Producer: Ronnie Godeanu

Design Director: Sabina Daley

Designer: Lenny Drozner

Writer: David Malakoff

Animation: Lenny Drozner, Radik Shvarts

Page Building: Brian Santalone

Production Artists: Leela Corman, Meiza Fleitas

Production Assistant: Peter Tierney

Technical Director: Brian Lee

Scientific Consultant: Gianna Savoie

Thirteen Online is a production of Thirteen/WNET New York’s Kravis Multimedia Education Center in New York City. Anthony Chapman, Director of Interactive & Broadband. Carmen DiRienzo, Vice President and Managing Director, Corporate Affairs.

© 2001 Thirteen/WNET New York

All Rights Reserved

About the Writer

David Malakoff is a journalist covering research discoveries and the politics of science for SCIENCE MAGAZINE in Washington, D.C. His writing has appeared in a wide range of venues, including THE ECONOMIST, THE WASHINGTON POST, and ABCNews.com. He lives with his wife and three children — NATURE lovers all — in Alexandria, Virginia.

Television Credits:

A co-production of Green Umbrella Ltd., Thirteen/WNET New York, Trebitsch Produktion International GmbH, and Devillier Donegan Enterprises

Funder Credits

Funding for the TV series NATURE is made possible in part by Park Foundation. Major corporate support is provided by Canon U.S.A., Inc., Ford Motor Company, and TIAA-CREF. Additional support is provided by the nation’s public television stations.

In a mountain rainforest on the island of Trinidad, at the narrow entrance to a deep and noxious cave, TRIUMPH OF LIFE series producer Nick Upton and cameraman Jim ClarBatse prepare for an unusual challenge. Several hundred thousand bats, including vampire bats, live in the cave, along with millions of other creatures. When darkness comes, the bats will rush to fill the night sky. Upton’s goal is to film this fantastic exodus from inside the cave. The results are on view in the six-part NATURE series TRIUMPH OF LIFE.

From Nick Upton’s Diary:

“This is our sixth day at the cave. With luck, it will be our last and we can move on. I won’t miss lugging the equipment up that mountain terrain, and then lowering it piece by piece on a rope down a 30-foot shaft into the caveBats. But that isn’t the worst of it. When Jim and I need to clear our access ladder for a scene, we’ve had to enter the cave through the squeeze hole — an incredibly narrow passage that you have to wriggle through feet first. It bends in the middle and ends in a four-foot drop into piles of bat guano. It’s no joke, especially for a six-foot-three, 210-pounder like me. I’ve come close to getting stuck more than once. And all the while you’re maneuvering, bats are fluttering near your face and the cockroaches are skittering along the walls. We did this as many as six times some nights. Once, when I was about halfway through the squeeze-hole by myself, I knocked out the battery of my head-lamp and was stranded in total darkness. It took several jittery minutes to reinsert the battery and reconnect its wires by touch. Of course, I knew Jim would look for me eventually, but being wedged in solid rock with all that life teeming around me in the darkness made those minutes feel like hours.”

Night of the Guano

“The darkness, however, is by no means the only threatening aspect of this environment. The extreme heat and humidity are stifling, and the air is acrid with gases rising off the huge heaps of guano. Inhaling fungal spores in the air can cause a serious disease called histoplasmosis, so we wore face masks all the time. As for the creatures that share the cave with the bats, most are harmless, even the creepy-looking whip scorpions. But it’s essential to watch out for the poisonous snakes. The intense heat means that protective clothing is out, and one night I was bitten by a blood-sucking bug that sometimes carries a debilitating disease. But I managed to dislodge it before it could really go to work.

“Despite all the creatures in the cave and the dangers of navigating it, one thing above all else stands out as the most objectionable aspect of this underground environment — it seethes with millions of four-inch cockroaches. They live on the bat droppings and sometimes the ground actually seems to pulsate with them. In truth, the roaches aren’t really a physical danger, but they can be a bit disconcerting when they fly into you in the dark or crawl under your shirt.”

Rescuing the Pups

“Perhaps this will surprise some viewers, but the bats pose no danger either. BatsAnd that’s just as well, because in a few moments, Jim and I and a camera will be positioned between the cave’s exit and the third of a million bats that will fly past us at full speed. This should allow us to capture an amazing spectacle. So far, we’ve recorded some truly intimate aspects of bat behavior, such as feeding, breeding, and the dramatic rescuing of bat pups that fall from the roof of the cave by ‘baby-sitter’ bats. Until now, this fascinating behavior had been witnessed only by a handful of researchers. Capturing these scenes required a subtle touch. We used an infrared filming system to avoid disturbing the bats, and spent five long days in the cave, working in total darkness most of the time.

caption goes here

“However, the bats aren’t nearly so sensitive leaving the cave, and so for this scene we’ll use normal filming lights, powered by a large generator, which, by the way, we and our guide had to drag up the mountain, nearly killing ourselves.”

