Trees and ladders: A critique of the theory of human cognitive and behavioural evolution in Palaeolithic archaeology

Abstract

The modern biological model of (human) evolution is that of a branching tree. By contrast, prevailing models for human cognitive evolution remain unilinear in character, representing a ladder. The linear ladder model is the result of the opposition of an ethnographic and a primate reference frame for cognition, representing the two ends of what by definition becomes a linear line of evolution. It forces all types of behaviour that are not considered fully “modern” to assume a position at a lower level of cognition. The linear model is in addition pushed by the (flawed) perception of a linear encephalization trend over time. The structure of this linear model is not fundamentally based in either modern evolutionary theory or the archaeological record. The model itself is even structurally immune to constraints from pertinent data. Adopting a branching tree model instead has serious implications for views on hominin cognition and particularly the meaning of being “behaviourally modern”. In a branching model, “modern behaviour” no longer has a unique status as being by necessity the most sophisticated level of cognition, turning many of the traditional implications derived from the possession of “modern behaviour” moot. The challenge that adoption of a branching tree model creates is that ways have to be devised to account for unique cognitive expressions that are not covered by the existing framework of ethnography and primatology. In addition, notions about the “superiority” of “modern behaviour” over other forms of cognitive expression have to be abandoned. The advantage is that the model is structured to pertinent archaeological data and actually testable with archaeological data. Two case studies from the Lower and Middle Palaeolithic of Europe probe the construction of unique models for mobility strategies “bottom up” from archaeological data, providing a unique alternative to mobility models and their cognitive implications as derived from “bottom down” application of an ethno-primatological framework.