Monday, December 22, 2008

Earliest evidence of cave-dwelling humans.

A research team led by Professor Michael Chazan, director of the University of Toronto's Archaeology Centre, has discovered the earliest evidence of our cave-dwelling human ancestors at the Wonderwerk Cave in South Africa.
Stone tools found at the bottom level of the cave — believed to be 2 million years old — show that human ancestors were in the cave earlier than ever thought before. Geological evidence indicates that these tools were left in the cave and not washed into the site from the outside world.
Archaeological investigations of the Wonderwerk cave — a South African National Heritage site due to its role in discovering the human and environmental history of the area — began in the 1940s and research continues to this day.

Wonderwerk Cave: Basic Information

Location: Northern Cape Province, South Africa between Danielskuil and Kuruman
How did the Cave Form: The cave formed by water action in the Dolemite rocks of the
Asbestos Hills. This rock formation is over 2 billion years old, some of the oldest rock
on earth, so we do not know when exactly the cave formed.

Basic properties of the cave; The cave runs 130 meters from front to back.
How was Wonderwerk discovered: Local farmers dug up large parts of the cave in the
1940’s to sell the sediments for fertilizer. Subsequently a series of brief archaeological
excavations began. Peter Beaumont of the McGregor Museum carried out major
excavations at the site between 1978-1993.

The Discovery
Using a combination of dating methods it has been possible to date the bottom level
reached by Peter Beaumont in the front part of the cave to 2 million years ago.
A small number of very small stone tools have been recovered from excavations in this
level.

Geological evidence indicates that these tools were deposited in the cave by human
ancestors, not washed into the site from the outside.

The combination of stone tools indicating the presence of human ancestors and the dating
of the level leads to the conclusion that human ancestors (hominids) were in the cave 2
million years ago.

This is the earliest evidence for intentional cave occupation by human ancestors.
There were a number of species of hominids in southern Africat 2 million years ago. The
most likely candidate as the manufacturer of the stone tools found at Wonderwerk is
Homo habilis.

The oldest known stone tools from sites in Ethiopia date to 2.4 million years. The
Wonderwerk Cave discoveries are those close in age to the very earliest known stone
tools and similar in date to the bottom levels at Olduvai Gorge.

How Was the Site Dated
The deposits at Wonderwerk Cave built up over time so that the deeper one excavates the
layers become older. The trick is to figure out exactly how old the levels are.
We used two methods that together provide a secure date.

For Paleomagnetic Dating Hagai Ron of the Hebrew University took small samples of
soil from the entire sequence (over fifty samples). These samples allow him to measure
changes in he earth’s magnetic field and to correlate the Wonderwerk sequence with a
global timescale for changes in the magnetic field (known as reversals).

For Cosmogenic Burial Age Ari Matmon, also from the Hebrew University, took soil
samples and carefully prepared them in the lab. He then sent these samples to an atomic
accelerator in the United States where a procedure to measure isotopes, much like the
method used in carbon dating, was carried out. Unlike carbon dating, Cosmogenic Burial
Age dating can provide very old dates.

Why was this so difficult? Most well dated early sites are in East Africa where there are
volcanic ash layers that can be dated using the Argon method. In southern Africa we
lack these ash layers so that we need to develop new methods. The first use of
Cosmogenic Burial Age dating in South Africa was at the Cradle of Humankind. Our
results show the value of this method, particularly when combined with Paleomagnetic
dating, for archaeological research both in the region and globally.

Ancient African exodus mostly involved men

Modern humans left Africa over 60,000 years ago in a migration that many believe was responsible for nearly all of the human population that exist outside Africa today.

Now, researchers have revealed that men and women weren't equal partners in that exodus. By tracing variations in the X chromosome and in the non-sex chromosomes, the researchers found evidence that men probably outnumbered women in that migration. The scientists expect that their method of comparing X chromosomes with the other non-gender specific chromosomes will be a powerful tool for future historical and anthropological studies, since it can illuminate differences in female and male populations that were inaccessible to previous methods.

