Tuesday, September 27, 2011


A lock of hair, collected by a British anthropologist a century ago, has yielded the first genome of an Australian Aborigine, along with insights into the earliest migration from the ancestral human homeland somewhere in northeast Africa. The Aboriginal genome bolsters earlier genetic evidence showing that once the Aborigines’ ancestors arrived in Australia, some 50,000 years ago, they somehow kept the whole continent to themselves without admitting any outsiders.

The Aborigines are thus direct descendants of the first modern humans to leave Africa, without any genetic mixture from other races so far as can be seen at present. Their dark skin reflects an African origin and a migration and residence in latitudes near the equator, unlike Europeans and Asians whose ancestors gained the paler skin necessary for living in northern latitudes. “Aboriginal Australians likely have one of the oldest continuous population histories outside sub-Saharan Africa today,” say the researchers who analyzed the hair, a group led by Eske Willerslev of the Natural History Museum of Denmark.

Dr. Willerslev is an expert at working with ancient DNA, which is usually highly fragmented. Use of the ancient hair reduced the possibility of mixture with European genes and sidestepped the political difficulties of obtaining DNA from living Aborigines. The DNA in the Aboriginal genome, when compared with DNA from other peoples around the world, shows that when modern humans first migrated out of Africa the ancestors of the Aborigines split away from the main group very early, and before Europeans and East Asians split from each other, Dr. Eske and his colleagues write in an article published online Thursday in the journal Science. Based on the rate of mutation in DNA, the geneticists estimate that the Aborigines split from the ancestors of all Eurasians some 70,000 years ago, and that the ancestors of Europeans and East Asians split from each other about 30,000 years ago.

The Aborigine occupation of Australia presents a series of puzzles, starting with the nature of their stone tools. The early stone tools found in Australia are much simpler than the Upper Paleolithic tools that appear in Europe at the same era. “I don’t understand why they looked so primitive,” said Richard Klein, a paleoanthropologist at Stanford University. Primitive as the tools may be, the first inhabitants of Australia must have possessed advanced boat-building technology to cross from the nearest point in Asia to Sahul, the ancient continent that included Australia, New Guinea and Tasmania until the rise of sea level that occurred at the end of the last ice age, 10,000 years ago. But there is no archaeological evidence for boats, Dr. Klein said.

Despite the Aborigines’ genetic isolation, there is evidence of some profound cultural exchange that occurred around 6,000 years ago. The stone tools become more sophisticated, and the population increased. The Aborigines did not domesticate plants or animals, but a wild dog, the dingo, first appears in the archaeological record at this time. Researchers led by Peter Savolainen of the Royal Institute of Technology in Stockholm reported this month in the journal Proceedings of the Royal Society B that they had traced the spread of the dingo across the islands of the Pacific by analyzing ancient DNA in the bones of Polynesian dogs. The dingo originated on the Asian mainland and became part of the Polynesian domestic menagerie along with the pig, the chicken and the rat. This ensemble had reached New Zealand by A.D. 1250. How the dingo arrived in Australia is an “enigma,” Dr. Savolainen writes, because none of the other elements of Polynesian culture are found there. Even stranger, dogs always travel with their masters, yet there is no sign yet of Polynesian genes in the Aborigine population.

Most of Australia is a forbidding desert, and this barrier may have been the downfall of most invasions, whether of people or of animals, Dr. Klein said. The ancestors of the Aborigines were lucky enough to find their way south, where there is more vegetation, and the dingo is a skillful hunter, able to look after itself. But this leaves unexplained the cultural changes that began around or shortly after the dingo’s arrival. “Something remarkable happened in Australia 6,000 to 4,000 years ago, and it involved much more than the dingo,” Dr. Klein said.


The site at La Cotte de St Brelade reveals a near-continuous use of the cave site spanning over a quarter of a million years, suggesting a considerable success story in adapting to a changing climate and landscape, prior to the arrival of Homo sapiens.

The La Cotte ravine has revealed the most prolific collection of early Neanderthal technology in North West Europe, including over 250,000 stone tools. These include stones with sharpened edges that could be used to cut or chop, known as hand axes. The huge amounts of carefully manufactured tools show just how
technologically skilled early Neanderthal groups were.

"The artifacts from the site don't just tell us about what people were doing at the site itself, but throughout the landscapes that are now underneath the channel,"
continues Dr Scott. "Neanderthals were traveling to Jersey already equipped with good quality flint tools, then reworking them, very, very carefully so as not to waste anything. They were extremely good at recycling."

