Saturday, April 25, 2015

Eurogenes Admixture results for Motala HGs


(Link) to the spreadsheet
(Link) to the blog post where "Davidski" has posted the spreadsheet in the comments section.

Thursday, April 23, 2015

What I'm reading now: Coevolution of Composite-Tool Technology, Constructive Memory and Language

I guess I'm a little late to the party, but in any case, for the last few days, I've been enjoying this deeply considered multi-disciplinary paper from 2010 by Stanley Ambrose.

Coevolution of Composite-Tool Technology, Constructive Memory, and Language
Implications for the Evolution of Modern Human Behavior
Current Anthropology
Volume 51, Supplement 1, June 2010
(Link) open access

Abstract:  The evolution of modern human behavior was undoubtedly accompanied by neurological changes that enhanced capacities for innovation in technology, language, and social organization associated with working memory. Constructive memory integrates components of working memory in the medial prefrontal cortex to imagine alternative futures. Enhanced mental time travel permits long range strategic planning. Within this broadly conceived area of cognitive neuropsychology, I will focus on two stages of the evolution of cognitive faculties for planning. The first involves executing complex sequences of actions involving manufacture of multicomponent artifacts; the second involves enhanced planning through information sharing, which required the establishment of extended regional social interaction networks based on trust and cooperation. Both stages were probably accompanied by important innovations in grammatical speech.

Wednesday, April 15, 2015

World’s oldest stone tools discovered in Kenya

Science Magazine
Michael Balter

SAN FRANCISCO, CALIFORNIA—Researchers at a meeting here say they have found the oldest tools made by human ancestors—stone flakes dated to 3.3 million years ago. That’s 700,000 years older than the oldest-known tools to date, suggesting that our ancestors were crafting tools several hundred thousand years before our genus Homo arrived on the scene. If correct, the new evidence could confirm disputed claims for very early tool use, and it suggests that ancient australopithecines like the famed “Lucy” may have fashioned stone tools, too.

Until now, the earliest known stone tools had been found at the site of Gona in Ethiopia and were dated to 2.6 million years ago. These belonged to a tool technology known as the Oldowan, so called because the first examples were found more than 80 years ago at Olduvai Gorge in Tanzania by famous paleoanthropologists Louis and Mary Leakey. Then, in 2010, researchers working at the site of Dikika in Ethiopia—where an australopithecine child was also discovered—reported cut marks on animal bones dated to 3.4 million years ago; they argued that tool-using human ancestors made the linear marks. The claim was immediately controversial, however, and some argued that what seemed to be cut marks might have been the result of trampling by humans or other animals. Without the discovery of actual tools, the argument seemed likely to continue without resolution.

Now, those missing tools may have been found. In a talk at the annual meeting of the Paleoanthropology Society here, archaeologist Sonia Harmand of Stony Brook University in New York described the discovery of numerous tools at the site of Lomekwi 3, just west of Lake Turkana in Kenya, about 1000 kilometers from Olduvai Gorge. In 2011, Harmand’s team was seeking the site where a controversial human relative called Kenyanthropus platyops had been discovered in 1998. They took a wrong turn and stumbled upon another part of the area, called Lomekwi, near where Kenyanthropus had been found. The researchers spotted what Harmand called unmistakable stone tools on the surface of the sandy landscape and immediately launched a small excavation.

More tools were discovered under the ground, including so-called cores from which human ancestors struck off sharp flakes; the team was even able to fit one of the flakes back to its original core, showing that a hominin had crafted and then discarded both core and flake in this spot. The researchers returned for more digging the following year and have now uncovered nearly 20 well-preserved flakes, cores, and anvils apparently used to hold the cores as the flakes were struck off, all sealed in sediments that provided a secure context for dating. An additional 130 pieces have also been found on the surface, according to the talk.

“The artifacts were clearly knapped [created by intentional flaking] and not the result of accidental fracture of rocks,” Harmand told the meeting. Analysis of the tools showed that they had been rotated as flakes were struck off, which is also how Oldowan tools were crafted. The Lomekwi tools were somewhat larger than the average Oldowan artifacts, however. Dating of the sediments using paleomagnetic techniques—which track reversals in Earth’s magnetic field over time and have been used on many hominin finds from the well-studied Lake Turkana area—put them at about 3.3 million years old.

Although very recent research has now pushed back the origins of the genus Homo to as early as 2.8 million years ago, the tools are too old to have been made by the first fully fledged humans, Harmand said in her talk. The most likely explanation, she concluded, was that the artifacts were made either by australopithecines similar to Lucy or by Kenyanthropus. Either way, toolmaking apparently began before the birth of our genus. Harmand and her colleagues propose to call the new tools the Lomekwian technology, she said, because they are too old and too distinct from Oldowan implements to represent the same technology.

Researchers who have seen the tools in person are enthusiastic about the claim. The finds are “very exciting,” says Alison Brooks, an anthropologist at George Washington University in Washington, D.C. “They could not have been created by natural forces … [and] the dating evidence is fairly solid.” She agrees that the tools are too early to have been made by Homo, suggesting that “technology played a major role in the emergence of our genus.”

The claim also looks good to paleoanthropologist Zeresenay Alemseged of the California Academy of Sciences here, a leader of the team that found cut marks on the Dikika animal bones. (At the meeting, another team member presented new arguments for the cut marks’ authenticity.) “With the cut marks from Dikika we had the victim” of the stone tools, Alemseged says. “Harmand’s discovery gives us the smoking gun.”

On aurait découvert les plus anciens outils au monde

Sciences et Avenir

Plus vieux que le genre humain lui-même, ces outils sont datés de 3,3 millions d'années et ont été mis au jour au Kenya.

Le lac Turkana, au Kenya, photographié depuis la Station spatiale internationale par l'astronaute italienne Samantha Cristoforetti. C'est dans cette région que les outils ont été découverts.

Les plus anciennes pierres taillées, exhumées à l’est du Kenya, auraient 3,3 millions d’années (voir notre carte plus bas) ! C'est ce que viennent d'annoncer des chercheurs new-yorkais lors du dernier meeting annuel de la société de paléoanthropologie, qui se tenait du 14 au 15 avril 2015 à San Francisco (Etats-Unis). Soit 700 000 ans de plus que les plus anciens outils connus à ce jour… Et leur découverte suggère que des ancêtres des hominidés façonnaient déjà des outils des centaines de milliers d’années avant que le genre Homo ne s’épanouisse. Car une découverte récente a eu beau vieillir le genre humain de 400.000 ans, le tout premier des Homo n’aurait que 2,8 millions d’années.

Les chercheurs auraient mis au jour plus d’une centaine d’éclats, de "cœurs" (ou blocs initiaux ) et d’ "enclumes" qui pourraient être la signature d’un atelier très archaïque de taille d’outils préhistoriques. Le tout reposait dans des sédiments datés de 3,3 millions d’années grâce aux techniques éprouvées du paléomagnétisme.

Comment ont été faits ces "premiers outils sculptures" ?

À partir d’une pierre, les hominidés débitent grossièrement des éclats qui leur serviront à couper, râcler, etc. Ils sculptent aussi de gros galets sur lesquels ils aménagent différents types de tranchants. Ce type primitif d'outils, connus sous le nom de "choppers", se retrouvent en Asie comme en Afrique et au Moyen-Orient. (Voir à ce sujet les dessins d’Eric Boeda dans Sciences et Avenir de Janvier 2008).
Les plus anciennes pierres taillées connues jusqu’à présent venaient de Gona en Ethiopie et étaient datées de 2,6 millions d’années. On parle à leur sujet  de "galets aménagés" ou encore d'industrie "Olduwayenne", parce qu'elles été trouvées pour la première fois, dès les années 1960, dans la gorge d’Olduvaï en Tanzanie. A l'époque, les chercheurs les attribuaient à l'Homo habilis (l'homme habile). Depuis, les spécialistes sont nombreux à penser que d'autres hominidés que nos ancêtres directs Homo auraient pu façonner des outils à leur main. En 2010, le site d’El Dikka, en Ethiopie, a ainsi livré des os vieux de 3,4 millions d’années - l'âge de Lucy et de sa famille australopithèque - portant des entailles de coupe, possiblement laissées par des outils, mais la découverte reste très discutée, comme l'explique le journaliste Michael Balter, qui a suivi la conférence de paléoanthropologie de San Francisco pour le site d’actualités de la revue américaine Science.

Fabriqué par le Kenyanthrope ?

Cette fois, c’est le site de Lomekwi, à l’est du lac Turkana, au Kenya, qui a livré de multiples outils " intentionnellement façonnés ", a expliqué Sonia Harmand de l’université Stony Brook à New York devant un parterre de paléoanthropologues. Or, ces trésors d’artefacts – "qui ne peuvent en aucun cas être le résultat de fractures accidentelles de la roche" selon la chercheuse – ont été trouvés à quelque pas du site qui avait déjà livré le curieux Kenyanthrope Platyops. Un ancêtre possible de l'homme, doté d’une drôle de face plate et vieux de 3,2 millions à 3,5 millions d’années. De là à imaginer que c’est cet hominidé qui a fabriqué les plus anciens outils au monde, il n'y a qu'un pas… La controverse ne fait sans doute que commencer. La découverte de Sonia Harmand, d'Hélène Roche (CNRS) et de leurs collègues devra faire l’objet d’une publication dans une revue de science spécialisée afin de pouvoir être discutée par les spécialistes du monde entier.

Les hominidés en Afrique entre 3 et 4 millions d’années:

Tuesday, April 14, 2015

A place in time: Situating Chauvet within the long chronology of symbolic behavioral development

Genevieve von Petzinger, April Nowell
Journal of Human Evoltion
Volume 74, September 2014, pages 37-54
Since the discovery of the Grotte Chauvet (Ardèche, France) in the mid-1990s, there has been a debate regarding the accuracy of assigning this site to the Aurignacian period. The main argument stems from a perceived lack of agreement between the radiocarbon age of the imagery (>32,000 years BP [before present]) and its stylistic complexity and technical sophistication, which some believe are more typical of the later Upper Paleolithic. In this paper we first review the evidence for symbolic behavior among modern humans during the Aurignacian in order to explore the question of whether Chauvet's images are anachronistic. Then, using a database of non-figurative signs found in Paleolithic parietal art, we undertake a detailed comparison between Chauvet's corpus of signs and those found in other French Upper Paleolithic caves. While we conclude that there is substantial evidence to support an Aurignacian date for Grotte Chauvet, we also suggest that it may be time to revisit some of the cultural boundaries that are currently in use in Paleolithic archaeology.

Genevieve von Petzinger: Ice Age Rock Art Geometric Signs