Notes from an excavation
Russell L. Ciochon and his team are in Indonesia investigating the
geological source and age of one of the world's biggest caches of Homo
erectus.
Miriam Frankel
Russell L. CiochonRussell L. Ciochon, who heads the team at the
Ngandong site, with a gorilla skull.Tom Jorgensen
In the early 1930s, 14 Homo erectus fossils and 25,000 vertebrate
remains were unearthed near the muddy Solo River at Ngandong in Java,
Indonesia, by a research team from the Netherlands. Some 80 years
later, this remains one of the world's largest caches of this early
human. It could also be evidence of the species' swansong. A team has
now returned to Ngandong, armed with the original Dutch survey
documents, to answer some long-standing questions about the age of the
fossils and the ancient sediment that they were buried in. Nature
talked to Russell L. Ciochon, a palaeoanthropologist at the University
of Iowa in Iowa City, while his team was digging at Ngandong.
Why is this fieldwork so important?
H. erectus from Ngandong potentially lived in the last part of the Ice
Age at the same time that Homo sapiens inhabited other parts of the
Old World, and Homo floresiensis (the 'hobbit') was still living in
caves on the Indonesian island of Flores. This was a very intriguing
period in the saga of human evolution.
According to the Dutch team who discovered them, the H. erectus
specimens were deposited by the Solo River. The fact that the present
river is so near to the deposits that contained the H. erectus
specimens could indicate that the deposits and fossils are far younger
than the oldest known H. sapiens in Africa, which would mean that the
two species actually coexisted. But attempts to date Ngandong over the
past 30 years have proved inconclusive. This is partly because we
don't know enough about the Ngandong geology and can't be sure that
the dated samples from earlier excavations came from the discovery
bed. Our team is the first to focus on the geological context of the
fossils1. This was possible because geoarchaeologist Frank Huffman
from the University of Texas at Austin obtained the long-forgotten
survey documents from the 1930s2.
Ngandong siteIndonesian team leader Yahdi Zaim (left) and Rob Scott
excavate the bone bed.O. Frank Huffman
What have you found at the site?
During our expedition, we have recovered more than 800 fossils from a
bone bed — a geological deposit with a dense collection of bones. The
excavations have provided our geological team, which includes
University of Iowa geoarchaeologist Art Bettis, with details on the
site's sediments that shed new light on how the bone bed was created.
We believe that the detailed analysis of the site's geology and the
circumstances of burial of the bone bed will provide the crucial
information to evaluate the dating and other contentious issues
surrounding the remains.
We found no stone artefacts at the site, but these are rare at most
Javan H. erectus sites. It is one of the unique features of the Java
record that remains to be explained.
What can the fossils tell us about the daily lives of these late
members of H. erectus?
Although we don't have direct evidence, we believe that H. erectus
exploited the resources in the area, probably by hunting or
scavenging. Other clues about their lives can be found by looking at
the non-human fossils, and what they can tell us about the ecology at
the time. A member of our team, Robert Scott of Rutgers University in
New Jersey, specializes in such fossils and found that they are mostly
made up of large bovids — ancestors of the Javan banteng and water
buffalo — as well as deer, Stegodon (an extinct elephant), rhinoceros,
panther, crocodiles and turtles. The large percentage of bovids and
deer could indicate that H. erectus lived in an open woodland or
grassland environment.
Also, on the basis of estimates from partial skeletons of H. erectus
from other sites, we think that the Ngandong H. erectus was probably
between 1.66 and 1.85 metres tall — similar to the average human
height in the United States today.
Solo RiverThe Solo River, which runs near the Homo erectus site.O.
Frank Huffman
What can the Ngandong excavation site tell us about the evolution and
extinction of H. erectus?
The 14 H. erectus fossils are thought to represent a late stage in the
evolution of the species. As a group, they have a significantly larger
average brain size than that found in any other H. erectus fossils.
Palaeoanthropologists don't like to use terms such as 'advanced' to
distinguish one fossil group from another, but that term would
certainly apply to the Ngandong fossils. After arriving on Java about
1.6 million years ago3, H. erectus apparently lived in 'splendid
isolation' without competition from any other human species.
It is possible that when H. sapiens eventually reached Java, it could
have competed with H. erectus for scarce island resources, leading to
the extinction of the latter. But it is more likely that some unique
geological or climatic event resulted in the extinction of Javan H.
erectus, as is the case with most species. However, it does seem that
the Ngandong group is the best evidence we have for the last
occurrence of this species worldwide.
