In this important book, the biosocial perspective employed by the authors attempts to integrate what is known about teenage pregnancy in this and other cultures with evolutionary data on mammalian and human physiological development. The 32 essays, drawn from the biological, behavioral, and social sciences, are organized into four major sections: 'The Life Cycle and Biological Development"; "Development: Emotional, Cognitive, and Sexual"; "Comparative Dimensions: Species, History, and Culture"; and "The Modern World." Each section challenges a number of common Western assumptions about the "problem" presented by teenage pregnancy.
In her key essay, editor Lancaster points out that it is impossible to understand human physiology without understanding the huntinggathering lifestyle for which it was designed-a lifestyle that has characterized 99% of the million or so years of human evolution. Women in early foraging societies reached menarche around age 15 or later, followed by several years of" adolescent subfertility" (temporary sterility). (Reiter's essay shows that ovulatory frequency rises from 15% just after menarche to 90% in the 6th postmenarchal year). Thus, although premarital adolescent sexual activity has been common and socially accepted in over 60% of known cultures, most girls did not actually become pregnant until around age 18, at which time they were adequately supported by simple societies organized around firm institutions of marriage and family. Evolution, in other words, has historically given the female body a period of time to act as an adult both socially and sexually without assuming the responsibilities of the maternal role.
Konner and Shostak's provocative essay demonstrates that the age of menarche has been steadily declining for the past 150 years all over the world, generally as the result of improved nutrition and health. (In presenting their evidence, these authors dispel the commonly held notion that Juliet's age of 14 was normal for childbearing in medieval Europe-in Shakespeare's original source for the story, the heroine was 18). This trend in human maturation is one of the most profound changes in the biology of the species in recorded history. Although early adolescent sexual activity is biogically and cross-culturally normal, pregnancies resulting from such behavior are a new phenomenon. This fact has important implications for those who would condemn today's sexually active adolescents as immoral: the morality of the last few centuries in Western Europe is far from representative of most human cultures. Konner and Shostak point out that the earlier onset of menarche can be expected to enhance the already strong biological sex drive among adolescents, and suggest that much of the drive for the sexual liberalization of the last three decades came from teenagers themselves in response to their accelerated sexual maturation. They stress that American society is still unprepared to cope with this major evolutionary change.
Eveleth's essay on timing of menarche informs us that in traditional societies where caloric intake is still restricted, menarche still occurs late, and the birth of the first child even later. In contemporary societies, rural populations and lower socioeconomic groups average later menarche than urban and upper socioeconomic groups, as do athletes and dancers engaged in constant extreme energy expenditure. In the U.S., the average age of menarche for whites of European descent is 12.8 years, and for blacks is 12.5 years-the earliest in the world. Thus, some American girls will begin menarche at age 9, many more at age 10, and 75% by age 13.5. However, as Lancaster notes, adult pelvic capacity is not attained until ages 17 to 18: thus we are confronted with a very recent split of six years between the female's ability to conceive and her physiological fitness for delivery.
Here emerges a recurrent theme of the book-that the term "teenage pregnancy" masks critical developmental differences between young, middle and older teenage mothers. Garn et al's essay on the biology of teenage pregnancy stresses that it is not an aberration that automatically places both mother and fetus at risk, as many physicians who treat pregnant teens seem to think, but is in fact the norm for most of the world. Addressing the common assumption that the "teenage factor" alone contributes to low birth weight babies, the authors were surprised by their own finding that only low prepregnancy weight and low weight gain during pregnancy correlate directly with low birth weight babies, no matter what the mother's age; thus the smaller size of the teenager's baby is in harmonious accord with the smaller size of the mother herself. The potential problem arises for the youngest of the teenagers, in whom more of the pregnancy weight gain goes to the placenta or to the maternal tissue stores than to the fetus. For such young teens, the authors advise a compensatory larger weight gain of 4kg or more during pregnancy.
A number of other essays address the issues of social adaptation for teenage mothers and babies, stressing that the "social problem" focus of research on teen pregnancy may have blinded researchers from considering teenage parenting in its wider socioeconomic and ethnic context. Suggestive findings are presented on the role of the father, on the lack of communication about sexuality and reproduction between adolescents and their parents (peers and siblings tend to have a far greater effect on regular contraceptive use than parents!), on the correlations between teenage pregnancy and child abuse, the cultural differences between blacks and Hispanics that affect child-rearing practices, and the negative aspects of teen pregnancy outcome that often result not from age but from lack of social support and loss of educational and employment opportunities.
This is an important book which will certainly be of service not only to anthropologists but also to childbirth educators, social workers, and health care practitioners. It calls into question the common cultural notion of teenage pregnancy as an inherently pathological condition, while at the same time pointing out the vast cultural and physiological differences between being pregnant at 13 and at 18, with the latter being a norm for the majority of our evolutionary past, while the former was a physiological impossibility until very recently in our history. Only the cultural nature of the extended period of adolescence in our society makes pregnancy problematic for the 18-year-old, while in no social system has pregnancy been the norm for the younger teenager. This long adolescence, during which the maturity, education, and experience requisite for successful coping can be developed, is not an evolutionary aberration but a necessary adaptation to its increasing complexity. Although teenage pregnancy is an entirely predictable outcome of that complexity, our society is barely beginning to be engaged in supporting and accomodating the biological and social reality of this entirely modern phenomenon. This book represents an important step in that process.
As an anthropologist I appreciate the thoroughness of the book's coverage of available data, as well as its theoretical contributions to the issue. As the mother of a 10-year-old daughter, I am empowered by the book's information on average age of puberty and menarche, by its discussion of the cross-cultural normality of adolescent sexual behavior, and most especially by the information that those young teenagers whose parents are open and frank with them about their bodies are most likely to have high self-esteem and to postpone initial coitus until age 16 or later-that is, until a time when pregnancy would represent far less physiological and social dissonance than in their early teens. (This is a piece of information that I have already put to immediate use!) Anthropology is at its best when, as in this book, it can broaden and deepen our understanding of such relevant and poignant social issues as school-age pregnancy, offer practical suggestions for positive response, and pinpoint the most important questions that will stimulate further much-needed research.