While gossip columnists may have full reign over the sex lives of Hollywood stars, scientists have invaded the habitats of some of the most infamous cheating animals to reveal some real life monkey business. Today’s red carpet headline: “Free-spirited bonobos seek perpetual orgies with any available male or female in any combination.”

In the animal kingdom, when it comes to mating, promiscuity is the rule rather than the exception. About 90 percent of mammals have multiple mates, and cheating on social mates is observed in almost all species. In fact, only 3 to 10 percent of mammals are even socially monogamous.

We’ve identified some animals with unusual mating practices and behaviors. Find out why these animals are such hot commodities and why evolution favors their promiscuous behavior.

It’s the planet’s awful truth worth gossiping about.

Think you have a good sex life? Think again.

Check out these swingers and how they make the scene:

1. Fire-colored Beetles and Lightning Bugs Black Light Rave: Fire-colored beetles sometimes use toxic substances as aphrodisiacs. The male entices his mate by presenting a chemical offering known as cantharidinan, which is secreted from a gland in his head. More of the chemical is transferred to the female beetle in the male’s sperm. And she, in turn, transfers the chemical to her eggs, which are protected by the chemical from predators. And, talk about incredible diversity of approaches to sex — there are female lightning bugs that have one flash pattern to attract males of their own species with which to mate, and another that mimics the pattern of a different species. The false come-on is a trap — any males of the other species that respond are eaten.
2. Honey Bee Queens Reign Supreme: In hives, females rule. Early in a queen’s life, she makes several mating flights and can mate with anywhere from one to more than 40 drones. When a queen flies by, the males mob her, deposit their sperm, and then subsequently die. While the drones may not appreciate this lethal affair, the worker bees in the colony prefer more promiscuous queen bees. In fact, the number of partners a honey bee queen has influences how attractive the queen is to the several thousand worker bees in the hive and how long her reign is likely to be. Promiscuity may also improve colony disease resistance by boosting the genetic diversity of her offspring. The queen stores and uses the sperm of all these males throughout her lifetime so she can focus on her most important job of laying eggs. In a successful hive, the bees are buzzing: “Long live the queen!”
3. Bonobos Throw a Big Sex Party: Some animals do not conform to any mating system and engage in frequent sex with many partners. Probably the most well-known example are bonobo chimpanzees, known for the frequency, creativity, indiscernibility and variability in their sexual interactions. Both males and females mate with multiple partners to ease social tensions within the group and practice free love with bonobos of both sexes — even while hanging upside down.
4. Desperately Seeking Topi Antelopes: Thirty days of unending sex makes for some tired topis. Over-amorous females, fertile only one day a year, seek out the most desirable males and hound them to absolute exhaustion. Biologists have observed that males often turn down mating opportunities — Say it ain’t so! That’s right — this species exhibits sexual behavior that’s the reverse of most animals, in that females are aggressive, while the males are standoff-ish. In the topi battle of the sexes, females take the lead — mating several times with each of about four males on average.
5. Birds Make Desperate Housewives: The hedge sparrow has an incredible mating game that never seems to end. Even after the female sparrow has paired with a male, she keeps her eye out for other possibilities. Extramarital partners and sexual communes are common for these polyandrous females because it means they can have more offspring. Like the hedge sparrow, female barn swallows also shop around for multiple male sexual partners, and the males that are small, dark and handsome get the girls. The females judge the males by their looks, and if the male breast and belly feathers lose their sheen, it’s a cue to the female to start looking elsewhere for her next mate.
6. Elephant Seal Beach Blanket Bingo: While you’re watching to make sure no one takes your towel-draped lounge chair on the beach, male elephant seals are watching to make sure no one takes their bathing beauties. Large, blubbery male elephant seals called “beach masters” protect their gals from other guys trying to move in on their territory. A single breeding bull may control a harem of 100 or more, and only the biggest and most fearsome bulls get to mate. The males only become beach masters after they duke it out amongst themselves with their pendulous noses and teeth. Fights can involve bloody clashes and repeated strikes until one male submits and the other one stands victorious.
7. Jumping Spiders Dance Dance Revolution: A jumping spider is more than just a pretty face. These guys have hidden talents way beyond anything you’ve seen on reality shows, “Dancing with the Stars” and “American Idol.” Once onstage, the male spider attracts the gaze of the females, and then begins to coordinate an elaborate show involving singing and dancing. The females pick up the sound vibrations, while the male waves his front legs and zigzags in an intricate courtship “flamenco dance” routine. With his tufted legs straight up in the air, the male beats his abdomen and moves his legs rapidly. After a dramatic crescendo, he taps a female gently on the back and then tries to mount her. If the male doesn’t get it just right, he suffers a fate worse than a brutal critique from “American Idol” judge Simon Cowell. If his performance is flawed, he’s liable to end up as dinner.
8. North American Elk Hoedown: It’s all about posturing and foreplay for these strapping guys. Bull elk compete with one another for the right to breed with a herd of females during a two-month long mating season. Depending on his level of experience, a bull elk can be the master of a harem of anywhere from 5 to 60 cows, as the female elk are called. Mature, antlered bulls compete for cows by displaying their antlers, necks and bodies, and emit strong, musky odors and “bugle.” If this “tough-guy” approach doesn’t work, the bulls may have a scuffle and put those antlers to good use.
9. Bower Birds Build Love Shacks: In the name of love, bower birds may take out your garbage and rival even the best recycling program. These charmers will build elaborate structures, called bowers, out of everything from leaves and sticks to bottle caps and clothespins. And, that’s just the architecture. The males are also multi-talented interior designers, and may use a leaf or twig to paint the inner walls with a stain made from chewed plants, charcoal, and saliva. The bower serves to show off the male’s strength, and attract and seduce one or more mates. When a female arrives to inspect the structure, the male entertains her with an elaborate dance. Once the show is over, the female most often shows her approval by mating with the male and then flying off to build a nest in the neighborhood. Then the male is open for business again: Ladies welcome!
10. Birds of Paradise Flash and Flutter: When it comes to courtship displays, these species are the fashion icons of the bird world, donning lacy feathers, head ribbons, shiny breast shields — even bonnets. In these elaborate “costumes,” the male birds put the moves on the ladies and launch into theatrical routines. Taking a step back in time, the birds get boogying and downright funky. They hop and shake, flap and flutter — until the female is won over by the male bird with the best feathers and razzle-dazzle display.

