Percussively flaked stone artefacts constitute a major source of evidence relating to hominin behavioural strategies and are, essentially, a product or byproduct of a past individual's decision to create a tool with respect to some broader goal. Moreover, it has long been noted that both differences and recurrent regularities exist within and between Palaeolithic stone artefact forms. Accordingly, archaeologists have frequently drawn links between form and functionality, with functional objectives and performance often being regarded consequential to a stone tool's morphological properties. Despite these factors, extensive reviews of the related concepts of form and function with respect to the Lower Palaeolithic remain surprisingly sparse. We attempt to redress this issue. First we stress the historical place of form-function concepts, and their role in establishing basic ideas that echo to this day. We then highlight methodological and conceptual progress in determining artefactual function in more recent years. Thereafter, we evaluate four specific issues that are of direct consequence for evaluating the ongoing relevance of form-function concepts, especially with respect to their relevance for understanding human evolution more generally. Our discussion highlights specifically how recent developments have been able to build on a long historical legacy, and demonstrate that direct, indirect, experimental, and evolutionary perspectives intersect in crucial ways, with each providing specific but essential insights for ongoing questions. We conclude by emphasising that our understanding of these issues and their interaction, has been, and will be, essential to accurately interpret the Lower Palaeolithic archaeological record, tool-form related behaviours of Lower Palaeolithic hominins, and their consequences for (and relationship to) wider questions of human evolution.
We suggest a seven-grade model for the evolution of causal cognition as a framework that can be used to gauge variation in the complexity of causal reasoning from the panin-hominin split until the appearance of cognitively modern hunter-gatherer communities. The intention is to put forward a cohesive model for the evolution of causal cognition in humans, which can be assessed against increasingly fine-grained empirical data from the palaeoanthropological and archaeological records. We propose that the tracking behaviour (i.e., the ability to interpret and follow external, inanimate, visual clues of hominins) provides a rich case study for tracing the evolution of causal cognition in our lineage. The grades of causal cognition are tentatively linked to aspects of the Stone Age/Palaeolithic archaeological record. Our model can also be applied to current work in evolutionary psychology and research on causal cognition, so that an inter-disciplinary understanding and correlation of processes becomes increasingly possible.
In the current opinion paper, we provide a comparative perspective on specific aspects of primate empathic abilities, with particular emphasis on the mirror neuron system associated with mouth/face actions and expression. Mouth and faces can be very salient communicative classes of stimuli that allow an observer access to the emotional and physiological content of other individuals. We thus describe patterns of activations of neural populations related to observation and execution of specific mouth actions and emotional facial expressions in some species of monkeys and in humans. Particular attention is given to dynamics of face-to-face interactions in the early phases of development and to the differences in the anatomy of facial muscles among different species of primates. We hypothesize that increased complexity in social environments and patterns of social development have promoted specializations of facial musculature, behavioral repertoires related to production and recognition of facial emotional expression, and their neural correlates. In several primates, mirror circuits involving parietal-frontal regions, insular regions, cingulate cortices, and amygdala seem to support automatic forms of embodied empathy, which probably contribute to facial mimicry and behavioural synchrony. In humans these circuits interact with specific prefrontal and temporo-parietal cortical regions, which facilitates higher order cognitive functions such as cognitive empathy and mental state attribution. Our analysis thus suggests that the evolution of higher forms of empathy, such as mentalizing, is also linked to the coupling between the perceptual and motor system related to face processing, which may have undergone a process of exaptation during primate phylogeny.
The Early Stone Age archaeological record does not become persistent and widespread until approximately 2.0-1.7 million years ago, when Oldowan sites spread across Africa and ultimately into Eurasia. However, good records of hominin behavior from this important time interval are uncommon. Here we describe recent findings from the two million year old Oldowan site of Kanjera South, on the Homa Peninsula of southwestern Kenya. Kanjera South is the oldest Oldowan site with large assemblages of stone artifacts and well-preserved archaeological fauna. Our research indicates that hominin activities were situated in an open habitat within a grassland dominated ecosystem, the first documentation of an archaeological site in such an open setting. Hominins selectively collected and transported stone materials (30% of the lithic assemblage) over longer distances (at least 10 km) than is typical for the Oldowan, reflecting their preference for hard, easily-flaked lithologies unavailable on the northern half of the Homa Peninsula. They deployed different technological strategies to more intensively utilize these hard, non-local raw materials. Artifacts were used for a variety of tasks, including butchering small antelopes probably obtained by hunting, working wood, working soft plant material, and processing underground storage organs. These data suggest that the Kanjera hominins utilized a technological system that allowed them to extract nutrient dense animal and plant foods from their environment. This shift towards the acquisition of nutritious, hard-to-acquire foods in packets large enough to be shared may have facilitated brain and body size expansion in the genus Homo.