What has been the most exciting moment of the expedition so far?
The first high point came after several excavation pits were opened.
We found boundaries of the original excavations not seen since the
1930s. This revealed untouched bone beds fitting the parameters
originally described by the Dutch team. We are reliving the days of
the discovery made nearly 80 years ago, and meeting present-day
research objectives as we unearth the past.
What is a typical day at the site like?
We've been excavating for 24 days without a break. The days blur
together and we often lose track of time. There is a routine to
systematic palaeoanthropological excavation: opening an excavation
pit, digging down to the bone bed, carefully mapping the strata as we
proceed, exposing the fossils, assigning the fossil a number, charting
its xyz coordinates, removing the fossil, and then sampling the strata
for geological analysis and dating.
ADVERTISEMENT
natureconferences
How does the Javan H. erectus compare with those from other sites in
the world and where did it actually come from?
We spend a lot of time discussing this question. The earliest H.
erectus fossils date to about 1.8 million years ago — appearing nearly
simultaneously in both East Africa and at Dmanisi in the Republic of
Georgia. So H. erectus from Africa and Georgia represent critical
comparisons for any Javan H. erectus. It is thought that the species
evolved in Africa and spread out of the continent to the Republic of
Georgia and to Java over a very short timespan — perhaps less than
100,000 years. However, the most primitive and smallest H. erectus
fossils come from Dmanisi. Anatomically, Dmanisi H. erectus shares
features with both the African and Javan H. erectus, so it may
actually be the centre of origin for the species. If you compare
Ngandong H. erectus with those from elsewhere, it is clear that the
most derived population is from Ngandong.
source
http://news-releases.uiowa.edu/2010/july/072810ciochon.html
University of Iowa News Release
July 28, 2010
Photo: Russ Ciochon (left), Frank Huffman, Yahdi Zaim and Art Bettis
stand in an excavation pit at Ngandong. Photo Credit: Maija E. Sipola.
UI anthropologist describes early human dig site in Nature News story
A University of Iowa anthropologist and his colleagues are featured in
the July 28 online edition of Nature News discussing their latest dig
to determine the geological source and precise age of the remains of
Homo erectus on the island of Java. Homo erectus is a distinct species
of early man that lived in Java between about 1.6 million and 50,000
years ago, or perhaps more recently.
Nature News is a publication of the journal Nature. A Q&A about the
dig can be found at http://www.nature.com/news/2010/100728/full/news.2010.377.html.
Russell L. Ciochon (sha-HAN), professor of the Department of
Anthropology in the University of Iowa College of Liberal Arts and
Sciences, led the large-scale excavation for Homo erectus remains at
Ngandong, Java, for 24 days during July. The interdisciplinary U.S.
team included UI associate professor of geoscience Arthur Bettis, UI
anthropology graduate student Shelby Putt of Fort Wayne, Ind., UI
geoscience graduate student Maija Sipola of Babbitt, Minn., and
research faculty from the University of Texas and Rutgers University.
What they found at the site is expected to advance scientists'
understanding of the evolution and adaptations of early Asian humans.
Ciochon said the team recovered more than 800 fossils from a bone bed
and the excavations revealed details on sediments at the site telling
how the bone bed was created.
"The site's geology and the circumstances of burial of the bone bed
will provide crucial information to evaluate the dating and other
contentious issues surrounding the Ngandong human remains," he said.
Living approximately 50,000 years ago during the last portion of the
Ice Age, Homo erectus fossils at Ngandong represent a surviving relic
population on the island of Java. Other early humans in Asia that date
to this same time range are our own species, Homo sapiens (China and
Australia), and the 'hobbit' (Homo floresiensis), an island dwarf
survivor on the isolated island of Flores, east of Java.
The excavation site itself dates to the 1930s, when Homo erectus
fossils and 25,000 vertebrate remains were first found at Ngandong
along the shores of the Solo River in Java. Although it is one of the
largest sites of Homo erectus bones, the exact age of the fossils
remains in doubt, with the result that the fossils may or may not be
evidence of one of the last occurrences of the species.
Ciochon's team returned to the site some 80 years later, along with
the original Dutch survey documents to attempt to answer some of the
questions about the age of the fossils and their geological source.
Ciochon said that it was exciting to relive history by opening the
excavation pits and observing the boundaries of the original
excavations and the untouched bone beds -- sites not seen since the
1930s.
The dig was funded by a $35,000 grant from the Wenner-Gren Foundation
for Anthropological Research, New York.
No comments:
Post a Comment