The Evolution of Marriage

COMMENTARY Marriage and Family

The Evolution of Marriage

May 17, 2014 8 min read

Former Visiting Fellow, DeVos Center

Ryan T. Anderson, Ph.D., researches and writes about marriage, bioethics, religious liberty, and political philosophy.

‘A girl for every boy, a boy for every girl”: That’s the main thesis of William Tucker’s engaging new book. With polygamy, you see, there isn’t a girl for every boy, and the leftover boys must find some other — usually disruptive and frequently violent — way to pass their time. But the “unique social contract of monogamy — a male for every female, a female for every male — lowers the temperature of sexual competition and frees its members to work together in cooperation. It is at this juncture that human societies — even human civilizations — are born.”

Tucker is not himself an academic, but he is a smart journalist, and Marriage and Civilization: How Monogamy Made Us Human is the result of some 20 years of reading through the scholarly literature on marriage and thinking through the implications. It’s written for “the average reader,” and covers some “subjects that many scholars and academics in the field seem to find uncomfortable.” Indeed, Tucker comes to some rather politically incorrect views. His work is a clear-headed presentation of a “biological, anthropological, and historic understanding of the role that monogamy has played in the evolution of human society” — and by monogamy Tucker doesn’t simply mean any old union of two people, but an exclusive and more or less permanent union of a man and woman, husband and wife, father and mother.

Monogamy so understood doesn’t happen by chance. In a certain sense, “human monogamy — the pair-bonding of couples within the framework of a larger social group — is not entirely a natural institution.” After all, “monogamy does not sustain itself ‘naturally.’” And yet, when monogamy is lived out, human civilization flourishes. As Tucker puts it, “The rule is: those who form traditional families succeed; those who don’t fail.”

Because monogamy doesn’t grow on trees, “it requires rules — rules that must be continuously enforced by the members practicing it.” So, while “monogamy is manifestly a more equitable and successful way to organize a society, it is always under siege and forever fragile.” And if a society “becomes lax or indifferent about upholding its norms, the advantages will quickly unravel — as we are plainly witnessing in the America of today.”

Yet this isn’t what we witnessed in the America of mid-century. Men and women paired off, raised children as a unit, and more or less stuck together for life. To give just one statistic: Throughout the 1940s, ’50s, and early ’60s, percentages of births to unwed mothers were in the single digits. As Tucker notes, “the phenomenon of ‘single motherhood’ was virtually unknown.” In 1965, when the Moynihan Report was issued, the concern was that the out-of-wedlock birth rate for blacks was 25 percent. Today 40 percent of all children, 50 percent of Hispanics, and 70 percent of African Americans are born outside of marriage.

And this breakdown of marriage most hurts the least well-off. A leading indicator of whether someone will know poverty or prosperity is whether, growing up, he or she knew the love and security of having a married mother and father. Marriage reduces the probability of child poverty by 80 percent. The reason is simple: Marriage attaches a child’s father to his mother, and then attaches that committed pair to the child. As Tucker notes: “Children without fathers are more at risk for drug and alcohol abuse, dropping out of school, depression, delinquent behavior, crime, early sexual activity, and having illegitimate children in the next generation. They are more at risk for abuse, molestation, and incest.”

“The art of fatherhood,” however, “does not come naturally but is a skill that must be passed on from generation to generation.” Citing the work of Charles Murray, Tucker points out that the upper class is still enforcing and living by the rules of social monogamy, while the lower and middle classes are taught “the message that marriage doesn’t matter, that illegitimacy is no big deal, and that there is nothing wrong with being on the public dole.”

Yet the bulk of Tucker’s book is concerned not with these contemporary issues, but with the deep biological roots of monogamy. Unfortunately his presentation of the literature isn’t as clear as it could be, as he tells a historical story of the academic study of these origins without clearly presenting which theories stand the test of time and which were passing fads that we must reject. Still, he tells an interesting story of how “polymorphous polygamy” in chimpanzee communities — a form of “sexual communism” where “every male gets to mate with every female” — transformed into human monogamy. Tucker discusses theories that argue that, without monogamy, “the evolution of the human brain would not have been possible,” and that various biological factors affecting fitness for survival of the group as a whole led to pair-bonding. Evolution, Tucker writes, isn’t so much a matter of “Kill or Be Killed” as of “Be Fruitful and Multiply.”

The idea is that high-status males are the big winners of polygamy, but an alpha male who mates exclusively with an alpha female gets assurance that she’ll bear his — and only his — offspring, and she gets assurance that he’ll stick around for the long haul to help raise the child and protect her from aggressors. The same is then true for the beta male and beta female, and gamma, “and so on down the line — much the way it happens in high school.” Monogamy is a form of what game theorists call “Nash equilibrium”: It does not maximize the outcome for each and every individual, but it does “optimize everyone’s individual outcome in a way that maintains the integrity of the entire society.” And, more specifically, “monogamy usually emerges only where the demands of the environment require special care and protection for the young.”

