While field experience became increasingly valorized, the analytical aperture of the observer's vision was becoming steadily narrowed by metropolitan theory and the fashion of the times for a harder, more racialist conception of difference. A critical step in this process was the development of a capacity to derive both racial and temporal separation from location — to move from mapping difference across space to proposing hierarchies of value that could be transposed onto these spatialized distinctions and, ultimately, to conceive of separation in space and in race as a fundamental difference in evolutionary time (Fabian 1983).

The function of cardinality with respect to space is similar to that of teleology for time, imposing a moral load on locations and directions (or temporal sequences), and linking them through gradients (or developmental trajectories). The classic distinctions between Melanesian and Polynesian or Malay and Papuan are also fundamentally geographic distinctions, specific valuations of particular spatial end-points that serve to anchor racial clines. Crawfurd's physical and moral gradient for the Indian Archipelago maps racial difference and social evolution in space. Given his primary focus and point of departure in Southeast Asian philology, the 'monster island' of New Guinea looms on the distant horizon as a dark foil in Crawfurd's racial schema.^[61] So, too, Earl's Malayu-Polynesian 'line of improvement' links the 'civilised' or civilizable 'brown race' of Malays and Polynesians in space, touching only lightly on the geographically intermediate but 'savage' Papuans of the north coast of New Guinea (1849-50:2-3).

Under these terms, the racial cartographer retains control only over the end points of the gradient. All else, necessarily, is shown in varying tones of grey. A concern for racial taxonomy requires rather more than gradients, however, and seeks instead to establish boundaries. If he was a keen observer, Wallace was an equally avid taxonomist and he was insistent that his human and zoological schemes matched one another (1880a:592-3): 'it is important to point out the harmony which exists, between the line of separation of the human races of the Archipelago and that of the animal productions of the same country'.^[62] Though Wallace is famous for his zoogeographic boundary — dubbed the Wallace Line in 1868 by Thomas Henry Huxley (1825-1895)^[63] — less well-known is his 'ethnological' line, running to the east of the Wallace Line (Figure 16):

He first identified this line between human races in March 1857, locating it where it passed to the west of the island of Giloloor Halmahera:

Wallace was by no means the first to propose such a line: Marsden (1834:3) had identified New Guinea as 'the common, though not the precise boundary' between his regions of Hither Polynesia (from Madagascar to the Malay Archipelago) and Further Polynesia (from Island Melanesia to Easter Island); the philologist Robert Gordon Latham (1812-1888) had written of 'lines of demarcation' separating 'the Australians, Tasmanians, and Papuans on one side, and the Malays &c. on the other' (1860:219, 222); and Dumont d'Urville (1832) had published his map of the great divisions of Oceania which showed a boundary between 'Mélanésie' and 'Malaisie' lying just off the west coast of New Guinea.^[64]

Much as Dumont d'Urville (1832:20) had claimed his quadripartite division of Oceania and its inhabitants to be 'natural', so too Wallace (1880a:19, 591) insisted that his 'line of separation' between Malays and Papuans was 'true and natural' and 'very significant of the same causes having influenced the distribution of mankind that have determined the range of other animal forms'. A number of scholars have suggested that it was the impetus of accounting for human variation at Gilolo that led Wallace to his discovery of natural selection in animal species.^[65] He was adamant that 'If mankind can be classed at all into distinct varieties, surely the Malays and Papuans must be kept for ever separate'. By this logic, if people of Malay appearance and moral composition were found to the east of this line, it was as a consequence of their 'maritime enterprise and higher civilization'.^[66]

As George Gaylord Simpson (1977) has observed, Wallace's zoological line marked only the western limit of the Australasian fauna; Lydekker's Line, which approximates the submerged continental shelf of Sahul (incorporating New Guinea, the Raja Ampat and Aru islands, as well as Australia and Tasmania), eventually established the eastern limit of the Asiatic fauna but between these two lines there lay an extensive intermediate or transitional zoological zone. Much as later naturalists were vexed by questions of the significance of this intermediate zone, Wallace's ingenuity was put to the test by the problem of the process of 'admixture' or 'commixture' that, in his conception, had produced the human groups geographically intermediate between the Malay and the Papuan. His attempt to resolve this issue leads from the question of the cardinality of comparison to that of a topography of racial purity through which the geographical separation and presumed temporal sequence of Malays and Papuans became transformed into a racial hierarchy.