While the researchers cannot say for sure why more men than women participated in the dispersion from Africa—or how natural selection might also contribute to these genetic patterns—the study's lead author, Alon Keinan, notes that these findings are "in line with what anthropologists have taught us about hunter-gatherer populations, in which short distance migration is primarily by women and long distance migration primarily by men."

Tuesday, December 9, 2008

Late Neandertals & human contact in Iberia

Late Neandertals and modern human contact in southeastern Iberia

It is widely accepted that Upper Paleolithic early modern humans spread westward across Europe about 42,000 years ago, variably displacing and absorbing Neandertal populations in the process. However, Middle Paleolithic assemblages persisted for another 8,000 years in Iberia, presumably made by Neandertals. It has been unclear whether these late Middle Paleolithic Iberian assemblages were made by Neandertals, and what the nature of those humans might have been.

New research, published Dec. 8 in the Proceedings of the National Academy of Sciences, is now shedding some light on what were probably the last Neandertals.

The research is based on a study of human fossils found during the past decade at the Sima de la Palomas, Murcia, Spain by Michael Walker, professor at Universidad de Murcia, and colleagues, and published by Michael Walker, Erik Trinkaus, professor of Anthropology at Washington University in St. Louis, and colleagues.

The human fossils from the upper levels of the Sima de las Palomas are anatomically clearly Neandertals, and they are now securely dated to 40,000 years ago. They therefore establish the late persistence of Neandertals in this southwestern cul-de-sac of Europe. This reinforces the conclusion that the Neandertals were not merely swept away by advancing modern humans. The behavioral differences between these human groups must have been more subtle than the Middle-to-Upper Paleolithic technological contrasts might imply.

In addition, the Palomas Neandertals variably exhibit a series of modern human features rare or absent in earlier Neandertals. Either they were evolving on their own towards the modern human pattern, or more likely, they had contact with early modern humans around the Pyrenees. If the latter, it implies that the persistence of the Middle Paleolithic in Iberia was a matter of choice, and not cultural retardation.

From the Sima de las Palomas, other late Neandertal sites, and recent discoveries of the earliest modern humans across Europe, a complex picture is emerging of shifting contact between behaviorally similar, if culturally and biologically different, human populations. Researchers are coming to see them all more as people, flexibly making a living through the changing human and natural landscapes of the Late Pleistocene.

Friday, December 5, 2008

Ancient empires declined during dry spell

Cave's climate clues show ancient empires declined during dry spell

The decline of the Roman and Byzantine Empires in the Eastern Mediterranean more than 1,400 years ago may have been driven by unfavorable climate changes.

Based on chemical signatures in a piece of calcite from a cave near Jerusalem, a team of American and Israeli geologists pieced together a detailed record of the area's climate from roughly 200 B.C. to 1100 A.D. Their analysis, to be reported in an upcoming issue of the journal Quaternary Research, reveals increasingly dry weather from 100 A.D. to 700 A.D. that coincided with the fall of both Roman and Byzantine rule in the region.

The researchers, led by University of Wisconsin-Madison geology graduate student Ian Orland and professor John Valley, reconstructed the high-resolution climate record based on geochemical analysis of a stalagmite from Soreq Cave, located in the Stalactite Cave Nature Reserve near Jerusalem.

"It looks sort of like tree rings in cross-section. You have many concentric rings and you can analyze across these rings, but instead of looking at the ring widths, we're looking at the geochemical composition of each ring," says Orland.

Using oxygen isotope signatures and impurities — such as organic matter flushed into the cave by surface rain — trapped in the layered mineral deposits, Orland determined annual rainfall levels for the years the stalagmite was growing, from approximately 200 B.C. to 1100 A.D.