This requires, of course, sexual restraint and the rules that make monogamy and fidelity possible. Tucker observes that humans have devised the “universal fig leaf,” as “social monogamy requires that some parts of our personalities remain forever hidden from the public.” After all, “every human society has created some form of marriage” that “requires the couple to pledge their fidelity to each other” and “also draws a line between the bonded pair and the group.” This is radically different from, for example, the behavior of the bonobos, who engage in sex as casually as humans shake hands. But “bonobos have remained chimpanzees. We evolved into something different. It is our sexual repressions that have made us human.”

Tucker goes through human history at blazing speed, and not just Western and Christian history: He also discusses monogamy in India and China, and polygamy in Mormonism and Islam. On Mormonism and Islam, I fear he moves too quickly and paints with too broad a brush, especially as he tries to defend “the link between polygamy and violence.” It is also a shame that the book moves from the founding of Rome to the French Revolution with only six pages on Christianity’s influence on monogamy — a chapter without a single reference to Augustine or Aquinas — even while Tucker argues that “Christianity played the crucial role in making monogamy the norm in Western society.”

One topic that receives relatively little discussion is that of redefining marriage to include same-sex relationships. “From an evolutionary standpoint, gay marriage is a non-starter,” he states. “It is only a few decades old and has played no part in evolutionary or human history.” Tucker takes no position in this book on same-sex marriage, but cautions those who do support it: Given the importance of social rules for sustaining social monogamy, he insists that “supporters of same-sex marriage draw a stark line . . . between acceptance of gay marriage and acceptance of an ‘anything-goes’ attitude toward marriage, which says that it makes no difference whether people tie the knot or live in sin, whether they marry a man and a woman or marry two wives or three wives.”

Sadly, though, some of the push for redefining marriage has taken place precisely under the guise of an anything-goes attitude. For example, a 2011 New York Times profile of gay activist Dan Savage, headlined “Married, with Infidelities,” introduced Americans to the term “monogamish” — relationships where partners would allow sexual infidelity provided they were honest about it. The article explained: “Savage says a more flexible attitude within marriage may be just what the straight community needs.” The story added that sexual exclusivity “gives people unrealistic expectations of themselves and their partners.”

Rather than striving for faithfulness to one spouse, some advocates argue for allowing marriage to be sexually open. And if marriage can be redefined to be sexually open, why should it be limited to two people in the first place? The liberal online journal Salon in August 2013 posted a woman’s account of her shared life with a husband, boyfriend, and daughter under the headline “My Two Husbands.” The subhead: “Everyone wants to know how my polyamorous family works. You’d be surprised how normal we really are.”

A certain type of polyamorous relationship has even motivated advocates to create the word “throuple,” which is similar to “couple” but with three people. The word appeared in a 2012 article in New York magazine that described a specific “throuple” this way: “Their throuplehood is more or less a permanent domestic arrangement. The three men work together, raise dogs together, sleep together, miss one another, collect art together, travel together, bring each other glasses of water, and, in general, exemplify a modern, adult relationship.”

If it’s sexually open, and if it has multiple partners, why should marriage be permanent? An August 2013 op-ed in the Washington Post introduced the word “wedlease,” as the author wondered why marriage should be permanent when so little else in life is. Why not have temporary marriage licenses, as with other contracts? “Why don’t we borrow from real estate and create a marital lease?” the author wrote. “Instead of wedlock, a ‘wedlease.’” He continues: “Here’s how a marital lease could work: Two people commit themselves to marriage for a period of years — one year, five years, ten years, whatever term suits them. The marital lease could be renewed at the end of the term however many times a couple likes. . . . The messiness of divorce is avoided and the end can be as simple as vacating a rental unit.”

Whatever one thinks about the morality of sexually open marriages, multi-partner marriages, and by-design-temporary marriages, the social costs will run high. The marital norms of monogamy, sexual exclusivity, and permanency make a difference for society. These new words and the reality they reflect undermine public understanding of what marriage is and why it matters for society.

At its most basic level, marriage is about attaching a man and a woman to each other as husband and wife to be father and mother to any children their sexual union produces. When a baby is born, there is always a mother nearby: That is a fact of reproductive biology. The question is whether a father will be involved in the life of that child and, if so, for how long. Marriage increases the odds that a man will be committed both to the children that he helps create and to the woman with whom he does so.

Marriage, rightly understood, brings together the two halves of humanity (male and female) in a monogamous relationship. Husband and wife pledge to each other to be faithful by vows of permanence and exclusivity. Marriage provides children with a relationship with the man and the woman who made them.

If a man does not commit to a woman in a permanent and exclusive relationship, the likelihood of creating fatherless children and fragmented families increases. The more sexual partners a man has, and the shorter-lived those relationships are, the greater the chance he creates children with multiple women. When his attention and resources are thus divided, a long line of consequences unfolds for both mother and child, and for society as a whole.

Tucker closes the book by posing a question: Will we honor marriage or will we create a “kind of ‘state polygamy’ where women congregate around the major source of wealth — the government — while men slink off into their separate quarters to pursue a fading warrior culture — played out this time on video games”? Will we honor the most noble aspect of human nature — one that doesn’t come “naturally” but requires work and rules to make us flourish?

In short, will we insist on the ideal of a girl for every boy, a boy for every girl — and a mother and father for every child?

 - Ryan T. Anderson is the William E. Simon Fellow at the Heritage Foundation.

Originally appeared in National Review