Cover; Battle of the Sexes; Exclusive Online Issues; by Staff Editor; 1 Page(s)

Table of Contents; Battle of the Sexes; Exclusive Online Issues; by Staff Editor; 1 Page(s)

In Brief; Battle of the Sexes; Exclusive Online Issues; by Kate Wong, Greg Mone, Sarah Graham, Michael Schirber, JR Minkel, Kristin Leutwyler; 6 Page(s)

Sometimes it pays to be a wimp--at least if you're a male cockroach. According to a study of the Tanzanian roach Nauphoeta cinerea published in the March 7, 2001 Proceedings of the Royal Society, females prefer low-ranking males to dominant ones any day. Trysts with weaklings, it seems, leave the females roaches in better shape than do encounters with more aggressive males. Yet when females do land a wimp (the high-ranking males do their best to thwart these couplings), they produce fewer sons. This, Allen Moore of the University of Manchester and his colleagues suggest, is the cost of the females' opting for safer sex.

Roaches aren't the only creatures in which females choose subordinate males. Previous studies have documented this preference in about a dozen species, including certain birds and salamanders. Exactly why the female roaches have fewer sons as a result of this choice, however, is a mystery. Paradoxically, producing fewer sons might actually maximize reproductive fitness: with fewer males in the next generation, the sons of these females with eyes for wimps might be more successful in themselves finding mates.

Mating Strategies in Butterflies; Battle of the Sexes; Exclusive Online Issues; by Ronald L. Rutowski; 5 Page(s)

As any postpubescent human knows, interest in potential mating partners is heavily influenced by sensory cues. A glimpse of lustrous hair or of piercing eyes can suddenly cause a man to be smitten with a woman, or she with him. The detection of a provocative scent or a sensuous touch may also kindle desire.

Grace Kelly's or Errol Flynn's obvious charms notwithstanding, an unbiased observer might find butterflies far more sensually appealing than humans. Perhaps unsurprisingly then, visual and other sensory cues also appear to govern these tiny creatures' decisions about mates. At stake is nothing less than the opportunity to produce offspring carrying an individual's genes through time.

How Females Choose Their Mates; Battle of the Sexes; Exclusive Online Issues; by Lee Alan Dugatkin and Jean-Guy J. Godin; 6 Page(s)

Picture a man who has a way with the ladies, and a character not unlike James Bond may spring to mind. He's clever, classy, fearless and flashy--characteristics that are almost universally appealing to the opposite sex. Throw in the powerful sports car, and you have a nearly irresistible combination.

That females often flock to the most ostentatious males is not a phenomenon unique to humans. In many different species, successful males--those that sire the most offspring--are often larger or more brightly colored or "show off" with more vigorous courtship displays.

Glandular Gifts; Battle of the Sexes; Exclusive Online Issues; by Darryl T. Gwynne; 3 Page(s)

In 1859, the year evolutionary theory burst onto the scene with the publication of Charles Darwin's On the Origin of Species, Captain John Feilner of the U.S. Cavalry was exploring northern California. He was eventually killed by Indians, but not before he had reported to the Smithsonian Institution his observations on the habits of grasshoppers. After the mating act, he noted, "a small bag--evidently the ovary--is attached to the body of the female close to the tail."

Almost half a century later, across the globe in France, pioneer ethologist Jean Henri Fabre filled in the details of this curious copulation. In The Life of the Grasshopper, a volume devoted to orthopteran insects in his Entomological Memories (Souvenirs entomologiques), Fabre correctly identified the bag as originating from the male. He wrote that an opalescent structure "similar in size and color to a mistletoe berry" was attached to the spermatophore, a separate sperm-filled package, and eaten by the female in a "final banquet" culminating the mating sequence.

Monogamy and the Prairie Vole; Battle of the Sexes; Exclusive Online Issues; by C. Sue Carter and Lowell L. Getz; 6 Page(s)

Observation of the mating and pup-rearing habits of nondescript, brown rodents that live under weeds and grasses might not seem an obvious way to improve knowledge of monogamy. After all, most humans can attest to the complexity of male-female relationships. Yet studies of the prairie vole (Microtus ochrogaster), a common pest throughout the midwestern U.S., have led us on a fascinating scientific journey from our starting point in ecology to the exploration of the neuroendocrinology of social bonds. Unlike most rodents, prairie voles form long-lasting pair bonds, and both parents share in raising their young. Our studies have provided a new understanding of the importance of two hormones, oxytocin and vasopressin, which are well known for their respective roles in reproduction and body water regulation. Work with voles now suggests that these hormones are involved in the development of monogamy.

