Collis, an Englishman from the University of Cambridge, was hostile to the methodology of German professor Gustaf Kossinna and was hostile to Celts as an ethnic identity coalescing around a concept of hereditary ancestry, culture and language (claiming this was "racist"). Aside from this Collis was hostile to the use of Classical literature and Irish literature as a source for the Iron Age period, as exemplified by Celtic scholars such as Barry Cunliffe. Throughout the duration of the debate on the historicity of the ancient Celts, John T. Koch stated that it is "the scientific fact of a Celtic family of languages that has weathered unscathed the Celtosceptic controversy." Collis was not the only figure in this field. The two other figures most prominent in the field were Malcolm Chapman with his "The Celts: The Construction of a Myth" (1992) and Simon James of the University of Leicester with his "The Atlantic Celts: Ancient People or Modern Invention?" (1999). In particular, James engaged in a particularly heated exchange with Vincent Megaw (and his wife Ruth) on the pages of "Antiquity". The Megaws (along with others such as Peter Berresford Ellis) suspected a politically motivated agenda; driven by English nationalist resentment and anxiety at British Imperial decline; in the whole premise of Celtosceptic theorists (such as Chapman, Nick Merriman and J. D. Hill) and that the anti-Celtic position was a reaction to the formation of a Scottish Parliament and Welsh Assembly. For his part, James stepped forward to defend his fellow Celtosceptics, claiming that their rejection of the Celtic idea was politically motivated, but invoked "multiculturalism" and sought to deconstruct the past and imagine it as more "diverse", rather than a Celtic uniformity. Attempts to identify a distinct Celtic Race were made by the "Harvard Archaeological Mission to Ireland" in the 1930s, led by Earnest Hooton, which drew the conclusions needed by its sponsor-government. The findings were vague and did not stand up to scrutiny, and were not pursued after 1945. The genetic studies by David Reich suggest that the Celtic areas had three major population changes, and that the last group in the Iron Age, who spoke Celtic languages, had arrived in about 1000 BCE, after the building of iconic supposedly-Celtic monuments like Stonehenge and Newgrange. Reich confirmed that the Indo-European root of the Celtic languages reflected a population shift, and was not just a linguistic adoption.