Mandrills are from Mars, Lemurs are
from Venus: Valentines Day in a Darwinian World
by Alex Hawes
Men and Women
Women and Men
It will never work
-Erica Jong
I think people should mate for life, like pigeons, or Catholics
-Woody Allen, Manhattan
Tis soon the season of red roses and dark chocolate, a time for declarations of undying love. Noble beasts, many Homo sapiens aspire to faithfulness til death do us part. But does this dedication come naturally? Consider an excerpt from a recent episode of The Oprah Winfrey Show, essential material for research into the human animal. Oprahs frequent guest, self-proclaimed relationship expert Iyanla Vanzant, spoke with men about their cheating hearts:
| OPRAH WINFREY: This is Ed here. He says that hes cheatingthat cheating on women is in his genes... IYANLA VANZANT: Is that true? Did you say that? ED: I did say that. VANZANT: Which gene? Do you mean gene or organ? (Laughter in the audience.) ED: Gene... VANZANT: Explain that. ED: Okay, I have a father who loved women. He had a lot of relationships. As a matter of fact, he had like twenty-seven different kids by different women. (Audience hisses.) VANZANT: Dont judge his daddy. You do not know his daddy. Hush your mouth... ED: I didnt know my father either. What happened was... VANZANT: (interrupting) Howd you know he had all them women? ED: II learned this later on. I finally met him in my twenties. He separated from my mom when I was a little kid... VANZANT: Why do you cheat? ED: ...Its not really cheating. Itsyou knowI, I, I like beautiful women. VANZANT: I like grits, I dont eat them every day. WINFREY: I do too. VANZANT: I love grits... ED: There isthere is a major difference between grits and women, okay. VANZANT: I wouldnt know that. ED: Oh, I know. |
Like Ed, some of evolutionary biologys fiercest scientific advocates scoff at the notion of monogamy. Men, they say, are born promiscuous. Guys seek variety, gals dedicationor so the theory goes. The man on the street may find comfort in this hypothesis, that the hand of evolution blindly molded his wandering eyes. Women roll their eyes at such self-serving sentiment.
Ever since females got stuck with the egg, males have had the opportunity to shirk parental obligations and spousal loyalty. This is our legacy as animals. Yet it may not be our only legacy. Behavioral studies on primate sex roles have flourished in the last 25 years, gradually painting a more complex portrait of female strategies. Not only has this evidence finally brought the female half into models explaining hominid evolution, it has broadened the range of choices considered natural for modern humans as a whole. Paternal care and monogamy too can bring Darwinian benefits to males and their offspring, recent behavioral studies suggest. Monogamous marriage may not be a biological aberration after all.
In his 1871 book The Descent of Man and Selection in Relation to Sex, Charles Darwin declared that the rules of natural selection, which serve flowers and finches, apply equally to humans. Man, Darwin found, is no different from a peacock; he struts his hour on the stage for the chicks. Darwin marveled at the adaptations evolved through the male animals struggle for access to females. But he never considered the costs.
Evolutionary biologists reduce sex to simple math. The sum total of biological existence equates with a single variable, reproductive successthe number of genes (bound up in packets we call babies) that one leaves to posterity. A males reproductive success can potentially vary far more than a females. Male animals, after all, can spread their numerous seeds far and wide, while females can produce only one expensive eggand thus one litterat a time. Whereas one Moroccan emperor is said to have fathered 888 children, few women can bear more than a dozen children in their lifetime.
But polygamy (or polygyny, the more specific term denoting one male having several female mates) can have its drawbacks. Polygyny introduces risk, in essence, raising the stakes. Assuming the typical 50:50 sex ratios of most mammals, if one male has four mates, three males have none.
Animals dont normally accept celibacyevolutionary failureeasily. Many male animals, from stag beetles to elephant seals, expend valuable energy testing one another in battle. Male Irish elk wielded 12-foot-wide, 100-pound antlers, which likely served to intimidate other males and to impress prospective mates. Their fossilized antlers now decorate the mantles of Europes castles and country manors, for the Irish elk went extinct 11,000 years ago.
The elks racks, it is believed, simply became too large. Struggling to nourish their mineral-hungry antlers and navigate those massive appendages through the dense forest, the overburdened males couldnt survive long enough for their antlers to fulfill their purpose of vanquishing rivals and winning mates. Steroid-pumped weightlifters and silicone-inflated swimsuit models should heed the Irish elks lesson: Vanitys arms race can escalate to the point of tragedy.
Hoggamus, higgamus
Men are polygamous
Higgamus, hoggamus
Women are monogamous
-Attributed to William James
Many feminists view Darwinian theories on sex with skepticism, or bile. Feminist theory often cloaks male dominance in terms of power, denying that significant biological differences exist between men and women. So-called "Darwinian feminists," like Sarah Blaffer Hrdy of the University of California-Davis and Meredith Small of Cornell University, have taken another tack. Natural selection does shape human behavior, they say. But it emboldens women as much as men, and in ways that would surprise many testosterone-obsessed theorists.
