Evidence of early humans living on the coast in South Africa, harvesting food from the sea, employing complex bladelet tools and using red pigments in symbolic behavior 164,000 years ago, far earlier than previously documented, is being reported in the Oct. 18 issue of the journal Nature. The international team of researchers reporting the findings include Curtis Marean, a paleoanthropologist with the Institute of Human Origins at Arizona State University and three graduate students in the School of Human Evolution and Social Change.
“Our findings show that at 164,000 years ago in coastal South Africa humans expanded their diet to include shellfish and other marine resources, perhaps as a response to harsh environmental conditions,” notes Marean, a professor in ASU’s School of Human Evolution and Social Change. “This is the earliest dated observation of this behavior.”
Further, the researchers report that co-occurring with this diet expansion is a very early use of pigment, likely for symbolic behavior, as well as the use of bladelet stone tool technology, previously dating to 70,000 years ago.
These new findings not only move back the timeline for the evolution of modern humans, they show that lifestyles focused on coastal habitats and resources may have been crucial to the evolution and survival of these early humans.
Searching for beginnings
After decades of debate, paleoanthropologists now agree the genetic and fossil evidence suggests that the modern human species – Homo sapiens – evolved in Africa between 100,000 and 200,000 years ago.
Yet, archaeological sites during that time period are rare in Africa. And, given the enormous expanse of the continent, where in Africa did this crucial step to modern humans occur.
“Archaeologists have had a hard time finding material residues of these earliest modern humans,” Marean says. “The world was in a glacial stage 125,000 to 195,000 years ago, and much of Africa was dry to mostly desert; in many areas food would have been difficult to acquire. The paleoenvironmental data indicate there are only five or six places in all of Africa where humans could have survived these harsh conditions.”
In seeking the “perfect site” to explore, Marean analyzed ocean currents, climate data, geological formations and other data to pin down a location where he felt sure to find one of these progenitor populations: the Cape of South Africa at Pinnacle Point.
“It was important that we knew exactly where to look and what we were looking for,” says Marean. This type of research is expensive and funding is competitive. Marean and the team of scientists who set out to Pinnacle Point to search for this elusive population, did so with the help of a $2.5 million grant from the National Science Foundation’s Human Origins: Moving in New Directions (HOMINID) program.
Their findings are reported in the Nature paper “Early human use of marine resources and pigment in South Africa during the Middle Pleistocene.” In addition to Marean, authors on the paper include three graduate students in ASU’s School of Human Evolution and Social Change: Erin Thompson, Hope Williams and Jocelyn Bernatchez. Other authors are Miryam Bar-Matthews of the Geological Survey of Israel, Erich Fisher of the University of Florida, Paul Goldberg of Boston University, Andy I.R. Herries of the University of New South Wales (Australia), Zenobia Jacobs of the University of Wollongong (Australia), Antonieta Jerardino of the University of Cape Town (South Africa), Panagiotis Karkanas of Greece’s Ministry of Culture, Tom Minichillo of the University of Washington, Ian Watts from London and excavation co-director Peter J. Nilssen of the Iziko South African Museum.
The Middle Stone Age, dated between 35,000 and 300,000 years ago, is the technological stage when anatomically modern humans emerged in Africa, along with modern cognitive behavior, says Marean. When, however, within that stage modern human behavior arose is currently debated, he adds.
“This time is beyond the range of radiocarbon dating, yet the dates on the finds published here are more secure than is typical due to the use of two advanced and independent techniques,” Marean says.
Uranium series dates were attained by Bar-Matthews on speleothem (the material of stalagmites), and optically stimulated luminescence dates were developed by Jacobs. According to Marean, the latter technique dates the last time that individual grains of sand were exposed to light, and thousands of grains were measured.
Migrating along the coast
“Generally speaking, coastal areas were of no use to early humans – unless they knew how to use the sea as a food source” says Marean. “For millions of years, our earliest hunter-gatherer relatives only ate terrestrial plants and animals. Shellfish was one of the last additions to the human diet before domesticated plants and animals were introduced.”
