By 1872, Krefft was convinced that the Aboriginal remains collected by the Australian Museum bore striking anatomical similarities to the ancient 'stone age' remains recently discovered in the limestone cliffs of the Vézère river valley in the Dordogne region in France. As Krefft had learned from reading the 1869 address by Paul Broca (1824-1880) to the Académie des Sciences, the most important of these discoveries had been the fossil­ized remains of four adults and an infant in a rock shelter uncov­ered during the construction of a railway line at Cro-Magnon (Broca 1873:305-9).

Broca (1873:426-8) was fascinated by what he and other French researchers presumed, on the basis of animal bones and various items of material culture found with the Cro-Magnon skeletons, to have been the development of an ancient race through three distinct societal stages before sudden extinction. They took the Cro-Magnons to have been a morphologically distinct race whose bodily characteristics bore no relation to less ancient remains found in barrow mounds or to modern Europeans. The thigh bones, for example, were much thicker than in any modern human race though seemingly closer in shape to modern men than were those of the higher apes. The skulls were much longer than those of modern European races with cranial sutures sufficiently similar to those of modern 'savage nations' to encourage the conclusion that they were probably on the same level in terms of social sophistication. Even so, Broca believed that their skulls showed 'signs of a powerful cerebral organisation' which he took as suggesting that they might have been constrained in achieving their full evolutionary potential by unknown environmental or social factors. Indeed, Broca was drawn to speculate that their extinction was due to their having been a peaceable people who were intellectually and technologically incapable of resisting the intrusion into the Vézère of a more aggressive and better-armed race.

Krefft was inspired by Broca to see remarkable affinities between the apparent course of human evolu­tion in prehistoric Europe and the drama of racial supersession seemingly being played out in the Australian colonies, although the question remains open as to whether Krefft, in embracing Broca's reasoning as to the fate of the Cro-Magnons, also accepted Broca's polygenist explanation of human origins. Broca's fascination with the Cro-Magnon remains was in large measure due to his seeing them as providing clear morphological evidence that humanity had not evolved as Darwinians suggested through the evolutionary transformation of one ancestral type.

Whatever he thought of Broca's polygenist transformism, Krefft, over several newspaper articles published in Sydney during early 1873, argued that Australia's indigenous race exempli­fied the same three stages of societal development posited by Broca for the race whose remains had been discovered at Cro-Magnon. 'Comparing the weapons of our savages with these descriptions of the learned Frenchman', he wrote (1873b), 'we must acknowledge that he has hit the proper distinction to a point'. In Western Australia, he added, there lived 'sav­ages with scarcely any covering except a cape of wallaby skin, without possum rugs and with the roughest lump of granite embedded in grass-tree gum for a hatchet'. These people clearly corresponded to the earliest era of Cro-Magnon society whereas the people living along the Murray and inhabiting coastal New South Wales were in Krefft's estimation obviously 'more advanced'. Like the socially more advanced Cro-Magnons, they fashioned stone hatchets with ground edges and carved or drew hunting scenes. Finally, in Krefft's eyes, the inhabitants of New Guinea were modern counterparts to the Cro-Magnon race in the third phase of social development preceding their extinction. By contrast, the Maori of New Zealand were a distinct, more advanced, 'intelligent' race who might in different circumstances have colonized Australia where they 'would have made short work with our gentle savages' and 'given future invaders more trouble than they gave them in their limited islands, though even there they proved hard to conquer'.

Krefft's conjectural racial history appears to have attracted no public comment in either Sydney or London media. Possibly, as he later claimed in a letter to Darwin, his evolutionary beliefs were a factor in his dismissal from the post of curator of the Australian Museum in 1874 (Butcher 1994:52-4). However, regardless of its reception, Krefft's comparative prehistory vividly illustrates how, by the mid-1870s, competing racial discourses licensed the imaginative reconstruction of human history as a universal narrative of racial struggle and supersession.^[22] Yet Krefft did not simply bring the Darwinian conception of speciation together with Broca's speculative human history. Certainly, his collecting of Aboriginal bodily remains is a striking instance of convergence between seemingly disparate discourses on the issue of examining those remains. Moreover, the implications of that discursive convergence were doubly pernicious for Indigenous Australian people, given shared polygenist and Darwinian expectations of racial supersession and extinction. However, Krefft's position at the hub of colonial collecting practice also shows that Australia increasingly served as a critical zone of intellectual feedback to the metropole, with practical ramifications for diverse strands of the European science of race.