Late Pleistocene Demography and the Appearance of Modern Human Behavior

TLDR

Modern human behavior is marked by increased symbolic and technological complexity, with the Upper Paleolithic emerging ~45,000 years ago in western Eurasia but similar features appearing ~45,000 years earlier in southern Africa. The study demonstrates that demography is a major determinant of cultural complexity maintenance. Genetic estimates of regional population size over time reveal that early Upper Paleolithic European densities matched those in sub‑Saharan Africa when modern behavior first appeared, showing that variations in subpopulation density and migration structure cultural skill accumulation. Thus, demographic factors alone can explain geographic differences in the timing of modern behavior’s emergence without requiring enhanced cognitive capacity.

Abstract

The origins of modern human behavior are marked by increased symbolic and technological complexity in the archaeological record. In western Eurasia this transition, the Upper Paleolithic, occurred about 45,000 years ago, but many of its features appear transiently in southern Africa about 45,000 years earlier. We show that demography is a major determinant in the maintenance of cultural complexity and that variation in regional subpopulation density and/or migratory activity results in spatial structuring of cultural skill accumulation. Genetic estimates of regional population size over time show that densities in early Upper Paleolithic Europe were similar to those in sub-Saharan Africa when modern behavior first appeared. Demographic factors can thus explain geographic variation in the timing of the first appearance of modern behavior without invoking increased cognitive capacity.