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Archaeologists investigate Ice Age hominins' adaptability to climate change

Computational modeling that examines evidence of how hominin groups evolved culturally and biologically in response to climate change during the last Ice Age also bears new insights into the extinction of Neanderthals. Details of the complex modeling experiments conducted at Arizona State University and the University of Colorado Denver will be published in the December issue of the journal Human Ecology, available online Nov. 17.

Computer agents (colored dots) simulating prehistoric hunter-gatherer groups are superimposed over a map of Late Pleistocene western Eurasia. Grey shows Pleistocene land area with lowered sea levels, black lines show modern coastlines, white areas show ice sheets. The blue dots represent groups of "modern" humans, red dots represent groups of Neanderthals, and yellow dots represent groups with biological mixtures of modern and Neanderthal genes. This is a snapshot of the simulation after hundreds of cycles in which the hunter-gather groups have higher mobility in response to changing glacial climate. The data and corresponding analyses were cited by archeologists from Arizona State University and the University of Colorado Denver in findings published in the December issue of the journal Human Ecology, available online Nov. 17 [Credit: Michael Barton/Arizona State University]

"To better understand human ecology, and especially how human culture and biology co-evolved among hunter-gatherers in the Late Pleistocene of Western Eurasia (ca. 128,000-11,500 years ago) we designed theoretical and methodological frameworks that incorporated feedback across three evolutionary systems: biological, cultural and environmental," said Michael Barton, a pioneer in the area of archaeological applications of computational modeling at Arizona State University.

"One scientifically interesting result of this research, which studied culturally and environmentally driven changes in land-use behaviors, is that it shows how Neanderthals could have disappeared not because they were somehow less fit than all other hominins who existed during the last glaciation, but because they were as behaviorally sophisticated as modern humans," said Barton, who is lead author of the published findings.

The paper "Modeling Human Ecodynamics and Biocultural Interactions in the Late Pleistocene of Western Eurasia" is co-authored by Julien Riel-Salvatore, an assistant professor of anthropology at the University of Colorado Denver; John Martin "Marty" Anderies, an associate professor of computational social science at ASU in the School of Human Evolution and Social Change and the School of Sustainability; and Gabriel Popescu, an anthropology doctoral student in the School of Human Evolution and Social Change at ASU.

"It's been long believed that Neanderthals were outcompeted by fitter modern humans and they could not adapt," said Riel-Salvatore. "We are changing the main narrative. Neanderthals were just as adaptable and in many ways, simply victims of their own success."

The interdisciplinary team of researchers used archeological data to track behavioral changes in Western Eurasia over a period of 100,000 years and showed that human mobility increased over time, probably in response to environmental change. According to Barton, the last Ice Age saw hunter-gathers, including both Neanderthals and the ancestors of modern humans, range more widely across Eurasia searching for food during a major shift in the Earth's climate.

The scientists utilized computer modeling to explore the evolutionary consequences of those changes, including how changes in the movements of Neanderthals and modern humans caused them to interact – and interbreed – more often.

According to Riel-Salvatore, the study offered further evidence that Neanderthals were more flexible and resourceful than previously assumed.

"Neanderthals had proven that they could roll with the punches and when they met the more numerous modern humans, they adapted again," Riel-Salvatore said. "But modern humans probably saw the Neanderthals as possible mates. As a result, over time, the Neanderthals died out as a physically recognizable population."

To reach their conclusion, the researchers ran a computer program for the equivalent of 1,500 generations showing that as Neanderthals and modern humans expanded their yearly ranges, the Neanderthals were slowly absorbed by more numerous modern humans until they had disappeared as a recognizable population.

"We tested the modeling results against the empirical archaeological record and found that there is evidence that Neanderthals, and moderns, did adapt their behaviors in the way in which we modeled," explained Barton. "Moreover, the modeling predicts the kind of low-level genetic admixture of Neanderthal genes that are being found in the newest genetic studies just now being published.