While cave formations have previously been used as climate indicators, past analyses have relied on relatively crude sampling tools, typically small dental drills, which required averaging across 10 or even 100 years at a time. The current analysis used an advanced ion microprobe in the Wisconsin Secondary-Ion Mass-Spectrometer (Wisc-SIMS) laboratory to sample spots just one-hundredth of a millimeter across. That represents about 100 times sharper detail than previous methods. With such fine resolution, the scientists were able to discriminate weather patterns from individual years and seasons.

Their detailed climate record shows that the Eastern Mediterranean became drier between 100 A.D. and 700 A.D., a time when Roman and Byzantine power in the region waned, including steep drops in precipitation around 100 A.D. and 400 A.D. "Whether this is what weakened the Byzantines or not isn't known, but it is an interesting correlation," Valley says. "These things were certainly going on at the time that those historic changes occurred."

The team is now applying the same techniques to older samples from the same cave. "One period of interest is the last glacial termination, around 19,000 years ago — the most recent period in Earth's history when the whole globe experienced a warming of 4 to 5 degrees Celsius," Orland says.

Formations from this period of rapid change may help them better understand how weather patterns respond to quickly warming temperatures.

Soreq Cave — at least 185,000 years old and still active — also offers the hope of creating a high-resolution long-term climate change record to parallel those generated from Greenland and Antarctic ice cores.

"No one knows what happened on the continents… At the poles, the climate might have been quite different," says Valley. "This is a record of what was going on in a very different part of the world."

Thursday, December 4, 2008

Modern Iberia: Sephardic Jewish lineage: 19.8%

Past religious diversity and intolerance have profound impact on genetics of Iberian people

New research suggests that relatively recent events had a substantial impact on patterns of genetic diversity in the southwest region of Europe. The study, published by Cell Press on December 4th in the American Journal of Human Genetics, shows that geographical patterns of ancestry appear to have been influenced by religious conversions of both Jews and Muslims in the Iberian Peninsula.

"Most studies of European genetic diversity have focused on large-scale variation and interpretations based on events in prehistory, but migrations and invasions in historical times may also have profound effects on genetic landscapes," explains senior study author Prof. Mark A. Jobling from the Department of Genetics at the University of Leicester. Prof. Jobling and colleagues performed a sophisticated genetic analysis of 1140 males from the Iberian Peninsula and the Balearic Islands, focusing on the Y chromosome, which is passed down from fathers to sons.

The researchers found a remarkably high level of Sephardic Jewish (19.8%) and North African (10.6%) ancestry in their large sample of Y chromosomes from the modern population. The Iberian Peninsula has a complex recent history that involves the long-term residence of these two diverse populations with distinct geographical origins and unique cultural and religious characteristics.

The large proportion of Sephardic Jewish ancestry does not fit with simple expectations from the historical record. "Despite alternative possible sources for lineages [to which] we ascribe a Sephardic Jewish origin, these proportions attest to a high level of religious conversion, whether voluntary or enforced, driven by historical episodes of social and religious intolerance that ultimately led to the integration of descendants," offers Prof. Jobling.

Additionally, the prominent North African lineage in Iberian populations exhibits low diversity, which favors its arrival after the conquest of 711 AD, and the geographical distribution of North African Ancestry in the peninsula does not reflect the initial colonization and subsequent withdrawal. "This is likely to result from later enforced population movement – more marked in some regions than others," explains Prof. Jobling.

The research demonstrates that both immigration events from the Middle East and North Africa over the last two millennia and introduction of new Y-chromosome types driven by religious conversion and intermarriage have had a dramatic impact on modern populations in Spain, Portugal, and the Balearic Islands. In addition, the findings indicate that recent history should be considered when investigating the impact of events occurring during the earlier prehistory of Europe. The research was funded by the Wellcome Trust.