The chief criterion that defines monogamy is a lifelong association between a male and a female. Within this broad definition lie several characteristics that are easily observed. Males and females of monogamous species tend to be about the same in size and appearance. Mated pairs will defend the nest and territory from intruders, and both parents care for the young. Monogamous mammals may form complex social groups that include an extended family and offspring of various ages. Incest is avoided within these families; adult young usually do not reproduce as long as they live with related family members. Finally, we should point out that although common in birds, monogamy is rare in mammals. In an exhaustive survey, Devra G. Kleiman of the National Zoological Park in Washington, D.C., found that only about 3 percent of mammals are monogamous.

The Loves of the Plants; Battle of the Sexes; Exclusive Online Issues; by Londa Schiebinger; 4 Page(s)

From Aristotle through Darwin and beyond, observers have infused nature with sexuality and gender. The great Swedish taxonomist Carl Linnaeus was thus not alone in imagining that plants have vaginas and penises and reproduce on "marriage beds." Although naturalists tended to believe that gender was a given of nature, the traits they ascribed to organisms have changed with shifting notions of masculinity and femininity in Western culture. For Aristotle, mares were sexually wanton, going "a-horsing" to satisfy their unbridled appetites. But in later centuries, females throughout nature--with the exception of Linnaeus's lusty flowers--were said to evince a patient modesty. Even among insects, females were observed to "repel the first [sexual] attacks of the males" and, in so doing, to win the respect of their paramours.

Since the Enlightenment, science has stirred hearts and minds with its promise of a neutral and privileged viewpoint, above and beyond the rough and tumble of political life. With respect to women, however, science is not a neutral culture. Gender--both the real relations between the sexes and cultural renderings of those relations--shaped European natural history and, in particular, botany. Crucial to this story is that Europeans who wrote about nature in this era were almost exclusively male.

Bonobo Sex and Society; Battle of the Sexes; Exclusive Online Issues; by Frans B. M. de Waal; 7 Page(s)

At a juncture in history during which women are seeking equality with men, science arrives with a belated gift to the feminist movement. Male-biased evolutionary scenarios--Man the Hunter, Man the Toolmaker and so on--are being challenged by the discovery that females play a central, perhaps even dominant, role in the social life of one of our nearest relatives. In the past few years many strands of knowledge have come together concerning a relatively unknown ape with an unorthodox repertoire of behavior: the bonobo.

The bonobo is one of the last large mammals to be found by science. The creature was discovered in 1929 in a Belgian colonial museum, far from its lush African habitat. A German anatomist, Ernst Schwarz, was scrutinizing a skull that had been ascribed to a juvenile chimpanzee because of its small size, when he realized that it belonged to an adult. Schwarz declared that he had stumbled on a new subspecies of chimpanzee. But soon the animal was assigned the status of an entirely distinct species within the same genus as the chimpanzee, Pan.

Sex Differences in the Brain; Battle of the Sexes; Exclusive Online Issues; by Doreen Kimura; 6 Page(s)

Men and women differ not only in their physical attributes and reproductive function but also in many other characteristics, including the way they solve intellectual problems. For the past few decades, it has been ideologically fashionable to insist that these behavioral differences are minimal and are the consequence of variations in experience during development before and after adolescence. Evidence accumulated more recently, however, suggests that the effects of sex hormones on brain organization occur so early in life that from the start the environment is acting on differently wired brains in boys and girls. Such effects make evaluating the role of experience, independent of physiological predisposition, a difficult if not dubious task. The biological bases of sex differences in brain and behavior have become much better known through increasing numbers of behavioral, neurological and endocrinological studies.

We know, for instance, from observations of both humans and nonhumans that males are more aggressive than females, that young males engage in more rough-and-tumble play than females and that females are more nurturing. We also know that in general males are better at a variety of spatial or navigational tasks. How do these and other sex differences come about? Much of our information and many of our ideas about how sexual differentiation takes place derive from research on animals. From such investigations, it appears that perhaps the most important factor in the differentiation of males and females and indeed in differentiating individuals within a sex is the level of exposure to various sex hormones early in life.