Before, the earliest evidence for human use of marine resources and coastal habitats was dated about 125,000 years ago. “Our research shows that humans started doing this at least 40,000 years earlier. This could have very well been a response to the extreme environmental conditions they were experiencing,” he says.
“We also found what archaeologists call bladelets – little blades less than 10 millimeters in width, about the size of your little finger,” Marean says. “These could be attached to the end of a stick to form a point for a spear, or lined up like barbs on a dart – which shows they were already using complex compound tools. And, we found evidence that they were using pigments, especially red ochre, in ways that we believe were symbolic,” he describes.
Archaeologists view symbolic behavior as one of the clues that modern language may have been present. The earliest bladelet technology was previously dated to 70,000 years ago, near the end of the Middle Stone Age, and the modified pigments are the earliest securely dated and published evidence for pigment use.
“Coastlines generally make great migration routes,” Marean says. “Knowing how to exploit the sea for food meant these early humans could now use coastlines as productive home ranges and move long distances.”
Results reporting early use of coastlines are especially significant to scientists interested in the migration of humans out of Africa. Physical evidence that this coastal population was practicing modern human behavior is particularly important to geneticists and physical anthropologists seeking to identify the progenitor population for modern humans.
“This evidence shows that Africa, and particularly southern Africa, was precocious in the development of modern human biology and behavior. We believe that on the far southern shore of Africa there was a small population of modern humans who struggled through this glacial period using shellfish and advanced technologies, and symbolism was important to their social relations. It is possible that this population could be the progenitor population for all modern humans,” Marean says."
Wednesday, October 17, 2007
Thursday, October 11, 2007
New findings solve human origins mystery
An extraordinary advance in human origins research reveals evidence of the emergence of the upright human body plan over 15 million years earlier than most experts have believed. More dramatically, the study confirms preliminary evidence that many early hominoid apes were most likely upright bipedal walkers sharing the basic body form of modern humans. On October 10th, online, open-access journal PLoS ONE will publish the report based on research from Harvard University’s Museum of Comparative Zoology and from the Cedars Sinai Institute for Spinal Disorders that connects several recent fossil discoveries to older fossils finds that have eluded adequate explanation in the past.
Recent advances in the field of homeotic genetics together with a series of discoveries of hominoid fossils vertebrae now strongly suggest that a specific genetic change that generated the upright bipedal human body form may soon be identified. The various upright “hominiform” hominoids appear to share this morphogenetic innovation with modern humans. Homeotics concerns the embryological assembly program for midline repeating structures such as the human vertebral column and the insect body segments.
The report analyses changes in homeotic embryological assembly of the spine in more than 200 mammalian species across a 250 million year time scale. It identifies a series of modular changes in genetic assembly program that have taken place at the origin point of several major groups of mammals including the newly designated ‘hominiform’ hominoids that share the modern human body plan.
The critical event involves a dramatic embryological change unique to the human lineage that was not previously understood because the unusual human condition was viewed as “normal.”
“From an embryological point of view, what took place is literally breathtaking,” says Dr. Aaron Filler, a Harvard trained evolutionary biologist and a medical director at Cedars Sinai Medical Center’s Institute for Spinal Disorders. Dr. Filler is an expert in spinal biology and the author of three books about the spine – “Axial Character Seriation in Mammals” (BrownWalker 2007), “The Upright Ape” (New Page Books 2007), and “Do You Really Need Back Surgery” (Oxford University Press 2007).
In most vertebrates (including most mammals), he explains, the dividing plane between the front (ventral) part of the body and the back (dorsal) part is a “horizontal septum” that runs in front of the spinal canal. This is a fundamental aspect of animal architecture. A bizarre birth defect in what may have been the first direct human ancestor led to the “transposition” of the septum to a position behind the spinal cord in the lumbar region. Oddly enough, this configuration is more typical of invertebrates.
