`We're about three hours into a 10-hour boat ride up a tributary of the Amazon River when it really sinks in that we're entering a different universe.
One of our guides is using a machete to kill a pair of poisonous snakes slithering around on the riverbank, right where I'd been standing moments earlier. And he's laughing about it.
We're heading upriver to a place no reporter has ever been before: a remote jungle village, home to isolated Indians who, in many ways, live now as they have for hundreds, if not thousands, of years.
We got the idea for this trip after seeing pictures that came out in May of "uncontacted" Amazonian Indians. The aerial photos show naked warriors, painted red, aiming arrows at a plane flying overhead. The pictures caused a sensation, giving millions of people the feeling that they were staring across a chasm at their ancient selves.
(There was some controversy about whether those photos were legitimate. The paper that started that rumor recently ran an apology.)
We obviously couldn't visit the Indians in the pictures. They clearly don't want visitors. What's more, we carry germs to which they are not immune.
However, when we reached out to the group that publicized the photos, Survival International, which advocates for Indians worldwide, they were able to get us extremely rare access to another isolated tribe, called the Enawene Nawe.
The members of this tribe have had enough exposure to outsiders to develop immunities. They have also had enough exposure to know that allowing in a reporter might help them get their story out -- because the Enawene Nawe believe they are in mortal danger.
My producer, Almin Karamehmedovic, and I take the interminable journey up the river to the tribe's village with a representative from Survival International, Fiona Watson, who will be translating for us.
En route, we're assaulted by blinding heat and enormous, dive-bombing insects. We have no idea what to expect when we get there.
We're hoping to arrive at the village during daylight. But as our boat chugs along, the sun gets low in the sky and it gets completely, utterly dark.
At one point, using only flashlights to see the way, our drivers pull over to the side of the river to kill a sleeping crocodile.
Fish jump out of the water and whiz through the air. One of them lands in the boat.
When we finally arrive at the village, it's the middle of the night.
In the exhilarating early moments, we see Indians emerging from the darkness in various states of undress. We see a tree full of green parrots. We see the obscure outlines of the huge, communal huts in which the Enawene Nawe live.
For a people who deliberately shunned the outside world until recently, they are remarkably friendly.
One of the first people we meet is nicknamed "the Bear." It's not for nothing that he got this name. He's a strapping young guy with a big, easy smile and a high-pitched laugh. The Bear grabs a bunch of our bags and announces that we'll be staying with him.
Walking into the enormous hut where the Bear lives is unforgettable. It's the type of thing curious journalists live for. The place houses perhaps seven different families. We hear babies crying, a strange language being spoken, fires crackling. (It gets surprisingly cold there at night.)
The ceiling must be 30 feet high. The thatch room is held up by wooden poles.
Each family has its own area of the hut, where they tie up their hammocks and store their belongings. The Bear ties up hammocks for Almin and me right next to where he and his wife and children sleep. This will be our home for four days.
In the darkness of the hut, lit only by fires and flashlights, we're surrounded by the curious. Most of them children. I do my best to communicate greetings.
Everyone here is extremely receptive. It's hard to tell who's more curious about whom.
The first thing we notice is that the Enawene Nawe wear very limited amounts of clothing. (Although, to our surprise, we do see people wearing T-shirts, which they get from health workers and anthropologists who visit.)
Also: everyone has the same haircut -- men, women and children. In the back, it's like a mullet; in front it's a Three Stooges-style bowl cut.
Once our hammocks are tied up and our fire is lit, the crowd clears out and we try to get some sleep.
Just a few hours later, however, we're woken up to a strange sound coming from outside the hut.
It's 4:30 in the morning and the male members of the Enawene Nawe are engaged in an ancient ritual. They're circled around a bonfire, chanting in deep rhythmic tones.
Their religion governs nearly every aspect of their lives. They believe that the demanding spirits they serve could wipe them out if they don't follow a very detailed script every day. The ceremony is sacred, but the men don't seem to mind our approaching and filming. It lasts until dawn.
As the sun comes up, we get our first clear glimpse of the village. There are about 500 people living there, in about a dozen huts built in a circle around a main courtyard.
We see men going off to tend their gardens in the forests, carrying bows and arrows (in case they encounter a jaguar), women gathering wood for the morning fires, and parrots waddling around, snacking.
We're again surrounded by kids, staring and laughing. Some of them are carving up raw stalks of sugar cane for breakfast.
The pace here couldn't be more different from our world. The list of daily activities is quite short.
Fishing is a big one.
The Enawene Nawe use ancient fishing methods, like submerging poison roots in water, which stuns the fish, who then float to the surface.
They also use more modern tools, like motor boats, goggles and swim trunks, which they've also acquired from their limited contacts with the outside.
We notice, though, that they only seem to latch onto the bits of modernity that help them live their ancient lives more easily. Just because they use some of our technology does not mean they want to live like us.
While we're out fishing, I ask the Bear if he could ever imagine living like we do. "I don't want that way of life at all," he says. "Absolutely not."
