Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unique skull find rebuts theories on species diversity in early humans

18.10.2013
Paleoanthropologists from the University of Zurich have uncovered the intact skull of an early Homo individual in Dmanisi, Georgia.

This find is forcing a change in perspective in the field of paleoanthropology: human species diversity two million years ago was much smaller than presumed thus far. However, diversity within the «Homo erectus», the first global species of human, was as great as in humans today.

This is the best-preserved fossil find yet from the early era of our genus. The particularly interesting aspect is that it displays a combination of features that were unknown to us before the find. The skull, found in Dmanisi by anthropologists from the University of Zurich as part of a collaboration with colleagues in Georgia funded by the Swiss National Science Foundation, has the largest face, the most massively built jaw and teeth and the smallest brain within the Dmanisi group.

It is the fifth skull to be discovered in Dmanisi. Previously, four equally well-preserved hominid skulls as well as some skeletal parts had been found there. Taken as a whole, the finds show that the first representatives of the genus Homo began to expand from Africa through Eurasia as far back as 1.85 million years ago.

Diversity within a species instead of species diversity

Because the skull is completely intact, it can provide answers to various questions which up until now had offered broad scope for speculation. These relate to none less than the evolutionary beginning of the genus «Homo» in Africa around two million years ago at the beginning of the Ice Age, also referred to as the Pleistocene. Were there several specialized «Homo» species in Africa at the time, at least one of which was able to spread outside of Africa too? Or was there just one single species that was able to cope with a variety of ecosystems? Although the early Homo finds in Africa demonstrate large variation, it has not been possible to decide on answers to these questions in the past. One reason for this relates to the fossils available, as Christoph Zollikofer, anthropologist at the University of Zurich, explains: «Most of these fossils represent single fragmentary finds from multiple points in space and geological time of at least 500,000 years. This ultimately makes it difficult to recognize variation among species in the African fossils as opposed to variation within species».

As many species as there are researchers

Marcia Ponce de León, who is also an anthropologist at the University of Zurich, points out another reason: paleoanthropologists often tacitly assumed that the fossil they had just found was representative for the species, i.e. that it aptly demonstrated the characteristics of the species. Statistically this is not very likely, she says, but nevertheless there were researchers who proposed up to five contemporary species of early «Homo» in Africa, including «Homo habilis», «Homo rudolfensis», «Homo ergaster» and «Homo erectus». Ponce de León sums up the problem as follows: «At present there are as many subdivisions between species as there are researchers examining this problem».

Tracking development of «Homo erectus» over one million years thanks to a change in perspective

Dmanisi now offers the key to the solution. According to Zollikofer, the reason why Skull 5 is so important is that it unites features that have been used previously as an argument for defining different African «species». In other words: «Had the braincase and the face of the Dmanisi sample been found as separate fossils, they very probably would have been attributed to two different species». Ponce de León adds: «It is also decisive that we have five well-preserved individuals in Dmanisi whom we know to have lived in the same place and at the same time». These unique circumstances of the find make it possible to compare variation in Dmanisi with variation in modern human and chimpanzee populations. Zollikofer summarizes the result of the statistical analyses as follows: «Firstly, the Dmanisi individuals all belong to a population of a single early Homo species. Secondly, the five Dmanisi individuals are conspicuously different from each other, but not more different than any five modern human individuals, or five chimpanzee individuals from a given population».

Diversity within a species is thus the rule rather than the exception. The present findings are supported by an additional study recently published in the PNAS journal. In that study, Ponce de León, Zollikofer and further colleagues show that differences in jaw morphology between the Dmanisi individuals are mostly due to differences in dental wear.

This shows the need for a change in perspective: the African fossils from around 1.8 million years ago likely represent representatives from one and the same species, best described as «Homo erectus». This would suggest that «Homo erectus» evolved about 2 million years ago in Africa, and soon expanded through Eurasia – via places such as Dmanisi – as far as China and Java, where it is first documented from about 1.2 million years ago. Comparing diversity patterns in Africa, Eurasia and East Asia provides clues on the population biology of this first global human species.

This makes «Homo erectus» the first «global player» in human evolution. Its redefinition now provides an opportunity to track this fossil human species over a time span of 1 million years.

Literature:
David Lordkipanidze, Marcia S. Ponce de León, Ann Margvelashvili, Yoel Rak, G. Philip Rightmire, Abesalom Vekua, and Christoph P.E. Zollikofer. A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo. Science. October 18, 2013. doi: 10.1126/science.1238484
Ann Margvelashvili, Christoph P. E. Zollikofer, David Lordkipanidze, Timo Peltomäki, Marcia S. Ponce de León. Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles. Proceedings of the National Academy of Sciences of the United States of America (PNAS). September 2, 2013. doi: 10.1073/pnas.1316052110

Project: Research and development collaborative work with huge leverage

The new research findings on Dmanisi are based on collaborative work ongoing for many years between the Anthropological Institute at the University of Zurich and the Georgian National Museum in Tbilisi. The Dmanisi project is financed by SCOPES (Scientific co-operation between Eastern Europe and Switzerland), a research program co-funded by the Swiss National Science Foundation (SNSF) and the Swiss Agency for Development and Co-operation (SDC). This research tool operates with a comparatively modest budget, but has a major and positive impact on the research landscape in the participating countries.

Contacts:
Prof. Christoph P.E. Zollikofer
Anthropological Institute
University of Zurich
Phone: +41 44 635 54 27
E-mail: zolli@aim.uzh.ch
Dr. Marcia S. Ponce de León
Anthropological Institute
University of Zurich
Phone: +41 44 635 54 27
E-mail: marcia@aim.uzh.ch
Weitere Informationen:
http://www.mediadesk.uzh.ch/articles/2013/schaedelfund-dmanisi.html
– News release from the University of Zurich in German and with comprehensive, high-resolution PICTURES and a VIDEO of the excavation
http://www.mediadesk.uzh.ch/articles/2013/schaedelfund-dmanisi_en.html
– News release from the University of Zurich in English and with comprehensive, high-resolution PICTURES and a VIDEO of the excavation

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

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>