The new thinking of Darwinian feminists was not entirely original. A short four years after Darwin published The Descent of Man, Antoinette Brown Blackwell politely questioned the authors objectivity in her own book, The Sexes throughout Nature. Blackwell admitted that Darwin had elegantly traced the evolution of masculine traits, like a peacocks rainbow of feathers or a mandrills protruding canines. "But he seems never to have looked to see whether or not the females had developed equivalent feminine characters," she remarked.
Blackwells critique went largely unnoticed for decades. Indeed, throughout the past century, the female animal time and again has been described as passive, even coy, in popular magazines and academic journals alike. The scientific basis for these presentations, however, has been stretched thin to cover preconceived notions of gender.
The study of behavior, whether that of furry monkeys or naked apes, suffers from one fatal flaw: observer bias. Researchers in the field admit to "physics envy"jealousy over hard sciences nanometer-thin precision. Behaviorists cant escape the demons of subjectivity.
Take your average cop. According to one study, police officers using radar flag male drivers 50 percent more often than female drivers. Yet when officers judge speeding with the naked eye, they pull over men 250 percent more often, the valid trend becoming quintupled through stereotyping.
Now consider your noble primatologist, lying on her back in the leech-infested underbrush of some festering jungle. Her binoculars are getting increasingly heavy to hold, the crick in her neck ever sharper, as she strains to discern the soap opera playing out in the branches 50 feet above. Suddenly, a monkey snatches a fig from another, driving the subordinate away. But was that Charlene or Charlie taking flight? It had Charlies ear tuft, butnohed never get driven off like that. The researcher pencils a notch down for Charlene in the column "submissive behavior," and the encounter becomes further grist for the statistical mill. Yet it was Charlie who dashed off, tail between his legs.
Subconscious preconceptions can snowball into erroneous theories with unwarranted outcomesas you may well explain to the traffic judge next time. Darwinian feminists scrutinize sex research for such subtle biases. No challenge delights them more than the assumption of female passivity.
Primatologist Sarah Blaffer Hrdy revived Antoinette Brown Blackwells century-old critique in her landmark book, The Woman Who Never Evolved, published in 1981. Hrdy too challenged Darwins assumptions. But now she had supporting evidence from long-term studies of primates and other animals. Doing the fairer sex a disservice perhaps, Hrdy showed that female primates can be just as domineering, back-stabbing, and philandering as males.
To understand monogamys place in human evolution, primatologists have sought out clues from our closest relations, monkeys and apes. The study of primates began, logically enough, where we hominids evolved: the plains of East Africa. There, large troops dominated by alpha malesbaboons being the most well-known and well-studied examplerepresent the norm. The savannas long vistas allowed for easy behavioral observation by the early primatologists of the 1950s and 60s. Those same clear views allow dominant male animals to monitor their mates and rivals efficiently, making polygyny worth the initial fight for control.
But as the primatological record has become more complete, researchers have discovered a wealth of other social systems. Taken broadly, the female primate can be "dominant, subordinate, equal, or not interested," writes Hrdy.
On one extreme, some species interact only when absolutely necessary: when mating. Even among the generally gregarious great apes, one speciesthe orang utanflies solo. The immense, shaggy male, by virtue of size, has a hard time maneuvering through the trees; he sticks instead to the ground, encountering females only when looking to mate. And it is only in the orang utan, this unusually asocial primate, that forced mating is commonly observed. Rape, we should take comfort knowing, is not at all a requisite of primate life.
Sex roles can flip in primates too. In a few rare instances, females themselves rule the roost. Nowhere is this trait more common than on the island of Madagascar, where female lemurs reign supreme. Ring-tailed lemur females assert their preeminence aggressively, driving males away from cherished fruits and tamarind pods. Female sifaka lemurs, however, dominate without a fight. Why? Sifaka females give birth during the dry season, when little food is available. Pregnancy and the ensuing demands of lactation push lemur mothers to the nutritional edge. Male sifakas, scientists speculate, defer peacefully so that their matesand, more importantly, their potential offspringmight survive.
In species where females suffer fewer ecological hardships, males can get away with less chivalry. But even in species characterized by female harems, such as mandrills and gorillas, male dominance doesnt mean absolute control. Females play the field, sneaking off for a tumble in the jungle with peripheral males. In chimpanzees, whose troops include multiple adults of both sexes, females disappear for days at a time. Genetic fingerprinting shows that more than 50 percent of chimps are fathered by males outside the troop.
That Moroccan emperor may have thought all those 888 children were his, but how many of his concubines were sneaking away to the pantry to cavort with the dapper prince? Ambiguous paternity elicits wider male support for a female and her infantfrom the alpha male shes mated with publicly, and from any pretenders to the throne shes mated with surreptitiously.
