David Good's parents come from different countries - hardly unusual in the US where he was raised. But the 25-year-old's family is far from ordinary - while his father is American, his mother is a tribeswoman living in a remote part of the Amazon. Two decades after she left, David realised he had to find her.
After three days on the Orinoco River, David Good felt sick.
He had been eaten alive by the relentless biting gnats, he was tired and thirsty. The air was dank and humid. Fierce rays of sunlight bounced off the surface of the piranha-filled river as the 40-horsepower motor puttered and the launch pushed further upriver, deeper into the Amazon.
His stomach was a knot of apprehension - he had not slept the previous night at all.
He was not a natural traveller or explorer. The lawns and parks of eastern Pennsylvania were his habitat and this trip to the Venezuelan Amazon - in July 2011 - was his first outside the US since early childhood.
And yet - as everyone kept telling him - things were going well. Normally, travellers heading to the Orinoco headwaters had to stop at the Guajaribo Rapids, unload all their goods and haul them overland, before pulling the boats past the treacherous rocks by rope.
But it was raining heavily, off and on, and the river was higher than it had been for years. So Jacinto, a local indigenous man in charge of the tiller, was able to shoot the rapids, fiercely opening and closing the throttle, and steering the aluminium launch left and right of the rocks.
A few hours later, the boat turned a corner and suddenly shouts could be heard from the riverside. It could only be members of the Yanomami tribe - no white people lived so far upriver.
"They started screaming 'Motor! Motor!' because it's a big event - they don't hear motors too often," says David. He expected to see them with bows and arrows, but they had come unarmed. Word had gone ahead and the little boat was expected.
"I saw children and men and women on the riverbank just waiting for us to arrive. The women were all topless, the men had shirts and shorts on."
They had come from the village of Hasupuweteri. As David disembarked they began speaking rapidly in the Yanomami language and prodding him.
"I was just completely mobbed - all the women and the children gathered around me. I had so many hands all over me, pulling my ear, touching my nose, touching my hair," he recalls. At 5'5" (1.6m) David was used to being the smallest in a group, but he found himself nervously standing above the Yanomami, who are one of the world's shortest ethnic groups.
It was not the first time the people of Hasupuweteri had encountered nabuh - white people. But the nabuh they had met before had been missionaries, medics and anthropologists.
They knew that David was different - he was not looking to save their souls or their lives or ask strange questions. He was looking for his mother.
The Yanomami live in 200-250 villages in an area of 60,000 square miles (96,500 square kilometres) of jungle, sprawling across the Venezuela-Brazil border.
This is the region where the English adventurer Sir Walter Raleigh believed he would discover the untold riches of El Dorado - he launched two expeditions up the Orinoco in 1595 and 1616.
But in the 20th Century it was the Yanomami themselves who excited the imagination of scientists, journalists and artists from the developed world.
The Yanomami are a diverse group. They vary from relatively Westernised communities living close to church missions to villages which have no regular, direct contact with the outside world - although they will trade goods with villages that do.
Village life centres around a shapono - a large oval or round dwelling made out of wood. The entire village lives under the thatched roof of the shapono, cooking at separate family hearths and sleeping in hammocks. It is an arena for the rituals of trade and shamanism, for public rants and fights.
In 1968, the US anthropologist Napoleon Chagnon published his bestseller Yanomamo: The Fierce People. He described the tribe as being prone to petty disputes - usually over women - which escalate into wars between villages. He painted a picture of a world where chronic warfare, gang rape and murder were all facts of life.
It was as a graduate student of Chagnon's that David Good's father, Kenneth Good, first travelled to the Amazon in 1975. He travelled up the Orinoco past the Guajaribo Rapids, just as his son did 36 years later. He made his home in a little hut a short distance from the Hasupuweteri.
The plan was to stay for 15 months of fieldwork, measuring the animal protein intake of all the village members. This was to give Chagnon the data he needed to show his many critics that inter-village warfare was not related to the scarcity of food but stemmed from the drive to maximise reproductive success.
Good dutifully weighed every spider monkey and armadillo hunted by the tribe. They laughed at this strange display. If he explained to them he wanted to know how heavy an animal was, they would ask why he didn't just pick it up.
Towards the end of the 15 months, Good was becoming fluent in the Yanomami language, but he was also becoming dissatisfied with the narrow focus of his research brief.
