The discovery of fire by humans: a long and convoluted process.

Numbers of animal species react to the natural phenomenon of fire, but only humans have learnt to control it and to make it at will. Natural fires caused overwhelmingly by lightning are highly evident on many landscapes. Birds such as hawks, and some other predators, are alert to opportunities to catch animals including invertebrates disturbed by such fires and similar benefits are likely to underlie the first human involvements with fires. Early hominins would undoubtedly have been aware of such fires, as are savanna chimpanzees in the present. Rather than as an event, the discovery of fire use may be seen as a set of processes happening over the long term. Eventually, fire became embedded in human behaviour, so that it is involved in almost all advanced technologies. Fire has also influenced human biology, assisting in providing the high-quality diet which has fuelled the increase in brain size through the Pleistocene. Direct evidence of early fire in archaeology remains rare, but from 1.5 Ma onward surprising numbers of sites preserve some evidence of burnt material. By the Middle Pleistocene, recognizable hearths demonstrate a social and economic focus on many sites. The evidence of archaeological sites has to be evaluated against postulates of biological models such as the 'cooking hypothesis' or the 'social brain', and questions of social cooperation and the origins of language. Although much remains to be worked out, it is plain that fire control has had a major impact in the course of human evolution.This article is part of the themed issue 'The interaction of fire and mankind'.

Variability in an early hominin percussive tradition: the Acheulean versus cultural variation in modern chimpanzee artefacts.

Percussion makes a vital link between the activities of early human ancestors and other animals in tool-use and tool-making. Far more of the early human actions are preserved as archaeology, since the percussion was largely used for making hard tools of stone, rather than for direct access to food. Both primate tools and early hominin tools, however, offer a means to exploring variability in material culture, a strong focus of interest in recent primate studies. This paper charts such variability in the Acheulean, the longest-lasting tool tradition, extant form about 1.7 to about 0.1 Ma, and well known for its characteristic handaxes. The paper concentrates on the African record, although the Acheulean was also known in Europe and Asia. It uses principal components and discriminant analysis to examine the measurements from 66 assemblages (whole toolkits), and from 18 sets of handaxes. Its review of evidence confirms that there is deep-seated pattern in the variation, with variability within a site complex often matching or exceeding that between sites far distant in space and time. Current techniques of study allow comparisons of handaxes far more easily than for other components, stressing a need to develop common practice in measurement and analysis. The data suggest, however, that a higher proportion of traits recurs widely in Acheulean toolkits than in the chimpanzee record.

Elongation as a factor in artefacts of humans and other animals: an Acheulean example in comparative context.

Elongation is a commonly found feature in artefacts made and used by humans and other animals and can be analysed in comparative study. Whether made for use in hand or beak, the artefacts have some common properties of length, breadth, thickness and balance point, and elongation can be studied as a factor relating to construction or use of a long axis. In human artefacts, elongation can be traced through the archaeological record, for example in stone blades of the Upper Palaeolithic (traditionally regarded as more sophisticated than earlier artefacts), and in earlier blades of the Middle Palaeolithic. It is now recognized that elongation extends to earlier Palaeolithic artefacts, being found in the repertoire of both Neanderthals and more archaic humans. Artefacts used by non-human animals, including chimpanzees, capuchin monkeys and New Caledonian crows show selection for diameter and length, and consistent interventions of modification. Both chimpanzees and capuchins trim side branches from stems, and appropriate lengths of stave are selected or cut. In human artefacts, occasional organic finds show elongation back to about 0.5 million years. A record of elongation achieved in stone tools survives to at least 1.75 Ma (million years ago) in the Acheulean tradition. Throughout this tradition, some Acheulean handaxes are highly elongated, usually found with others that are less elongated. Finds from the million-year-old site of Kilombe and Kenya are given as an example. These findings argue that the elongation need not be integral to a design, but that artefacts may be the outcome of adjustments to individual variables. Such individual adjustments are seen in animal artefacts. In the case of a handaxe, the maker must balance the adjustments to achieve a satisfactory outcome in the artefact as a whole. It is argued that the need to make decisions about individual variables within multivariate objects provides an essential continuity across artefacts made by different species.

Artefacts of apes, humans, and others: towards comparative assessment and analysis.

This paper explores issues of technology and artefacts in a comparative cross-species frame, using archaeological examples and modern data sets to illustrate points about process and content. It develops the argument that regardless of species, artefacts have a special significance as external projections of the mind, often necessitating cognitive judgements on the basis of several variables and subject to influences by cultural tradition, functional needs, and raw materials. In humans, apes, and other tool using animals, behaviour overlaps in some respects and is vastly different in others. Overlapping aspects are worth seeking out and exploiting, as they provide opportunities to investigate factors influencing variation and to gain insights into cognition. Recent primatological research establishes much more foundation for continuity, but many of the details of artefacts and their variation remain to be explored. This paper presents case studies of variability and standardisation that suggest the limits on variation are as tight in some chimpanzee produced artefacts as in many produced by humans, and functional constraints appear to operate more strongly on some parts of artefacts than others. Thus, degree of standardisation cannot be used as a simple index to 'refinement,' but the widespread overlap in standardisation between human and nonhuman artefacts greatly expands the scope for study.

Early archaeological sites, hominid remains and traces of fire from Chesowanja, Kenya.

Recent investigations of Lower Pleistocene sites at Chesowanja have yielded in situ Oldowan and Oldowan-like stone artefacts, evidence of fire and a fragmentary 'robust' australopithecine cranium. Burnt clay found at one artefact locality dated to >1.42±0.07 Myr is the earliest known evidence of fire associated with a hominid occupation site.