Monkeying Around
Neanderthal-Denisovan ancestors interbred with a distantly related hominin
Alan Rogers, Nathan Harris & Alan Achenbach
Science Advances, February 2020
Abstract:
Previous research has shown that modern Eurasians interbred with their Neanderthal and Denisovan predecessors. We show here that hundreds of thousands of years earlier, the ancestors of Neanderthals and Denisovans interbred with their own Eurasian predecessors — members of a “superarchaic” population that separated from other humans about 2 million years ago. The superarchaic population was large, with an effective size between 20 and 50 thousand individuals. We confirm previous findings that (i) Denisovans also interbred with superarchaics, (ii) Neanderthals and Denisovans separated early in the middle Pleistocene, (iii) their ancestors endured a bottleneck of population size, and (iv) the Neanderthal population was large at first but then declined in size. We provide qualified support for the view that (v) Neanderthals interbred with the ancestors of modern humans.
The evolution of early symbolic behavior in Homo sapiens
Kristian Tylén et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
How did human symbolic behavior evolve? Dating up to about 100,000 y ago, the engraved ochre and ostrich eggshell fragments from the South African Blombos Cave and Diepkloof Rock Shelter provide a unique window into presumed early symbolic traditions of Homo sapiens and how they evolved over a period of more than 30,000 y. Using the engravings as stimuli, we report five experiments which suggest that the engravings evolved adaptively, becoming better-suited for human perception and cognition. More specifically, they became more salient, memorable, reproducible, and expressive of style and human intent. However, they did not become more discriminable over time between or within the two archeological sites. Our observations provide support for an account of the Blombos and Diepkloof engravings as decorations and as socially transmitted cultural traditions. By contrast, there was no clear indication that they served as denotational symbolic signs. Our findings have broad implications for our understanding of early symbolic communication and cognition in H. sapiens.
Human occupation of northern India spans the Toba super-eruption ~74,000 years ago
Chris Clarkson et al.
Nature Communications, February 2020
Abstract:
India is located at a critical geographic crossroads for understanding the dispersal of Homo sapiens out of Africa and into Asia and Oceania. Here we report evidence for long-term human occupation, spanning the last ~80 thousand years, at the site of Dhaba in the Middle Son River Valley of Central India. An unchanging stone tool industry is found at Dhaba spanning the Toba eruption of ~74 ka (i.e., the Youngest Toba Tuff, YTT) bracketed between ages of 79.6 ± 3.2 and 65.2 ± 3.1 ka, with the introduction of microlithic technology ~48 ka. The lithic industry from Dhaba strongly resembles stone tool assemblages from the African Middle Stone Age (MSA) and Arabia, and the earliest artefacts from Australia, suggesting that it is likely the product of Homo sapiens as they dispersed eastward out of Africa.
Palaeolithic seafaring in East Asia: Testing the bamboo raft hypothesis
Yousuke Kaifu et al.
Antiquity, December 2019, Pages 1424-1441
Abstract:
The earliest colonisation of oceanic islands by Homo sapiens occurred ~50 000–30 000 years ago in the Western Pacific, yet how this was achieved remains a matter of debate. With a focus on East Asia, the research presented here tests the hypothesis that bamboo rafts were used for these early maritime migrations. The authors review the evidence for Palaeolithic seafaring in East Asia as the context for an experimental archaeology project to build two bamboo watercraft. Sea trials demonstrate the unsuitability of bamboo, at least in East Asia, indicating that more sophisticated and durable vessels would have been required to traverse the Kuroshio Current.
Dental microwear as a behavioral proxy for distinguishing between canids at the Upper Paleolithic (Gravettian) site of Předmostí, Czech Republic
Kari Prassack et al.
