Unit 6
Living in Groups: Female Strategies

In previous units we examined how female strategies for increasing reproductive success are at the core of so many emergent social and behavioural trends observed in primates. This, as we observed, is due to the disproportionate amount of investment female mammals must place in reproduction vis-à-vis males, and the different limiting factors on fitness that result from these different levels of parental investment. Whereas male reproductive success (RS) is primarily limited by access to ovulating females, female RS is limited by access to resources, such as food, water, and protection from infanticide. Given this situation, female primates have evolved strategies for maximizing access to energetic resources. Depending on the dietary requirements of a female primate and the distribution of her required resources, one such strategy is to live in social groups. This unit will explore the ecology of female relationships, the different types of relationships between females, and the ecological, demographic, and phylogenetic factors that determine variation in female sociosexual behaviour. We will then look at the social dynamics that exist between females living in different grouping patterns under different competitive regimes, and we will pay particular attention to the complex matrilocal societies typical of many of the cercopithecines. Here we will explore the intricacies of dominance rank, rank inheritance, and life among kin. We then look at the dynamics of females living in non female-bonded groups, and how behavioural domains associated with competition, affiliation, and relationships with males differ from matrilocal, kin-based societies.

Objectives

When you have completed Unit 6, you should be able to

1. describe the types of relationships that exist between female primates living in different kinds of groups.
2. explain how differences in within- and between-group competition affect female relationships.
3. describe matrilocal societies and the dynamics of female relationships within them.
4. discuss the concept of rank, the different ways in which rank is acquired and maintained, and distinguish between basic (independent) and dependent rank.
5. describe relationships among females living in groups without kin, and how those relationships differ from matrilocal societies.
6. discuss why females of some species might be organized in a fission-fusion social grouping pattern, and describe female relationships in these groups.
7. discuss some of the population-level consequences of different female strategies.
8. discuss the dynamics of living with one’s kin and its implications for rank and dominance.
9. discuss the mechanisms by which individuals might be able to recognize kin when interacting with group members.

Viewing Assignments

In preparation for the final examination, you must watch at least four videos of the five options listed in Units 6 through 11. Each unit gives you two video options, so that by the end of Unit 11 you should have watched four videos from these five options:

The New Chimpanzees or The Nut-Cracking Chimpanzees of Tai Forest
Family of Chimps or Primate/Human Interaction
Can Chimpanzees Talk or Ape Genius
Gremlins: Faces in the Forest or 3 Monkeys
The Rain Forest Imperative or Gorillas in the Midst of Man

It does not matter the order in which you watch your video options, but the viewing assignments for each unit offer you a guide. Remember, completing a viewing assignment differs from watching a video for pleasure. You should consider watching each video twice: once to get an overview, and once to make notes. Study questions or instructions for viewing are supplied for each video; be certain that you read them over before you begin watching, and keep them in mind as you complete the assignment and make your notes.

Unit 6 Viewing Assignment

Watch one of the videos listed below.

National Geographic
1995  The New Chimpanzees. 60 min. Washington: National
Geographic Society.

This video is a survey of thirty years of research on chimpanzees in the wild. The program focuses on the similarities between chimpanzees and early humans through rare and unusual behaviours observed over the years by several researchers. It pays particular attention to the variability of behaviours and cultural traditions found in different populations across Africa. This program also provides an interesting look at chimpanzee intelligence.

If you choose this video, then in preparation for the examination, be certain that you can answer the questions given below.

1. What is the typical social structure of chimpanzee groups?
2. What are paramilitary patrols, and what is their function?
3. How does the study of chimpanzees help us understand human evolution?
4. What differences in hunting strategies exist between different populations, and why do these differences exist?
5. What are the effects of chimpanzee hunting on the colobus population?
6. What differences exist in meat sharing in the different populations of chimpanzees?
7. What is unusual about some of the infanticide observed among some groups of chimpanzees?
8. In what ways are bonobos different from common chimpanzees?
9. How is dominance different between the two ape species?
10. How is sexual behaviour used in bonobo society?
11. How do females show their infants how to crack open nuts?
12. What differences in tool use exist among different populations of chimpanzees?
13. Why do some chimpanzees swallow some leaves whole?
14. Provide examples of symbolic communication among chimpanzees.

or

Boesch, Christophe, and Hedwige Boesch-Achermann
1991  The Nut-Cracking Chimpanzees of Tai Forest. 25 min.
University Park, PA: Penn State.

This video presents a detailed look at the unique tool making and tool using behaviours of the chimpanzees of the Tai forest. The video focuses not only on the technique, but on the development of this behaviour, and on sex differences in nut-cracking techniques.

1. If you choose this video, then in preparation for the examination, be certain that you can answer the questions given below.
2. What are the different methods used to crack open nuts?
3. How do males and females differ in nut-cracking behaviour?
4. How is nut cracking learned from infancy to adulthood?
5. How do females encourage the learning process of the infants?
6. What are the two components of the tools used?

Alternative Reading Assignment

If you cannot complete the viewing assignment before the final examination, you must do the alternative reading assignment instead. You may combine the reading with viewing assignments so that you have a total of four video and reading combinations. For example, you can watch three videos and do one reading assignment for the final examination. Or, if you cannot watch any videos, then you must complete four reading assignments from the five options presented in Units 6-11. The reading materials can be ordered from the library. Be sure you can answer the questions below each assignment.

Unit 6 Alternative Reading Assignment

If you cannot complete the viewing assignment, you must do the alternative assignment below.

Luft, Joan, and Jeanne Altmann.
1998  Chapter Three, Mother Baboon. In: The Primate
Anthology: Essays on Primate Behavior, Ecology and
Conservation from Natural History. Ciochon, Russell L., and
Richard A. Nisbett, eds. Pp. 19-27. Upper Saddle River, NJ:
Prentice-Hall.

In preparation for the examination, be sure that you can answer the questions below.

1. In what national park is the baboon study discussed in this chapter located?
2. What specific questions about mother-infant relationships did the researchers focus on?
3. What role does experience play in determining the type of care a mother provides?
4. Aside from the mother, what other individuals can be important to an infant’s well-being, and how?
5. What is the principle factor that seems to determine the age at which mothers push their infants toward independence?
6. Which group of females is more likely to be “protective” of their infants for longer, and why?
7. Why would selection favour low-ranking females biasing the sex of their infants toward males?