"Measuring the animals and calculating the [protein] yields was insufficient," he later wrote. "Food gathering and intake had to be placed in the cultural context."
To get to know that context better he moved into the village shapono and observed as many of the daily rituals as he could. He went on treks, hunts and observed funeral rites. The Hasupuweteri called him shori - brother-in-law.
And he began to question the picture of the Yanomami that Chagnon had painted in his book.
"He thought that the Yanomami weren't as fierce as they were represented to be," says David Good. "And I think there's some substance to that, because my father ended up living there 12 years, and I couldn't imagine living 12 years with a savage, warlike, fierce people.
"So he became enamoured with the people. And he fell in love - he fell in love with my mum."
One day in 1978, the headman of the Hasupuweteri presented Good with a proposition.
"'Shori,' he said, 'you come here all the time to visit us and live with us… I've been thinking that you should have a wife. It isn't good for you to live alone,'" wrote Good in his 1991 memoir, Into the Heart: An Amazonian Love Story.
At first Good refused, but over time he came around to the idea. "I found myself thinking that maybe being married down here wouldn't be so horrendous after all: certainly it would be in accordance with their customs. In a way the idea even became attractive. After all, what better affirmation could there be of my integration with the Hasupuweteri?"
When he relented, the headman said, "Take Yarima. You like her. She's your wife."
Yarima, the headman's younger sister, was a vivacious young girl whom Good did indeed like. But he was 36 and Yarima wasn't older than 12.
There was no wedding ceremony and the match was not consummated - it was part of the Yanomami system of child betrothal, designed to shore up ties between families and prevent conflict. Yarima remained at her mother's hearth in the shapono. She occasionally brought Good his food, and he spent more time with her than with the other children.
But with every trip he made upriver, Good and Yarima became closer, and the theoretical tie between them felt more real. The villagers began to treat them as a married couple, and he thought of her more and more when he was away from the Amazon.
Unlike doctors or psychologists, there is no fixed code of practice barring relationships between anthropologists and the subjects of their research. There is much debate about whether sex is ever permissible in the field, either for enjoyment or study.
In Kenneth Good's case, it was not about research - he and Yarima developed a romantic attachment. She affectionately called him Big Forehead. He called her Bushika - Little One.
"Where do you draw the line - if there is one?" Good asks, in the documentary film Secrets of the Tribe. "Seeing as I have lived with them so long, that line fades away - there is no line."
Age is unknown amongst the Yanomami since they have no counting system (they only have words for "one", "two" and "many"). So in his memoir, Good is not specific about Yarima's age when they first had sex - he wrote that she was "about 15".
Yarima would have married another man if he had backed out of the betrothal. She had had her first period and so, in Yanomami culture, was of an age to settle with a husband and have a family.
"We're always trying to judge from our own perspective - an ethnocentric view," says David Good. "You have to keep in mind our ancestors didn't have to go through the maturation of adolescence that we have to go through in the modern world. Girls became married and started having children after their first period.
"And I always tell people, my father married my mother, but my mother also married my father. You know, it was a mutual agreement between two people and it's not like he snatched her away. This was a marriage based on love and romance and friendship."
The reason David was mobbed when he got off the boat on the Orinoco river was that he was famous. His father was remembered by the older Hasupuweteri, while the younger ones had grown up with stories of how Yarima and Kenneth's children had been raised in the world of the nabuh.
His mother, they told him, was at the village of Irokaiteri, 10 minutes further up the river. But he would not be permitted to complete the journey by boat - he was altogether too interesting.
Instead, he was taken to the village shapono. A young man called Mukashe was introduced to David as his half-brother. He ran off into the jungle to fetch their mother.
After 19 years, David would have to wait a few more hours to meet his mother.
David's father married into an Amazonian tribe, but it was impossible for him to live in the Amazon indefinitely.
He could not hunt and live like a true Yanomami tribesman. He needed extra food and medicine and special permits to remain in the region. This meant he had to continue academic work. But getting grants for fieldwork was difficult. Moreover, whenever he temporarily left, to make contact with academics or raise funds, Yarima was left in danger in the male-dominated Yanomami society.
On one of his trips downriver, when he had been held up for several months, she had been gang-raped, abducted and badly assaulted - her ear was ripped.
This precipitated Yarima's first contact with the modern world. Good took her to the town of Puerto Ayacucho, to get her ear attended to.