The mechanical effect of the transposition was to make horizontal or quadrupedal stance inefficient. “Any mammal with this set of changes would only be comfortable standing upright. I would envision this malformed young hominiform – the first true ancestral human – as standing upright from a young age while its siblings walked around on all fours.”
The earliest example of the transformed hominiform type of lumbar spine is found in Morotopithecus bishopi an extinct hominoid species that lived in Uganda more than 21 million years ago. “From a number of points of view,” Filler says, “humanity can be redefined as having its origin with Morotopithecus. This greatly demotes the importance of the bipedalism of Australopithecus species such as Lucy (Australopithecus afarensis) since we now know of four upright bipedal species that precede her, found from various time periods on out to Morotopithecus in the Early Miocene.”
Recent advances in the field of homeotic genetics together with a series of discoveries of hominoid fossils vertebrae now strongly suggest that a specific genetic change that generated the upright bipedal human body form may soon be identified. The various upright “hominiform” hominoids appear to share this morphogenetic innovation with modern humans. Homeotics concerns the embryological assembly program for midline repeating structures such as the human vertebral column and the insect body segments.
The report analyses changes in homeotic embryological assembly of the spine in more than 200 mammalian species across a 250 million year time scale. It identifies a series of modular changes in genetic assembly program that have taken place at the origin point of several major groups of mammals including the newly designated ‘hominiform’ hominoids that share the modern human body plan.
The critical event involves a dramatic embryological change unique to the human lineage that was not previously understood because the unusual human condition was viewed as “normal.”
“From an embryological point of view, what took place is literally breathtaking,” says Dr. Aaron Filler, a Harvard trained evolutionary biologist and a medical director at Cedars Sinai Medical Center’s Institute for Spinal Disorders. Dr. Filler is an expert in spinal biology and the author of three books about the spine – “Axial Character Seriation in Mammals” (BrownWalker 2007), “The Upright Ape” (New Page Books 2007), and “Do You Really Need Back Surgery” (Oxford University Press 2007).
In most vertebrates (including most mammals), he explains, the dividing plane between the front (ventral) part of the body and the back (dorsal) part is a “horizontal septum” that runs in front of the spinal canal. This is a fundamental aspect of animal architecture. A bizarre birth defect in what may have been the first direct human ancestor led to the “transposition” of the septum to a position behind the spinal cord in the lumbar region. Oddly enough, this configuration is more typical of invertebrates.
The mechanical effect of the transposition was to make horizontal or quadrupedal stance inefficient. “Any mammal with this set of changes would only be comfortable standing upright. I would envision this malformed young hominiform – the first true ancestral human – as standing upright from a young age while its siblings walked around on all fours.”
The earliest example of the transformed hominiform type of lumbar spine is found in Morotopithecus bishopi an extinct hominoid species that lived in Uganda more than 21 million years ago. “From a number of points of view,” Filler says, “humanity can be redefined as having its origin with Morotopithecus. This greatly demotes the importance of the bipedalism of Australopithecus species such as Lucy (Australopithecus afarensis) since we now know of four upright bipedal species that precede her, found from various time periods on out to Morotopithecus in the Early Miocene.”
Human migrations in the circum-Pacific Region
A new study by Kevin Pope of Geo Eco Arc Research and John Terrell of The Field Museum adds insight into the migration of anatomically modern humans out of Africa and into Asia less than 100,000 years before present (BP). The comprehensive review of human genetic, environmental, and archaeological data from the circum-Pacific region supports the hypothesis, originally based largely on genetic evidence, that modern humans migrated into eastern Asia via a southern coastal route. The expansion of modern human populations into the circum-Pacific region occurred in at least four pulses, in part controlled by climate and sea level changes in the Late Pleistocene and Holocene epochs. The initial “out of Africa” migration was thwarted by dramatic changes in both sea level and climate and extreme drought in the coastal zone. A period of stable climate and sea level 45,000-40,000 years BP gave rise to the first major pulse of migration, when modern humans spread from India, throughout much of coastal southeast Asia, Australia, and Melanesia, extending northward to eastern Russia and Japan by 37,000 years BP.
