Unit 6
Infant Development

In this unit, we look at the physical and behavioural development of infants. We first review the concepts of r-selection and k-selection, and discuss their relation to altricial and precocial development. We then consider the roles of mothers, alloparents, and other group members in the behavioural and social development of the infant. We also discuss Harlow’s controversial deprivation studies of infant development. Finally, we examine the effects of the age and experience of the mother on the infant’s development, and the potential effects of the sex of the infant on its development.

Objectives

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

1. explain the difference between altricial development and precocial development.
2. discuss the relationship between r-selection vs. k-selection and altricial vs. precocial development.
3. explain the relationship between growth rates and altricial and precocial development.
4. explain the relationship between relative brain size and altricial and precocial development.
5. discuss the reasons for differential male and female development.
6. name and explain the social factors that affect infant development.
7. discuss the value of deprivation studies.
8. explain how the sex of the infant can influence the mother’s rearing style.
9. explain how ecological variables can influence the mother-infant relationship.

Viewing Assignment

If you wish to complete your next viewing assignment now, you may choose one of the two videos listed below.

Tamarin

1998 Baboon Tales. Montreal: CinéFête.

This video is an in-depth look at a troop of olive baboons in their natural habitat, with a particular focus on infant development. The video also presents information about the general behaviours of baboons.

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

1. Describe the general development of infants, and the factors affecting it.
2. What role does alloparenting play in olive baboon?
3. Why do males form friendships with infants?
4. What is infant buffering?
5. Provide examples of body language among olive baboons.
6. What happens during group encounters?
7. What role does friendship play in baboon society?

Rosenberg, M., and A. Warren

1997 A Lemur’s Tale. New York: Nature Video Library.

This video describes the general features of the social organization and habitats of several lemur species, with a focus on the ringtailed lemur and the sifaka. The film follows one group throughout a one-year period. Among the highlights of the video is a focus on infant development, and on how infants learn the skills necessary for survival.

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

1. Describe the chronological development of infants, from birth to independence.
2. What differences exist in infant development and mothers’ rearing styles?
3. How differently do twins develop compared to single infants?
4. What is the most common cause of death among infants?
5. What is the typical mourning routine of lemurs?
6. Provide examples of social learning among lemurs.
7. What types of encounters do ringtailed lemurs have with other primates?
8. Which sex is philopatric?
9. How do male and female behaviours change during the breeding season?
10. How long are females sexually receptive?

Note: Once you have completed the viewing assignment to your satisfaction, please return the video to the Athabasca University Library as soon as possible: the number of copies is limited, and other students will need it. Remember, too, to submit your request for the video for your next viewing assignment—see pages 83-84 in Unit 7 of the Study Guide.