View Full Version : No Hobbits-Yes Down Syndrome?

08-08-2014, 02:32 PM
New research is apparently throwing doubt on the idea that there was a new and distict human species informally known as 'hobbits'...check it out

Flores bones show features of Down syndrome, not a new 'Hobbit' human

"In October 2004, excavation of fragmentary skeletal remains from the island of Flores in Indonesia yielded what was called "the most important find in human evolution for 100 years." Its discoverers dubbed the find Homo floresiensis, a name suggesting a previously unknown species of human.

Now detailed reanalysis by an international team of researchers including Robert B. Eckhardt, professor of developmental genetics and evolution at Penn State, Maciej Henneberg, professor of anatomy and pathology at the University of Adelaide, and Kenneth Hs, a Chinese geologist and paleoclimatologist, suggests that the single specimen on which the new designation depends, known as LB1, does not represent a new species. Instead, it is the skeleton of a developmentally abnormal human and, according to the researchers, contains important features most consistent with a diagnosis of Down syndrome.
"The skeletal sample from Liang Bua cave contains fragmentary remains of several individuals," Eckhardt said. "LB1 has the only skull and thighbones in the entire sample."
No substantial new bone discoveries have been made in the cave since the finding of LB1.
Initial descriptions of Homo floresiensis focused on LB1's unusual anatomical characteristics: a cranial volume reported as only 380 milliliters (23.2 cubic inches), suggesting a brain less than one third the size of an average modern human's and short thighbones, which were used to reconstruct a creature standing 1.06 meters (about 3.5 feet tall). Although LB1 lived only 15,000 years ago, comparisons were made to earlier hominins, including Homo erectus and Australopithecus. Other traits were characterized as unique and therefore indicative of a new species.
A thorough reexamination of the available evidence in the context of clinical studies, the researchers said, suggests a different explanation.
The researchers report their findings in two papers published today (Aug. 4) in the Proceedings of the National Academy of Sciences.
In the first place, they write, the original figures for cranial volume and stature are underestimates, "markedly lower than any later attempts to confirm them." Eckhardt, Henneberg, and other researchers have consistently found a cranial volume of about 430 milliliters (26.2 cubic inches).
"The difference is significant, and the revised figure falls in the range predicted for a modern human with Down syndrome from the same geographic region," Eckhardt said.
The original estimate of 3.5 feet for the creature's height was based on extrapolation combining the short thighbone with a formula derived from an African pygmy population. But humans with Down syndrome also have diagnostically short thighbones, Eckhardt said.
Though these and other features are unusual, he acknowledged, "unusual does not equal unique. The originally reported traits are not so rare as to have required the invention of a new hominin species."
Instead, the researchers build the case for an alternative diagnosis: that of Down syndrome, one of the most commonly occurring developmental disorders in modern humans.
"When we first saw these bones, several of us immediately spotted a developmental disturbance," said Eckhardt, "but we did not assign a specific diagnosis because the bones were so fragmentary. Over the years, several lines of evidence have converged on Down syndrome."
The first indicator is craniofacial asymmetry, a left-right mismatch of the skull that is characteristic of this and other disorders. Eckhardt and colleagues noted this asymmetry in LB1 as early as 2006, but it had not been reported by the excavating team and was later dismissed as a result of the skull's being long buried, he said.
A previously unpublished measurement of LB1's occipital-frontal circumference -- the circumference of the skull taken roughly above the tops of the ears -- allowed the researchers to compare LB1 to clinical data routinely collected on patients with developmental disorders. Here too, the brain size they estimate is within the range expected for an Australomelanesian human with Down syndrome.
LB1's short thighbones not only match the height reduction seen in Down syndrome, Eckhardt said, but when corrected statistically for normal growth, they would yield a stature of about 1.26 meters, or just over four feet, a figure matched by some humans now living on Flores and in surrounding regions.
These and other Down-like characteristics, the researchers state, are present only in LB1, and not in the other Liang Bua skeletal remains, further evidence of LB1's abnormality.
"This work is not presented in the form of a fanciful story, but to test a hypothesis: Are the skeletons from Liang Bua cave sufficiently unusual to require invention of a new human species?" Eckhardt said.
"Our reanalysis shows that they are not. The less strained explanation is a developmental disorder. Here the signs point rather clearly to Down syndrome, which occurs in more than one per thousand human births around the world."
Additional context is available on the authors' website at www.LiangBuaCave.org.
Story Source:
The above story is based on materials provided by Penn State. The original article was written by David Pacchioli. Note: Materials may be edited for content and length.
Journal References:
Maciej Henneberg, Robert B. Eckhardt, Sakdapong Chavanaves, and Kenneth J. Hs. Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis. PNAS, 2014; DOI: 10.1073/pnas.1407382111
Robert B. Eckhardt, Maciej Henneberg, Alex S. Weller, and Kenneth J. Hs. Rare events in earth history include the LB1 human skeleton from Flores, Indonesia, as a developmental singularity, not a unique taxon. PNAS, 2014; DOI: 10.1073/pnas.1407385111"


