The issue of ‘knowability’ in relation to the origins and distribution of the language families of the world is addressed, and recent advances in historical linguistics and molecular genetics reviewed. While the much-debated problem of the validity of the concept of the language ‘macrofamily’ cannot yet be resolved, it is argued that a time depth for the origins of language families greater than the conventional received figure of c. 6000 years may in some cases be appropriate, allowing the possibility of a correlation between language dispersals and demographic processes following the end of the Pleistocene period. The effects of these processes may still be visible in the linguistic ‘spread zones’, here seen as often the result of farming dispersals, contrasting with the linguistic ‘mosaic zones’ whose early origins may sometimes go back to initial colonization episodes during the late Pleistocene period. If further work in historical linguistics as well as in archaeology and molecular genetics upholds these correlations a ‘new synthesis’, whose outlines may already be discerned, is likely to emerge. This would have important consequences for prehistoric archaeology, and would be of interest also to historical linguists and molecular geneticists. If, however, the proposed recognition of such patterning proves illusory the prospects for ‘knowability’ appear to be less favourable.