The Australian Aboriginal approach to stone technology is often characterised as highly flexible, a phenomenon well-documented by ethnographic observation. In the Australian context, it would appear that a stone's function was only loosely related to its form. Nevertheless, many ethnographic studies recognise that artefact manufacture was "aimed at" producing specific forms (Home and Aiston 1924:92). This study examines the extent of rigidity in artefact manufacture through an archaeological analysis of a large stone assemblage from Camooweal, northwestern Queensland, Australia. The reduction sequence which created the assemblage is modeled and the rigidity of the various trajectories comprising the reduction sequence is assessed by the degree to which blanks for "aimed at" forms crossed between trajectories. While the ethnographic literature indicates that various artefact categories tended to be used in an ad hoc fashion, the results of the technological analysis indicate that blank production for "aimed at" forms was, in fact, relatively rigid. This stands at odds with sweeping generalisations about the flexibility of Aboriginal lithic technology.

The archaeological records in the Old World and Australasia reflect a pattern of simple approaches to stone flaking in early stone tool assemblages followed by a later proliferation in more complex approaches. Although the pattern is similar in structure, the proliferation of complex flaking occurred much later in Australasia. 'Simple' stone flaking can be characterized as the arrangement of flake removals in chains and 'complex' approaches involved a hierarchical arrangement. Some archaeologists see the proliferation of hierarchical reduction sequences as a reflection of hominin cognitive changes, but 'Homo sapiens' colonizers of Australia - carrying a toolkit made by simple chaining - were cognitively modern. The Australian proliferation has been explained as a response to ecological conditions but this proximate explanation fails to account for the complex nature of hierarchical reduction sequences. Demographic modeling that links the emergence of complex stone flaking to population structure or growth better accounts for the proliferations in both the Old World and Australasia. Efforts to reconstruct hominin migrations through Asia by focusing on the 'derived' parts of stone toolkits track demographically-linked trends rather than initial emigration events.

Stone flaking is achieved through integral sets of geometrical identifications and motor actions collectively referred to as the 'flake unit'. Early trends in technological evolution involved elaborating the internal complexity of the flake unit and later trends involved elaborating the way that flake units were combined. Studies by developmental psychologists suggest that internal and external increases in complexity reflect advances in cognitive ability. Homo floresiensis combined the simplest type of flake units by arranging them in chains rather than stacking them hierarchically. Thus Homo floresiensis lithic technology does not indicate high levels of cognitive ability.

Wallacea, the zone of oceanic islands separating the continental regions of Southeast Asia and Australia, has yielded sparse evidence for the symbolic culture of early modern humans. Here we report evidence for symbolic activity 30,000-22,000 y ago at Leang Bulu Bettue, a cave and rock-shelter site on the Wallacean island of Sulawesi. We describe hitherto undocumented practices of personal ornamentation and portable art, alongside evidence for pigment processing and use in deposits that are the same age as dated rock art in the surrounding karst region. Previously, assemblages of multiple and diverse types of Pleistocene "symbolic" artifacts were entirely unknown from this region. The Leang Bulu Bettue assemblage provides insight into the complexity and diversification of modern human culture during a key period in the global dispersal of our species. It also shows that early inhabitants of Sulawesi fashioned ornaments from body parts of endemic animals, suggesting modern humans integrated exotic faunas and other novel resources into their symbolic world as they colonized the biogeographically unique regions southeast of continental Eurasia.

Excavations at Saruq al-Hadid, Dubai, have recovered a large assemblage of stone artefacts, including backed microliths, from a dense midden of animal bone deposited during the mid-second millennium BC. Stoneworkers at Saruq al-Hadid combined simple core reduction methods with sophisticated backing techniques to produce the microliths. Unstandardized flake blanks were backed directly, or were truncated into segments which were subsequently backed. The final stage of backing was carefully controlled and was probably accomplished using a pressure technique; the backed surface on many microliths is distinctively domed in profile. Most microliths are asymmetrical in shape and many display a distinctive scalene triangle morphology. The microliths probably functioned as armatures for arrows, although other functions are possible. Here we contextualize microlith production at Saruq al-Hadid through a review of late prehistoric microlith traditions in south-eastern Arabia and neighbouring regions of Asia and Africa. This raises intriguing but unresolved issues related to preceding technological traditions, cultural connections, and group identity.