The northward push of modern humans along the eastern coast of Asia stalled north of 43° N latitude, probably due to the inability of the populations to adjust to cold waters and tundra/steppe vegetation. The ensuing cold and dry Last Glacial period, ~33,000-16,000 year BP, once again brought dramatic changes in sea level and climate, which caused abandonment of many coastal sites. After 16,000 years BP, climates began to warm, but sea level was still 100 m below modern levels, creating conditions amenable for a second pulse of human migration into North America across an ice-free coastal plain now covered by the Bering Sea.
The stabilization of climate and sea level in the early Holocene (8,000-6,000 years BP) supported the expansion of coastal wetlands, lagoons, and coral reefs, which in turn gave rise to a third pulse of coastal settlement, filling in most of the circum-Pacific region. A slight drop in sea level in the western Pacific in the mid-Holocene (~6,000-4,000 year BP), caused a reduction in productive coastal habitats, leading to a brief disruption in human subsistence along the then densely settled coast. This disruption may have helped initiate the last major pulse of human migration in the circum-Pacific region, that of the migration to Oceania, which began about 3,500 years BP and culminated in the settlement of Hawaii and Easter Island by 2000-1000 years BP.
The northward push of modern humans along the eastern coast of Asia stalled north of 43° N latitude, probably due to the inability of the populations to adjust to cold waters and tundra/steppe vegetation. The ensuing cold and dry Last Glacial period, ~33,000-16,000 year BP, once again brought dramatic changes in sea level and climate, which caused abandonment of many coastal sites. After 16,000 years BP, climates began to warm, but sea level was still 100 m below modern levels, creating conditions amenable for a second pulse of human migration into North America across an ice-free coastal plain now covered by the Bering Sea.
The stabilization of climate and sea level in the early Holocene (8,000-6,000 years BP) supported the expansion of coastal wetlands, lagoons, and coral reefs, which in turn gave rise to a third pulse of coastal settlement, filling in most of the circum-Pacific region. A slight drop in sea level in the western Pacific in the mid-Holocene (~6,000-4,000 year BP), caused a reduction in productive coastal habitats, leading to a brief disruption in human subsistence along the then densely settled coast. This disruption may have helped initiate the last major pulse of human migration in the circum-Pacific region, that of the migration to Oceania, which began about 3,500 years BP and culminated in the settlement of Hawaii and Easter Island by 2000-1000 years BP.
Tuesday, September 25, 2007
Extraterrestrial Impact Source of Ice Age Extinctions
At the end of the Pleistocene era, wooly mammoths roamed North America along with a cast of fantastic creatures – giant sloths, saber-toothed cats, camels, lions, tapirs and the incredible teratorn, a condor with a 16-foot wingspan.
About 12,900 years ago, these megafauna disappeared from the fossil record, as did evidence of human remains. The cause of the mass extinction and the human migration is a mystery. Now a team of scientists, including Brown University planetary geologist Peter Schultz, provides evidence that an asteroid impact likely caused the sudden climate changes that killed off the mammoths and other majestic beasts of prehistory.
In the Proceedings of the National Academy of Sciences, the international team lays out its theory that the mass extinctions in North America were caused by one or more extraterrestrial objects – comets or meteorites – that exploded over the Earth or slammed into it, triggering catastrophic climate change.
The scientists believe that evidence for these extraterrestrial impacts is hidden in a dark layer of dirt sometimes called a black mat. Found in more than 50 sites around North America, this puzzling slice of geological history is a mere three centimeters deep and filled with carbon, which lends the layer its dark color. This black mat has been found in archaeological digs in Canada and California, Arizona and South Carolina – even in a research site in Belgium.
The formation of this layer dates back 12,900 years and coincides with the abrupt cooling of the Younger Dryas period, sometimes called the “Big Freeze.” This coincidence intrigued the researchers, led by Richard Firestone of Lawrence Berkeley National Laboratory, who thought that the black mat might be related to the mass extinctions.
