It makes no biological or demographic sense that the world's population grew to its present size in less than 10 ky. Nor does it account for the vast areas of the globe that were fully inhabited during the Middle and Upper Pleistocene. Comparatively large populations must have arisen during the latter, setting the stage for a Holocene population ‘explosion’. Indeed, for the breadth of adaptation and production of modern people to occur around the world there had to be larger populations in the Upper Pleistocene than has been proposed. The ‘explosion’ itself is not so much an explosion but a time at which some sections of humanity began to change their lifestyles so that they became very visible. Escalation in population growth was taking place long before this.

It is also illogical to expect that Homo erectus lived in patches of splendid isolation around the world without some form of genetic interaction with neighbours. We are a group animal; gregarious, in need of company; we do not travel on our own; indeed we have to have others around us because we are too weak to survive when we try to face nature on an individual or small group basis. The erectine successes and the viable populations that arose from them can be traced from the Lower to the Upper Pleistocene and are testimony to that company.