"In other words, successful behavioral adaptations to severe environmental conditions made Neanderthals, and other non-moderns about whom we know little, vulnerable to biological extinction, but at the same time, ensured they made a genetic contribution to modern populations," Barton said.

The authors noted that "the methods we illustrate here offer a robust, new framework in which researchers can begin to examine the effects that such invisible characteristics could have on the observable record."

"The kind of modeling we did in this research is very new in paleoanthropology, as is the continental scope of the archaeological analysis we used to test the model results," noted Barton.

"However, such computational modeling can refine our understanding of long-term human impact on the environment that can help inform land-use decisions for our future," said Barton, who also is co-director of ASU's Center for Social Dynamics and Complexity, which leverages the emerging field of complex systems to foster interdisciplinary research on fundamental questions of social life.

The research presented in Human Ecology was supported in part by the National Science Foundation, a Fulbright Senior Research Fellowship and a Fulbright Graduate Student Fellowship.

Source: Arizona State University [November 17, 2011]

Skeleton of ancient human relative may yield skin

As London's Natural History Museum takes delivery of two replica fossils, palaeontologists hint that they have discovered tools with the fossils, and mummified skin on the bones.

Australopithecus sediba fossils [Credit: Natural History Museum]

It is strangely moving to hold it, knowing that this is an exact replica of a hand of one of our most ancient relatives. The bones looked frail and slight lying on the black felt, but fit snugly on my palm, knuckles lining up to knuckles. This woman, who died 1.9 million years ago after falling down a watering hole in what is now South Africa, had hands remarkably similar to mine.

This morning, the University of the Witwatersrand in Johannesburg, South Africa, gave a full cast of her fossil to the Natural History Museum in London, along with a cast of a child of the same species, Australopithecus sediba. Together, the two impressive fossils are calling into question the history of our species, and offering never-seen-before insights into how our very early ancestors lived.

At 1.977 million years old, the pair were nearly contemporary with Homo erectus, yet were discovered at the Malapa cave site in South Africa, far from the Great Rift Valley of Ethiopia, which has traditionally been considered the cradle of humanity.

Mixed-up kid

The morphology of their bones – an odd mix of structures similar to ones seen in chimpanzees, australopithecines and even Homo erectus – backs up the notion that this is a transition species. Had some of the bones been found separately, says discoverer Lee Berger of the University of the Witwatersrand, it's likely they would have been ascribed to the different species of Australopithecus.

The fossils' hands and feet suggest that it could climb trees and yet was also bipedal. One possible explanation for these fossils' presence in South Africa, says Chris Stringer of the Natural History Museum, is that environmental changes drove several simultaneous changes in australopithecines across the continent. "It's possible that the environment was becoming drier and more open, encouraging changes like meat-eating and upright walking. What if we were doing this in parallel in different places?"

That could explain the emergence of several transition species at roughly the same time in different parts of Africa, including present-day Ethiopia and South Africa. Most of those species would have died out, leaving just one that evolved into modern humans.

No toothpicks

So far we have had only a tiny glimpse at what these two fossils can tell us. This morning, Berger gave tantalising hints of what is yet to come.

Their tooth enamel is being studied for signs of what the pair's diet would have been – and traces of their last meal are still embedded in the crowns of their teeth. Tools have also been found in the area, and are being studied to see if A. sediba could have made them.

If so, they would not be the oldest tools ever found – those date back to around 2.5 million years ago, and evidence of butchery going back to 3.4 million years ago. "But what we have never found is direct association of an early hominid species with lithics [stone tools]," says Berger.

We have to be careful about what we conclude, however, he warns. For one thing, it is hard to definitively associate a tool found at a site with nearby hominid bones. If a fossil were definitely linked to a tool or set of tools, though, anthropologists would have a unique opportunity to explore how our bodies and brains shaped tools, and were shaped by them. "Given the brain, the dental reduction that's taken place, the long arms and the hands, what those tools are and how they're made will give us great insight into the formative process," says Berger.