Exodus

“The sun has gone down, and already we can hear thousands of bats flitting around in a deeper portion of the cave, calling loudly. The charge is about to begin, and Jim and I have done all we can to prepare ourselves. And here they come, directly towards us, whizzing by our faces by the hundreds at first, then quickly by the thousands, the tens of thousands, the hundreds of thousands — pouring out into the night through the narrow exit. On and on it goes, for 40 heart-stopping minutes. But it seems like only five minutes to us, as we frantically switch lenses, change camera positions, adjust the lights, and record the eerie sounds.

“This is our chance to record this moment forever. It has been one of the most amazing experiences of my life — an entire civilization of bats swooping past us just inches away. And what an unforgettable demonstration of the astounding accuracy of their sonar abilities, for not one bat ever struck us! For the unique achievement inside that cave, I have the greatest admiration for my long-suffering cameraman. Jim seemed totally unfazed by the conditions; but then, he’s one of the real ‘hard men’ of wildlife filmmaking. As for me, despite all the hard work and discomfort, I find myself lookingBat forward to returning here some day. There is much more to film and to learn. Bats are remarkable animals, far more intelligent and sociable than people realize. I feel privileged to be in their strange, underground world and to have the opportunity to share the experience with the viewers of NATURE.”

A Powerful Organ Hearts, eyes, flippers and wings — evolution has forged many remarkable body structures. But none is more amazing than the brain, that bundle of nerve cells that allows us to sense our surroundings, sort out information, and make decisions. Indeed, the great importance of BRAIN POWER to evolution is the subject of this week’s installment of NATURE’s TRIUMPH OF LIFE series.

Brains are not essential to life. Many organisms, from algae to jellyfish, get along just fine without a central information-processing center. But there is no question that a brain gives many animals an edge. For in the struggle for survival, brawn often gives way to a brain that can outthink a competitor.

Not all brains are equal, however. Some brains consist of just a few hundred or few thousand cells, just enough to sense changes in light or temperature, or to sniff out important smells. Others, like ours, contain billions of cells, enabling everything from language to tool-making.

But simple is often more than enough to assure an animal’s survival. A flatworm’s basic brain, for instance, helps it sniff out earthworms, making the worm a lethal hunter. And while a honeybee’s brain is bigger than a flatworm’s, it is still not all that complex. Nonetheless, the bee is capable of amazing feats of memory, as BRAIN POWER shows.

In their short two-month lives, worker bees must learn to remember where nectar-producing flowers are located in relation to the hive, and exactly what time of day they produce the sweet liquid. The life-or-death memorization is aided by an amazing change in the bee’s brain: as it needs to retain more information, the brain grows, adding tens of thousands of cells on an as-needed basis! Once, scientists believed that such brain-changing abilities were limited to just a few animals. In recent years, however, evidence has shown that many animals’ brains are more flexible than once thought possible. Some birds, for instance, grow new brain tissue during the breeding season — perhaps to sing more complex songs — then lose the cells once mating is over. Other bird brains grow or shrink for migration.

T1 56K

Watch this clip to find out how a bee’s brain can sense changes in time.

You need the free RealPlayer to view the clip.

Researchers have even had to rethink their views of the human brain. Once, they believed that our brains grew only during childhood. It was believed that once we reached adulthood, we only lost — and never gained — brain cells. But surprising new studies show that we continue to add some kinds of brain cells throughout life. And other research shows that although our brains are usually very specialized, with particular parts responsible for certain activities, the human brain can sometimes reorganize itself. People who have lost speech or coordination due to stroke or brain injuries, for instance, can sometimes regain those abilities by “training” a new part of the brain to take over. Such findings have raised new hopes for treating serious brain injuries and birth defects.

Scientists, however, are still puzzling over the question of why we evolved such big, complex brains. Clearly, they are a big help in outsmarting predators and finding food. But our brains may also be a product of social pressures. We expend enormous energy in forging complex social relationships and alliances, whether within a family, among neighbors, or among nations. Making these relationships work requires creative thinking, constant problem-solving, and the ability to understand how another person is thinking — all tasks that call for some serious brain power. Over time, evolution favored those individuals with the best social and survival skills.

For the moment, our brains have made us the most influential species on earth. Our tool-making skills have allowed us to reconstruct the landscape, building cities and plowing fields where forests and grasslands once reigned. We’ve figured out how to make the desert bloom, pumping water from far below the earth to quench our thirsts. And, unintentionally, we may even be altering the planet’s climate by burning massive quantities of coal, oil, and wood that produce carbon dioxide and other global warming gases.