Monday, December 1, 2008

Mosses from the Tyrolean Iceman’s alimentary tract

What we eat can say a lot about us – where we live, how we live and eventually even when we lived. From the analysis of the intestinal contents of the 5,200-year-old Iceman from the Eastern Alps, Professor James Dickson from the University of Glasgow in the UK and his team have shed some light on the mummy’s lifestyle and some of the events leading up to his death. By identifying six different mosses in his alimentary tract, they suggest that the Iceman may have travelled, injured himself and dressed his wounds. Their findings1 are published in the December issue of Springer’s journal Vegetation History and Archaeobotany, which is specially dedicated to Oetzi the Iceman.

The Iceman is the first glacier mummy to have fragments of mosses in his intestine. This is surprising as mosses are neither palatable nor nutritious and there are few reports of mosses used for internal medical treatments. Rather, mosses recovered from archaeological sites tend to have been used for stuffing, wiping and wrapping.

Dickson and colleagues studied the moss remains from the intestines of the Iceman on microscope slides, to find out more about his lifestyle and events during the last few days of his life. Their paper describes in detail the six different mosses identified and seeks to provide answers to two key questions in each case. Firstly, where did the Iceman come in contact with each species; secondly, how did each come to enter his alimentary tract.

In particular, the authors suggest that one type of moss is likely to have been used to wrap food, another is likely to have been swallowed when the Iceman drank water during the last few days of his life, and yet another would have been used as a wound dressing. One type of moss in the Iceman’s gut is not known in the region where the mummy was found, implying that the Iceman must have travelled.

Other papers in this special issue of Vegetation History and Archaeobotany look at subfossil caprine dung from the discovery site of the Iceman, plant economy and village life in Neolithic lake dwellings at the time of the Alpine Iceman, and the significance of the Tyrolean Iceman for the archaeobotany of Central Europe.

Evidence from dirty teeth: Ancient Peruvians ate well

Earliest human consumption of beans, pacay

Starch grains preserved on human teeth reveal that ancient Peruvians ate a variety of cultivated crops including squash, beans, peanuts and the fruit of cultivated pacay trees. This finding by Dolores Piperno, staff scientist at the Smithsonian Tropical Research Institute and the National Museum of Natural History, and Tom Dillehay, professor of archaeology at Vanderbilt University, sets the date of the earliest human consumption of beans and pacay back by more than 2,000 years and indicates that New World people were committed farmers earlier than previously thought.

In northern Peru’s √Ďanchoc Valley, Dillehay and colleagues recovered human teeth from hearths and floors of permanent, roundhouse structures. Human bone, plant remains and charcoal closely associated with the teeth are approximately 6,000 to 8,000 years old according to carbon- dating techniques.

Piperno examined 39 human teeth, probably from six to eight individuals. “Some teeth were dirtier than others. We found starch grains on most of the teeth. About a third of the teeth contained large numbers of starch grains,” Piperno said.

To identify the starch grains, Piperno compared the particles in tooth scrapings with her modern reference collection of starch grains from more than 500 economically important plants. “We found starch from a variety of cultivated plants: squash, Phaseolus beans—either limas or common beans, possibly, but not certainly the former, pacay and peanuts,” said Piperno. “Parts of plants that often are not evident in archeological remains, such as the flesh of squash fruits and the nuts of peanuts, do produce identifiable starch grains.”

Starch from squash found on the teeth affirms that early people were eating the plants and not simply using them for nonfood purposes, such as for making containers or net floats. Whether or not some of the earliest cultivated plants, such as squashes, were grown as dietary items has been a long-debated question among students of early agriculture.

Evidence that foods had been cooked was also visible on some of the starch grains. “We boiled beans in the lab to see what cooked starch grains looked like—and recognized these gelatinized or heat-damaged grains in the samples from the teeth,” said Piperno. Starch from raw and roasted peanuts looks similar, probably because it is protected within the hull.

Starch grains from four of the crops were found consistently through time indicating that beans, peanuts, squash and pacay were important food sources then, as they are today. “Starch analysis of teeth, which, unlike other archaeobotanical techniques, provides direct evidence of plant consumption, should greatly improve our ability to address other important questions in human dietary change relating to even earlier time periods,” said Piperno.