“Change alone is unchanging,” the ancient Greek philosopher Heraclitus once wrote. But even such a wise man didn’t know the half of it. As NATURE’s The Body Changers shows, researchers have discovered that all kinds of animals — from sea slugs and caterpillars to songbirds and people — undergo constant and often remarkable physical changes during their lives. And scientists continue to discover that we can change our bodies in ways once thought impossible.

A butterfly will emerge from this body changer.

Each of us knows from personal experience that the passage of time is marked by constant variation and modification. From a single cell unable to live on its own, we multiply into creatures composed of trillions of cells able to move about freely. Our bodies grow taller, heavier, and hairier as we mature, then shrink and wrinkle as we age. Our hair may change color and our voices modulate from a howling cry to a quivery whisper.

But even these dramatic physical alterations are overshadowed by the extraordinary transformations experienced by other creatures profiled in The Body Changers. Fleet-flying dragonflies, for instance, start life as swimming nymphs that paddle about beneath the surface of a pond or river. High-leaping frogs take their first trips as awkward, wriggling tadpoles. And the elegant, fragile butterfly emerges from a capsule spun by a chunky, crawling, earth-bound caterpillar.

Still other animals are able to execute even more amazing tricks. Salamanders can regrow legs snipped off by hungry turtles, while lizards routinely rebuild tails that break away, by design, in the mouths of predators. Male deer grow magnificent antlers that are used for just one season and then discarded, like a wedding dress banished to the back of the closet. And some songbirds remold their brains every spring, adding and subtracting neurons as needed. When more brainpower is needed to sing and remember their courtship songs, their brains swell. But when breeding season is over, they conserve energy by scaling back.

Such modern-day adaptations are the product of millions of years of evolution — another process dependent on change. Many researchers, for instance, believe today’s birds began as dinosaurs, while people evolved from tree-dwelling apes. Over the eons, seemingly insignificant changes began to add up, separating new species from the old. The genetic flaw that produced feathers on some mutant dinosaur, for instance, may have helped keep it warmer and enhanced its survival. Later, the feathers might have helped its offspring become better hunters and eventually fliers. It was just a short flap, in geologic time, to modern birds, which bear just a fleeting resemblance to their forebearers.

We’ll probably never know for sure just how all these changes took place, or why they occurred. It is difficult to follow the biological path that brought us here back into the mists of time. But researchers continue to make surprising new discoveries about our ability to change. For years, for instance, scientists believed that it was nearly impossible for humans and related apes to grow new brain cells. Conventional wisdom held that the most important parts of our brains were pretty much set by the age of three or four, and would grow no more.

Are brain cells continually added to all primate brains?