La Cotte's collapsed cave system contains intact ice age sediments spanning a quarter of a million years, revealing a detailed sequence of Neanderthal
occupation and occasional abandonment, against a background of changing climate. "The site is the most exceptional long-term record of Neanderthal behavior
in North West Europe," says Dr Matt Pope from the Institute of Archaeology at University College London.


A new study suggests that Homo erectus, a precursor to modern humans, was using advanced toolmaking methods in East Africa 1.8 million years ago, at least 300,000 years earlier than previously thought. The study, published this week in Nature, raises new questions about where these tall and slender early humans originated and how they developed sophisticated tool-makingtechnology. Homo erectus appeared about 2 million years ago, and ranged across Asia and Africa before hitting a possible evolutionary dead-end, about 70,000 years ago. Some researchers think Homo erectus evolved in East Africa, where many of the oldest fossils have been found, but the discovery in the 1990s of equally old Homo erectus fossils in the country of Georgia has led others to suggest an Asian origin. The study in Nature does not resolve the debate but adds new complexity. At 1.8 million years ago, Homo erectus in Dmanisi, Georgia was still using simple chopping tools while in West Turkana, Kenya, according to the study, the population had developed hand axes, picks and other innovative tools that anthropologists call "Acheulian." "The Acheulian tools represent a great technological leap," said study co-author Dennis Kent, a geologist with joint appointments at Rutgers University and Columbia University's Lamont-Doherty Earth Observatory. "Why didn't Homo erectus take these tools with them to Asia?" In the summer of 2007, a team of French and American researchers traveled to Kenya's Lake Turkana in Africa's Great Rift Valley, where earth's plates are tearing apart and some of the earliest humans first appear. Anthropologist Richard Leakey's famous find--Turkana Boy, a Homo erectus teenager who lived about 1.5 million years ago-was excavated on Lake Turkana's western shore and is still the most complete early human skeleton found so far. Six miles from Turkana Boy, the researchers headed for Kokiselei, an archaeological site where both Acheulian and simpler "Oldowan" tools had been found earlier. Their goal: to establish the age of the tools by dating the surrounding sediments. Past flooding in the area had left behind layers of silt and clay that hardened into mudstone, preserving the direction of Earth's magnetic field at the time in the stone's magnetite grains. The researchers chiseled away chunks of the mudstone at Kokiselei to later analyze the periodic polarity reversals and come up with ages. At Lamont-Doherty's Paleomagnetics Lab, they compared the magnetic intervals with other stratigraphic records to date the archeological site to 1.76 million years. "We suspected that Kokiselei was a rather old site, but I was taken aback when I realized that the geological data indicated it was the oldest Acheulian site in the world," said the study's lead author, Christopher Lepre, a geologist. The oldest Acheulian tools previously identified appear in Konso, Ethiopia, about 1.4 million years ago, and India, between 1.5 million and 1 million years ago. The Acheulian tools at Kokiselei were found just above a sediment layer associated with a polarity interval called the "Olduvai Subchron." It is named after Tanzania's Olduvai Gorge, where pioneering work in the 1930s by Leakey's parents, Louis and Mary, uncovered a goldmine of early human fossils. In a study in Earth and Planetary Science Letters last year, Lepre and Kent found that a well-preserved Homo erectus skull found on east side of Lake Turkana, at Koobi Fora Ridge, also sat above the Olduvai Subchroninterval, making the skull and Acheulian tools in West Turkana about the same age. The skill involved in manufacturing a hand axe suggests that Homo erectus was dexterous and able to think ahead. At Kokiselei, the presence of both tool-making methods-Oldowan and Acheulian-- could mean that Homo erectus and its more primitive cousin Homo habilis lived at the same time, with Homo erectus carrying the Acheulian technology to the Mediterranean region about a million years ago, the study authors hypothesize. Delson wonders if Homo erectus may have migrated to Dmanisi, Georgia, but "lost" the Acheulian technology on the way. The East African landscape that Homo erectus walked from about 2 million to 1.5 million years ago was becoming progressively drier, with savanna grasslands spreading in response to changes in the monsoon rains. "We need to understand also the ancient environment because this gives us an insight into how processes of evolution work-how shifts in early human biology and behavior are potentially caused by changes in the climate, vegetation or animal life that is particular to a habitat," said Lepre. The team is currently excavating a more than 2 million year old site in Kenya to learn more about the early Oldowan period. http://www.eurekalert.org/pub_releases/2011-08/teia-hss082911.php

