Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

No hobbits in this shire

23.08.2006
The skeletal remains found in a cave on the island of Flores, Indonesia, reported in 2004, do not represent a new species as then claimed, but some of the ancestors of modern human pygmies who live on the island today, according to an international scientific team.

The researchers also demonstrate that the fairly complete skeleton designated LB1 is microcephalic, while other remains excavated from the site share LB1's small stature but show no evidence of microcephaly, since no other brain cases are known. Microcephaly is a condition in which the head and brain are much smaller than average for the person's age and gender. It can be present at birth or develop afterwards and is associated with a complex of other growth and skeletal anomalies.

"Our work documents the real dimensions of human variation here," says Dr. Robert B. Eckhardt, professor of developmental genetics and evolutionary morphology, department of kinesiology, Penn State. He notes that "LB1 looks different if researchers think in terms of European characteristics because it samples a population that is not European, but Australomelanesian, and further because it is a developmentally abnormal individual, being microcephalic."

Teuku Jacob, laboratory of bioanthropology and paleoanthropology, Gadjah Mada University, Indonesia, was granted permission to study the original bones by Radien P. Soejono, National Archaeological Research Center, Jakarta, Indonesia. The analysis by Jacob's full research team, including Eckhardt and others mentioned below, demonstrates that claims of a new species – "Homo floresiensis" -- commonly called hobbits, are incorrect.

Jacob and colleagues found four major areas of evidence where the 2004 evaluation was wrong: geographical factors, craniofacial asymmetry, dental traits, and postcranial abnormalities. They discuss these areas in today's (Aug 21) online edition of the Proceedings of the National Academy of Sciences.

Those proposing a separate species had claimed that early human ancestors, Homo erectus, traveled to the island about 840 thousand years ago and evolved into "Homo floresiensis," based on the discovery of stone tools on the island. This claim assumed that there was no subsequent human migration to the island until after "Homo floresiensis" died out about 15,000 years ago. Jacob and colleagues contend this is false since pygmy elephants (Stegodon) arrived on the island at least two separate times, and during periods of low sea levels Flores was isolated from other islands by only a few kilometers, as shown by K. Hsü, National Institute of Earth Sciences, Beijing. Repeated influxes by later humans were not only possible, but likely.

For LB1'S cranium, face, dentition, skeleton, they find that many of the key features previously said to be diagnostic of a new species still are present in the Rampasasa pygmies on the island today, along with evidence for growth abnormalities.

One error made in the earlier proposal of a new species was that "comparisons of LB1 were made mostly with Homo sapiens from other geographic areas of the world, principally Europe," the researchers note. "Yet it would have been logical even for a supposedly novel human species from the Australomelanesian region to have been compared with other human populations, present as well as past, from that region," they added.

"To establish a new species, paleoanthropologists are required to document a unique complex of normal traits not found in any other species," says Eckhardt. "But this was not done. The normal traits of LB1 were not unique, and its unusually small braincase was not normal."

To study LB1's traits, 94 cranial features and 46 features of its mandible were compared to values for modern humans. All fell within the normal range of variation for Australomelanesians. Two anatomical details, particular grooves in the cranial base singled out as "not seen in modern humans," in the 2004 new species announcement are, according to Alan Thorne, archaeology and natural history, Research School of Pacific and Asian Studies, Australian National University, Canberra, commonly found in Australian and Tasmanian crania.

Dental configuration also can be used to designate a new species. The original researchers argued that a CT scan showed the absence of a third molar and that there was some atypical positioning of other teeth. However, Maciej Henneberg, anatomical sciences, University of Adelaide, Australia and Etty Indriati, laboratory of bioanthroplogy and paleoanthropology, Gadjah Mada University, found an existing socket and a tooth fragment in the space where the molar supposedly was missing. The unusually positioned teeth were there, but such teeth also are found in a sample of Rampasasa pygmies who still live on Flores.

LB1 is short in stature and has a small brain, but rather than a sign of a new species, the researchers consider this to represent microcephaly. The ratios of LB1's cranial capacity and stature are similar to ratios found over several generations in some 20th-Century families of microcephalics.

Understanding normal biological development may be the key to showing that LB1 really is pathological. Of 184 syndromes that include microcephaly, 57 also include short stature; some also include facial asymmetry and dental anomalies. Henneberg notes that "while we do not in this paper diagnose the specific syndrome present, many characteristics point to an abnormal developmental disorder."

To visualize the facial asymmetry, David W. Frayer, professor, department of anthropology, University of Kansas, composed split photographs of LB1's face, combining two left or two right sides as composite faces. The dissimilarities from the original face and between the two left or right composites were striking. To quantify these differences the researchers compared left and right side measurements on the original face.

"I was looking for a standard of how much asymmetry was normal and eventually found a review article covering dozens of papers, some published nearly a century ago in England's prestigious Galton Laboratory" says Eckhardt. "While most faces are not perfectly symmetrical, asymmetry of the facial skeleton that exceeds about 1 percent is unusual."

He and Adam J. Kuperavage, graduate student, kinesiology, Penn State, found that six of seven measurements were larger on LB1's right side by as much as 40 percent, while the seventh was 6 percent larger on the left. LB1's craniofacial asymmetry indicates that this individual was not developmentally normal.

Another supposed indication of a new species was the unusual robustness of the leg bones. "CT scans show that the cortex, the outer solid bone, is very thin, not robust at all," says Henneberg. "The bone is thin and straight. The attachment of the muscles suggests muscle paralysis."

Eckhardt found that the low degree of humeral torsion – twisting of the upper arm bone between the shoulder and elbow – also was not a sign of a new species, but of developmental problems. The normal humeral torsion for a human is about 142 degrees, but LB1 has only 110 degrees of torsion. However, humeral torsion is influenced by both genetic and developmental factors, with about two thirds coming from inherited programming and one third from use. With disuse, torsion is usually only about 110 degrees. Both humeral torsion in the arm and the muscle markings on the femur and tibia in the leg indicate an individual with movement disabilities.

While other skeleton parts were found with LB1 in the same cave, no other cranial parts attributed to this population were unearthed and LB1 is the only reasonably complete skeleton.

The researchers conclude that "The LB1 individual exhibits a combination of characteristics that are not primitive but instead regional, not unique but found in other modern human populations, particularly some still living on Flores, and not derived but strikingly disordered developmentally."

"LB1 is not a normal member of a new species, but an abnormal member of our own," says Eckhardt.

A'ndrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Life Sciences:

nachricht Rutgers scientists discover 'Legos of life'
23.01.2018 | Rutgers University

nachricht Researchers identify a protein that keeps metastatic breast cancer cells dormant
23.01.2018 | Institute for Research in Biomedicine (IRB Barcelona)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Optical Nanoscope Allows Imaging of Quantum Dots

Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.

Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Rutgers scientists discover 'Legos of life'

23.01.2018 | Life Sciences

Seabed mining could destroy ecosystems

23.01.2018 | Earth Sciences

Transportable laser

23.01.2018 | Physics and Astronomy

VideoLinks Science & Research
Overview of more VideoLinks >>>