On the acquisition and propagation of a new food habit in the natural group of the Japanese monkey at Takasaki - Yama

Abstract

This paper reports how the wild Japanese monkeys at Mt. Takasaki-Yama (City of Oita, Kyusyu) adapted themselves, in terms of food habits, to the change of environments, which was caused by the contact with men. This report contains following problems; 1) acquisition of new food habits, namely one of acculturation problems, 2) the difference in the acquiring capacity of new habits with references to age and sex, 3) the diffusion of new habits among the group members, 4) relation between the diffusion and the social structure of the group, 5) problems about inter — and intra — communication. This group of Takasaki-Yama was first provisionized with sweet potatoes, wheat and apples in November 1952. At the beginning of provisionization, the monkeys there ate sweet potatoes and wheat but not apples. Howewer, they gradually get used to apples and now eat them. In January 1953, peanuts were given to them. It took four months for the whole group to start eating them, although they did not eat at all at the beginning. Summer oranges (natumikan in Japanese), damsons and soy beans were likewise accepted as their new food. These food materials were accepted relatively rapidly. On the contrary boiled rice, bread, biscuits and candies were difficult to be accepted. The monkeys are quite indifferent to them even now, though five and a half years has already passed since the beginning of provisionization and a great many sightseers have been giving them to the monkeys every day just like in a zoo. From the above mentioned observations, candies were thought to be the most appropriate food material to be used for the investigation on the acquisition process of new food among monkeys. Candies were not quite new to the monkeys in July 1954, because sightseers had been giving them quite a lot. However there were very few who ate the candies at that time. In this test the monkey's reaction to candies were classified according to the degree of interest and the following three categories were adopted; 1) paid no attention and did not eat at all; 2) showed interest but did not eat; 3) showed interest and ate. The method of test was quite a simple one. Having given candies to every individual who was identified, its reaction was observed. Six series of tests were conducted as follows from July 1954 to September 1955. 1st test......July 11–14, 1954 4th test......May 6–14, 1955 2nd test......August 20–30, 1954 5th test......July 3–15, 1955 3rd test......March 22–28, 1955 6th test......September 12–30, 1955 Results: