High latitude,late Campanian (Cretaceous) Radiolaria from offshore south-eastern Tasmania

A well-preserved, low diversity (ten species), high latitude (palaeolatitude 70°S) radiolarian fauna is recorded from shallow-water late Campanian (Late Cretaceious) sediments recovered in cores taken from the continental slope of southeastern Tasmania. These are the first Radiolaria described from Cretaceous rocks of southeastern Australia. Most forms are previously described species but a new species of Petasiforma is described. Age control is provided by dinoflagellates but the radiolarian fauna is similar to late Campanian-Maastrichtian faunas described from Campbell Plateau. A late Campanian age can also be determined from the Radiolaria, which are correlated with the Patulibracchium dickinsoni Zone. The site has subsided some 3200 m since deposition, at an average rate of about 40–45 m/Ma, consistent with other indicators in the region. Radiolaria are similar to other coeval plankton in exhibiting high latitude characteristics.     

Social Cooperation and Resource Management DynamicsAmong Late Hunter-Fisher-Gatherer Societies in Tierra del Fuego (South America)

This paper presents the theoretical basis and first results of an agent-based model (ABM) computer simulation that is being developed to explore cooperation in hunter–gatherer societies. Specifically, we focus here on Yamana, a hunter-fisher-gatherer society that inhabited the islands of the southernmost part of Tierra del Fuego (Argentina–Chile). Ethnographical and archaeological evidence suggests the existence of sporadic aggregation events, triggered by a public call through smoke signals of an extraordinary confluence of resources under unforeseeable circumstances in time and space (a beached whale or an exceptional accumulation of fish after a low tide, for example). During these aggregation events, the different social units involved used to develop and improve production, distribution and consumption processes in a collective way. This paper attempts to analyse the social dynamics that explain cooperative behaviour and resource-sharing during aggregation events using an agent-based model of indirect reciprocity. In brief, agents make their decisions based on the success of the public strategies of other agents. Fitness depends on the resource captured and the social capital exchanged in aggregation events, modified by the agent’s reputation. Our computational results identify the relative importance of resources with respect to social benefits and the ease in detecting—and hence punishing—a defector as key factors to promote and sustain cooperative behaviour among population.     

First fossil fish (Teleostei,Siluriformes) from the Late Pleistocene of Santa Fe Province,Argentina

Vallone, E.R., Vezzosi, R.I. & Cione, A.L. February 2017. First fossil fish (Teleostei, Siluriformes) from the Late Pleistocene of Santa Fe Province, Argentina. Alcheringa 00, 000–000. ISSN 0311-5518.

The record of fossil fish from the Pleistocene of Argentina is poor. Here we describe the first ichthyofauna from Late Pleistocene riverbank beds in the Salado River of Santa Fe Province, Argentina. The material consists of isolated pectoral and dorsal fin spines, together with skull fragments. Four species-level taxa referable to three families can be identified: Pterodoras granulosus (Doradidae), Pimelodus cf. maculatus and Pimelodus cf. albicans (Pimelodidae) and cf. Hypostomus sp. (Loricariidae). Specimens attributed to Pterodoras granulosus and Pimelodus maculatus represent a minimum age for origin of these taxa. The Salado River assemblage includes the richest record of Pleistocene catfishes yet documented from southern South America.

Evelyn Romina Vallone [evelynvallone@conicet.gov.ar] and Raúl Ignacio Vezzosi [vezzosiraul@gmail.com], Laboratorio de Paleontología de Vertebrados, CICYTTP-CONICET, Materi y España, (3105) Diamante, Entre Ríos, Argentina; Alberto Luis Cione [acione@museo.fcnym.unlp.edu.ar], División Paleontología de Vertebrados. Museo de La Plata. Paseo del Bosque s/n, (1900) La Plata, Argentina.     

