In their landmark 2010 paper, “The weirdest people in the world?”, Henrich, Heine, and Norenzayan outlined a serious methodological problem for the psychological and behavioural sciences. Most of the studies produced in the field use people from Western, Educated, Industrialised, Rich and Democratic (WEIRD) societies, yet inferences are often drawn to the species as a whole. In drawing such inferences, researchers implicitly assume that either there is little variation across human populations, or that WEIRD populations are generally representative of the species. Yet neither of these assumptions is justified. In many psychological and behavioural domains, cultural variation begets cognitive variation, and WEIRD samples are recurrently shown to be outliers. In the years since the article was published, attention has focused on the implications this has for research on extant human populations. Here we extend those implications to the study of ancient _H. sapiens_, their hominin forebears, and cousin lineages. We assess a range of characteristic arguments and key studies in the cognitive archaeology literature, identifying issues stemming from the problem of sample diversity. We then look at how worrying the problem is, and consider some conditions under which inferences to ancient populations via cognitive models might be provisionally justified.