An ecocultural model predicts Neanderthal extinction through competition with modern humans

Abstract

Archaeologists argue that the replacement of Neanderthals by modern humans was driven by interspecific competition due to a difference in culture level. To assess the cogency of this argument, we construct and analyze an interspecific cultural competition model based on the Lotka−Volterra model, which is widely used in ecology, but which incorporates the culture level of a species as a variable interacting with population size. We investigate the conditions under which a difference in culture level between cognitively equivalent species, or alternatively a difference in underlying learning ability, may produce competitive exclusion of a comparatively (although not absolutely) large local Neanderthal population by an initially smaller modern human population. We find, in particular, that this competitive exclusion is more likely to occur when population growth occurs on a shorter timescale than cultural change, or when the competition coefficients of the Lotka−Volterra model depend on the difference in the culture levels of the interacting species.Lotka−Volterra | cultural evolution | Paleolithic | feedback | replacement N eanderthals are a human species (or subspecies) that went extinct, after making a small contribution to the modern human genome (1, 2). Hypotheses for the Neanderthal extinction and their replacement by modern humans, in particular as recorded in Europe, can be classified into those emphasizing competition with modern humans and those arguing that interspecific competition was of minor relevance. Among the latter are the climate change (3) and epidemic/endemic (4) hypotheses. However, an ecocultural niche modeling study has shown that Neanderthals and modern humans exploited similar niches in Europe (5), which, together with a recent reassessment of European Paleolithic chronology showing significant spatiotemporal overlap of the two species (6), suggests a major role for interspecific competition in the demise of the Neanderthals.Replacement of one species (or population) by another is ultimately a matter of numbers. One competing species survives while the other is reduced to, or approaches, zero in size. In the classical Lotka−Volterra model of interspecific competition, this process is called competitive exclusion (7). If Neanderthals were indeed outcompeted by modern humans, the question arises: Wherein lay the advantage to the latter species? Many suggestions have been made, including better tools (8), better clothing (9, 10), and better economic organization (11). These hypotheses share the premise that modern humans were culturally more advanced than the coeval Neanderthals.The purpose of our paper is threefold. First, we extend the Lotka−Volterra-type model of interspecific competition by incorporating the "culture level" of a species as a variable that interacts with population size (12, 13). Here, culture level may be interpreted as the number of cultural traits, toolkit size, toolkit sophistication, etc. Although, as noted above, many anthropological and archaeological discussions i...

A phase transition induces chaos in a predator-prey ecosystem with a dynamic fitness landscape

“…Our findings thus fit within more general extensions of mathematical theories of evolution that include formalism from statistical and condensed matter physics [8, 58, 72, 73], suggesting that universal mechanisms may underly subtle transient properties observed in many natural ecosystems, including hysteresis and dynamical robustness [75]. …”

Cultural evolutionary theory: How culture evolves and why it matters

“…One of the hotly debated topics in human prehistory is the replacement of Neanderthals by modern humans ∼40,000 y ago. A recent study (129) proposed an ecocultural model that incorporated cultural differences between two competing species into Lotka-Volterra competition dynamics and showed that a difference in culture between moderns and Neanderthals could have driven the latter's extinction. This model explicitly includes cultural evolutionary dynamics and shows that a difference in population sizes between moderns in Africa and Neanderthals in Eurasia could have led to a difference in the cultural complexity between the two populations, allowing the small groups of moderns that migrated out of Africa to gradually outcompete the larger population of Neanderthals that they encountered.…”

Mosaic evolution and the pattern of transitions in the hominin lineage

“…In short, the higher the level of species richness, the greater the number of species likely to evolve, influenced by local and more global conditions, while extinction tended to be more influenced by local ecological factors. These broader studies and the emerging complexity of human evolution point the way to interactions between local and global influences, with variable outcomes, something that can be seen in greater detail in relation to Neanderthal extinction [61,62]. The appearance of new taxa-speciation-and the extinction of existing ones are all significant transitions in human evolution, ones where microevolutionary processes accumulate sufficiently across geographically structured groups for independent lineages to evolve and die out.…”