Oldest skin

The two fossils were found in chunks of rock that came out of a deep shaft in the ground. The shaft may have been a watering hole, and one hypothesis is that the woman and boy fell into it while seeking a drink – fractures in the bones may be signs of a fatal fall.

Other bones are sticking out of the sides of that hole, including human bones and the remains of animals that would have been around at the time – antelopes, hyenas and false sabre-toothed cats, for instance. As Berger puts it: "We have the animals and plants that were with them the minute they died."

But the most exciting possibility is that the woman and the boy – nicknamed Karabo – were mummified before they were fossilised. Many of the bones at Malapa are coated in a very thin layer of material that appears to be skin. There is at least the possibility that the two died in a deep, anoxic pool of water, which preserved them in ways never seen before.

If 'the bone coating does turn out to be skin, it will be the first discovery of soft tissue from an ancient hominin. Hair might be present, proteins such as keratin and even DNA might be extracted from the tissue, allowing us to dig even deeper into our history, and determine exactly how this species evolved, or even mated with other hominid species.

"It's not constructive to think about our ancestry as a linear chain of events," says Berger. "As scientists we would not have hoped to believe we could see a transitional, mosaic, evolving species in the mammalian record outside of horses – and here's one in our lineage, which is amazing."

Authors: Catherine Brahic and Rowan Hooper | Source: NewScientist [November 16, 2011]

Prehistoric men scarred, pierced, tattooed privates

Men in prehistoric Europe scarred, pierced and tattooed their penises, likely for ritualistic and social group reasons, according to a new study.

Warriors at Vermelhossa (Vila nova de Foz Coa, Portugal) [Credit: Javier Angulo/Discovery News]

Analysis of phallic decorations in Paleolithic art, described in the December issue of The Journal of Urology, may also show evidence of the world's first known surgery performed on a male genital organ. The alteration, or surgery, might have just been for ornamental purposes, or a piercing, the researchers suggest.

Lead author Javier Angulo, chair of the Department of Urology at Hospital Universitario de Getafe in Spain, explains that, like today, tattooing and manipulation of body parts have always functioned as a way for people to express themselves.

"[People] may feel that scars are a written story on the skin," he said.

"Making scars, holes to pick bones, and also writing on the skin -- tattooing -- may add meaning to an otherwise 'silly body,'" he added. "If one or several marks became popular or fashionable, they may be culturally elected as 'fancy' and 'desirable.' The face and areas around natural orifices are parts of the body with a higher tendency to be decorated and shown."

Angulo and colleagues Marcos García-Díez and Marc Martínez studied male genital representations in portable, mostly handheld sizes of art made in Europe approximately 38,000 to 11,000 years ago.

The pieces, researchers say, frequently mirrored what actually appeared on the male penis. Paleolithic art is known to be very naturalistic, so the artists were recreating what they saw.

Additionally, Angulo said that "Otzi and some mummies confirm tattoos were on their skin."

"Modern primitives did modify their bodies, including their genitals, with the use of tattooing, perforations and cuttings (scars) to change their appearance," Angulo said.

Phallic decoration became prevalent among men of the Magdalenian culture in France and Spain about 12,000 years ago, according to a study in The Journal of Urology. Analysis of the mostly hand-held art excavated from sites in France, Spain, Germany and the Ukraine shows that most of it was created in Europe approximately 38,000 years ago. Pictured here are several portable phallic pieces. The top line shows totally retracted or absent foreskin on the art pieces. The second line shows a replication of piercing, scaring and tattooing [Credit: Javier Angulo/Discovery News]

They therefore believe it is "highly probable that the marks left on these phalli are not decorative for the sake of the piece of art but rather a depiction of real-life details."

Many of the marks are geometric shapes, such as triangles or circles. Some designs appear to match those of figures seen within Paleolithic cave art from the same regions. This suggests that the symbols may have held important meanings for people then.