So the researchers studied black mat sediment samples from 10 archaeological sites dating back to the Clovis people, the first human inhabitants of the New World. Researchers conducted geochemical analysis of the samples to determine their makeup and also ran carbon dating tests to determine the age of the samples.
Directly beneath the black mat, researchers found high concentrations of magnetic grains containing iridium, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds and fullerenes packed with extraterrestrial helium – all of which are evidence for an extraterrestrial impact and the raging wildfires that might have followed.
Schultz, professor of geological sciences at Brown and an impact specialist, said the most provocative evidence for an extraterrestrial impact was the discovery of nanodiamonds, microscopic bits of diamond formed only from the kind of intense pressure you’d get from a comet or meteorite slamming into the Earth.
“We don’t have a smoking gun for our theory, but we sure have a lot of shell casings,” Schultz said. “Taken together, the markers found in the samples offer intriguing evidence that North America had a major impact event about 12,900 years ago.”
Schultz admits that there is little decisive evidence about the actual details about the impact and its effects. Scientists suspect that a carbon-rich asteroid or comets were the culprits. The objects would have exploded over North America or slammed into it, or both, shattering and melting ice sheets, sparking extreme wildfires, and fueling hurricane-force winds – all of which could have contributed to changes in climate that led to the cooling of the Younger Dryas period.
“Our theory isn’t a slam dunk,” Schultz said. “We need to study a lot more sediments to get a lot more evidence. But what is sobering about this theory of ours is that this impact would be so recent. Not so long ago, something may have fallen from the sky and profoundly changed our climate and our culture.”
About 12,900 years ago, these megafauna disappeared from the fossil record, as did evidence of human remains. The cause of the mass extinction and the human migration is a mystery. Now a team of scientists, including Brown University planetary geologist Peter Schultz, provides evidence that an asteroid impact likely caused the sudden climate changes that killed off the mammoths and other majestic beasts of prehistory.
In the Proceedings of the National Academy of Sciences, the international team lays out its theory that the mass extinctions in North America were caused by one or more extraterrestrial objects – comets or meteorites – that exploded over the Earth or slammed into it, triggering catastrophic climate change.
The scientists believe that evidence for these extraterrestrial impacts is hidden in a dark layer of dirt sometimes called a black mat. Found in more than 50 sites around North America, this puzzling slice of geological history is a mere three centimeters deep and filled with carbon, which lends the layer its dark color. This black mat has been found in archaeological digs in Canada and California, Arizona and South Carolina – even in a research site in Belgium.
The formation of this layer dates back 12,900 years and coincides with the abrupt cooling of the Younger Dryas period, sometimes called the “Big Freeze.” This coincidence intrigued the researchers, led by Richard Firestone of Lawrence Berkeley National Laboratory, who thought that the black mat might be related to the mass extinctions.
So the researchers studied black mat sediment samples from 10 archaeological sites dating back to the Clovis people, the first human inhabitants of the New World. Researchers conducted geochemical analysis of the samples to determine their makeup and also ran carbon dating tests to determine the age of the samples.
Directly beneath the black mat, researchers found high concentrations of magnetic grains containing iridium, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds and fullerenes packed with extraterrestrial helium – all of which are evidence for an extraterrestrial impact and the raging wildfires that might have followed.
Schultz, professor of geological sciences at Brown and an impact specialist, said the most provocative evidence for an extraterrestrial impact was the discovery of nanodiamonds, microscopic bits of diamond formed only from the kind of intense pressure you’d get from a comet or meteorite slamming into the Earth.
“We don’t have a smoking gun for our theory, but we sure have a lot of shell casings,” Schultz said. “Taken together, the markers found in the samples offer intriguing evidence that North America had a major impact event about 12,900 years ago.”
Schultz admits that there is little decisive evidence about the actual details about the impact and its effects. Scientists suspect that a carbon-rich asteroid or comets were the culprits. The objects would have exploded over North America or slammed into it, or both, shattering and melting ice sheets, sparking extreme wildfires, and fueling hurricane-force winds – all of which could have contributed to changes in climate that led to the cooling of the Younger Dryas period.
