The archaeological records in the Old World and Australasia reflect a pattern of simple approaches to stone flaking in early stone tool assemblages followed by a later proliferation in more complex approaches. Although the pattern is similar in structure, the proliferation of complex flaking occurred much later in Australasia. 'Simple' stone flaking can be characterized as the arrangement of flake removals in chains and 'complex' approaches involved a hierarchical arrangement. Some archaeologists see the proliferation of hierarchical reduction sequences as a reflection of hominin cognitive changes, but 'Homo sapiens' colonizers of Australia - carrying a toolkit made by simple chaining - were cognitively modern. The Australian proliferation has been explained as a response to ecological conditions but this proximate explanation fails to account for the complex nature of hierarchical reduction sequences. Demographic modeling that links the emergence of complex stone flaking to population structure or growth better accounts for the proliferations in both the Old World and Australasia. Efforts to reconstruct hominin migrations through Asia by focusing on the 'derived' parts of stone toolkits track demographically-linked trends rather than initial emigration events.