(To communicate, we have to use several translators. The translation goes from Enawene Nawe to Portuguese to English. It's quite a process.)
They fish and live by a simple rule: Take only what you need. Nothing more.
This notion is reinforced by their faith. They tell stories of the spirits killing tribe members who over-fished.
Their faith also requires them to share in order to survive out here in the supremely inhospitable jungle. Interestingly, that means that that extramarital affairs are accepted, for both sexes. (Although it's not considered to be polite to discuss this openly, we're told.)
One couple invites us in for lunch.
The diet here is extremely limited, consisting mostly of fish and also bread made out of yucca. (It's a starch -- kind of like potato.)
The food is placed in a big metal bowl on the floor. Everyone grabs with their hands. The husband, whose name is Marikerosone, is encouraging me to eat. In order to distract from the fact that I am having trouble stomaching the food (which tastes like cardboard to my dainty tongue), I decide to ask an impertinent question.
"This is a sensitive question," I say, "but if you want to be alone with your wife, if you want to be intimate with your wife, you're living in this room full of people. How do you have privacy?"
After a lengthy process of translation, Marikerosone breaks into a high-pitched laugh (one of the most charming Enawene Nawe cultural traits) and throws his food at me.
Then he explains that they get plenty of privacy at night once people fall asleep.
Apparently so. He has seven children and his wife is pregnant with number eight.
Spending time here in this village really gets me thinking about our modern notions of "progress" and "sophistication." The Enawene Nawe don't have high technology or high finance (or last names or currency, for that matter), but they also don't have crime, poverty, hierarchy or drugs. Living here, you don't have to worry about losing your job, getting ahead or having as much stuff as your neighbor.
In fact, not only do the tribe members take only what they need, but they also seem to need less to make them happy.
The simplicity of their lives frees them up to do some of the things that we in the outside world have sometimes lost in our lives: spend time with the kids, enjoy nature, laugh.
But while this is a happy place, there is also, we learn, a constant, nagging fear.
The Enawene Nawe believe they are on the edge of oblivion.
According to their faith, when the world began, two groups of people emerged from giant stone: the Indians and everyone else (who they call "the whites"). The Indians took only a stone ax, and let the white have technology and disease.
Now, the two civilizations are colliding.
The Indians' take-only-what-you-need world is in a clash with our modern, take-all-you-want juggernaut, and the Indians are losing.
Marikerosone brings us to see huge swaths of the tribe's ancestral land that have been deforested and destroyed by ranchers. He also brings us to the spot in the river where the Brazilian government is hoping to build a hydroelectric dam, which the tribe believes will ruin their traditional fishing grounds.
When Marikersone talks about the threats to his people, the happy glint in his eye disappears.
"They will kill the fish," he says of the government. "They will kill the environment. They will destroy everything. And it will mean that they want to kill us, too, as a people because we won't have anything left."
This is not an abstract threat. We're told of tribes throughout the Amazon (there are more than 200 in Brazil alone) are being slaughtered and driven off their land by ranchers, loggers and miners engaged in what's been called the "rape of the Amazon." An area twice the size of Colorado has been cut down in the Brazilian Amazon in the last 40 years.
The same thing that threatens the Indians threatens all of us. If the Amazon goes away, it will put the process of global warming (which scientists say is already creating stronger storms, heat waves and droughts) on steroids.
In his own way, one of the Enawene Nawe elders, a man named Kawaree, seems to understand this.
"If our land is destroyed," he tells us, pointing at me and my team, "we will die ... and you will die. .. and you will die. The only difference is you don't know it."
The Enawene Nawe are keenly aware of horror stories involving tribes in other parts of the jungle.
In fact, Survival International tells us about a tribe, called the Akunste, that is now down to its final six members.
We travel deeper into the Amazon to see for ourselves.
The Akuntsu live on a protected patch of jungle, completely surrounded by cattle ranchers. There's an outpost of government officials who live nearby full time, to protect the Indians.
One of these government officials takes us down the jungle path, past the Entry Prohibited signs, to the Akuntse village.
After an hour's walk, we see them. The final six.
They are incredibly friendly, embracing us and staring into our eyes. They ask me if I'm a doctor or a shaman.
There are four women left. Many of them are getting on in age. Genetically, it is virtually impossible for the Akuntse to survive. These six are all that's left of what was once a civilization with its own religion, culture and language.
Virtually no one outside the tribe speaks their language. The government official with us is actually the one who made first contact with this tribe in the mid-1990s. (He later shows us video of the encounter. The tribe members are so scared some of them are literally shaking.) From what he can piece together, ranchers massacred the tribe for their land. (The bullet wounds in the men corroborate that story.) Since no bodies have ever been found, no charges have been brought.
One of the men tells us he saw his parents shot before his eyes.
Another tells us he wants revenge on the whites who destroyed his tribe.
As the final members of the Akuntsu take us into their hut, the eldest male plays us a mournful song on his homemade flute. I realize that this is perhaps his most eloquent means of telling his story, and that what we're watching is a real-time human extinction.