The short flight there was terrifying for Yarima - but the town itself was overwhelming. Upriver Yanomami pictured nabuhs living in villages much like their own, but with more nabuhs wearing their nabuh clothes. They had no idea that the forest ever came to an end, to be replaced by open spaces of cool hard ground and huge square houses.
"Every little aspect of this world was new and unique and strange to her," says David Good. "When you turn on a car, it kind of looks like an animal with the headlights - I heard stories she would hide behind a bush."
Another surprise awaited Yarima when she and Kenneth Good checked into a hotel - the mirror. She had never seen her full reflection before. "She freaked out," says David. "She hid behind a bed and my dad had to cover the mirror with blankets, just so she wouldn't be scared anymore."
Yarima adapted to some things very quickly.
She grasped the idea of using clothes for decoration and she enjoyed shopping. After overcoming her initial fears, she loved travelling by car, motorbike and aeroplane. Wondrous machines like elevators, Good wrote in his memoir, she accepted as examples of nabuh magic.
But other things were more difficult for her to grasp.
In the Amazon, food takes time to hunt or grow. It is never wasted or refused. "'Are you hungry?' is a question without meaning," wrote Good. "You might as well ask a person if he cared to breathe air." So the experience of a supermarket, in which an almost limitless amount of food sat, ready-picked and plucked, or of restaurants, where one was presented with a choice of what to eat, made the world feel upside down.
Yarima also feared the police. When she left the jungle, in the mid-80s, upriver Yanomami had heard of the police, but they pictured them as being an especially fierce tribe who all lived in the same village. Myths abounded about what they might do if they caught you - a common belief was that they ate stray Yanomami tribespeople.
In Caracas, Yarima warily observed the policemen and policewomen with their guns. Whenever she saw them her eyes searched for their police children and police babies.
The end of Kenneth and Yarima's Amazonian life together came in 1986, four years after they had consummated their marriage and eight years after their betrothal.
Kenneth had failed to secure the grants he needed to stay in the region and sank deeper and deeper into debt. On 17 October 1986, they took a Pan Am flight to New York.
Within a week they were married legally at Delaware County Courthouse. Nine days later, David was born on a hospital bed in Philadelphia.
His sister Vanessa was born just over a year afterwards on a banana leaf in the Amazon, while the family were on a trip back to Hasupuweteri. A baby brother, Daniel, came along three years later.
David has happy memories of his mother.
"I remember being with her - we used to have this little routine, where we'd stop by Dunkin' Donuts and get coffee and donuts," he says. He recalls her love of rollercoasters and how they would wrestle together. "I don't remember a sad or distressed mum, not at all," he says.
But life in New Jersey was not working out for Yarima. It wasn't the weather, food or modern technology but the absence of close human relations. The Yanomami day begins and ends in the shapono, open to relatives, friends, neighbours and enemies. But Yarima's day in the US began and ended in a closed box, cut off from society.
Other than Kenneth, no-one could communicate with Yarima in her own language and she had no means of speaking with her family back home.
In Hasupuweteri, the men disappeared for a few hours in the day to go hunting, but husbands did not disappear all day, every day. Yarima would spend the day at home or roaming the shopping malls. Good also gave her video and sound recordings from Hasupuweteri that she would listen to over and over.
Together with a co-writer, David Chanoff, Kenneth wrote his memoir, which was reviewed well, sold well and was translated into nine languages. He and Yarima became minor celebrities, appearing in People magazine three times. Articles appeared in newspapers with titles like Americanization Of A Stone Age Woman and Two Worlds: One Love.
A 1992 film with National Geographic charted the family's first visit back to the jungle for almost four years.
A five year-old David is seen squabbling with Vanessa over a heavy bunch of plantains, while baby Daniel is carried on Yarima's back in a sling attached to a headband, in the traditional Yanomami style.
The film contains some joyful moments of Yarima showing off her children to her sister and going crab hunting again in the creeks, but it also captures her despondency.
"They say I have become a nabuh," Yarima's translated voiceover tells us.
"I live in a place where I do not gather wood and no-one hunts. The women do not call me to go kill fish. Sometimes I get tired of being in the house, so I get angry with my husband. I go to the stores and look at clothing.
"It isn't like in the jungle. People are separate and alone. It must be that they do not like their mothers."
