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The significance of the archaeological record unearthed in the SHK fluvial landscape represents a noteworthy dataset to study in greater detail the expression of inter-assemblage variability during the formally labelled Developed Oldowan/Acheulean interface in Olduvai Gorge. A precise stratigraphic interval, laterally continuous, and preserving fractions of anthropogenic activity at different points of the same fluvial network makes it feasible to identify the variable techno-economic ways in which hominins responded to the local paleo-landscape in a short time unit. In this work we present the results of the comparative techno-economic study of the three lithic collections retrieved from the time unit defined by an isochronous litho-stratigraphic volcanic horizon deposited in the fluvial landscape of SHK Main site and SHK Extension. The combined use of this isochrone plus the archaeo-stratigraphic method to refine time-averaging constraints offers for the first time an assessment of the nature of technological variation within different fractions of the same fluvial landscape at ~ 1.5 Ma in Middle Bed II. The goal of this analysis is to look closely at inter-assemblage variability in a unit of time with a coherent degree of synchronicity and to add new data to the Developed Oldowan/Acheulean gradient. [ABSTRACT FROM AUTHOR]

FLK West (Olduvai Gorge) constitutes one of the most relevant archeological resources for the study of the Acheulean in East Africa. This site presents a number of unique characteristics that make it an exceptional archeological document: a precise chronological framework, a multi-component site with six different archeological units bearing a rich lithic and faunal record, the oldest association of stone tools and processed fauna, and a well-preserved paleoenvironmental context. For these reasons, FLK West constitutes a remarkable opportunity to undertake a micro-spatial analysis at an archaeo-unit level. This work pursues a first approach to the intra-site study of the archeological associations preserved in the densest patches documented in the lowermost levels (L4 to L6) of the FLK West sequence. For this purpose, a variety of analyses will be considered, including archaeo-stratigraphy, a preliminary refitting program and, more specifically, the inspection of spatial horizontal correlations between archeological remains. The most significant spatial patterns observed point to differences in the distribution of diagnostic Acheulean implements with respect to specimens included in knapping categories and faunal remains. These observations open up the possibility to explore the debated functional meaning of large Acheulean tools from a complementary spatial perspective. [ABSTRACT FROM AUTHOR]

In recent years, a “high-resolution” archaeological approach is being successfully applied in a number of Paleolithic intra-site spatial analyses. This perspective encompasses the integration of data provided by a number of sources (such as soil micro-morphology, archaeo-stratigraphy, site formation studies, or lithic conjoining) in order to identify minimal behavioral entities in archaeological palimpsests. To date, this type of approach has been applied to African ESA contexts only cursorily. Here, we present the results of our methodological effort in order to make progress towards meeting some of the basic standards of current high-resolution approaches in the East African ESA record, revolving around the concept of synchronicity. This approach has been applied to the newly discovered site of SHK Extension, adjacent to and pene-contemporaneous with the classical SHK Main site (Olduvai Gorge), where a total area of 30 m2 has been unearthed. By a detailed archaeo-stratigraphic study of the archaeological sequence, in combination with other procedures focusing on the micro scale of the spatial analysis, we can confidently dissect the different archaeo-units of this anthropogenic aggregate. These archaeo-units must be interpreted as micro-palimpsests showing a level of synchronicity as accurate as possible. In the present work, this methodology constitutes the referential criterion for assemblage grouping and it is the baseline for the subsequent technological study of the different anthropogenic entities identified at SHK Extension. [ABSTRACT FROM AUTHOR]

Social hierarchy is a potent modulator of behavior, that is typically established through overt agonistic interactions between individuals in the group. Once established, social ranks are maintained through subtler interactions allowing the redirection of energy away from agonistic interactions towards other needs. The available tasks for assessing social rank in rats allow the study of the mechanisms by which social hierarches are formed in early phases but fail to assess the maintenance of established hierarchies between stable pairs of animals, which might rely on distinct neurobiological mechanisms. Here we present and validate a novel trial-based dominancy assay, the modified Food Competition test, where established social hierarchies can be identified in the home cage of non-food deprived pairs of male rats. In this task, we introduce a small conflict in the home cage, where access to a new feeder containing palatable pellets can only be gained by one animal at a time. We found that this subtle conflict triggered asymmetric social interactions and resulted in higher consumption of food by one of the animals in the pair, which reliably predicted hierarchy in other tests. Our findings reveal stable dominance status in pair-housed rats and provide a novel tool for the evaluation of established social hierarchies, the modified Food Competition test, that is robust and easy to implement. [ABSTRACT FROM AUTHOR]

All newborn mammals cry. The neural circuit that stimulates mothers to look after crying offspring has been identified in mice — along with a mechanism that promotes maternal behaviour only after prolonged calls from pups.The brain pathway that prompts oxytocin release to induce maternal care. [ABSTRACT FROM AUTHOR]

Studies the behavioral, neuroendocrine and neurochemical effects of the imidazoline I[sub 2] receptor selective ligand BU224 in naive rats and rats exposed to the stress of the forced swim test. Reduction of immobility and increase in mild swimming; Increased plasma ACTH and corticosterone levels; Decreased 5-HT turnover in the hippocampus and hypothalamus.