04-07-2016, 07:06 PM
If indeed these were not Hobbits but AMH, that would put AMH in Indonesia at least 60000ybp.

Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia
Sutikna et al.

"the skeletal remains of H. floresiensis and the deposits containing them are dated to between about 100 and 60 kyr ago, whereas stone artefacts attributable to this species range from about 190 to 50 kyr in age ...

Coverage by Ellen Callaway http://www.nature.com/news/did-humans-drive-hobbit-species-to-extinction-1.19651

Tom Higham, an archaeological scientist at the University of Oxford, UK, says that the latest dating work is compelling. “These results are tantalizingly close to the earliest evidence for modern humans in the region, which might suggest a causal link to the subsequent disappearance of H. floresiensis,” Higham adds.

and John Hawks http://johnhawks.net/weblog/fossils/flores/sutikna-liang-bua-stratigraphy-dating-2016.html

"The new stratigraphic and chronological evidence for Liang Bua indicates that a pedestal of remnant deposits, dating to more than ~46 kyr cal. BP, has an erosional upper surface that slopes steeply downwards to the north and is unconformably overlain by sediments younger than ~20 kyr cal. BP. All skeletal remains assigned to H. floresiensis are from the pedestal deposits dated to approximately 100–60 kyr ago, while stone artefacts reasonably attributable to this species range from about 190 kyr to 50 kyr in age. Parts of southeast Asia may have been inhabited by Denisovans or other hominins during this period, and modern humans had reached Australia by 50 kyr ago. But whether H. floresiensis survived after this time, or encountered modern humans, Denisovans or other hominin species on Flores or elsewhere, remain open questions that future discoveries may help to answer."

04-07-2016, 09:41 PM
The issue is still hotly debated. This article from 2015 (http://www.pnas.org/content/112/7/E604.full) provides additional argument that Homo floresiensis is a distinct species.
Henneberg et al. (1) and Eckhardt et al. (2) choose not to mention a number of other traits shared by the LB1 and LB6 mandibles that are also inconsistent with attribution to H. sapiens. Fig. 1 presents a CT scan of the LB1 mandible. It is obvious from this that, as has been pointed out previously (3), LB1 exhibits internal buttressing of the mandibular symphysis. This trait, which is also seen in LB6 (3), appears in earlier Homo but not H. sapiens. LB1 and LB6 also exhibit a strong extramolar sulcus, a trait found in early hominins but not H. sapiens (3). Additionally, LB1s and LB6s tooth root morphology differs from that seen in H. sapiens (3). DS cannot explain the presence of these traits in LB1 and LB6. Researchers who have studied modern people diagnosed with DS have not found these traits to be among the mandibular and dental features of DS (5, 6).

04-08-2016, 06:36 AM
Always the same arguments: taken separately, the traits fall within the modern human range of variation. But nobody can find a medical condition explaining all traits (the teeth by example). Moreover, this article is only assessing the fact that "it could have been....". Statistically, perhaps. But what are the odds to have several examples in a same place with a rare medical condition?

It's always interesting to confront different points of view. But homo florensiensis seems to generate something other. It reminds me of the way how an admixture of Homo sapiens with homo neanderthalensis was debated before (and after!) 2010. Very touchy.