Taking The Measure Of A Hobbit

In the February 25 Issue:

Taking the measure of a hobbit

Study of fossil skull suggests ancient creature could have been Homo sapiens

By Alexandra Witze

Web edition : Monday, August 8th, 2011

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HUMAN OR HOBBIT?Its discoverers claim that a tiny skull from the Indonesian island of Flores (left, with human skull on right) represents a new species of hominid. But a new analysis comparing the skull’s dimensions with those of people who have a genetic disorder called microcephaly suggests that the fossil belonged to a human who had that condition.P. Brown

There’s just no getting ahead when you’re a hobbit. Anthropologists are arguing yet again over whether a tiny 18,000-year-old Indonesian skull represents a separate species of little human cousins, or an ordinary Homo sapiens with an abnormally small head.

New data compare the fossil to a large group of modern humans with microcephaly, a genetic condition that makes the head smaller than usual. Measurements of the hobbit skull suggest its proportions fall within the range of microcephalic Homo sapiens, researchers report August 8 in the Proceedings of the National Academy of Sciences.

“Previously published papers that seemed to show that it can’t be a microcephalic are open to doubt,” says coauthor Ralph Holloway, an anthropologist at Columbia University in New York.

The hobbit story began in 2003, when archaeologists unearthed the skull and other bones of a female hominid on the island of Flores. Her discoverers argued she represented a member of a human genus that had survived until relatively recently, and dubbed it Homo floresiensis.

But some scientists charged that because the hobbit’s skull is so small, it might have just been a microcephalic Homo sapiens. To test that question, anthropologist Dean Falk of Florida State University in Tallahassee compared the skull’s internal dimensions to those of nine microcephalic humans and 10 normal humans. In a 2007 paper, she concluded the hobbit skull was still best assigned to its own species.

Now anthropologist Robert Vannucci of New York University and his colleagues, including Holloway, have measured relative brain dimensions using both MRI imaging and internal casts, or endocasts, of skulls. They compared the hobbit’s measurements against those of 21 microcephalic and 118 normal infants and children, along with 10 adult microcephalics and 79 normal adults.

With this larger group to study, Vannucci’s team concludes the hobbit actually falls in the range of microcephalic humans.

But Falk counters that the new work looked at the wrong skulls. Brains keep growing in microcephalics until about the age of four, she says, meaning that most of the infants studied by Vannucci’s team shouldn’t have been included. She also notes that the team at times used handheld calipers to measure rubber endocasts of skulls, which she says is less accurate than the three-dimensional computed tomography imaging used in her study.

Perhaps the only thing the hobbit warriors agree on is the need for more fossils to study. The skull remains the only braincase found of the hobbit people. Archaeologists have, however, unearthed other bones from at least eight other individuals. Together, the remains of these nine tiny people add up to a complete picture of a distinct creature that warrants its own species name, says hobbit co-discoverer Peter Brown of the University of New England in Armidale, Australia.

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Comments 5

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Microencephaly is usually accompanied by severely impaired intellectual development, with mental retardation being common. With the hunter-gatherer culture demanding as it is, what are the odds that an individual with a severe mental handicap will survive beyond childhood 18000 years ago?

Maybe that skull does represent a member of a separate branch of the Homo genus that has been subjected to Foster's Rule (the Island effect).

TitoTheThird

Aug. 9, 2011 at 11:30am
So, the brain volumes are comparable in this study. I am not sure this is the important thing. Does the morphology of the skull more closely resemble the micrcephalics, or a skull somewhere on the human ancestor continuim. Can this be determined. I seem to remember vaquely some work on this. To me it does look as if the Hobbit shows some primitive traits .
Do microcephalics?

Stuart Keith

Aug. 11, 2011 at 2:51pm
@Stuart: Dean Falk has been making a similar point about skull morphology for some time. She argues that if you put the hobbit endocast next to those of various microcephalics, the shapes are simply quite different -- with the hobbit having a long, low profile with an occipital lobe that projects farther back than the cerebellum compared to the microcephalics.

Alexandra Witze

Aug. 15, 2011 at 9:08am
The 18,000-year-old Indonesian skull appears to be a Homo erectus descendant. Note the absence of forehead. This raises the question, did Homo sapiens have encounters with Homo erectus? Probably.

JohnUmana

Aug. 16, 2011 at 10:30am
Alexandra, what I love about this debate is the fuss's really over whether "human cousins" - your term - can be viable as a species with such small brains, especially a small brained species that seems to've exhibited sufficient intelligence to mysteriously survive migrating across a region of sea both enormous in expanse and enormously difficult to navigate WITH a boat, never mind without a boat.

Yet if brain size's so problematical here, then how enormously more difficult to explain away the great dirty 'secret' of Evolution, the mystery of how more than one hundred people - and that's only the KNOWN ones - can hold down jobs as tax inspectors, lecturers, etc., in the 21st Century without having a brain at all !

alan borky

Aug. 16, 2011 at 10:30am

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