“Our theory isn’t a slam dunk,” Schultz said. “We need to study a lot more sediments to get a lot more evidence. But what is sobering about this theory of ours is that this impact would be so recent. Not so long ago, something may have fallen from the sky and profoundly changed our climate and our culture.”
Monday, September 17, 2007
Sodom?
Archaeologist Steven Collins is directing a dig at a site he believes to be the infamous city of Sodom,
Collins, dean of the College of Archaeology at Trinity Southwest University in Albuquerque, N.M., has searched for a decade for Sodom and Gomorrah, which the Bible says were sinful cities destroyed by God. The excavation is of a Bronze Age site in Jordan, near the Dead Sea.
Collins is seeking to determine the authenticity of Old Testament patriarchal narratives, particularly the stories of Abraham, Isaac, Jacob, Joseph, Moses and Joshua.
He said findings of pottery and a mud-brick-and-earth rampart indicate that the city was destroyed in the Middle Bronze Age at about 2000 B.C., the time of Abraham and the story of the destruction of Sodom and Gomorrah. He is using biblical text, archaeology and geography in his quest.
www.findadig.com/collins
Collins, dean of the College of Archaeology at Trinity Southwest University in Albuquerque, N.M., has searched for a decade for Sodom and Gomorrah, which the Bible says were sinful cities destroyed by God. The excavation is of a Bronze Age site in Jordan, near the Dead Sea.
Collins is seeking to determine the authenticity of Old Testament patriarchal narratives, particularly the stories of Abraham, Isaac, Jacob, Joseph, Moses and Joshua.
He said findings of pottery and a mud-brick-and-earth rampart indicate that the city was destroyed in the Middle Bronze Age at about 2000 B.C., the time of Abraham and the story of the destruction of Sodom and Gomorrah. He is using biblical text, archaeology and geography in his quest.
www.findadig.com/collins
Wednesday, September 12, 2007
Role of climate in Neanderthal extinction
New evidence on the role of climate in Neanderthal extinction
THE mystery of what killed the Neanderthals has moved a step closer to resolution after an international study led by the University of Leeds has ruled out one of the competing theories – catastrophic climate change – as the most likely cause.
The bones of more than 400 Neanderthals have been found since the first discoveries were made in the early 19th century. The finds suggest the Neanderthals, named after the Neander Valley near Düsseldorf, where they were first recognized as an extinct kind of archaic humans, inhabited Europe and parts of western Asia for more than 100,000 years.
The causes of their extinction have puzzled scientists for years – with some believing it was due to competition with modern humans, while others blamed deteriorating climatic conditions. But a new study published today in Nature has shown that the Neanderthal extinction did not coincide with any of the extreme climate events that punctuated the last glacial period.
The research was led by Professor Chronis Tzedakis, a palaeoecologist at the University of Leeds, who explained: “Until now, there have been three limitations to understanding the role of climate in the Neanderthal extinction: uncertainty over the exact timing of their disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record.”
The team’s novel method – mapping radiocarbon dates of interest directly onto a well-dated palaeoclimate archive – circumvented the last two problems, providing a much more detailed picture of the climate at the possible times of the Neanderthal disappearance.
The researchers applied the new method to three alternative sets of dates for the timing of the Neanderthal extinction from Gorham’s Cave, Gibraltar, a site which is thought to have been occupied by some of the latest surviving Neanderthals:
a set of generally accepted but older dates (around 30-32,000 radiocarbon years ago)
newly-suggested younger dates (around 28,000 radiocarbon years ago)
more contentious dates (around 24,000 radiocarbon years ago).
The team showed that during the first two sets of dates, Europe was experiencing conditions similar to the general climatic instability of the last glacial period – conditions the Neanderthals had already proved able to survive.