"It is widely understood that these designs are part of an unknown code," Angulo said, adding that some of them might have been made exclusively for a decorative purpose. Tattoos today follow the same coda, for the most part. A lion tattoo on a man's arm may only mean that the man likes the look, not that the lion means anything special to him.

Angulo added that other possible explanations for the symbols include: "territorial signs or landmarks, shamanistic repetitive marks in the passage to an unconscious world, some forms of primitive counting, the investigation of non-figurative artistic expression playing with spaces and light and darkness…Who knows?"

What is clear is that phallic decoration became more prevalent among men of the Magdalenian Culture in France and Spain about 12,000 years ago.

"That could be part of a cultural phenomenon related to a concrete time and space," Angulo said.

Another finding of the study is that prehistoric men seemed to favor preputial retraction, or drawing back of the foreskin. As a result, the scientists think it's likely that early males practiced circumcision as both a way to prevent disease and for affiliation purposes. To this day, ritual or religious circumcisions occur within several cultures.

For the prehistoric cultures, Angulo believes that their "canon of beauty” changed over time. Earlier humans of the Gravettian culture, known for characteristic tools such as carving blades, appear to have favored more exaggerated depictions of sexuality, as is evident in many of their "Venus" figurines of naked women. The Magdalenians, on the other hand, had a more naturalistic concept of beauty, according to the authors.

For a separate study, Liam Brady of Monash University's Center for Australian Indigenous Studies, looked at early body art in Australia. He told Discovery News that such research might provide clues into the mindset and actions of early cultures.

Brady explained, "Distinctive design conventions can be considered markers of social interaction so, in a way (they are) a cultural signature of sorts that archaeologists can use to understand ways people were interacting in the past."

The past may additionally be tied to the present, as Angulo and his team suspect that the Paleolithic phallic art may show the anthropological origin of current male genital piercing and tattooing.

Author: Jennifer Viegas | Source: Discovery News [November 11, 2011]

3.6 million-year-old "family" may not be related

A famous trail of footprints once thought to have been left behind by a family of three human ancestors may have actually been made by four individuals traveling at different times.

Laetoli footprints, Tanzania [Source: Web]

In a new examination of Laetoli in northern Tanzania, where a 3.6-million-year-old track of footprints of the bipedal human ancestor Australopithecus is preserved, researchers now argue that the classic understanding of this site is mistaken. The footprints have been buried since the mid-1990s for preservation, but a section recently opened for study as Tanzanian officials make plans for a museum on the site.

Preserved at Laetoli are two lines of hominid prints, along the crisscrossing tracks of early rabbits and other animals. The site is the earliest example of an upright, humanlike gait in our ancestors. Early analysis had suggested the tracks were laid down by three individuals, evolutionary relatives of the famous Australopithecus aferensis "Lucy," discovered in Ethiopia. One Australopithecus walked next to another, while a third, smaller individual trailed behind, stepping in the tracks of one of the larger individuals.

Researchers speculated that the three Australopithecus walkers were a male, female and juvenile — a "first family" of upright walkers. But new high-resolution photographs reveal a different story, said study researcher Brent Breithaupt, a paleontologist at the U.S. Bureau of Land Management (BLM) in Cheyenne, Wyo.

The multiple-footprint impressions appear to contain not two sets of toe-prints, but three, Breithaupt said. And all of the individuals who walked through the plain had the same-sized feet.

"So instead of having three individuals of different sizes, with the sizes related to different ages, there are probably four individuals of the same size moving through this area, perhaps not traveling as a group," Breithaupt told LiveScience.

New look at old footprints

The Australopithecus tracks were first uncovered in the 1970s by researchers led by anthropologist Mary Leakey. While taking a break, the scientists struck up a rowdy elephant-dung fight on the Serengeti Plain. In the hilarity, one researcher practically tripped over the Laetoli footprints.

