Out of Africa date brought forwardMarch 22, 2013 by Lin Edwards
Ötzi the Iceman, a well-preserved natural mummy of a Chalcolithic (Copper Age), who was found in 1991 in the Schnalstal glacier in the Ötztal Alps. Credit: South Tyrol Museum of Archaeology (Phys.org)
—A study on human mitochondrial DNA has led to a new estimate of the time at which humans first began to migrate out of Africa, which was much later than previously thought.
The new study by an International group of evolutionary geneticists used mitochondrial DNA from the remains of ancient modern humans to estimate the rate of genetic mutations. Three of the skeletons were from the Czech Republic and dated at 31,000 years old, two were 14,000 years old, from Oberkassel, Germany. Another sample used was the natural mummy Ötzi the Iceman, who lived some time between 3350 and 3100 BC. The most recent skeleton was that of a man who lived in medieval France 700 years ago, while the oldest was dated at 40,000 years ago, and came from Tianyuan in China. The results suggest that the genetic divergence between African and non-African humans began between 62 and 95 thousand years ago, which tallies with other studies estimating the time through dating of stone tools and fossils, but they disagree with the results of recent genetic studies that estimated the migration began much earlier, up to 130 thousand years ago or even before. The previous studies sequenced the entire genome of living humans to count the number of genetic mutations (around 50) in newborn babies compared to the parents to determine the generational mutation rate. This then provided the a molecular "clock," which could be extrapolated backwards to date important events in human evolution.
Triple burial from Dolni Vestonice in the Czech Republic. Credit: J. Svoboda
The new study sequenced mitochondrial DNA from fossils of ancient modern humans rather than living humans. The fossils were dated using radiocarbon dating methods. Since the samples were from humans who lived up to 40,000 years ago, mutations that have occurred in the genome since they died would be missing, and the samples provided a range of calibration points for their estimation of the start of the migration.
The disagreement in dating the migration between the new study and previous genetic research could be due to underestimating the number of new mutations in a generation of living humans because of the difficulty of discriminating between true mutations and mistaken ones and because of a desire to avoid false positives. Under-counting would lead to an older estimate for the migration from Africa and other important events. The new date, which agrees with the archaeological evidence, shows that modern humans were in Europe and Asia before and after the most recent glaciation, and they were therefore able to survive and adapt to a dramatically changing climate. The paper was published in the journal Current Biology on 21st March.
A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes, Current Biology, 21 March 2013, DOI: 10.1016/j.cub.2013.02.044
Journal reference: Current Biology © 2013 Phys.org
Read more at: http://phys.org/news/2013-03-africa-date-brought.html#jCp
Read more at: http://phys.org/news/2013-03-africa-date-brought.html#jCp
Lao skull earliest example of modern human fossil in Southeast AsiaAugust 20, 2012
The researchers found skull fragments that date to 63,000 years ago. Credit: Laura Shackelford
An ancient skull recovered from a cave in the Annamite Mountains in northern Laos is the oldest modern human fossil found in Southeast Asia, researchers report. The discovery pushes back the clock on modern human migration through the region by as much as 20,000 years and indicates that ancient wanderers out of Africa left the coast and inhabited diverse habitats much earlier than previously appreciated.