But in 1999, in a finding that eventually could lead to new methods for treating brain diseases and injuries, Princeton University scientists discovered that new brain cells are continually added to the brains of adult monkeys. Brain researchers Elizabeth Gould and Charles Gross found that the monkeys add neurons to several regions of the cerebral cortex that are crucial for memory, high-level decision making, and for recognizing and learning about the world. The results strongly imply that the same process occurs in humans, because monkeys and humans have similar brain structures. “If what they have shown holds true for all primates, including humans, it means we really need to rewrite the book on brain development and the way that experience can affect the brain,” says William T. Greenough, director of the neuroscience program at the University of Illinois’ Beckman Institute.

At the time of the discovery, Gross asked the question shared by many: “If the cerebral cortex is important in memory, how could it change?” He went on to explain, “In fact, the opposite view is at least as plausible: if memories are formed from experiences, these experiences must produce changes in the brain.”

Practical applications of the discovery could be years, even decades away. But the results suggest that scientists may one day exploit natural repair mechanisms to treat brain injuries or diseases, such as Alzheimer’s and Parkinson’s diseases. The discovery also may require scientists to draw a less bold distinction between the brains of humans and other animals, says Fernando Nottebohm of Rockefeller University, who has pioneered the study of changing bird brains. “What you can say now,” he says, “is that the primate brain is more like that of songbirds.” That, indeed, is a change in thinking.

Evolution makes the surreal seem commonplace in NATURE’s The Body Changers.

In The Metamorphosis, Franz Kafka wrote about a hapless fellow who awakens one day to find he has changed into a cockroach. In the world of fiction, this is an example of surrealism; in the natural world, it typifies an everyday occurrence.

Many animals have a special ability to transform themselves, for the sake of survival, reproduction, or both. And, as anyone who has watched a caterpillar become a butterfly knows, some animals experience two very different existences, in effect, living for a time as one creature and then changing into another. NATURE probes the intriguing subject of physical transformation in The Body Changers.

The program explores a broad range of creatures with astonishing abilities, from the redwing blackbird, whose brain dramatically changes shape to accommodate the chants and songs of mating rituals, to a fungus that transforms itself into something resembling a stalk that plays a vital role in the proliferation of roundworms.

To order a copy of The Body Changers, please visit the NATURE Shop.

Online content for The Body Changers was originally posted May 2000.

A female bower bird considers her options.

Gerald Borgia, a University of Maryland bower bird expert, believes the different kinds of bowers all serve essentially the same function: to make visiting female bower birds feel comfortable by protecting them from overeager males. Courtship rituals, he notes, almost always involve males and females standing with the bower between them, like a fence. In the case of the maypole-building Macgregor’s bower bird, for instance, the courting pair warily circles the central tower. Only when the female chooses to stop and allow the male to approach can mating occur. “The bower probably started as a protective device,” Borgia concludes. “It allows females to get close enough to get a good look without feeling threatened. The male that builds something that makes the females feel most comfortable is likely to see more females.” Borgia has also detected a relationship between bower type and intensity of the male’s display. The male Spotted bower bird, for instance, builds a wide straw wall and performs a relatively energetic display full of dance steps and dramatic poses. In contrast, species building smaller barriers have toned-down displays that are probably less threatening to females.

A male bower bird checks his handiwork. Other researchers have noticed a link between the showiness of a bower bird’s plumage and the intricacy of its bower: in general, the drabber the bird, the fancier the bower will be. Some believe this reflects an evolutionary choice: drab birds compensate for their dull appearances by building flashier nests.

A male bower bird checks his handiwork.

Borgia has also noticed that bower complexity sometimes varies with topography. For instance, species living on hilltops build more modest bowers than those living in valleys. The explanation, he says, may be the amount of light that penetrates the forest in the two kinds of habitat. Ridge tops are often shrouded in clouds, allowing only dim light. Hence, to best show off their decorations, bower birds living here may build more open bowers to make best use of available light. In contrast, light is less of an issue in the valleys, so bower birds can afford to have more elaborate roofed structures.

Surprisingly, Borgia has found that bower birds that build similar-shaped bowers aren’t necessarily closely related to each other. Using a DNA fingerprinting technique, he and his colleagues drew a family tree for bower birds that showed their evolutionary relationships. It suggested that species that evolved at different times have independently learned to build similar kinds of bowers, possibly because they faced similar kinds of environmental conditions.

But close observation can reveal important differences in the seemingly-similar structures, Borgia says. Where one species may build its bower from the bottom up, for instance, the other may start a similar structure at the top and build down. Similarly, some species put the entrance to their bowers on the uphill side, while similar structures built by other species face downhill. Nobody knows whether young bower birds learn such practices from their elders, or whether they are encoded in their genes at birth. It is a much-debated question that Borgia hopes to answer in future studies by rearing native males in captivity with and without mature tutors.