A few months after the making of the film, on another return trip to Hasupuweteri, Yarima decided to stay.
"I was up here with my sister in the United States and my mum and my brother were down there in the Amazon," recalls David. "And I remember my dad saying: 'Look, I'm going to go back to the jungle, and I'm going to go get your mum and I'm going to go get your brother and then I'll be back.'"
Kenneth returned to New Jersey with baby Daniel but no Yarima. David says that as the days turned into months, he slowly realised his mother wasn't coming back.
Yarima asked Kenneth to send Vanessa down to be raised in Hasupuweteri, but he refused. All three children were brought up in Rutherford, New Jersey, then Pennsylvania.
David came to resent his unusual family background.
"Growing up, I used to go to those annual anthropology meetings," he recalls. "And I could hear people saying, 'Oh, those are Yarima's kids!' Sort of like I was an experiment, you know?"
On one occasion, an anthropologist asked him what he wanted for Christmas. When David gave the standard reply for his age and era - a Nintendo games console - the woman was shocked.
"She's like, 'A Nintendo games console? You're just a typical American kid! I thought you would be different.' And that was ingrained on my mind for the rest of my life and helped fuel my hatred for my heritage. I just didn't want to have anything to do with it."
David tried to become that typical American kid. He played baseball and got a paper round. He told his father that if anyone asked, he was to say he was Hispanic, not Yanomami.
He did well at school, getting straight As and earning his place on the honour roll. But inside, he was a mess. He was consumed with hatred for the mother who had abandoned him - but he thought about her almost every day.
He started to drink. He broke up with a girlfriend of four years and dropped out of school.
"I felt like I was slipping away," he says. "And I knew what it was - it wasn't all to do with my mum's leaving, but that's what it stemmed from."
When he was about 21 he watched, for the first time, the National Geographic film that he had participated in when he was five. When he saw his mother's face and heard her speak, he broke down in floods of tears.
He was with a friend at the time. "She put it so simply. She said, 'You know, there's nothing really wrong with you. You lost your mum.'"
Shortly afterwards, David read his father's memoir and began to read up on Yanomami culture.
"I started having an understanding as to why she left and what she'd dealt with up here," he says. "I realised that… I don't think she could've made it up here, you know? As far as her being a Yanomami mother is concerned, teaching me Yanomami ways - it's virtually impossible."
When he was about 22, he felt a sudden yearning to reconnect with his Yanomami heritage.
In 2009, following some enquiries from his father, David was put in touch with Hortensia Caballero, an anthropologist at the Venezuelan Institute for Scientific Research who knew Yarima. She also knew David - she had met him on her first trip to the upper Orinoco, when he was a one-year-old baby.
After that, Caballero had met up with Yarima in the 90s and in 2001, but she had not seen Yarima since.
"He started telling me that he was very interested in finding out about his mother," Caballero says. "It was a very beautiful thing. David is a very sensitive guy - he has a great heart."
The opportunity to help David didn't come until February 2011. While Caballero was doing some workshops on land demarcation in Mavaca, a mission close to Yanomami country, she organised a quick detour up past the Guajaribo Rapids.
She found Yarima amongst the Irokaiteri. The community had splintered from the Hasupuweteri, and were in the middle of building a new shapono.
For Caballero, it is important that the Yanomami have some control over their interactions with nabuh. She wanted to make sure that the village was ready to welcome David before he made the trip.
"The people gathered together in the village they were building," she says. "Everybody spoke, especially the leaders. And then I asked Yarima, I told her she had to tell me her demands. She said, 'Yes, I really want to have David here.'"
Caballero asked the village to write a letter of invitation to David to help him get a permit to visit the protected area.
David added the letter to a file of photographs and news clippings of interviews with his parents from the 90s - evidence of who he was and of his right to visit the forest. He also included his Venezuelan passport, since foreigners are no longer permitted in protected areas. It was uncertain whether this document would stand up to close scrutiny, since the photo on the inside cover was of an 18-month-old baby (amazingly, it was indeed good enough for the military checkpoint in the Amazon).
His family watched as he made his final preparations for the trip (David says that his brother and sister have so far shown no strong desire to be reunited with their mother). "My sister laughed at me," he says. "She said, 'How are you going to make it? You're scared of a ladybug.'"
