Attempts to understand the evolution within the genus Homo in Australasia have relied on two main theories. The Multiregional scenario suggests that cranial morphology reveals a long-standing continuity between fossil and recent hominids in the region. Out of Africa theorist have favoured the idea that Homo sapiens evolved in Africa, migrated outward, and replaced archaic hominids, such as Homo erectus in Australasia. Neither Multiregionalists nor Out of Africans have factored (seriously) in the unique geographic and ecological context in which variation in Australasian members of the genus Homo evolved. Nonetheless, the mammalian faunas of this region have been strongly shaped by the existence of zoogeographic barriers and different ecological zones. Taking an environmental perspective on the evolutionary history of the human lineage in this region leads to an third and possibly more plausible scenario in which both local evolution and replacement play a role. The continuing importance of the zoogeography of Australasia is evidenced in the cranial variations seen within modern humans of this region, which can be divided into a Sunda (“Asian”) and a Sahul (“Australo-Melanesian”) cranial pattern.

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The Marshall Island material is from five locations: the most southern Ebon Atoll; Kwajalein, Majuro, and Ujae atolls in the middle of the archipelago; and the southern Utrik Atoll. All but the Majuro skeletal and dental material was collected by MIW during archaeological excavations between 1993-1997. Crown dimensions and morphological observations were made of the teeth.
Shoveling was present on the upper incisors ranging from trace to semi-shovel in 92% of I¹'s and 90% of I²'s. This was a somewhat higher percentage than for Yap upper incisors, although it was not significant and the degree of shoveling was similar (Harris and others, 1975). The hypercone of the upper molars was always present on M^1-2 but was absent 17% on M³. Carabelli's trait had a low incidence in Oceania and cusps with free apices were rare. In precontact Marshallese, the cusps were present on M¹ 39% which was about 10% higher than reported for Yap (Harris and others, 1975). There was a medium-sized cusp with an independent apex in 11% of M¹'s. Of six dm²'s 33% had Carabelli's cusps. The Y occlusal groove pattern on M₁ is fairly high in the Pacific (Swindler and others, 1998) and was present 90% of the time, the same figure reported for M₁ in Yap (Harris and others, 1975). The presence of cusp six varied from 3% to 70% on M1 in the Pacific. The latter figure was for Yap which was significantly higher than the 55% found in the Marshallese. M₂ (21%) and M₃ (50%) were more variable. The metrical analysis revealed several significant differences in tooth size among the peoples of Micronesia. The teeth from Palau and Kiribati were usually larger than those from the Marshall Islands and Guam. The teeth of Native Australians are generally the largest in the Pacific.
The dental evidence suggested that the precontact people living on the small atolls and coral islands in the eastern areas of Micronesia were in many ways dentally similar to the modern day Yapese who were found to be dentally more closely affiliated with people to the east (Polynesia) than to the south (Melanesia) (Harris and others, 1975).

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Genetic polymorphism of the C1R subcomponent of human complement component C1 was investigated in 105 Indonesians, 141 Bangladeshis, 186 Tibetans, 101 South Africa blacks, 100 South Africa whites, and 24 Samoans. These population data fitted the Hardy-Weinberg equilibrium. A geographical cline of the C1R^*1 frequency was observed in Japanese<Aboriginal Taiwanese<Chinese<Tibetans<Indonesians. The C1R^*8, which was considered to be characteristic of Japanese, was not found in the above population groups examined.

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