An elephant jam. It’s not an uncommon sight on the streets of Bangkok, Thailand, where Asian elephants are known to walk the streets, sometimes snarling traffic with their lumbering bulk. Drivers may curse and horns honk, but the elephant will not be hurried.

This week, NATURE takes a close look at The Urban Elephant, traveling from Bangkok’s crowded streets to the quiet forested hills of Tennessee to examine the close and often complicated relationships people have forged with these giant creatures. It tells the bittersweet stories of a few of the thousands of Asian elephants that live out their lives in captivity; in circuses, zoos, farms, and isolated forest logging camps.

Researchers believe that less than 40,000 endangered Asian elephants still survive in the wild, down from 1.5 million to 2 million in 1970. But there are thousands more Asian elephants living in captivity, since the animal has long been viewed as a prized captive. It is, for instance,a valued beast of burden in India and across Southeast Asia. For thousands of years, elephants have pulled plows, carried cargo, hauled lumber from forests, and ferried passengers across shallow rivers. Guided by expert elephant riders called “mahouts,” many Asians consider elephants to be the smart, rugged alternative to modern machines.

Elephants on city streets are a familiar sight in Bangkok.

But not all Asian elephants still live in their homelands. As early as 1796, resourceful traders began shipping the animals to Europe and North America, where they became celebrated curiosities. By the 19th century, Asian elephants were a staple of zoos and traveling circuses. Again, the animals’ intelligence and staying power proved prized; circus trainers, for instance, could train a young elephant to perform amazingly agile moves, knowing it might be able to occupy the spotlight for much of its 60-year life span. Some of the circus elephants featured on NATURE’s The Urban Elephant, for instance, have been performing since the late 1940s.

But some former circus trainers believe performing elephants deserve a different life. As The Urban Elephant shows, they have set up sanctuaries — such as The Elephant Sanctuary in Tennessee — where the one-time big-top stars can retire and live quietly alongside others of their kind.

Similarly, in Sri Lanka, conservationists are working to create better lives for that nation’s elephants. In addition to working to protect wild habitat, they have created the Pinnawala Orphanage, featured on The Urban Elephant. It was founded in 1975 to take care of the many baby elephants found orphaned in the forest after their mothers died, or who were captured or killed. It also takes in captive elephants that have been mistreated by their owners, or wild elephants that have run afoul of expanding human communities, outcast because they have trampled crops or attacked farmers.

In Canada and the United States, however, zoo officials face a different problem: a shortage of baby elephants. Because Asian elephants do not easily breed in zoos, captive populations have been dwindling.

If nothing changes, the population will be gone within 50 years, experts estimate. So, with most zoos unwilling to obtain or barred from capturing new animals from the wild, they are taking increasingly sophisticated steps to maintain their herds. At the National Zoo in Washington, D.C., for instance, researchers have successfully pioneered the use of artificial means to impregnate their female elephants. Soon, “test tube” elephants could become routine, and even help restock animals into the wild.

That day is still far off. Meanwhile, at Canada’s African Lion Safari, caretakers have had remarkable success getting their group of 11 Asian elephants, which includes 3 males, to breed without special assistance. Since 1985, the animal park has welcomed 7 baby Asian elephants. That record is especially impressive because each pregnancy lasts nearly two years, meaning that growing a herd is a slow and arduous task. But elephant program director Charlie Gray says the waiting is worth it, since the breeding program is improving our understanding of elephants. Working with researchers at the University of Guelph, for instance, African Lion Safari has helped develop tests that can pinpoint when a female elephant is ready to breed.

Understanding such intimate details may eventually help people live in harmony with the endangered Asian elephant. As NATURE’s The Urban Elephant shows, these remarkable animals long ago learned to adapt to the sometimes cruel demands of people. Now, perhaps, we can return the favor by helping these proud animals reclaim their wild heritage.

In 1839, an American diplomat named John Lloyd Stephens was exploring the jungles of western Honduras when he came upon an abandoned city of stone rising out of the thick vines and brush.

“The city was desolate,” he later wrote. “It lay before us like a shattered bark in the midst of the ocean, her masts gone, her name effaced, her crew perished, and none to tell whence she came, to whom she belonged, how long her voyage, or what caused her destruction. … All was mystery, impenetrable mystery.”

Today, archaeologists know that Stephens stumbled across Copan, one of the great monumental cities built about 1,500 years ago by the ancient Maya. Researchers believe that up to 3.4 million Maya once roamed the jungles and plains of Central America before their civilization collapsed, leaving behind less than a million people — and scores of ruined cities complete with massive stone pyramids, ceremonial plazas, and carved monuments. As NATURE’s Deep Jungle: The Beast Within shows, many such structures are still hidden within the jungle, waiting to be uncovered by researchers.

The Maya’s Copan isn’t the only great jungle city that now feels like a ghost town. Angkor, located in Cambodia, is another metropolis that flourished in the forests. Archaeologists believe that this ancient city once covered 835 square miles and supported as many as a million people.

What happened to these previously thriving cultural centers? Although there is still much debate, researchers increasingly believe that the cities simply became too big for the local environment to support. Forest clearing may have altered local climates, perhaps reducing water supplies and making farmers more vulnerable to periodic bouts of drought or disease. According to this hypothesis, deforestation started a cultural domino effect, sparking violent conflicts over natural resources that ultimately spiraled out of control, forcing massive migration to safer areas and leaving these once vibrant cities to crumble with neglect.

Today, new technologies are allowing cities to sprout again in the jungles of the Amazon and South Asia. In the ancient Maya and Angkor civilizations, local resources were eventually strained. Now, deep wells bring water, while food and energy flow from sources that are often continents away. It’s still too early to tell if, this time around, humans will win their battle to survive within the jungle.

In the meantime, city residents continue to discover indigenous tribes who have long called the jungle their home. Every year, officials in Brazil, Indonesia, and other tropical nations report making contact with previously unknown groups of jungle dwellers who speak their own languages and have had virtually no contact with the outside world. In Indonesia, for instance, the government recently recognized the Vahudate and Aukedate tribes — tall, dark people with curly hair and an unusual form of sign language. In Brazil, specialists are still debating whether several Amazon tribes are truly new, or simply subgroups of known forest tribes.

Whatever the answers to such questions, one thing is clear: these people of the jungle know their environment intimately. In NATURE’s Deep Jungle, for instance, viewers meet the BaAka of Central Africa as they help a researcher track western lowland gorillas. The BaAka are one of several tribes known as pygmies because of their short stature. Adults often reach just four feet in height.

There are about 20,000 BaAka tribe members living in the forests of the Dzanga-Sangha national park. They live off the jungle, stalking and catching game with nets and weapons, and harvesting a wide array of fruits and roots. They build their shelter with few flexible poles and some leaves or bark. Such skills have led the BaAka to become invaluable guides to researchers in one of the most challenging environments on Earth, the jungle.