Were 'hobbit' hominids island dwarfs?

Apr 16, 2013
Remains of Indonesia's hobbit-sized humans (L) and modern human (R) in Yogyakarta, on November 5, 2004. Japanese scientists on Tuesday waded into a row over so-called "hobbit" hominids whose remains, found on a remote Indonesian island a decade ago, have unleashed one of the fiercest disputes in anthropology.

Japanese scientists on Tuesday waded into a row over so-called "hobbit" hominids whose remains, found on a remote Indonesian island a decade ago, have unleashed one of the fiercest disputes in anthropology.

The most detailed computerised scan of a skull of Homo floresiensis—"Man of Flores"—backs theories that the minute humans were a local product of evolution, they said.

Marooned descendants of a hominid called Homo erectus, these people progressively "dwarfed," becoming smaller and smaller to match the availability of food on the island, they suggested.

The findings are a knock to rival hypotheses that surfaced after an Australian-Indonesian team unearthed the bizarre remains in a cave in 2003.

Dubbed after the wee folk in J.R.R. Tolkien's tale, the "hobbits" were just over a metre (3.25 feet) tall, weighed around 25 kilos (55 pounds) and had a brain roughly the size of a chimp's, our closest primate relative.

The find raised huge questions about the human odyssey.

Was H. floresiensis a separate species?

And if so, how come it shared the planet with Homo sapiens some 13,000 years ago, when—so far as was known—anatomically modern man was the sole, supreme strain of human?

A team led by Yousuke Kaifu of the National Museum of Nature and Science in Tokyo measured the brain capacity of "LB1," the most intact specimen out of nine found on Flores, using a computed tomography (CT) scanner.

They put the at 426 cubic centimetres (14.4 fluid ounces), somewhat higher than earlier estimates of around 400 cc (13.5 fluid ounces), but still only a third of a H. sapiens brain, which is around 1,300 cc (40.5 fluid ounces).

The small brain size, argues the Kaifu team, is consistent with a slimmed-down descendant of —"upright man" who was the first human to leave Africa.

H. erectus lived from around 1.7 million years ago to roughly 50,000 years ago. points to a creature that was about the size and weight of H. sapiens, but with a smaller brain.

Kaifu's team believe that the hobbits' ancestor was a scrawnier, Javanese version of erectus. Its brain size would have been around 860 cc (29 fluid ounces).

Its descendants, cut off from the rest of the world, went through thousands of years of diminution, scaling down in size to match availability of food on the island, according to their theory.

This phenomenon, known as insular dwarfing, is well known among biologists. Indeed, Flores at the time had a pygmy elephant called a stegadon, butchered remains of which were found in the floor of the hobbits' cave.

"Contrary to expectations by some researchers, it is possible that large-bodied Javanese Homo erectus migrated to the solitary island and evolved into by marked island dwarfism," Kaifu believes.

Two other ideas have come forward to explain the mysterious folk.

One is that they were descendants of a much earlier, small-brained hominid called Homo habilis. But, say critics, no evidence has ever been found that this human reached Asia.

The other is that the Flores bones are simply those of H. sapiens who suffered from a neurological disability called dwarf cretinism, possibly because of iodine deficiency in their diet. This would have made their brains abnormally small.

But, say naysayers, cretinism does not explain how the little were smart enough to kill animals, use fire and wield stone tools to butcher their prey.

The insular dwarfism theory is not new, but Kaifu said he can further back it by a computer simulation from 20 worldwide populations of modern humans.

These show that the scaling down of H. floresiensis' brain, in line with its tiny body, is entirely possible.

"New models of the brain-size reduction in the evolution of H. floresiensis... show (a) more significant contribution of scaling effect than previously claimed," according to the paper, appearing in the British journal Proceedings of the Royal Society B.

Explore further: Researchers create methylation maps of Neanderthals and Denisovans, compare them to modern humans

More information: Research paper: rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2013.0338

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Lurker2358
1 / 5 (8) Apr 16, 2013
They put the brain size at 426 cubic centimetres (14.4 fluid ounces), somewhat higher than earlier estimates of around 400 cc (13.5 fluid ounces), but still only a third of a H. sapiens brain, which is around 1,300 cc (40.5 fluid ounces).


You know, ancient superstitious cultures hated dwarves and midgets. They may have been exiled to the island, by people suspecting they were possessed by evil spirits, or some such, and then they just populated the island afterwards. Would work similar to the way Australia was populated by the English.

Another possibility is the Taupo eruption might have separated the midgets somehow. Sea level changes or such, the midgets walk to the island, sea level change again, midgets can't get back off the island, but the tall people can...sea level changes some more...midgets are stuck.
Birger
4.3 / 5 (3) Apr 17, 2013
Simple solution: Ask Svante Pääbo and his colleagues at the Max Planck institure to sequence the genome of the "hobbits".
Torbjorn_Larsson_OM
5 / 5 (1) Apr 17, 2013
@Lurker: Flores is famous for being on the other side of the Wallace line. Meaning there were never a land bridge, and these hominds are evidence that H. erectus rafted at times.

Also, the first Flores tools are ~ 800 000 years old. Too old for Taupo (~ 27 000 years).

@Birger: Pääbo tried and failed so far. The wet bones are like "papier mache", and generally DNA degrades fast in hot climates.

I'm sure they will try again if better teeth, bones or techniques present themselves.
rwinners
1 / 5 (1) Apr 17, 2013
Oh. Models. How do you model human evolution in the past?
Torbjorn_Larsson_OM
not rated yet Apr 18, 2013
@rwinners: Same as you model all processes, by using the available observational and theoretical constraint. "Past" have nothing to do with it, all our observations is in the past of our lightcone. It is "future" that is a problem, having to wait for the next observation.

Population models of hominid species such as ours is all the rage now after 3 subspecies of humans (Moderns, Neanderthals, Denisovans) have been sequenced. But here they model biological scaling, based on surface/weight ratios and what it means for organs. Dogs are especially helpful for calibrating the models I think, seeing the selected size differences.

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