The Social Behavior of Older Animals

16 All Passion Spent

chapter 16 All Passion Spent A fter a long eventful life, many animals seem happy to wind down their activities, all passion spent. Previous chapters considered two wearied but comfortable pairs of long-lived gorillas, Beethoven and Effie, and Rafiki and Coco (Fossey 1983). The first part of this chapter discusses older animals studied as part of specific population research projects dealing with primate species (Japanese monkeys, Java monkeys, baboons, and chimpanzees). Then it turns to other aging individuals who were observed more casually by field scientists in the course of their research (buffalo, bushbuck, lions, wildebeests, red deer, waterbuck , right whales, and elephants). The chapter concludes with a look at older individuals under the control of human beings (Asian working elephants , a captive tiger, and dogs). Population Studies monkeys Japanese monkeys have been thoroughly studied. Japan would seem the obvious place to observe these animals, given their name, but they now also live in Texas. In the 1950s, there were 34 Japanese monkeys in the Arashiyama troop, living wild in the forests near Kyoto. It was difficult for nosy zoologists to see what the monkeys were up to every day, so the men spread sweet potatoes in open areas near the woods to lure them to where their activities could be scrutinized. Thanks to this extra food, the population not only became less secretive , but quickly expanded, with the monkeys dividing into two daughter groups, A and B. Group A, with about 150 members, began to wander farther afield, raiding local farms and households for food, so irate humans considered shooting them. Their zoological voyeurs were horrified at this possibility. Instead, in 1972 Japanese and American scientists jointly 167 agreed to transfer them to the United States. A new colony was started in Texas, first in a huge fenced enclosure near Laredo, and later in one near Dilley (Fedigan 1991). This colony was named the Arashiyama West troop, to distinguish it from their Arashiyama East relatives still living in Japan. Some old females remained among the Japanese monkey troop in Japan, and Masayuki Nakamichi from Osaka University decided to observe them, because of their advanced age (1984). Did they behave any differently than their younger sisters? She focused on 14 females, ranging in age from 11 to 29, watching what each individual was doing for 10 hours a day on three different days. Half of these animals were under 22 years old, and half over. During each individual’s three observation periods , a researcher noted down her activities, and which companions were near her, on a ten-second-interval checklist. Needless to say, Nakamichi had plenty of data to analyze—over 10,000 observations on the oldest animals, the ones which are of interest here: Op (29 years old), G1 (28), and Op’s sister Yu (27). None of these mothers had given birth in the past five years, and none was expected to live more than a few years longer. Results showed that the older females tended to spend much more time resting than did the younger ones, and that they were more withdrawn from social interactions such as grooming. Grooming is considered to be a tradable commodity that can be exchanged for such things as reciprocal grooming, reduction in aggression, increased access to a scarce resource , or access to a newborn. It is also important for psychological bonding (Nakamichi and Yamada 2007). Fortunately for the three oldsters , their greater apathy did not mean that they lost their dominance and their right to the best food. (Dominance tests were carried out between two monkeys by putting peanuts between them and seeing who grabbed them all.) If a female is dominant when young, she usually remains dominant throughout her lifetime, although she may become subordinate to her own offspring. Op remained dominant to most other females, but subordinate to one of her four daughters and to two granddaughters ; G1 was subordinate to three of her five daughters and to a granddaughter. Op and G1 were not close to their elder daughters, but did spend time with their youngest daughters. Grooming, which strengthened the social bond between groomer and groomee, was the best diagnostic for social activity. Op and G1 were 168 the social behavior of older animals completely lazy when it came to grooming other monkeys; they never did this. They, as well as Yu, seldom even groomed themselves—during a...