Journal of Archaeological Science, forthcoming
Abstract:
Morphological and genetic evidence put dog domestication during the Paleolithic, sometime between 40,000 and 15,000 years ago, with identification of the earliest dogs debated. We predict that these earliest dogs (referred to herein as protodogs), while potentially difficult to distinguish morphologically from wolves, experienced behavioral shifts, including changes in diet. Specifically, protodogs may have consumed more bone and other less desirable scraps within human settlement areas. Here we apply Dental Microwear Texture Analysis (DMTA) to canids from the Gravettian site of Předmostí (approx. 28,500 BP), which were previously assigned to the Paleolithic dog or Pleistocene wolf morphotypes. We test whether these groups separate out significantly by diet-related variation in microwear patterning. Results are consistent with differences in dietary breadth, with the Paleolithic dog morphotype showing evidence of greater durophagy than those assigned to the wolf morphotype. This supports the presence of two morphologically and behaviorally distinct canid types at this middle Upper Paleolithic site. Our primary goal here was to test whether these two morphotypes expressed notable differences in dietary behavior. However, in the context of a major Gravettian settlement, this may also support evidence of early stage dog domestication. Dental microwear is a behavioral signal that may appear generations before morphological changes are established in a population. It shows promise for distinguishing protodogs from wolves in the Pleistocene and domesticated dogs from wolves elsewhere in the archaeological record.
Stiffness of the human foot and evolution of the transverse arch
Madhusudhan Venkadesan et al.
Nature, forthcoming
Abstract:
The stiff human foot enables an efficient push-off when walking or running, and was critical for the evolution of bipedalism. The uniquely arched morphology of the human midfoot is thought to stiffen it, whereas other primates have flat feet that bend severely in the midfoot. However, the relationship between midfoot geometry and stiffness remains debated in foot biomechanics, podiatry and palaeontology. These debates centre on the medial longitudinal arch and have not considered whether stiffness is affected by the second, transverse tarsal arch of the human foot. Here we show that the transverse tarsal arch, acting through the inter-metatarsal tissues, is responsible for more than 40% of the longitudinal stiffness of the foot. The underlying principle resembles a floppy currency note that stiffens considerably when it curls transversally. We derive a dimensionless curvature parameter that governs the stiffness contribution of the transverse tarsal arch, demonstrate its predictive power using mechanical models of the foot and find its skeletal correlate in hominin feet. In the foot, the material properties of the inter-metatarsal tissues and the mobility of the metatarsals may additionally influence the longitudinal stiffness of the foot and thus the curvature–stiffness relationship of the transverse tarsal arch. By analysing fossils, we track the evolution of the curvature parameter among extinct hominins and show that a human-like transverse arch was a key step in the evolution of human bipedalism that predates the genus Homo by at least 1.5 million years. This renewed understanding of the foot may improve the clinical treatment of flatfoot disorders, the design of robotic feet and the study of foot function in locomotion.
World's oldest dendrochronologically dated archaeological wood construction
Michal Rybníček et al.
Journal of Archaeological Science, forthcoming
Abstract:
In 2018, during the construction of a motorway in the East Bohemian Region near the town of Ostrov (Czech Republic), archaeologists excavated a structure of a wooden water well lining with a square base area of 80 × 80 cm and 140 cm in height. Due to the excellent conservation of the oak timbers, studies of technological details and precise tree-ring dating were possible. The used trees were felled in the years 5256/55 BC, which makes this well the oldest dendrochronologically dated archaeological wooden construction worldwide. It is the third well from the Early Neolithic period that has been discovered in the Czech Republic within the last four years. The design consists of grooved corner posts with inserted planks. This type of construction reveals advanced technical know-how and, till now, is the only known type from this region and time period. Thanks to the combination of annually resolved and absolutely dated tree-ring widths (TRWs), the Czech oak TRW chronology has been significantly extended back to 5481 BC. Wood anatomical identification of fragments from the well filling show mainly oak (Quercus spp.) and hazel (Corylus spp.), indicating a local forest composition dominated by these taxa. The shape of the individual structural elements and tool marks preserved on their surface confirm sophisticated carpentry skills. Based on these observations, we established a model for the “chaîne opératoire” from forest utilization to the final artefact at the beginning of the Early Neolithic period.