A principal component analysis of the correlation matrix array 25 items concerning the status of adult male and female as well as of offspring in 108 societies revealed that the more polygynous the society is, the more aggressive adult males in society are toward adult females. The more the subsistence of a society is dependent on the labor of males, the more aggressive adults are towards offspring. Swaddling and infanticide are considered to work as that buffering the aggression and to simultaneously act as a r-strategy or a K-strategy, respectively, in terms of reproductive success in human societies. Overall high level of aggression in greate apes and humans is discussed in terms of possible dietary changes that have occurred to produce high sociability in primates.

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Amphipithecus and Pondaungia are enigmatic fossil primates discovered from the Pondaung district, Central Myanmar (Burma). Since the first discoveries early in this century, many researchers have discussed about their phylogenetic position: some authors regarded them as anthropoid primates (e. g. Pilgrim, 1927; Colbert, 1937), some as a kind of condylarths (Koenigswald, 1965), and others as lemuroid primates (Szalay, 1970; Szalay and Delson, 1979). Even after the second specimens discovered in 1970's, same controversy has been repeated by many researchers (Ba Maw et al., 1979; Ciochon et al., 1985; Ciochon and Holroyd, 1994).
In 1997 several new specimens of Amphipithecus and Pondaungia were discovered in the Pondaung district by Myanmar researchers (Anonymous, 1997). These new fossils provide us a plenty of information about their mandibular morphology, and suggest a possible plylogenetic relationship among Pondaung primates and Siamopithecus, which was discovered from Krabi, Thailand (Chaimanee et al., 1997).
The geological age of the Pondaung primates and Krabi primate have also been discussed by several workers (e. g. Holroyd and Ciochon, 1994; Ducrocq et al., 1992; 1995). In this paper we compared the fossil mammal lists of the Pondaung, Krabi, and several Southern Chinese Eocene faunas. Our conclusion is as follows: the Pondaung fauna is most similar to the Naduo fauna in Yunnan Province, China, and probably slightly older than the Krabi fauna in Thailand. The geological age of the Pondaung fauna is likely to be the Late Eocene rather than the late Middle Eocene advocated by Holroyd and Ciochon (1994).
More detailed comparisons among Middle to Late Eocene mammal faunas in Myanmar, Thailand, China, and Mongolia will make clear the evolutionary history of the Eocene primates in East Asia.

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The social relationships of 10 young adult males in a free-ranging group of Japanese macaques at Katsuyama, Okayama Prefecture, were examined pre- and post-fission. Before group fission, higher-ranking young adult males interacted less frequently with not only their mothers, but also with other matrilineally-related females than did lower-ranking males. Six-year-old males clearly formed two subgroups according to their relative rank, even though they did not form any clear subgroups at the age of two.
Higher-ranking males spent more time away from females of the group than did lower-ranking males. However, when it was time for artificial feeding, higher-ranking males obtained scattered food more frequently than lower-ranking males. After group fission, four of the five higher-ranking males and one of the five lower-ranking males remained in the main group, while three of the five lower-ranking males were in the fission group.
These differences in the social relationships of young adult males might reflect the female subgroups which appeared prior to group fission.

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An adult male captured at Nakatsu village, Wakayama Prefecture, was identified as an interspecific hybrid between the Japanese and Taiwan macaques. Electrophoretic analysis of diagnostic blood proteins (adenosine deaminase, ADA; NADH-dependent diaphorase, DIA; transferrin TF) strongly supported the occurrence of hybridization between native Japanese macaques and artificially introduced Taiwan macaques in the prefecture. The male had a Taiwanese-like mitochondrial DNA. This suggested that the hybrid resulted from a mating between an immigrant male of Japanese macaque and a group-member, female Taiwanese macaque in the northern area of the Arida River.

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Hershkovitz (1977), who classified the marmoset genus Callithrix into C. jacchus, C. argentata and C. humeralifer, presented the baseline for all the current research and investigation on the marmoset taxonomy. After then, however, some new forms have been described and there is still controversy in the species arrangements.
In the Atlantic region, C. jacchus, C. penicillata, C. kuhlii, C. geoffroyi, C. flaviceps and C. aurita are recognizable as distinct species on the basis of the information of natural hybridization and the trend of current marmoset taxonomy. On the other hand, it is difficult to show a general trend of species arrangements in the Amazonian forms because taxonomists are divided as to the species recognition. However, C. argentata, C. humeralifer, C. emiliae in Pará-Mato Grosso, and C. humilis at least are considered as valid species.

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