The team described its finding in a paper in Proceedings of the National Academy of Sciences. The scientists, who found the skull in 2009, were likely the first to dig for ancient bones in Laos since the early 1900s, when a team found skulls and skeletons of several modern humans in another cave in the Annamite Mountains. Those fossils were about 16,000 years old, much younger than the newly found skull, which dates to between 46,000 and 63,000 years old. "It's a particularly old modern human fossil and it's also a particularly old modern human for that region," said University of Illinois anthropologist Laura Shackelford, who led the study with anthropologist Fabrice Demeter, of the National Museum of Natural History in Paris. "There are other modern human fossils in China or in Island Southeast Asia that may be around the same age but they either are not well dated or they do not show definitively modern human features. This skull is very well dated and shows very conclusive modern human features," she said. No other artifacts have yet been found with the skull, suggesting that the cave was not a dwelling or burial site, Shackelford said. It is more likely that the person died outside and the body washed into the cave sometime later, she said. The find reveals that early modern human migrants did not simply follow the coast and go south to the islands of Southeast Asia and Australia, as some researchers have suggested, but that they also traveled north into very different types of terrain, Shackelford said. "This find supports an 'Out-of-Africa' theory of modern human origins rather than a multi-regionalism model," she said. "Given its age, fossils in this vicinity could be direct ancestors of the first migrants to Australia. But it is also likely that mainland Southeast Asia was a crossroads leading to multiple migratory paths
The discovery also bolsters genetic studies that indicate that modern humans occupied that part of the world at least 60,000 years ago, she said. "This is the first fossil evidence that supports the genetic data," she said. The researchers used radiocarbon dating and luminescence techniques to determine the age of the soil layers above, below and surrounding the skull, which was found nearly 2 1/2 meters (about 8.2 feet) below the surface of the cave. Researchers at Illinois used uranium/thorium dating to determine the age of the skull, which they determined was about 63,000 years old. Research fellow Kira Westaway, of Macquarie University in Australia (who dated the soils around the famous "hobbit" fossil found on Flores Island in Indonesia in 2003), conducted the luminescence analyses. These techniques measure the energy retained in crystalline particles in the soil to determine how much time has elapsed since the soil was last exposed to heat or solar radiation. She found that the layer of soil surrounding the fossil had washed into the cave between 46,000 and 51,000 years ago. "Those dates are a bit younger than the direct date on the fossil, which we would expect because we don't know how long the body sat outside the cave before it washed in," Shackelford said. "This fossil find indicates that the migration out of Africa and into East and Southeast Asia occurred at a relatively rapid rate, and that, once there, modern humans weren't limited to environments that they had previously experienced," she said. "We now have the fossil evidence to prove that they were there long before we thought they were there."
More information: "An Anatomically Modern Human in Southeast Asia (Laos) by 46 ka," PNAS, 2012
.Journal reference: Proceedings of the National Academy of Sciences
Provided by University of Illinois at Urbana-Champaign
[This skull is hardly "Modern", it is a particularly rugged "Archaic" and could well have been in the earlier Out of Africa migration which was under way by 100,000 (one hundred thousand) BC--Dale D.]
Read more at: http://phys.org/news/2012-08-lao-skull-earliest-modern-human.html#jCp
Modern humans emerged far earlier than previously thought
October 25, 2010
Fig. 1. The human remains from Zhiren Cave. The Zhiren 3 mandible in anterior (A), lateral left (B), and superior (C) views. The midsymphyseal cross-section of the Zhiren 3 mandible (D). The Zhiren 1M3 in buccal and mesial views (E), and the Zhiren 2 M3 in the same views (F). (Scale bar, 5 cm.) (Courtesy of Drs. LIU Wu and JIN Chang-Zhu)
(PhysOrg.com) An international team of researchers based at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, including a physical anthropology professor at Washington University in St. Louis, has discovered well-dated human fossils in southern China that markedly change anthropologists perceptions of the emergence of modern humans in the eastern Old World.
The research was published Oct. 25 in the online early edition of the Proceedings of the National Academy of Sciences. The discovery of early modern human fossil remains in the Zhirendong (Zhiren Cave) in south China that are at least 100,000 years old provides the earliest evidence for the emergence of modern humans in eastern Asia, at least 60,000 years older than the previously known modern humans in the region. "These fossils are helping to redefine our perceptions of modern human emergence in eastern Eurasia, and across the Old World more generally," says Eric Trinkaus, PhD, the Mary Tileston Hemenway Professor in Arts & Sciences and professor of physical anthropology. The Zhirendong fossils have a mixture of modern and archaic features that contrasts with earlier modern humans in east Africa and southwest Asia, indicating some degree of human population continuity in Asia with the emergence of modern humans. The Zhirendong humans indicate that the spread of modern human biology long preceded the cultural and technological innovations of the Upper Paleolithic and that early modern humans co-existed for many tens of millennia with late archaic humans further north and west across Eurasia.
Provided by Washington University in St. Louis
Read more at: http://phys.org/news/2010-10-modern-humans-emerged-earlier-previously.html#jCp
[Once again, two migrations Out of Africa, the older one around 100000 years ago and freaturing older, more rugged, more "Archaic" human beings most like some of the Australian Aboriginals, who preserve more of the people descended from these earlier colonists than anybody else-Dale D]