Sunday, September 11, 2011

Libya's sites seem OK

Libyan archaeologists are beginning to inspect the country's priceless historical sites, hoping part of their cultural heritage and economic future has not been ruined by war."It is the first time I go there since the war, Kadhafi's troops were inside and I want to know what happened," said Fadel Ali Mohammed, Libya's freshly appointed minister for antiquities. Setting out from the Tripoli hotel that has become his temporary home, the 62-year-old -- a doctor in archaeology and Greek philology -- begins the drive west to Sabratha, one of Libya's most treasured archaeological sites. Despite multiple checkpoints armed by young volunteer militiamen, it only takes 90 minutes to get there. But it is an anxious 90 minutes for the man who is now in charge of protecting Libya's past. Slowly Old Sabratha comes into focus. First a few Corinthian columns, then the top half of its show-stopping 1,800-year-old Roman theatre, strikingly cast against the waves of the southern Mediterranean.Despite battles raging in the area just weeks ago, it appears only one light-arms skirmish took place between Moamer Kadhafi's troops and the fighters who would come to overthrow him. Mohammed, who in the 1970s spent a year in Kadhafi's jails before fleeing to Greece, scans the west side of the 5,000-capacity theatre and comes across three bullet holes he says can be easily restored. The damage assessment from world-beating sites at Leptis Magna and Cyrene to the east are equally positive. With at least three of Libya's five UNESCO sites preserved, locals hope tourists will now flock to Libya like they do to neighbouring Egypt and Tunisia. "It was very difficult for tourists to come under the Kadhafi regime," said Hadi Mafuz, a Sabratha tourism official. [The Archaeological Institute of America group that I traveled with some 6 years ago was one of the few American groups allowed in Libya] I


An apelike creature with human features, whose fossil bones were discovered recently in a South African cave, is being greeted by paleoanthropologists as a likely watershed in the understanding of human evolution. The discoverer of the fossils, Lee Berger of the University of Witwatersrand in Johannesburg, says the new species, known as Australopithecus sediba, is the most plausible known ancestor of archaic and modern humans. Several other paleoanthropologists, while disagreeing with that interpretation, say the fossils are of great importance anyway, because they elucidate the mix-and-match process by which human evolution was shaped. Dr. Berger’s claim, if accepted, would radically redraw the present version of the human family tree, placing the new fossils in the center. The new species, in his view, should dislodge Homo habilis, the famous tool-making fossil found by Louis and Mary Leakey, as the most likely bridge between the australopithecenes and the human lineage. Australopithecenes were apelike creatures that walked upright, like people, but had still not forsaken the trees. Dr. Berger and his colleagues present this claim in five articles in the current issue of Science that describe various aspects of the new fossils. As is common in the field of paleoanthropology, the discoverer of a new fossil is seeking to place it as close as possible to the direct line of human descent, while others are resisting that interpretation. The principal significance of the new fossils is not that Australopithecus sediba is necessarily the direct ancestor of the human genus, other scientists said, but rather that the fossils emphasize the richness of evolutionary experimentation within the australopithecine group. Besides two skulls reported last year, researchers led by Dr. Berger have since retrieved an almost complete right hand, a foot and a pelvis. The bones are especially well preserved because their owners apparently fell into a deep cave and a few weeks later were swept into a sediment that quickly fossilized their bones. The rocks above the cave have gradually eroded away, bringing the fossils to the surface, where one was found by Dr. Berger’s 9-year-old son, Matthew, in 2008, while chasing his dog. That fall into the cave happened 1.977 million years ago, according to dating based on the rate of decay of uranium in the rock layer that holds the fossils. In the articles in Science, Dr. Berger’s team describes novel combinations of apelike and humanlike features in the hand, foot and pelvis of the new species. The hand, for instance, is apelike because it has long, strong fingers suitable for climbing trees, yet is also humanlike in having a long thumb that in combination with the fingers could have held tools in a precision grip. A cast of the inside of the skull shows an apelike brain, but one that had taken the first step toward being reorganized on human lines. This mixture of apelike and humanlike features suggests that the new species was transitional between the australopithecines and humans, the researchers said at a news conference on Wednesday. Given its age, Australopithecus sediba is just old enough to be the ancestor of Homo erectus, the first species that paleoanthropologists agree belonged to the human ancestry and which existed 1.9 million years ago. The new fossils display the modular way in which evolution operates: they have mostly known features but in novel combinations that have never been seen before. Both Dr. Bernard Wood (George Washington U) and Dr.Ian Tattersall (American Museum of Natural History) see Dr. Berger’s discovery as pointing to the great variety of australopithecine apes, from which it will be very difficult to select the particular species that gave rise to humans. Dr. Tattersall believes the leap to humans may have been brought about very suddenly, perhaps by a few critical genetic changes, which is why the transition is so hard to trace in the fossil record.