Integrative and Separationist Perspectives: Understanding the Causal Role of Cultural Transmission in Human Language Evolution

Biological evolution and cultural evolution are distinct evolutionary processes; they are apparent also in human language, where both processes contributed in shaping its evolution. However, the nature of the interaction between these two processes is still debated today. It is often claimed that the emergence of modern language was preceded by the evolution of a language-ready brain: the latter is usually intended as a product of biological evolution, while the former is believed to be the consequence of cultural processes. I label this account separationist, and I argue that current evidence coming from the archaeological and fossil record suggests that cultural evolution has played a pivotal role in shaping not only modern language but also the language-ready brain. I label the latter the integrative perspective. I analyze the two accounts from two different conceptual frameworks, the Standard Evolutionary Theory and the Extended Evolutionary Synthesis, and I discuss the limits of the sharp proximate–ultimate distinction in this specific case study arguing in favor of a causal feedback model. I extend the argument to the debate on gradual and punctuational evolutionary rates, suggesting that the debate on patterns in language evolution should leave room for discussion of the nature of the processes involved in producing those patterns, providing reasons in favor of the eco-evolutionary feedback dynamics underlying the integrative perspective.