Navigation Links
Flores bones show features of Down syndrome, not a new 'hobbit' human
Date:8/4/2014

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 thigh bones 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 thigh bones, 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 thigh bone with a formula derived from an African pygmy population. But humans with Down syndrome also have diagnostically short thigh bones, 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 thigh bones 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."


'/>"/>

Contact: Dave Pacchioli
dap1@psu.edu
814-865-9481
Penn State
Source:Eurekalert  

Related biology news :

1. Nitrogen source determined significant for inflorescence development in Phalaenopsis
2. Pod corn develops leaves in the inflorescences
3. Silk-based surgical implants could offer a better way to repair broken bones
4. Guys: Get married for the sake of your bones, but wait until youre 25
5. Calcium and vitamin D help hormones help bones
6. Putting flesh on the bones of ancient fish
7. Building healthy bones takes guts
8. Battling brittle bones... with broccoli and spinach?
9. Elk bones tell stories of life, death, and habitat use at Yellowstone National Park
10. BONESUPPORT für 2012 Top 100 Global Award von Red Herring ausgewählt
11. BONESUPPORT sélectionné en tant que 100 meilleures entreprises mondiales du Red Herring 2012
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Flores bones show features of Down syndrome, not a new 'hobbit' human
(Date:4/3/2017)... , April 3, 2017  Data ... precision engineering platform, detected a statistically significant ... product prior to treatment and objective response ... the potential to predict whether cancer patients ... to treatment, as well as to improve ...
(Date:3/29/2017)... CHICAGO , March 29, 2017  higi, the ... ecosystem in North America , today ... Partners and the acquisition of EveryMove. The new investment ... extensive set of tools to transform population health activities ... and lifestyle data. higi collects and secures ...
(Date:3/24/2017)... Research and Markets has announced the addition of the "Global ... to 2025" report to their offering. ... The Global Biometric Vehicle Access System Market ... the next decade to reach approximately $1,580 million by 2025. ... for all the given segments on global as well as regional ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... ... ... San Diego-based team building and cooking events company, Lajollacooks4u, has unveiled a ... new look is part of a transformation to increase awareness, appeal to new markets ... It will also expand its service offering from its signature gourmet cooking classes and ...
(Date:10/10/2017)... ... , ... Dr. Bob Harman, founder and CEO of VetStem Biopharma, Inc. ... The event entitled “Stem Cells and Their Regenerative Powers,” was held on August ... MPVM was joined by two human doctors: Peter B. Hanson, M.D., Chief of Orthopedic ...
(Date:10/10/2017)... ... October 10, 2017 , ... USDM Life Sciences ... the life sciences and healthcare industries, announces a presentation by Subbu Viswanathan and ... presentation, “Automating GxP Validation for Agile Cloud Platforms,” will present a revolutionary approach ...
(Date:10/9/2017)... ... , ... The award-winning American Farmer television series will feature 3 Bar Biologics ... at 8:30aET on RFD-TV. , With global population estimates nearing ten billion people ... to feed a growing nation. At the same time, many of our valuable resources ...
Breaking Biology Technology: