Promiscuity Is for The Birds


Mark Ryan and Carole Hausmann Ryan

Article ID:



Aug 4, 2023


Jun 9, 2009

This review first appeared in the Christian Research Journal, volume 24, number 3 (2002). For more information about the Christian Research Journal, click here.


Summary Critique of
The Myth of Monogamy:
Fidelity and Infidelity in Animals and People
David P. Barash, Ph.D., and Judith Eve Lipton, M.D.

Did you know that monogamy has been reported as the primary behavior for only 10 to 15 percent of all primate species and for only three percent of mammals? Did you know that monogamy in birds has traditionally been reported at better than 90 percent, but that recent DNA research has revealed a very different picture of the avian world? Basing their study on the assumption that the Darwinian evolutionary theory is true, as well as selected case studies of animal sexual behavior, authors David Barash and Judith Lipton insist that “aspiring monogamists are going against some of the deepest-seated evolutionary inclinations with which biology has endowed most creatures, Homo Sapiens included” (p. 1). They emphasize current studies of bird behavior as most informative to human behavior because, of all animals, birds and humans are generally more inclined toward monogamy and because in each both parents are involved in raising their young (4).

The Myth of Monogamy is coauthored by a husband and wife team: David P. Barash, Ph.D., received his doctorate in zoology and is currently professor of psychology at the University of Washington in Seattle. Judith Eve Lipton, M.D., is a psychiatrist. They delight in shattering ideas previously held concerning monogamy within the animal kingdom. Their book is bound to become assigned reading in human sexuality classes.

The authors say their interest is in finding commonality of patterns that provide “powerful evidence that human beings are not ‘naturally’ monogamous, as well as proof that many animals, once thought to be monogamous, are not” (1). Citing the remarkable variety of sexual and social behavior in the animal kingdom, they state, “It isn’t at all clear which is most ‘relevant’ to human beings” (4). They consistently, however, appeal to certain animal case histories when making comparisons to human beings, paying attention mainly to evidence that seems to support their thesis and ignoring evidence that does not. They also use controversial evidence to support some of their main contentions.

One of their most strident points is that animals engage in what they designate as “EPCs” because of sperm competition. (“EPC stands for extra-pair copulation, which simply means a copulation in which at least one participant is already socially mated to someone else.” 14). According to the paradigm of natural selection, biological success and failure is seen in terms of the number of children successfully born and raised. Males and females therefore engage in EPCs as an unconscious biological strategy in which more than one male competes to fertilize a female’s egg (123).

Sperm competition (“essentially another way of saying nonmonogamy,” 5) is well documented in various species of animals. When they apply this premise to human beings, however, their primary documentation comes from British biologists Robin Baker and Mark Bellis, two controversial researchers whose conclusions have been attacked as being inadequately supported by the data (161). They nevertheless use Baker and Bellis’s work to buttress their contention that humans engage in a lot more sex than is needed for reproduction because of sperm competition among males. The problem, as they themselves admit, is that contrary evidence may indicate that sperm competition is less important in the animal kingdom as a whole than they want to concede. Even the (frequently cited) research among chimpanzees, one of the most sexually active species known, is inconclusive in this area (169). The authors should heed their own warning that in science, as in other disciplines, the temptation is to sensationalize, overgeneralize, and ignore contrary evidence (169).

The authors briefly summarize evidence and theories contrary to their own, notably those of biologist Alexander Harcourt, who postulates that sperm competition involves individuals struggling toward a goal (fertilization) rather than competing with each other (170). (They give Harcourt less than one-tenth the space they reserve for the contested conclusions of Baker and Bellis.) Harcourt’s view fits much better with what is known about human reproductive anatomy. For example, the antisperm defenses in the female reproductive tract (in humans and other animals) ensure that only the healthiest sperm fertilize the egg, and “if a man produces ‘only’ 50 million sperm per ejaculation, he is generally considered sterile” (60). The authors assume that females (humans and otherwise) “create” a genital environment where sperm from various males compete (81–84). While this is observably true in other species (though certainly not all species), it is far from certain in human beings; rather, Harcourt’s and others’ contention of a “scramble competition” (170) among the individual male’s sperm better fits the evidence.

The authors’ overriding interest in “proving” sperm competition among human males leads to highly questionable suggestions regarding human behavior in related areas. For example, they argue that ovulation is secretive and hidden in women because women on an unconscious biological level are keeping their options open to encourage sperm competition among competing males (173). They also return to the questionable research and highly speculative conclusions of Baker and Bellis, noting “that women have a fully evolved unconscious preference for EPCs precisely when their fertility is highest, for much the same reasons that other species often engage in similar activities: to be inseminated by the best males and to encourage sperm competition among sexual partners” (173). While women’s increased sexual arousal during ovulation is well known, these speculations are unhelpful and unnecessary since it makes perfect biological sense for a woman’s body to indicate an increased desire for sex while it is fertile. The point again, biologically, is fertilization by the “best” sperm (i.e., most active and hence, hopefully, most healthy — though this is not guaranteed), not insemination by the “best males.”

Their speculations about other related human behaviors are even more fanciful. For example, they suggest that the preoccupation of many human males with pornography may be related to sperm competition: “On a primitive, biological level, pornographic images may activate the same system that prehistorically enabled men to respond to the dictates of sperm competition: If ‘your’ woman may recently have been having sex with someone else, you would be well advised to have sex with her, too, and right away!” (171). These authors apparently have succumbed to a tendency they themselves cite, namely, “that even in such a seemingly hard-headed pursuit as science, believing is seeing. More to the point, not believing is not seeing” (13).

Their definition of “myth” is much less clear and sophisticated than their discussion of biology. They state that the traditional view of monogamy in birds is “more myth than reality” (4), defining “myth” as a belief that is not in accordance with actual fact or reality. More telling is their critical citation of Jesus: “When Jesus famously observed that to lust after another is to commit adultery in one’s heart, he echoed and reinforced the myth of monogamy — the often unspoken assertion that even desire-at-a-distance is not only wrong, but a uniquely human sin” (2).

The authors’ anti-Christian bias leads to distortions in their interpretation of history and of biblical texts. Interestingly, Jesus does not show up again in their analysis until the last chapter of the book, where they conclude that even in the face of overwhelming evidence that monogamy is not “natural” to human beings, it is for many reasons preferable to our more natural inclinations. The authors see the beginnings of the Christian repression of sex in the words of Jesus in the Sermon on the Mount: “I tell you that anyone who looks on a woman lustfully has already committed adultery with her in his heart” (Matt. 5:28). Citing a development in the Western church that elevated chastity over marriage, they attribute this negative view of marriage and sexuality to St. Paul, quoting his words in 1 Corinthians 7:1–2: “It is good for a man not to touch a woman, nevertheless to avoid fornication let each man have his own wife and let each woman have her husband” (182). The views of Jesus and Paul, according to them, are “consistent with the fact that Christianity has historically taken a dim view sex generally” (182). Meanwhile, they approvingly quote Bertrand Russell in Marriage and Morals, saying, “the Christian view that all intercourse outside of marriage is immoral was…based upon the view that all sexual intercourse even within marriage is regrettable. A view of this sort which goes against biological facts can only be regarded by sane people as morbid aberration” (182).

The authors think the Old Testament is much more honest about sex, citing the many wives of David and Solomon. The authors neglect to notice that Jesus and Paul were Jews whose Bible was the Old Testament. Their views on sexuality were informed by Jewish biblical thought, which (as the authors point out) celebrates the material world and sexual intercourse within marriage (though condemning intercourse outside of marriage).

Jesus’ words in the Sermon on the Mount have nothing whatsoever to do with “a dim view of sex.” Rather, he is identifying the true source of human sinful behavior (including, in this case, adultery) as originating in the thoughts and intentions of the heart.

Likewise, if they had looked more deeply into Paul’s words in the passage they quote, they would have seen that Paul was answering specific questions posed by the Corinthians about marriage. Given the “present crisis” (Christians were being driven from their homes, imprisoned, tortured, and even killed for their faith), Paul advises that they should remain as they were: if married, remain married; if single, remain single. Because of sexual temptation, however, they were free to marry. In fact, instead of being “antisexuality,” Paul advised married couples never to abstain from sex except by mutual consent in order to pray and fast together — and then only for a limited time (1 Cor. 7). Later distortions of this biblical view of sexuality arose in the church mainly through the influence of some theologians of the Greek viewpoint, which devalued the material world and exalted the world of spirit or ideas, promoting a false dichotomy between them.

Had the authors paid closer attention to the evidence, they would have seen that Russell’s conclusions are blatantly false. The Jewish and Christian view of the rightness of sex within marriage and the wrongness of sex outside of marriage is based upon both faiths’ taking seriously their Scriptures. They believe these to be the revelation of a holy, covenant-making God, who (as we read in the Scriptures) created us along with all animals but distinguished us by breathing His breath of life into us, thereby forming us (male and female) in His own image (Gen. 1–2). According to the biblical account, woman was made out of man as a “suitable companion” for him to take away his loneliness. The passage concludes, “For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh” (Gen. 2:18–24). Jesus cites this passage, stating Moses allowed divorce “because your hearts were hard,” but adding that, according to the creation account, God created male and female to remain together as husband and wife (Mark 10:4–12). It logically follows that this “hardness of heart” is also why polygamy was allowed. Human preoccupation with, and distortion of, their sexuality began in the Garden of Eden: before they disobeyed God, “the man and his wife were both naked, and they felt no shame” (Gen. 2:25). After they disobeyed God, their nakedness became an issue for them (Gen. 3).

This brings us to the heart of our objection to the approach taken in this book. Bound within the narrow confines of Darwinism, in its first six chapters The Myth of Monogamy insists on reducing all sexual conduct (human and otherwise) to inexorable natural selection. Given this, is it really possible for humans to maintain a monogamous relationship? In their final chapter the authors reply with an unequivocal yes; but to support their final contention that monogamy, while not “natural” to humans, is nonetheless a good thing, they are forced to turn to areas outside of biology to make their point.

Their myth of biological, cultural, and historical evolution fails them, and myth it is, whether one takes it in their sense, as an untruth or unreality, or in a sense more commonly used today, as a story of prehistory, an account of origins. According to this contemporary definition, every society needs its myth of origins in order to explain the why of things. In the past few centuries Western culture gradually abandoned the biblical “myth” of origins and replaced it with the Darwinian (and post-Darwinian) myth of evolution (we can substitute the term model for myth, as many would prefer to do). The model of evolution may go a long way toward explaining certain phenomena such as changes and development within species, but its usefulness ends there. Scientists put forth models or theories about phenomena and then examine the evidence to see which models or theories are best supported by the data; for example, the evidence our authors gather in support of monogamy in their final chapter. Our question is this: Does the evidence better fit the evolution model or the biblical creation model?

They make many excellent points in favor of monogamy, among them a treatment of historian Denis de Rougemont’s view on the conflict in the West between passion and marriage. Our social structure stands on marriage, which, quoting de Rougemont, “cannot be founded on a fine ardor” (185). We are reminded of Jesus and Paul’s words on marriage. Civilization is rather founded, in Freud’s words, “on the repression of the instincts,” but also, according to our authors, “on the ascendancy of law” — indeed on “plain old-fashioned honesty and integrity” (189). They make a fine case for the deeply biblical notions of self-control and the power of social prohibition to aid in self-control (189). Their treatment of human jealousy and outline of possible historical developments that allowed for the practice of polygamy (e.g., the creation of large landowners who could afford to support more than one wife) flies in the face of their evolution model and supports the biblical model. Even their treatment of the biology of creatures speaks volumes on the incredible variety and design of human and animal reproductive tracts and practices. Take, for example, the enormously complex chemical warfare in fruit flies (128–29), or the mystery of women’s orgasms — a phenomenon that is totally unnecessary and irrelevant according to the evolution model (172–73), but, in the biblical model, is a supreme gift of God, who created sexuality.

Their last paragraph is the most telling. They conclude, “Monogamy among animals is a matter of biology. So is monogamy among human beings. But in the human case, monogamy is more. It is also a matter of psychology, sociology, anthropology, economics, law, ethics, theology, literature…. Not to mention love, trust, hope, disillusionment, fear, anger…life, and death. And just about everything else” (191–92). The evolution model leaves room only for biology — and a limited biology at that. The authors are left with a reductionism that can explain human complexity only in terms of our huge brain (187). The biblical model gives us good biology — and everything else.

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