It remains to be seen, however, whether even our brainpower will help us avoid the fate of so many other species in Earth’s history: extinction.

Gene Swapping Variety is indeed the spice of life. That is the message of THE MATING GAME, Part 2 of NATURE’s six-part TRIUMPH OF LIFE series. It takes a passionate look at the evolution of sex, which allows a species to pass its genes along from generation to generation.

Sex is everywhere. Bees do it and birds do it — and so do lizards and bacteria. In its simplest form, sex is the process of mixing genes from two parents into a new offspring. This gene swapping ensures that each generation is just a bit different from the one that came before, and that each individual is a bit different from others.

This variation gives the species a better chance of surviving changing conditions. A few individuals, for instance, might be able to survive a deadly new virus and carry on the species, while the rest die. Eventually, the virus-resistant newcomers might even evolve into a new species.

Just because sex is everywhere, however, doesn’t mean that all organisms do it the same way. Evolution has produced virtually every conceivable combination of mating behaviors, as THE MATING GAME shows.

A male’s bird’s bright plumage is more than just eye-catching. Colors can also tell a potential mate about the man’s health a vigor.

In some species, for instance, the males compete with each other for the chance to mate with females. But in others, it is the females who vie to be the more attractive mate. Sometimes, the female is bigger, in order to hold more eggs. But in others, such as humans, the male is typically a bit larger. In some species, the females do most of the hard labor of child rearing; in others, it is the male that does all the work. And in some species, such as many marine fish, the kids are left to fend for themselves.

Other animals have evolved especially creative approaches to sex. Some female lizards, for instance, don’t need males to reproduce. Each female can lay eggs that produce “clones,” or genetically identical baby lizards. While cloning allows the species to reproduce under very harsh environmental conditions, it also leaves the identical offspring much more vulnerable to disease or environmental changes.

Some marine worms have taken another approach — each individual is both male and female. These “hermaphrodites” have the option of being mother or father. And a few fish take the idea in another direction. They can change sexes depending on circumstances, spending part of their lives as males and part as females.

It all goes to show that sex is never simple. But it has proven an essential engine for the evolution of life on Earth.

Choreographed Cooperation Life may be a contest in which only the fittest individuals survive, but cooperation has also played a key role in evolution. WINNING TEAMS takes a close look at the alliances that animals have forged — with others of their own kind and very different organisms — in a bid to stay alive. In fact, teamwork occurs everywhere, from flocks of birds and herds of wildebeest to colonies of ants and termites.

For some animals, the motivation for joining together is defense. A flapping, pirouetting flock of birds, for instance, can make it harder for a hungry falcon to home in on a single victim. Similarly, a thundering, shifting herd of wildebeest can be an intimidating — and confusing — sight to a hungry lion. And in both cases, there are more eyes to keep on the lookout for attackers. There is, indeed, safety in numbers.

Not surprisingly, some predators have responded to herding defenses with teamwork of their own. Feeding dolphins, for instance, have been known to work together to herd schools of fish toward the surface, where the seafood meal finds it harder to hide. Lions also team up to spring the trap on wildebeest, with several lionesses needed to topple one of the big beasts. And early human hunters, of course, learned to work together to hunt creatures, such as woolly mammoths, that were many times their size.

In many insect societies, every individual in a hive or colony can be the offspring of a single queen, making them all siblings that share genes.

Other times, however, the benefits of teamwork are less obvious. Animals that feed together, for instance, can spread out and cover more territory, making it more likely that one will hit a mother lode of food. The strange Damaraland mole rats featured on WINNING TEAMS, for example, drill through the soil as a team of up to 40 family members, looking for the roots and tubers that fill their empty stomachs. For years, researchers were unaware of this choreographed cooperation, since the underground-living rats are quite secretive.

Similarly, the link between some plants and the birds that eat their seeds took years for researchers to recognize. These plants, which include some wild rose bushes, produce tough berries that, if dropped on the ground, won’t sprout. But if the same seed is eaten by a bird, and is then etched and cleaned by the bird’s stomach acids and excreted onto the ground, it is ready to germinate. Similarly, some flowers can be pollinated only by a particular insect. The arrangements have led some scientists to ponder who is getting the better deal: Are the birds and insects slaves to the plant, or is it the other way around? The answer lies in their “symbiotic” relationship — meaning both organisms benefit mutually from the other.

