confident is that the skeletal remains were quite unlike any human species ever before seen, modern or ancient.

As you can probably guess from the hobbit moniker, the individuals in question were rather on the short side. A grown adult stood about three and a half feet (1 metre) tall and weighed just 55 pounds (25 kg); that’s smaller than our australopithecine ancestor Lucy. Another difference from modern Homo sapiens is that the brain cavity is much smaller, only 380 cubic centimetres or so, which would make it about one third the size of our own. Nine individuals were found and one of those was a nearly complete specimen, an adult female, dubbed Flo. Initial estimates of the age of the remains put Flo in the region of 12,000 years old; this would make her and her kin contemporaneous with modern man who are known to have made it to Australia about 50,000 years ago.

Here is where the controversy begins, however. There is a camp of paleoanthropologists who believe that Flo isn’t a distinct species from us at all, they argue that she is merely a normal modern human who happened to have some kind of disease that made her shorter and her skull smaller. The leading contenders are some kind of syndrome resulting in microcephaly (one of symptoms of the suspected zika virus infection of pregnant women in Brazil currently); Laron Syndrome, which results in short stature and microcephaly; or Down Syndrome. If this group of remains were, in fact, diseased or had genetic mutations resulting in this particular phenotype then they wouldn’t be another species at all and Homo floresiensis would have ceased to be before the ink on the new exhibits in the Natural History Museums of the world has had a chance to be defaced by bored teenagers.

Plus, us humans don’t play nice. We’re not big on sharing our environment with competitors. We made short shrift of Homo neanderthalensis and Homo erectus and they were much bigger and stronger than little old Flo. Is it really likely that modern humans shared the island with H. floresiensis for tens of thousands of years without killing them off? And if we didn’t finish them then what did?

On the other hand, whilst those pathology based hypotheses go some way to explaining some of the features seen in the group, none of them really do a good job of explaining all of them. It’s not impossible that they were somehow ill, but they would have to be quite extraordinary examples and then, of course, we just happened to stumble upon those freakish outliers.

Those in favour of Flo as a new species argue that she is short due to island dwarfism, a well characterised trait whereby isolated populations with limited resources evolve to be smaller. Plus, would a microcephalic individual be likely to survive to adulthood in prehistoric Indonesia? Found in amongst the remains are tools crafted by Flo and her buddies, would a microcephalic population be likely to have advanced to tool use?

map
Flores Island. Google Maps.

Every couple of years a new paper is published by one side or the other and the debate revives anew armed with the latest analyses. The reason I am bringing this whole topic up today is that this week another such paper was published in Nature, this time on the side of Flo. The team that originally discovered her has conducted more digs and a barrage of multiple different dating tests on lots of different samples including the soil and rock around the bones and the bones themselves. The new results are very different from those first put forward.

Initial dating was done by analysing the material directly above the remains and this gave a result of about 12,000 years. Having dug more pits, however, the team have now realised that the sedimentary deposits in the cave are a lot more complicated than first thought. There was a period of several thousand years where the cave was exposed to floods. These floods eroded away many thousands of years of deposited material and left fresh sediment on top of it that was much younger than the layer immediately beneath; this, they say, accounts for the early date.

The new data puts the bones and the sediments immediately around them at between 60-80,000 years of age. This would mean that there potentially never was any overlap between Flo and her larger cousins thereby removing one of the two major arguments against the designation of a new species.

Naturally, the other side has already gotten its comeback in and they say that it doesn’t matter whether the remains are one thousand or one million years old, they’re still of a diseased Homo sapiens population.

The fact is that this won’t be properly cleared up until we have more data points. To be secure in our assertion of a new species we need more examples of Flo in different locations all showing the same features. For what it’s worth, which is basically nothing, I think it’s a new species. I think it’s more likely that a smaller version of us evolved in an isolated area than that we happen to have discovered freakish examples of ourselves. The real fun, though, will be in watching these two groups continue to thrash it out over the coming years. I’m excited.

cave
The Lian Bua cave, Flores, Indonesia. Image courtesy of Rosino
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One thought on “‘Hobbit’ Humans Much Older Than Previously Thought

  1. I do enjoy your posts on such events; always a healthy dose of skepticism to go along with your thorough research. I, too, look forward to finding out more about these small cousins of ours, and also ‘feel’ it’s a new species. If that is so, I also think it is quite likely our ancestors made short work of ridding themselves of the competition; we have always been the best killers around, often practicing our skills ‘just because we can’….

    gigoid, the dubious

    Liked by 1 person

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