But because the footprints are fragile, they were re-buried to keep them conserved, and re-opened only once in the 1990s. That means that much of the study of the footprints has been secondhand, said study researcher Neffra Matthews, a scientist at the BLM in Denver.

U.S. Bureau of Land Management team members Tom Noble, center, and Neffra Matthews, right, partner with the government of Tanzania in a recent re-excavation of the famous early hominid footprints discovered by the Leakeys at Laetoli in Tanzania [Credit: Vanessa Stepanek]

"Any secondary interpretations had to be made from the first interpretations or from a cast or reproduction," Matthews told LiveScience. "So not having access to that primary set of data kind of channeled the way the interpretations would go from then on."

In February 2011, however, a section of the track area was re-excavated for evaluation as a future museum site. Using a photographic technique that provides high-resolution three-dimensional views of the footprints, Matthews, Breithaupt and Charles Musiba, an anthropologist at the University of Colorado at Denver, and their colleagues from the U.S., Tanzania, Korea and Spain were able to get a new view of the footprints. The research was funded by Tanzania's Ministry of Tourism and Natural Resources.

Party of four

The three-dimensional data provided by the new technique revealed an extra set of toe-prints in the multiple-footprint impressions. Careful measurements revealed that each individual had a footprint that was about 7.5 inches (19 centimeters) long, suggesting that each Australopithecus was the same size.

In addition, the lone set of tracks neighboring the multi-footprint trail revealed that the individual's right foot was angled strangely compared with the left foot, Matthews reported Nov. 4 here at the annual meeting of the Society of Vertebrate Paleontologists.

"Not only do we notice there is a change in the angle, but we also notice there is more weight being placed on the left foot, possibly indicating that there is a problem with the right foot," Matthews said.

The findings are preliminary, and future plans to re-excavate more of the tracks could provide more information on how these ancient human ancestors walked and how many there were, she said.

The new findings raise questions of why Australopithecus might have been walking in each other's footprints, said Martin Lockley, a paleontologist at the University of Colorado at Denver who was not involved in the current study. They also highlight the importance of taking a hard look at the evidence so that modern biases don't creep into ancient stories, he said.

"We kind of idealized the interpretation of the evidence to have a family, a mother, father and a youngster," Lockley told LiveScience, adding that there is a temptation to interpret fossil finds through a modern lens.

"There's a temptation to say, 'Well, we've got this data and it must mean something,'" he said. "And where do we get our meaning? We get our meaning from our cultural experience. So we say, 'We've got happy families today, here's a family 3.5 million years ago.'"

The new evidence torpedoes that nuclear-family ideal, he said.

"The whole concept of the family, possibly two adults and a baby, it's kind of like the three bears: mama, papa and baby," Lockley said. "We've brought in an uncle or a sister or a brother or something."

Author: Stephanie Pappas | Source: LiveScience [November 08, 2011]

Modern humans arrived earlier in Southern Europe than previously believed

Virtual Anthropology allows new identification of first modern humans – Members of our species (Homo sapiens) arrived in Europe several millennia earlier than previously thought. At this conclusion a team of researchers, led by the Department of Anthropology, University of Vienna, arrived after re-analyses of two ancient deciduous teeth.

Mesial view of the specimen Cavallo-B (deciduous left upper first molar), the first European anatomically modern human. The white bar in the figure is equivalent to 1 cm [Credit: Stefano Benazzi]

These teeth were discovered 1964 in the "Grotta del Cavallo", a prehistoric cave in southern Italy. Since their discovery they have been attributed to Neanderthals, but this new study suggests they belong to anatomically modern humans.

Chronometric analysis, carried out by the Oxford Radiocarbon Accelerator Unit at the University of Oxford, shows that the layers within which the teeth were found date to ~43,000-45,000 cal BP. This means that the human remains are older than any other known European modern humans. The research work was published in the renowned science journal Nature.