The much more controversial date of around 24,000 radiocarbon years ago placed the last Neanderthals just before a large expansion of ice sheets and the onset of cold conditions in northern Europe. “But at that time, Gibraltar’s climate remained relatively unaffected, perhaps as a result of warm water from the subtropical Atlantic entering the western Mediterranean,” explained palaeoceanographer Isabel Cacho of the University of Barcelona.
“Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals,” concludes palaeonthropologist Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology. “Only the controversial date of 24,000 radiocarbon years for their disappearance, if proven correct, coincides with a major environmental shift. Even in this case, however, the role of climate would have been indirect, by promoting competition with other human groups.”
The work also has wider implications for other studies, as paleoclimatologist Konrad Hughen of the Woods Hole Oceanographic Institution explained: “Our approach offers the huge potential to unravel the role of climate in critical events of the recent fossil record as it can be applied to any radiocarbon date from any deposit.”
THE mystery of what killed the Neanderthals has moved a step closer to resolution after an international study led by the University of Leeds has ruled out one of the competing theories – catastrophic climate change – as the most likely cause.
The bones of more than 400 Neanderthals have been found since the first discoveries were made in the early 19th century. The finds suggest the Neanderthals, named after the Neander Valley near Düsseldorf, where they were first recognized as an extinct kind of archaic humans, inhabited Europe and parts of western Asia for more than 100,000 years.
The causes of their extinction have puzzled scientists for years – with some believing it was due to competition with modern humans, while others blamed deteriorating climatic conditions. But a new study published today in Nature has shown that the Neanderthal extinction did not coincide with any of the extreme climate events that punctuated the last glacial period.
The research was led by Professor Chronis Tzedakis, a palaeoecologist at the University of Leeds, who explained: “Until now, there have been three limitations to understanding the role of climate in the Neanderthal extinction: uncertainty over the exact timing of their disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record.”
The team’s novel method – mapping radiocarbon dates of interest directly onto a well-dated palaeoclimate archive – circumvented the last two problems, providing a much more detailed picture of the climate at the possible times of the Neanderthal disappearance.
The researchers applied the new method to three alternative sets of dates for the timing of the Neanderthal extinction from Gorham’s Cave, Gibraltar, a site which is thought to have been occupied by some of the latest surviving Neanderthals:
a set of generally accepted but older dates (around 30-32,000 radiocarbon years ago)
newly-suggested younger dates (around 28,000 radiocarbon years ago)
more contentious dates (around 24,000 radiocarbon years ago).
The team showed that during the first two sets of dates, Europe was experiencing conditions similar to the general climatic instability of the last glacial period – conditions the Neanderthals had already proved able to survive.
The much more controversial date of around 24,000 radiocarbon years ago placed the last Neanderthals just before a large expansion of ice sheets and the onset of cold conditions in northern Europe. “But at that time, Gibraltar’s climate remained relatively unaffected, perhaps as a result of warm water from the subtropical Atlantic entering the western Mediterranean,” explained palaeoceanographer Isabel Cacho of the University of Barcelona.
“Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals,” concludes palaeonthropologist Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology. “Only the controversial date of 24,000 radiocarbon years for their disappearance, if proven correct, coincides with a major environmental shift. Even in this case, however, the role of climate would have been indirect, by promoting competition with other human groups.”
The work also has wider implications for other studies, as paleoclimatologist Konrad Hughen of the Woods Hole Oceanographic Institution explained: “Our approach offers the huge potential to unravel the role of climate in critical events of the recent fossil record as it can be applied to any radiocarbon date from any deposit.”
Tuesday, September 4, 2007
Pigs brought to Europe by early farmers
Pig study sheds new light on the colonisation of Europe by early farmers
The earliest domesticated pigs in Europe, which many archaeologists believed to be descended from European wild boar, were actually introduced from the Middle East by Stone Age farmers, new research suggests.
The research by an international team led by archaeologists at Durham University, which is published today in the academic journal Proceedings of the National Academies of Sciences USA, analysed mitochondrial DNA from ancient and modern pig remains. Its findings also suggest that the migration of an expanding Middle Eastern population, who brought their ‘farming package’ of domesticated plants, animals and distinctive pottery styles with them, actually ‘kickstarted’ the local domestication of the European wild boar.