Walter E. Roth studied the Aboriginal people of northern and western Queensland between 1894 and 1904, making written descriptions, drawings and photographs of their lifestyles and artefacts. At this time Aboriginal people were undergoing sweeping cultural changes through contact with Europeans. One of these changes was the rapid and ongoing replacement of their traditional methods of toolmaking by new methods based on European materials.

The Kimberley region of Western Australia is one of the largest and most diverse rock art provenances in the world, with a complex stylistic sequence spanning at least 16 ka, culminating in the modern art-making of the Wunumbal people. The Gunu Site Complex, in the remote Mitchell River region of the northwest Kimberley, is one of many local expressions of the Kimberley rock art sequence. Here we report excavations at two sites in this complex: Gunu Rock, a sand sheet adjacent to rock art panels; and Gunu Cave, a floor deposit within an extensive rockshelter. Excavations at Gunu Rock provide evidence for two phases of occupation, the first from 7-8 to 2.7 ka, and the second from 1064 cal BP. Excavations at Gunu Rock provide evidence for occupation from the end of the second phase to the recent past. Stone for tools in the early phase were procured from a variety of sources, but quartz crystal reduction dominated the second occupation phase. Small quartz crystals were reduced by freehand percussion to provide small flake tools and blanks for manufacturing small points called nguni by the Wunambal people today. Quartz crystals were prominent in historic ritual practices associated with the Wanjina belief system. Complex methods of making bifacially-thinned and pressure flaked quartzite projectile points emerged after 2.7 ka. Ochre pigments were common in both occupation phases, but evidence for occupation contemporaneous with the putative age of the oldest rock art styles was not discovered in the excavations. Our results show that developing a complete understanding of rock art production and local occupation patterns requires paired excavations inside and outside of the rockshelters that dominate the Kimberley.

Human infants and primates use similar strategies to organize utterances and motor actions. These strategies, called "grammars of action," are initially similar followed by an ontogenetic divergence in children that leads to a separation of complex linguistic and action grammars. Thus, more complex grammars arose after the emergence of the hominin lineage. Stone tools are by-products of action grammars that track the evolutionary history of hominin cognition, and this study develops a model of the essential motor actions of stoneworking interpretable in action grammar terms. The model shows that controlled flaking is achieved through integral sets of geometrical identifications and motor actions collectively referred to as the "flake unit." The internal structure of the flake unit was elaborated early in technological evolution and later trends involved combining flake units in more complex ways. Application of the model to the archaeological record suggests that the most complex action grammars arose after 270 kya, although significant epistemological issues in stone artifact studies prevent a more nuanced interpretation.

Stone-flaking technology is the most enduring evidence for the evolving cognitive abilities of our early ancestors. Flake-making was mastered by African hominins ~3.3 ma, followed by the appearance of handaxes ~1.75 ma and complex stone reduction strategies by ~1.6 ma. Handaxes are stones flaked on two opposed faces ('bifacially'), creating a robust, sharpedged tool, and complex reduction strategies are reflected in strategic prior flaking to prepare or 'predetermine' the nature of a later flake removal that served as a tool blank. These technologies are interpreted as major milestones in hominin evolution that reflect the development of higher-order cognitive abilities, and the presence and nature of these technologies are used to track movements of early hominin species or 'cultures' in the archaeological record. However, the warranting argument that certain variations in stone tool morphologies are caused by differences in cognitive abilities relies on analogy with technical replications by skilled modern stoneworkers, and this raises the possibility that researchers are projecting modern approaches to technical problems onto our non-modern hominin ancestors. Here we present the results of novel experiments that randomise flake removal and disrupt the modern stoneworker's inclination to use higher-order reasoning to guide the stone reduction process. Although our protocols prevented goal-directed replication of stone tool types, the experimental assemblage is morphologically standardised and includes handaxe-like 'protobifaces' and cores with apparently 'predetermined' flake removals. This shows that the geometrical constraints of fracture mechanics can give rise to what appear to be highly-designed stoneworking products and techniques when multiple flakes are removed randomly from a stone core.