I was always surprised by the tendency of anthropologists to assign hard evolutionary 'milepoints' based on the very limited set of archeological data. Most egregious example is 'behavioral modernity' theory which claims that homo sapiens developed language, culture and art only relatively recently (30kya) because that's how old the currently oldest archeological finds of culture/art expression are. This doesn't stand up even to the simplest application of Occam's razor.