Mating offers more than just a means of reproduction; sexual activity can stimulate group cohesion too. The bonobo (also known as the pygmy chimpanzee) takes promiscuity to the extreme. For bonobos, sex is a way of life, their version of the handshake. Bonobo researcher Frans de Waal estimates that 75 percent of bonobo sex has nothing to do with reproductiontheres sex between males, between females, between juveniles, often to reduce tension over food competition. Compared with the oft-barbarous common chimpanzee, there is little violence in bonobo societies.
Social roles in bonobos diverge sharply from those of their chimp cousins in many other ways. Bonobo malesup against a united sisterhoodhave little power over females; chimp males dominate ruthlessly, to the point of seizing and killing infants that arent theirs. The two species both share nearly 99 percent of our genes. We have no greater genetic relationship to either, no evolutionary obligation to follow one system over the other.
Or to follow either.
Anyone who even for a moment thinks that what is natual is neccessarily desirable has only to remember that 90 percent of all species that ever evolved are now extict-- through natural processes... But the same perspective also lends an element of heroism and larger purpose to missions with aspire,despite the odds, to literally
change the rules of existance
-Sarah Blaffer Hardy
Romantics may believe in monogamous marriage in principle. Whether spousal dedication runs deep in our DNA coils, however, remains less clear. While common in birds, monogamy is rare in mammals. But exceptions prove instructive, so consider this: Among our mammalian brethren, the primate order contains more monogamous species than any other.
Monogamy represents an exercise in mutual self-interest: If a males offspring can survive only with his parental support, hes better off staying put. Helping ones genes survive, after all, matters just as much as spreading them. Females, in turn, should welcome the extra help of a faithful mate. Furthermore, monogamy offers an efficient means of reducing competition over food. A large group of unrelated animals tends to waste energy fighting amongst itself for access to food; monogamous family units have the advantage not only of smaller size, but of mutual self-interest.
While considered merely adaptive in evolutionary biologys cold calculus, primate marriages can warm a primatologists heart. Researchers have witnessed titi monkey partners tying the knotliterallyas mates huddle together on a branch, tails entwined. Indri lemurs, ghostly black-and-white primates with haunting yellow eyes, get hitched too. The male indri, a true gentleman, defers to his mate and child while feeding, allowing them their choice of the finest fruits and flowers. And theres our swinging ape cousins, the gibbons, whose partners sing siren-like duets at dawn to announce their family territory to the world.
Monogamy offers us hominids a solution to that eternal challenge: child-care. Human babies are among the most dependent of any primate infant, a side-effect of our evolved intelligence and erect posture. With expanded skulls requiring passage through birth canals narrowed by our bipedal anatomy, brainy babies must leave the womb at an earlier developmental stage than our primate cousins. Even after nine months, we enter the world premature.
Because human babies require constant nurturing over a prolonged period of infancy and childhood, a second provider and protectorthe fathercan help ensure his offsprings survival to maturity. While paternity in polygynous species remains uncertain, and fatherly behavior rare, the monogamous man knows his parenting efforts arent for naughtprovided, of course, his partner has been faithful too.
Dedicated mates produce healthier babies, healthier packages of DNA. Monogamy can win Darwins game.
Yet just when it looked safe, a new field of studyevolutionary psychologyhas emerged, bent on dividing the sexes again.
This amorphous field, which claims pieces of anthropology, biology, and psychology, has guided Darwinian theory to its logical conclusion: explaining how and why we think. Old habits dont die, and the preconceptions of gender have reemerged in evolutionary psychology. Psychologist Steven Pinker, a pioneer in the field, has pronounced the male brain kinky, the female brain clingy.
Pinker and other proponents of evolutionary psychology argue that the biology of the brain directs that more nebulous construct, the mind. Social roles emerge from our subconscious. The theory predicts that women will choose mates with the highest levels of testosterone (the muscle-men and masters of the corporate universe), while mens brains will turn on to the sight of ideal female traits (hourglass figures, bee-stung lips, full breasts)characteristics that hypothetically help ones partner survive, and in turn produce and provide for healthy children.
Primate studies, however, tell us that no single sex-role scheme prevails. Evolution through natural selection involves occasional mutationschanges to the gene pool offering novel solutions to lifes challenges. Social systems evolve through variation too.
Be faithful or dont be, its ultimately your choice. Like orang utans, we humans can lead lives of silent solitude, passing each other like ships in the night. We can hop from bed to bed like bonobos, our childrens paternity verified only through DNA analysis.
Or we can mimic the true romantics. Like gibbons we can sing sunrise duets, broadcasting our mutual devotion across the jungle canopy. Like titi monkeys we can snuggle, sitting in a tree-- K-I-S-S-I-N-G.
Alex Hawes, Associate Editor of ZooGoer, will tie the knot this summer with his lovely bride-to-be, Rachel.
ZooGoer 29(1) 2000. Copyright 2000 Friends of the National Zoo. All rights reserved.