While archaeologists already know that agriculture began about 12,000 years ago in the central and western parts of the Middle East, spreading rapidly across Europe between 6,800 – 4000BC, many outstanding questions remain about the mechanisms of just how it spread. This research sheds new and important light on the actual process of the establishment of farming in Europe.
Durham University’s Dr Keith Dobney explained: “Many archaeologists believe that farming spread through the diffusion of ideas and cultural exchange, not with the direct migration of people. However, the discovery and analysis of ancient Middle Eastern pig remains across Europe reveals that although cultural exchange did happen, Europe was definitely colonised by Middle Eastern farmers.
“A combination of rising population and possible climate change in the ‘fertile crescent’, which put pressure on land and resources, made them look for new places to settle, plant their crops and breed their animals and so they rapidly spread west into Europe.”
The research, funded by the Wellcome Trust, the Leverhulme Trust, the Arts and Humanities Research Council (AHRC) and the Smithsonian Institution also showed that within 500 years after the local domestication of the European wild boar, the new domestics completely replaced the Middle Eastern pigs that had arrived in Europe as part of the ‘farming package’.
Dr Greger Larson, who performed the genetic analysis said: “The domestic pigs that were derived from the European wild boar must have been considered vastly superior to those originally from Middle East, though at this point we have no idea why. In fact, the European domestic pigs were so successful that over the next several thousand years they spread across the continent and even back into the Middle East where they overtook the indigenous domestic pigs. For whatever reason, European pigs were the must have farm animal.”
The research is part of an ongoing research project based at Durham University which explores the role of animals in reconstructing early farming, ancient human migration and past trade and exchange networks around the world.
The earliest domesticated pigs in Europe, which many archaeologists believed to be descended from European wild boar, were actually introduced from the Middle East by Stone Age farmers, new research suggests.
The research by an international team led by archaeologists at Durham University, which is published today in the academic journal Proceedings of the National Academies of Sciences USA, analysed mitochondrial DNA from ancient and modern pig remains. Its findings also suggest that the migration of an expanding Middle Eastern population, who brought their ‘farming package’ of domesticated plants, animals and distinctive pottery styles with them, actually ‘kickstarted’ the local domestication of the European wild boar.
While archaeologists already know that agriculture began about 12,000 years ago in the central and western parts of the Middle East, spreading rapidly across Europe between 6,800 – 4000BC, many outstanding questions remain about the mechanisms of just how it spread. This research sheds new and important light on the actual process of the establishment of farming in Europe.
Durham University’s Dr Keith Dobney explained: “Many archaeologists believe that farming spread through the diffusion of ideas and cultural exchange, not with the direct migration of people. However, the discovery and analysis of ancient Middle Eastern pig remains across Europe reveals that although cultural exchange did happen, Europe was definitely colonised by Middle Eastern farmers.
“A combination of rising population and possible climate change in the ‘fertile crescent’, which put pressure on land and resources, made them look for new places to settle, plant their crops and breed their animals and so they rapidly spread west into Europe.”
The research, funded by the Wellcome Trust, the Leverhulme Trust, the Arts and Humanities Research Council (AHRC) and the Smithsonian Institution also showed that within 500 years after the local domestication of the European wild boar, the new domestics completely replaced the Middle Eastern pigs that had arrived in Europe as part of the ‘farming package’.
Dr Greger Larson, who performed the genetic analysis said: “The domestic pigs that were derived from the European wild boar must have been considered vastly superior to those originally from Middle East, though at this point we have no idea why. In fact, the European domestic pigs were so successful that over the next several thousand years they spread across the continent and even back into the Middle East where they overtook the indigenous domestic pigs. For whatever reason, European pigs were the must have farm animal.”
The research is part of an ongoing research project based at Durham University which explores the role of animals in reconstructing early farming, ancient human migration and past trade and exchange networks around the world.
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