Hominin cognition: The null hypothesis

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.

The arts and hemispheric specialization

Art was initially thought of as a single function linked mainly to spatial perception and right hemisphere functional specialization. Art was also considered to be diametrically opposed to language, further solidifying the right hemisphere specialization model. This view remained dominant for many decades. However, increase in published observations of artworks by professional artists following acquired unilateral hemispheric damage showed that quality artistic works can be produced when there is damage in either the left or the right hemisphere. With the advent of neuroimaging such as functional magnetic resonance imaging (fMRI), light was shed on the neural underpinning of the esthetics of artworks revealing activation in multiple regions across both hemispheres. The bulk of recent data suggests complementary hemispheric contributions to art production and esthetic evaluation of numerous art expressions. Similarly, creativity and imagination, upon which art expression depends, both appear to recruit interhemispheric processes. Culturally, the early evolutionary origin of art is associated mainly with Homo sapiens (HS) but, despite evidence for cerebral asymmetry based on fossil skulls, their emergence did not coincide with visual art making. A significant lag of hundreds of thousands of years intervened before humans produced art consistently and abundantly. By now, the arts are practiced ubiquitously throughout the globe, in all human societies.

Disguises and the Origins of Clothing

Thermoregulation is often thought to be a key motivating factor behind the origins of clothing. Less attention has been given, however, to the production and use of clothing across traditional societies in contexts outside of thermoregulatory needs. Here I investigate the use of disguises, modesty coverings, and body armor among the 10 hunter-gatherer societies in the Probability Sample Files (PSF) within the Human Relations Area Files (HRAF) World Cultures database, with a particular focus on disguise cases and how they compare with strategies of deception across other taxa. The employment of disguises-defined as altering one's appearance for purposes of deceiving conspecifics or other animals-is noted for eight of the 10 societies, with their use occurring in contexts of hunting, religious or cult practices, and war or interpersonal violence. Most hunter-gatherer disguises demonstrated clear similarities to cases of visual deception found in other species, with the majority of examples fitting categories of animal mimicry, masquerading as plants, disruptive coloration (camouflage), or background matching (camouflage), while disguises unique to humans involved the impersonation of culture-specific "spirit-beings." Clothing for modesty purposes (nine societies) and body armor (six societies) are also noted. I propose that strategic initiatives by individuals or groups to disguise or conceal themselves represents one possible initial pathway to the cultural evolution of clothing. There are likely multiple potential (nonexclusive) social and functional pathways to the emergence of clothing outside of thermoregulatory needs.