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Human fossil dated in St Andrews

An early human fossil, discovered in a remote part of Ethiopia and unveiled to the world today, was dated by geoscientists at the University of St Andrews.

The geological dating techniques, which dated the sediments surrounding the remains at 3.3 million years old, were carried out by researcher Dr Jonathan Wynn of the University of St Andrews, and Dr Diana Roman of the University of South Florida. Jonathan, now based at the University of South Florida, was working under the supervision of Professor Michael Bird at St Andrews, who developed the dating technique used to date Homo floresiensis, the new species reported to the world in 2004.

The most recent discovery made in the Afar region of Ethiopia is a very well preserved specimen of a juvenile female, aged approximately 3 years old, from the primitive human species Australopithecus afarensis. The skeleton represents the first juvenile remains from this chapter of human evolution, making it the oldest child ever discovered.

The fossil was discovered by the Dikika Research Project led by Dr Zeresenay Alemseged of the Max Planck Institute in Germany. Jonathan’s analysis of the surrounding sediments and soils are combined with analysis of the fauna by a team of paleontologists (Zeresenay Alemseged, Denis Geraads, Denne Reed and Rene Bobe) which paint a picture of the environment in which the fossil lived and died. With the establishment of a long-term record of local environmental change, the research also tells us about the effect of the global climate on the course of human evolution in this part of Ethiopia.

Jonathan said: “Because we have a very complete geological picture for the entire area, this is the most interesting part of the story, which goes well beyond providing the age of the fossil. First of all, it is easy to say that the environment was extremely different in many respects than the area today. Much of the reason for this difference may not be entirely due to some of the changes in global climate since that time, but due to changes in the tectonic patterns in this part of the rift. At the time this fossil was buried, the tectonic setting was quite different, and in many ways similar to areas that are now further north in Ethiopia.”

While the Leipzig-based anthropologist Dr Alemseged began and led the project in 1999, the initial discovery of the fossil was made in 2000. Working in collaboration with Zeresenay, Jonathan has been involved in providing the geological context since 2002. During this time, he spent up to two months a year in the field at the site at Dikika, to examine the area where the fossil was discovered. By building up details of the surrounding area, Jonathan and fellow researchers were able to get a clearer picture not only of the fossil’s geological age, but also the environmental conditions in which it lived.

Jonathan has been able to establish that the hominin lived in a ‘unique, lush environment’ surrounded by flowing water, forests, grassland and open vegetation, but which was also affected by widespread volcanic eruptions. Here the faunal evidence should not be underestimated. Animal fossils found in the surrounding area by palaeontologists from France and the U.S. reveal a range of habitats appropriate for hippos, crocodiles and snails, which would have lived near water, to the white rhino and relatives of the wildebeest that would have inhabited the more open parts of the landscape.

Since the international research team knew the basic geology of the discovery area, Jonathan’s role as a geologist was to construct a complete geological framework for the entire area (~100 square kilometers), to establish the age of the fossil, and the age of sediments in the entire area in addition to the nature of how the whole package of sediments are exposed across the region.

Jonathan, who has worked on similar discoveries in Kenya, said: “Once the fossil was found and identified, we needed to know a lot more about its context. The field area has a unique tectonic and environmental history that needed to be pieced together by first understanding the chronology.”

Jonathan and his colleague, Diana Roman gradually pieced the chronological information together by identifying unique volcanic deposits (by their “chemical fingerprints”) and using them to trace particular ‘age horizons’ throughout the area.

As a result, a clear picture of the unique area in which the species lived and died was developed by the international and multidisciplinary team.

Jonathan continued: “We can tell that the basin floor was dropping quickly enough that a relatively long lived lake was present at this time. This lake, and the delta that formed where the river ran into the lake provided a much more lush environment than today, with nearby standing and flowing water sources, surrounded by gallery forests. We can see from the sediments that the region was very much characterised by a mosaic of environment that ranged from forests and woodlands near the rivers, to seasonally flooded grasslands to a floodplain that would have supported more open vegetation.”

ENDS

NOTE TO EDITORS:

THE RESEARCHERS ARE AVAILABLE FOR INTERVIEW:

– Jonathan Wynn (Geology), Assistant Professor, Department of Geology, University of South Florida, USA, jwynn@cas.usf.edu, +1 – 813 974-9369

– Zeresenay Alemseged (Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany) From 16-24 September at National Museum of Ethiopia, Addis Ababa, Ethiopia Tel: +251 911 86 23 86, or +251 911 44 81 83; After 24, September Tel: +49 341 35 50 353; E-mail: zeray@eva.mpg.de , zeray@eva.mpg.de or zerayat@yahoo.com

– René Bobe (Paleoenvironment), Assistant Professor, Department of Anthropology, the University of Georgia, USA, renebobe@uga.edu, +1 (706) 542-1480

– Denis Geraads (Palaeontology) Senior researcher, CNRS UPR 2147, France, dgeraads@ivry.cnrs.fr , +33 – 1 43 13 56 21

– Denné Reed (Paleoecology), Assistant Professor, Dept. of Anthropology, University of Texas at Austin, USA, reedd@mail.utexas.edu, +1 -512 471- 7529

– Diana Roman (Geology), Assistant Professor, Department of Geology, University of South Florida, USA, droman@cas.usf.edu +1 – 813-974-2838,

COPIES OF THE RESEARCH PAPER (Nature, VOL.443 NO.7109, 21 SEPTEMBER 2006) ARE AVAILABLE FROM NATURE – CONTACT RUTH FRANCIS ON 020 7843 4562, EMAIL R.Francis@nature.com

NOTE TO PICTURE EDITORS:

IMAGES OF JONATHAN AND FELLOW RESEARCHERS AT WORK IN THE FIELD (AND OF THE STRIKING SURROUNDINGS) ARE AVAILABLE FROM THE PRESS OFFICE – CONTACT BELOW.

Issued by Beattie Media – www.beattiegroup.com On behalf of the University of St Andrews

Contact Gayle Cook, Press Officer on 01334 467227 / 462529, mobile 07900 050 103, or email gec3@st- andrews.ac.uk

Ref: Ethiopia fossil 200906 GEC

View the latest University press releases at http://www.st- andrews.ac.uk

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