Experimental protocols for the study of battered stone anvils from Olduvai Gorge (Tanzania)

Percussive activities are highly relevant in the economy of modern hunter-gatherer societies and other primates, and are likely to have been equally important during the Palaeolithic. Despite the potential relevance of percussive activities in the Early Stone Age, attempts to study battered artefacts are still rare. In order to establish protocols of analysis of battered tools, this paper pursues an interdisciplinary approach combining techno-typological, refit, use-wear and GIS studies of experimental anvils from Olduvai Gorge (Tanzania). The main aim is to classify types of damage on battered artefacts according to the percussive task performed, and hence identify patterns that can be used to interpret the Oldowan and Acheulean evidence. Our results indicate that abrasion marks on anvil surfaces are typical of nut cracking, while bone breaking leaves characteristic scars and abrasion marks on the edges of anvils. Pounding of soft materials such as meat and plants also causes battering of anvils, producing morphological and spatial patterns that can be discerned from the heavy breakage of anvils during bipolar flaking. By integrating macroscopic, microscopic and spatial analyses of experimental stone tools, this paper contributes to create a referential framework in which Early Stone Age battered artefacts can be interpreted.     

Application of GIS methods to retrieve orientation patterns from imagery; a case study from Beds I and II,Olduvai Gorge (Tanzania)

The role of natural processes in the formation of the Bed I and II sites at Olduvai Gorge (Tanzania) remains the subject of much debate, five decades after their original excavation. Preferred orientation of items is indicative of water disturbance, but compass bearings were not available in Mary Leakey's (1971) study. Using GIS methods, we have vectorized maps from 1960s excavations at Olduvai, and applied a range of statistical techniques to calculate items strike. The GIS analysis suggests strongly preferred orientation patterns in Bed I, and more heterogeneous angular histograms in Bed II. Two complementary lines of evidence support these results. Firstly, modelling of potential mapping errors provides a large interval of confidence for preferred orientation patterns. Second, the GIS study was extended to photographs of the earlier excavations and to maps from recent fieldwork at Olduvai; both yielded patterned arrangement of lithics and bones, and are consistent with results based on the analysis of the 1960s maps, i.e. a large number of the Bed I and II assemblages are preferentially oriented. These results highlight the potential of GIS applications to the analysis of imagery in Stone Age studies, and bear important implications for the understanding of the role of natural agents in site formation processes at Olduvai.     

Prehistoric hunters and gatherers of Brazil

Although carbon-14 dates prior to 13,000 B.P. have been obtained from several sites east and south of Amazonia, their reliability is uncertain. By about 11,000 B.P., however, two lithic traditions were widespread. The Uruguai tradition, characterized by bifacial stemmed projectile points, was associated with open vegetation in the south; the Itaparica tradition, emphasizing well-formed unifacial artifacts, had dispersed over the eastern tropical parklands. An enormous amount and variety of rock paintings and/or engravings are associated with the latter. Around 7000 B.P., two new traditions emerged to exploit new habitats. The Humaitá tradition, characterized by large bifacial tools and an absence of stone projectile points, expanded over the broad-leaved forests in the south, leaving the open landscapes dominated by the projectile point-using Umbu tradition. The sambaqui (shell midden) tradition, also emphasizing large bifaces, developed along rugged portions of the southern coast. By 4000 B.P., groups along the coast of Rio de Janeiro and Espírito Santo were using domesticated or semidomesticated plants, perhaps sweet manioc. Maize was being grown in Minas Gerais by about 3500 B.P. Carbon-14 dates from numerous sites indicate, however, that the hunter-gatherer way of life persisted in many places long after the advent of pottery-making horticulturalists. The existence of large temporal and spatial gaps even in regions with considerable investigation makes it difficult to reconstruct the process of evolution reflected in these archaeological complexes. Correlations between cultural traditions and environmental fluctuations indicate, however, that adaptation to changing conditions was a significant challenge faced by prehistoric Brazilian populations.     

Spatial distribution of US employment in an urban efficiency wage setting

We analyze whether efficiency wages operate in urban labor markets, within the framework proposed by Ross and Zenou, in which shirking at work and leisure are assumed to be substitutes. We use unique data from the American Time Use Survey (ATUS) that allow us to analyze the relationships between leisure, shirking, commuting, employment, and earnings. We confirm that shirking and leisure are substitutes, and present an estimate of this relationship, representing the only empirical test of the relationship between a worker's time endowment and shirking at work. Our findings point to the existence of efficiency wages in labor markets.     

Mitología e ingenio en el Poema heroico de San Ignacio de Domínguez Camargo

This article examines the mythological motifs in the Poema heroico de San Ignacio, by the Colombian poet Hernando Domínguez Camargo, not only as material extracted from a prestigious culture (i.e., classical culture), but as a starting point for the elaborations of wit, which is the main objective in the aesthetics of the wit.