Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sediba’s ribcage and feet were not suitable for running

11.04.2013
Researchers at Wits University in South Africa, including Peter Schmid from the University of Zurich, have described the anatomy of a single early hominin in six new studies. Australopithecus sediba was discovered near Johannesburg in 2008. The studies in Science demonstrate how our two million year old ancestor walked, chewed and moved.

The fossils discovered four years ago in Malapa near Johannesburg show a mixture of primitive features of australopiths and advanced features of later human species. The researchers led by Prof Lee Berger of Wits University are therefore of the opinion that the new species is currently the best candidate for a direct ancestor of our own genus Homo.


Reconstruction of Au. Sediba.
Lee Berger; University of the Witwatersrand


2D reconstruction by Peter Schmid of the 2 million year old Australopithecus sediba.
Lee Berger; University of the Witwatersrand

Researchers are now presenting new studies, including those of Peter Schmid, who taught and did research at the University of Zurich until he retired. Also involved were UZH students Nakita Frater, Sandra Mathews and Eveline Weissen.

Schmid has described the remains of Au. sediba’s thorax. “They show a narrow upper ribcage, as the large apes have such as orang-utans, chimpanzees and gorillas”, says Peter Schmid. The human thorax on the other hand is uniformly cylindrical. Along with the largely complete remnants of the pectoral girdle, we see the morphological picture of a conical ribcage with a raised shoulder joint, which looks like a permanent shrug. The less well-preserved elements of the lower thorax on the other hand indicate a slim waist, similar to that of a human being.

Conical ribcage makes it difficult to swing arms when walking

The narrow upper thorax of apes enables them to move the shoulder blade, which is important for climbing and brachiation in trees. Its conical shape makes it difficult, however, to swing their arms when walking upright or running, plus they were a similar length to an ape’s. This is why Schmid assumes that Au. sediba was not able to walk or run on both feet as well as humans. “They probably couldn’t run over longer distances, especially as they were unable to swing their arms, which saves energy”, says Schmid.

An examination of the lower extremities shows a heel, metatarsus, knee, hips and back, which are unique and unprecedented. Sediba must have walked with feet turned sharply inwards. This inward turn distinguishes it from other australopiths. The conclusion to be drawn is that our early ancestors were able to move around in a different way.

Arms for climbing and brachiation

Au. sediba was an experienced climber. This is shown by the remains of the upper arm, radius, ulna, scapula, clavicle and fragment of sternum found in Malapa. These clearly belong to a single individual, which is unique in the entire previously known fossil record of the earliest hominins. With the exception of the hand bones described above, the upper extremity is exceptionally original. Au. sediba, like all the other representatives of the Australopithecus genus, had arms that were suitable for climbing as well as possibly for brachiation. Perhaps this capability was even more pronounced than has been assumed for this genus hitherto.
Differences from Australopithecus afarensis

Based on the dental crowns the researchers assume that Au. sediba does not belong phylogenetically to the eastern African australopiths but is closer to Au. africanus and thus forms a southern African sister group. This has an impact on our modern understanding of the evolution of early hominins from the late Pliocene. As such, Au. sediba and maybe even Au. africanus were not descended from Au. afarensis.

The lower jaw of the female skeleton was also examined along with previously unknown incisors and premolars. As noted already on the skull and other areas of the skeleton, the mandibular remains show similarities with other australopiths. They differ, however, in size and shape as well as in ontogenetic growth changes of Au. africanus. These results support the hypothesis that Au. sediba is taxonomically different from Au. africanus. In the relevant differences the parts of the lower jaw appear most to resemble those representatives of early Homo.

An analysis of the cervical, thoracic, lumbar and sacral region of the spinal column shows that Au. sediba had the same number of lumbar vertebrae as modern man. The strong hollow back suggests that he was more advanced in this area than Au. africanus and may be more likely compared with Homo erectus.

The new studies show a unique image of a human species with a mosaic-like physique. Some body parts are similar to those of earlier and others to those of later hominins. “The numerous similarities with Homo erectus suggest that Au. sediba represents the most appropriate early form of the genus Homo”, says Peter Schmid. The previous candidates are too fragmentary to be capable of occupying this position.

Bibliography:

Peter Schmid, Steven E. Churchill, Shahed Nalla, Eveline Weissen, Kristian J. Carlson, Darryl J. de Ruiter, Lee R. Berger. Mosaic Morphology in the Thorax of Australopithecus sediba. Science April 12. 2013. Doi: 10.1126/science.1234598
Contacts:
Peter Schmid
Tel. 001 865-230-1832 (until 13.4.2013)
Tel. +411 371 23 45
Email: smidi@aim.uzh.ch

Beat Müller | Universität Zürich
Further information:
http://www.mediadesk.uzh.ch

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>