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The behavioral origins of Homo sapiens can be traced back to the first material culture produced by our species in Africa, the Middle Stone Age (MSA). Beyond this broad consensus, the origins, patterns, and causes of behavioral complexity in modern humans remain debated. Here, we consider whether recent findings continue to support popular scenarios of: (1) a modern human ‘package,’ (2) a gradual and ‘pan-African’ emergence of behavioral complexity, and (3) a direct connection to changes in the human brain. Our geographically structured review shows that decades of scientific research have continuously failed to find a discrete threshold for a complete ‘modernity package’ and that the concept is theoretically obsolete. Instead of a continent-wide, gradual accumulation of complex material culture, the record exhibits a predominantly asynchronous presence and duration of many innovations across different regions of Africa. The emerging pattern of behavioral complexity from the MSA conforms to an intricate mosaic characterized by spatially discrete, temporally variable, and historically contingent trajectories. This archaeological record bears no direct relation to a simplistic shift in the human brain but rather reflects similar cognitive capacities that are variably manifested. The interaction of multiple causal factors constitutes the most parsimonious explanation driving the variable expression of complex behaviors, with demographic processes such as population structure, size, and connectivity playing a key role. While much emphasis has been given to innovation and variability in the MSA record, long periods of stasis and a lack of cumulative developments argue further against a strictly gradualistic nature in the record. Instead, we are confronted with humanity's deep, variegated roots in Africa, and a dynamic metapopulation that took many millennia to reach the critical mass capable of producing the ratchet effect commonly used to define contemporary human culture. Finally, we note a weakening link between ‘modern’ human biology and behavior from around 300 ka ago. 1. Introduction 2. Conceptual changes: Modern packages, evolutionary scenarios, and trait lists 3. Reviewing the empirical evidence 3.1. Beginnings: Lithic technology of the Early/Middle Stone Age transition 3.2. Developments: Lithic technology of the Middle Stone Age during the late Middle and Late Pleistocene 3.3. Indicators for ecological flexibility and social complexity: Nonlithic archaeological material from the Middle Stone Age 4. Patterns in the record: Inferring a complex mosaic of cultural evolution in the Middle Stone Age 5. Causes and mechanisms of change 5.1. Behavioral complexity and changes in the human brain 5.2. Behavioral complexity and human demography 5.3. Future perspectives

In this study we synthesize terrestrial and marine proxy records spanning the last 620,000 years, to decipher pan-African climate variability, its drivers and potential linkages to hominin evolution. We find a tight correlation between moisture availability across Africa to Walker and Hadley Circulation variability that were most likely driven by changes in Earth´s eccentricity. Our results demonstrate that low latitude insolation rather than glacial-interglacial cyclicity was the predominant driver of pan-African climate change during the mid to late Pleistocene. We argue that these low-latitude climate processes governed the dispersion and evolution of vegetation, as well as mammals, in eastern and western Africa, ultimately by increasing resource-rich and stable ecotonal settings that have long thought to have been the preferred habitats of hominins.