top of page
Writer's pictureAdrianna Xue

Sex at Dawn Book Review

Sex At Dawn: How We Mate, Why We Stray, and What it Means for Modern Relationships


Authors: Christopher Ryan, Ph.D., and Cacilda Jethá, M.D.

Year Published: 2012

Main topics Covered: Human Sexuality, Evolution, Anthropology, Monogamy/Polyamory.

Written for: All Genders, All Sexual Orientations, Poly-Couples, Poly-Curious

Recommended for: Clinicians/Therapists and Clients

Perspectives taken: Heteronormative, Sex Positive, Opposition of the Standard Narrative

Type of Resource: Informative anthropological book on human sexuality

APA Citation: Ryan, C., & Jetha, C. (2012). Sex at Dawn: How we mate, why we stray, and what it means for modern relationships. New York: HarperPerennial. Print.


Book Overview:

Sex at Dawn is a captivating book that redefines the traditional meanings of “mating”, “love”, and “marriage”. Ryan and Jethá urge the reader to consider human sexuality in a completely new perspective. By challenging the standard narrative, Darwin’s evolutionary theory, and even pair bonding itself, the reader is able to see how the human being’s biological, anthropological, and cultural roots have been shaped by societal influence since the beginning of time. As the authors put it, “But with trust we strive to accept what we cannot understand”- perhaps what we have been taught to perceive as “natural” is, not so natural after all.


Sex at Dawn begins by presenting the well known narrative - that is, the female mates with the male for his resources, and the male mates with the female for optimal offspring. This implicates that we are engineered to care for offspring in a pair-bond family. The female is supposedly sexually coy to entice the male, while the male imposes monogamy to ensure paternity certainty (that his resources and investments are, indeed, going towards his own biological offspring). Under this assumption, there is reason to believe that males and females have conflicting agendas based on sexual selection but that monogamy is a key component. However by shifting gears and examining our ancestral roots (primitive relatives and alternative cultures) that authors show that monogamy is not so common after all. The book presents thriving matriarchal societies where paternity is unimportant. In fact, the authors present many collectivistic societies where uncles of the child or entire villages share resources to raise offspring.


Ryan and Jethá go a step further in this process and compare our anatomies to primate relatives, through the analysis of many species. By doing this they show that homosapien monogamy is socially constructed. They proclaim that it was with the rise of agriculture, property ownership, and capitalism that drove our need to consider our partners as “ours”. Marriage therefore, would be the cementing block that solidifies our ownership and resources, and does not align with biological human development. The evidence the authors present for this standpoint is astounding and plentiful, however it is impossible to summarize without delving deep into the book.


Another interesting argument Ryan and Jethá put forward is one that challenges the idea of the coy female. Evolutionists assert that the female must conceal her ovulation, and hide her sexuality to entice the male for security. However, by looking at the male and female body anatomically and physiologically (body size dimorphism, sperm competition theory, human testicular size and volume etc), one is able to see that the female is designed to hold multiple mates and seminal loads. Further evidence, such as female copulatory vocalization, the female orgasm, the structure of the reproductive tract, and erotic plasticity, all suggest evidence that the woman, just like the man, is evolved to be highly sexual- and flaunt it proudly. Not so coy after all.


One drawback that could be noted when reading Ryan and Jethá’s work, is that their arguments are founded on purposeful anatomical evolution and the practicality of the body to prove we are inherently poly, insinuating that looking at our past design should highlight how we are meant to live today. However the human body has evolved, developed and changed to meet our needs for this moment in time (i.e. tailbone, wisdom teeth, appendix etc). Another critique that could be made is the books heteronormativity. Sex at Dawn offers examples based on the assumption of heterosexual relationships. However, this gap is acknowledged in the last section of the book, taking a closer look at contemporary research that is gender and orientation-inclusive, revealing current trends in motivations for sex and arousal.


The authors end the book by acknowledging the evolution of the unconventionality of modern relationships. Whether the reader agrees with the author or not, this controversial book acknowledges that humans have multiple reproduction strategies, and human sexuality is, inherently, multidimensional. With light humour and thought provoking arguments, this book is sure to challenge the ‘normality’ of our ancient roots in regards to human sexuality.


About the Authors:


Christopher Ryan received a BA in English and American literature in 1984 and an MA and Ph.D. in psychology from Saybrook University, in San Francisco, CA twenty years later. Drawing upon his multi-cultural experience, Christopher’s research focused on trying to distinguish the human from the cultural. His doctoral dissertation analyzes the prehistoric roots of human sexuality, and was guided by the world-renowned psychologist, Stanley Krippner.


Cacilda Jethá was born in Mozambique to a family that had immigrated two generations earlier from Goa, India. As a child, she fled civil war to Portugal, where she received most of her education and medical training before returning to Mozambique in the late 1980s. Cacilda also conducted research (funded by the World Health Organization) on the sexual behavior of rural Mozambicans in order to help design more effective AIDS prevention efforts. After almost a decade in Mozambique, Cacilda returned to Portugal, where she completed her medical residency training in both psychiatry (at the prestigious Hospital de Julio de Matos in Lisbon) and occupational medicine.


Written by Westland Researcher Adrianna Xue

bottom of page