This review examined the hypothesis that a competition with the Cercopithecoidea accounts for the decline of the “Hominoidea” (properly speaking, non-cercopithecoid catarrhines on the present-day consensus of catarrhine taxonomy) from the beginning of the Miocene in Africa, originally put forward by P. Andrews (1981) [Species diversity and diet in monkeys and apes during the Miocene. In: Stringer C.B. (ed.), Aspects of Human Evolution. Taylor & Francis Ltd., London, pp. 25–61]. The updated African catarrhine fossil record revealed that there was neither an uprising of the diversity of the Cercopithecoidea nor a decline of non-cercopithecoid catarrhines by the early Late Miocene. The radiation of the cercopithecids and the decline of non-cercopithecoids coincidently occurred during 10–7 Ma. Prior to 10 Ma, colobines (and probably guenons) invaded African forests and became (potential) competitors of the non-cercopithecoids as frugivorous primates that can consume unripe fruits. The r-strategist cercopithecids were certainly more adaptive than presumably K-selected large non-cercopithecoids under the fluctuation and deterioration of environment after 10 Ma. However, it cannot be concluded whether the cercopithecids eventually replaced the non-cercopithecoid cattarhines through a direct competition. Between 10–7 Ma, a transition from the C3 to C4 environment has progressed in East Africa. The climatic change could have negatively affected the diversity and population size of the non-cercopithecoids. It might have also changed interspecific relations in primate communities. These possibilities can be evaluated only with a continuous and abundant fossil record of the cercopithecids (especially forest-living cercopithecines) and non-cercopithecoid catarrhines during this time period.

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Excavation research at the Sakitari-do cave site, Nanjo city, Okinawa, was conducted from 2009 to 2011. At the Trench 1, under the thick flowstone layer containing archaeological remains of Middle Jomon period, there are about 2 m thick soft brownish clay sediments divided into three layers (Layer I, II and III). Results of radiocarbon dating of charcoals from each layer are as followings; Layer I (upper): 12445 ± 40BP, 12475 ± 40BP, Layer II: 16370 ± 60BP, 16910 ± 60BP, 19260 ± 70BP, 19340 ± 50BP, Layer III (lower): 24410 ± 70BP, 32650 ± 130BP. These ¹⁴C dates show that these layers are Pleistocene sediments. From the upper part of the Layer I, we found a human deciduous canine with a few marine shells and three pieces of quartz probably introduced by humans, the marine shells and quartz being allochtonous to the cave area.

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In this study, we evaluate the regional differences among three local Hokkaido Ainu groups (of southwest, central, and northeast Hokkaido) and the Sakhalin Ainu in terms of the frequencies of 20 nonmetric cranial traits. The degree of regional difference is measured by Smith’s mean measure of divergence (MMD). The mean regional difference among the three local Hokkaido Ainu groups is slightly larger than that among the early modern peoples of the three Ryukyu Islands—the Amami, Okinawa, and Sakishima Islands—, and it is almost equivalent to that of the three mainland Japanese groups composed of the modern peoples of Tohoku, Kanto, and Kyushu districts. Among the three Hokkaido Ainu local groups, the northeast group is slightly different from the southwest and central Hokkaido groups. The mean regional divergence between the Sakhalin Ainu and Hokkaido Ainu is four times larger than that among the three local Hokkaido Ainu groups. The relations among the three local Hokkaido Ainu groups and the Sakhalin Ainu were also confirmed by Mahalanobis’ D² distances based on 18 craniofacial measurements.

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[in Japanese]

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[in Japanese]

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