Grotta del Cavallo, in Apulia, was discovered in 1960. It contained about 7 m of archaeological deposits spanning the period during which Neanderthals were replaced by modern humans. Two milk teeth were unearthed in 1964 by Arturo Palma di Cesnola (emeritus of the University of Siena) from the so-called Uluzzian archaeological layers.

The Uluzzian culture has been described from more than 20 separate sites across Italy, and is characterised by personal ornaments, bone tools and colourants; items typically associated with modern human symbolic behaviour. But the teeth from Cavallo were identified in the 1960's as Neanderthals who lived around 200,000 to 40,000 years ago. This attribution has been at the heart of a widely held consensus that the Uluzzian and the complex ornaments and tools within it were also produced by Neanderthals.

Comparison of micro-computed-tomography scans of teeth

Stefano Benazzi, post-doc at the Department of Anthropology at University of Vienna, and his colleagues were able to compare digital models derived from micro-computed tomography scans of the human remains from Grotta del Cavallo with those of a large modern human and Neanderthal dental sample:

Three-dimensional digital model of Cavallo-B (deciduous left upper first molar). Enamel is transparent to show the crown dentine [Credit: Stefano Benazzi]

"We worked with two independent methods: for the one, we measured the thickness of the tooth enamel, and for the other, the general outline of the crown. By means of micro-computed tomography it was possible to compare the internal and external features of the dental crown. The results clearly show that the specimens from Grotta del Cavallo were modern humans, not Neanderthals as originally thought."

New chronometric analyses of the Oxford Radiocarbon Accelerator Unit

Katerina Douka, post-doc at the Research Laboratory for Archaeology and History of Art at the University of Oxford, undertook a comprehensive programme of radiocarbon dating to establish a firm chronology for the finds. Previous dates for the Uluzzian were problematic and affected by contamination. Since the teeth were too small to date directly, Douka developed a new approach that focused on the dating of marine shells found in the same archaeological levels as the teeth.

Uluzzian artifacts from Grotta del Cavallo, Apulia, southern Italy [Credit: Annamaria Ronchitelli and Katerina Douka]

This approach showed that the modern human teeth must date to between ~43,000-45,000 years ago. Douka said, "Radiocarbon dating of Palaeolithic material is difficult because the levels of remaining radiocarbon are very low and contamination can be problematic. Shell beads are important objects of body ornamentation and have allowed us directly and reliably radiocarbon date items associated with these early Homo sapiens settlers of Europe."

Uluzzian culture was made by modern humans

"What the new dates mean", Benazzi summarised, "is that these two teeth from Grotta del Cavallo represent the oldest European modern human fossils currently known. This find confirms that the arrival of our species on the continent – and thus the period of coexistence with Neanderthals – was several thousand years longer than previously thought.

Grotta del Cavallo (red arrow) opens on the bay of Uluzzo, which is located in the Regional Natural Park of Portoselvaggio, Apulia, southern Italy [Credit: Annamaria Ronchitelli]

Based on this fossil evidence, we have confirmed that modern humans and not Neanderthals are the makers of the Uluzzian culture. This has important implications to our understanding of the development of 'fully modern' human behaviour. Whether the colonisation of the continent occurred in one or more waves of expansion and which routes were followed is still to be established."

International collaboration makes it possible

Gerhard Weber, head of the Core Facility for Micro-Computed Tomography and deputy head of the Department of Anthropology at University of Vienna, commented on the discovery in the following way: "Human fossil material is very rare, particularly well preserved deciduous teeth. It is only thanks to the collaboration of several European institutions that fossil remains were accessible.

The re-evaluation of the Cavallo material was only made possible through technical innovations developed in the last decade, known as 'Virtual Anthropology'. These new techniques developed for dental morphometrics and also new radiocarbon dating will help to address taxonomic questions associated with other contentious human fossil remains."

Source: University of Vienna [November 02, 2011]