The target article explores material culture datasets from three African forager groups. After demonstrating that these modern, contemporary human populations would leave scant evidence of symbolic behaviour or material complexity, it cautioned against using material culture as a barometer for human cognition in the deep past. Twenty-one commentaries broadly support or expand these conclusions. A minority offer targeted demurrals, highlighting (1) the soundness of reasoning from absence; and questioning (2) the “cognitively modern” null; (3) the role of hunter-gatherer ethnography; and (4) the pertinence of the inferential issues identified in the target article. In synthesising these discussions, this reply addresses all four points of demurral in turn, and concludes that there is much to be gained from shifting our null assumptions and reconsidering the probabilistic inferential links between past material culture and cognition.

Our species' behavioral and cognitive evolution constitute a key research topic across many scientific disciplines. Based on ethnographic hunter-gatherer data, Stibbard-Hawkes challenges the common link made between past material culture and cognitive capacities. Despite this adequate criticism, archaeology must retain a central role for studying these issues due to its unique access to relevant empirical evidence in deep time.

Stibbard-Hawkes challenges the link between symbolic material evidence and behavioural modernity. Extending this to non-human species, we find that personal adornment, decoration, figurative art, and musical instruments may not uniquely distinguish human cognition. These common criteria may ineffectively distinguish symbolic from non-symbolic cognition or symbolic cognition is not uniquely human. It highlights the need for broader comparative perspectives.

Shared intentionality is the derived hominin motivation and skills to align mental states. Research on the role of interdependence in the phylogeny of shared intentionality has only considered the archeological record of Homo heidelbergensis. But ethnographic and fossil data must be considered, too. Doing so suggests that shared intentionality may have been favored in Homo erectus to support persistence hunting.

The absence of symbolic material cultural objects in the archaeological record does not prove absence of symbolic cognition. Sometimes perishable materials are selected for symbolic roles, for practical concerns or to indicate a temporary condition. Also some symbolic functions may predate the use of durable materials. Finally, child play and artisan experimentations usually involve cheap and perishable materials. These are symbolic and representational activities that do not leave a material trace.

Stibbard-Hawkes forcefully alerts us to the pitfall of false-negative reasoning in symbolic archaeology. We highlight the twin problem of false-positive reasoning in what we call the “false-symbol problem.” False symbols are intuitively special entities that, owing to their non-utilitarian nature, invite symbolic interpretation. But they are not symbolic. We link the false-symbol problem to work in comparative primate cognition, taking “primate art” as our main example.

Stibbard-Hawkes shows that cultures using material symbols might well not leave traces of that practice in the archaeological record. The paper thus poses an important challenge: When is absence of evidence evidence of absence? This commentary uses behavioural ecology to make modest progress on this problem.

Stibbard-Hawkes' taphonomic findings are valuable, and his call for caution warranted, but the hazards he raises are being mitigated by a multi-pronged approach; current research on behavioural/cognitive modernity is not based solely on material chronology. Theories synthesize data from archaeology, anthropology, psychology, neuroscience, and genetics, and predictions arising from these theories are tested with mathematical and agent-based models.

Using modern hunter-gatherers to infer about early Homo sapiens only works if at least (a) modern hunter-gatherers represent an unbiased sample of humanity, and (b) modern hunter-gatherers act in ways similar to the behavior of early Homo sapiens. Both of these are false, leading to the problem of whether we can draw conclusions about early Homo sapiens from modern hunter-gatherers.

I expand Stibbard-Hawkes' exploration of symbolism and cognition to suggest that we also ought to reconsider the strength of connections between cognition and technological complexity. Using early weaponry as a case study I suggest that complexity may be “hidden” in early tools, and further highlight that assessments of technologies as linear and progressive have roots in Western colonial thought.

We welcome Stibbard-Hawkes's empirical contributions and discussion of interpretive challenges for archaeology, but question some of his characterizations and conclusions. Moving beyond critique, it is time to develop new research methods that eschew simplistic modern/premodern binaries. We advocate an inductive, probabilistic approach using multiple lines of evidence to infer the causes and consequences of behavioral variability across time and space.

We comment on the consequences of the target article for language evolution research. We propose that the default assumption should be that of language-readiness in extinct hominins, and the integration of different types of available evidence from multiple disciplines should be used to assess the likely extent of the realization of this readiness. The role of archaeological evidence should be reconsidered.

The article provides an important warning but its general conclusions should be nuanced: (i) When there is no evidence for it, we should depart from the hypothesis that a species lacks a particular cognitive capacity, and (ii) inferences from absence of evidence can be epistemically sound and scientifically strategic in cognitive and linguistic archaeology.

Stibbard-Hawkes presents a much-needed case for distinguishing between different types of evidence for cognition in past cultures. However, he does not outline an applicable approach for moving forward in making claims about the cognition of past cultures. We present an initial model for calibrating both absolute and comparative claims about past cultures' cognition and other traits.

Sports, team games, and physical skill competitions appear to be a human universal and may have been prevalent throughout the hominin lineage. These activities are cognitively complex and can be associated with a distinctive and symbolic material culture. Yet, many of the artifacts used by foraging groups for sports, team games, and athletic competitions often have a low preservation probability.

The target article rightly questions whether the archaeological record is useful for identifying sea changes in hominin cognitive abilities. This commentary suggests an alternative approach of synthesizing findings from primatology, evolutionary developmental biology, and paleoanthropology to formulate hypotheses about cognitive evolution in hominins that lived during the three million years that preceded the record of material culture (the Botanic Age).

Our commentary suggests that different materialities (fragile, enduring, and mixed) may influence cognitive evolution. Building on Stibbard-Hawkes, we propose that predictive brains minimise errors and seek information, actively structuring environments for epistemic benefits. This perspective complements Stibbard-Hawkes' view.

Stibbard-Hawkes's detailed demonstration that in the case of hunter-gatherer artifacts, absence of evidence is not evidence of absence must never be forgotten. The belief that there is a single coherent “human cognitive capacity” difference between modern humans and some unspecified earlier form should be rigorously re-examined.

Using Neanderthal symbolism, I extend on Stibbard-Hawkes to show that reconsidering the link between cognitive capacity and material culture extends beyond matters of preservation. A reconceptualization of behavioural modernity inclusive of both extant and extinct populations must begin with an honest theoretical separation of biological and behavioural modernity, which requires to critically engage with how we frame the underlying questions.

Innovations, such as symbolic artifacts, are a product of cognitive abilities but also of cultural context. Factors that may determine the emergence and retention of an innovation include the population's pre-existing cultural repertoire, exposure to relevant ways of thinking, and the invention's utility. Thus, we suggest that the production of symbolic artifacts is not guaranteed even in cognitively advanced societies.