Often overlooked is the important role that microscopic organisms play in the lives of many plants and animals. Some of these “symbiotic” bacteria live on the roots of plants, helping them draw nutrients from the soil. Others reside in the stomachs and intestines of everything from termites to humans, helping to digest food and remove toxins.

Without us, our stomach bacteria would die. But without the bacteria, we might fall prey to illness. It’s a classic case of the evolutionary ties that bind all life together in the drive to build highly competitive — and ultimately winning — teams.

Evolving For Advantage On some ancient battlefield, an early human soldier realized that a sharpened stick could become a deadly spear that would send the terrified enemy scrambling for safety. In response, the defeated soldiers came up with their own innovation: wooden shields that blunted the spears and suddenly turned the tables. It was then up to the attackers to devise another new weapon that could defeat the shields and restore their advantage. An arms race was born.

But it was far from the first. For billions of years, life on Earth has been engaged in its own ETERNAL ARMS RACE, the subject of Part 3 of NATURE’s TRIUMPH OF LIFE. As predators became better hunters, their prey also evolved better defenses.

The cheetah and its main prey, the Thompson’s gazelle, are the two speed champions of the Africa plains.

This drive to survive has produced remarkable hunting strategies, from frogs that are able to snare flying insects with long, elastic tongues, to cheetahs that work together to chase down fleet gazelles. But it has also shaped magnificent survival skills. Some moths, for instance, can sense a bat’s prey-seeking sonar pulses, and duck just in time to avoid the onrushing bat’s jaws.

Other animals have taken to deception, evolving colors and body shapes that provide perfect camouflage, making them invisible to predators. Some octopuses featured on THE ETERNAL ARMS RACE, for instance, can make themselves look just like poisonous sea snakes. Still other animals have taken the opposite tack, covering themselves in bright, outrageous colors that make it impossible for them to hide, but advertise the fact they can be distasteful or poisonous to eat. In the competition between hunter and hunted, no new tactic — from thicker armor or sharper teeth to better vision and hearing — is left untried. But only the successful traits — those that either let a predator catch more prey or allow the prey to survive attack — get passed along to the next generation. Meanwhile, the ultimately unsuccessful adaptations get left behind on evolution’s battlefield, victims of life’s eternal arms race.

Triumphant Origins

It is perhaps the greatest adventure story ever: how tiny pioneers came to settle on a seething molten ball of dust and gas, and slowly created a cosmic oasis teeming with a seemingly endless variety of life, from microscopic bacteria to whales the size of locomotives.

This week, NATURE’s TRIUMPH OF LIFE offers the first chapter in this amazing tale: the story of life on Earth. THE FOUR BILLION YEAR WAR explains how both conflict and cooperation have helped shape the species that today populate our world. And it profiles the winners and losers in this epic evolutionary contest — from the massive dinosaurs who disappeared long ago to the humble bacteria that have survived for billions of years virtually unchanged.

Nobody knows exactly where the seeds of life came from. Some believe the chemicals essential to life were brought here by meteorites, while others believe they arose naturally in the early oceans and atmosphere. But most researchers agree that carbon, hydrogen, oxygen, and nitrogen eventually linked up to form the basic molecules of life. Then, they slowly assembled into more and more complicated structures that could reproduce themselves. That set the stage for the blossoming of life.

At the heart of this amazing story is the quirky and chaotic process of evolution — the ability of organisms to change their behavior and body shape over time to adapt to changing circumstances. For instance, a flock of birds (let’s call them the “small beaks”) might face a changing climate that kills off its favorite food plant, which produces small, soft seeds that perfectly fit their small beaks. Luckily, due to random changes in their genetic codes, the flock produces a few newborn birds that have bigger beaks.

The largest dinosaur yet discovered is called Argentinosaurus, a 100–ton, 100-foot-long plant–eater.

Normally, the change might not make any difference. But in this changing environment, the bigger bills allow these few birds to feed on the bigger, harder seeds from another plant. As a result, this new variety of “big beaks” become healthier and are able to produce more big-beaked offspring than their smaller-beaked brethren. Eventually, over a long period of isolation, the small beaks die out and only the big beaks remain. A new species has evolved.

The great British biologist Charles Darwin first recognized the importance of the evolutionary process in the 1800s, in part by studying the differently shaped beaks of birds in the Galapagos Islands off Ecuador. Each island is home to a slightly different version of the finch, which have evolved specialized beaks to take advantage of particular food sources. The specialization means they don’t have to compete with other finches for food, improving the odds of survival.

Today, evolution continues — though generally too slowly to be obvious. It can take thousands or millions of years for a new species to evolve. Still, fossils tell us that change on Earth has been a constant and never-ending process. Despite the changes, however, life — in one form or another — has triumphed.