David thinks his father - by this time almost 70 - was worried for him, and frustrated that he couldn't be of more help after such a long break from the community. But he helped fund the trip, and he came with David to pick out the gifts to take to the village.
When he set off for the Amazon in July 2011, David knew only two Yanomami phrases, remembered from childhood. One was ya ohi - I'm hungry. They other was ya bos si shiti - my bum itches.
After David had been waiting for about three hours, Yarima burst into the Hasupuweteri shapono. She had run all the way there.
She was in her mid-40s, short, vigorous and strong. She had a basket around her head filled with roots she had gathered, which she threw to the ground while she tried to catch her breath. The village became hushed.
It had been two decades, but David recognised his mother.
"I knew it was her right away," he says. "I stood up and approached her. And then it just hit me - what do I do? Everything in me just wanted to hold her, to hug her, but that's not the Yanomami way of greeting people.
"So it was just this awkward encounter. I put my hand on her shoulder and she started trembling and crying. And I looked into her eyes and I just couldn't help but start crying myself."
"There was a silence," says Hortensia Caballero, who had come upriver with David. "What I remember was a silence. It was a very beautiful, intense moment. Of course all the women in the village, including me, found we had tears on our cheeks."
David started to speak softly in English. He said "I'm here, I'm finally here," and "I made it, I'm back" and "It's been so long".
Then he was flooded with memories of his mother from childhood, which he relayed to Caballero to translate into Spanish, so that Jacinto, the local boatman, could put them into Yanomami.
David did not ask his mother why she had left. Yarima asked if everyone was alive and well, but they did not discuss the past at all.
"I had this realisation," says David, "I don't really care what happened. I don't care about the controversy. I don't care what all these critics think. I don't care why she left. None of that matters to me now - I can leave that for everyone else to speculate. All I'm looking forward to is developing a bright future with my mum and my family and my people."
A video captured another emotional meeting, this time with his uncle (wrongly identified in the video as his grandfather). He had been headman while David's father had been in Hasupuweteri.
"He just grabbed me and was in my face - this emotion was just overcoming him," says David. "Of course, I didn't understand a word he was saying."
He later found out he was being given a Yanomami name which had come to his uncle in a vision - Anyopo-weh, which roughly translates as a way around an obstacle. He was also being thrust into Yanomami politics. His uncle was telling him that if anyone asked where he was from, he was to answer Irokaiteri, not the village that it had split away from, Hasupuweteri.
"They're really quick to establish your place in the village," he says. "It wasn't like my father's situation where he had to spend years gaining their trust to be accepted."
In fact, the Irokaiteri had a plan to cement David's place in the village. Soon after his meeting with his uncle, David's mother came up to him with two beautiful young girls.
"She said, 'This is your wife and this is your wife. You're going to have children with them.'"
David listened politely, thinking that perhaps "wife" was being used as a loose kinship term. The Yanomami classify relatives in a different way from Americans. For example, a maternal aunt is also addressed as "mother" and a paternal uncle as "father" (hence the mix-up over David's own uncle).
"I just sort of thought, you know, I have a brother there, a sister there, an uncle there - oh - and a wife here," he says. "But then, as I spent more time in the village it became evident to me that they were absolutely serious in becoming my wives."
Yarima began to push David to consummate marriages to the girls, who David thinks were in their late teens. On one occasion, while David was bathing in the river, the women ganged up on him, saying "Come on, we have to do this!" David instructed his translator to tell them he had a wife waiting for him back home - not true, but it made no difference to them anyway. He receded into the water, resisting their pleas.
The purpose of his visit to the jungle wasn't just to get closer to his mother, but to understand better what his father had gone through in the 1970s and 1980s.
Like his father before him, David found he was a constant source of amusement.
"The Yanomami have a particular sense of humour," says Caballero. "They always make jokes of everything and they love to tease, especially nabuhs."
The Yanomami have little concept of the very different lives of outsiders. Many put nabuhs' lack of practical and language skills down to the only thing it could be - stupidity.
"I would say Yanomami keye - I am Yanomami," says David. "And then I would fall down riverbanks, I'd trip over vines, I'd hit the wrong tree and all these biting ants would fall on my head… They just thought it was absolutely hilarious."
A couple of months after David first arrived at the village a big day came. He opened a small black box containing crackers and jam. These were emergency rations, in case he got sick of eating grub worms and termites - but he was in a culture where everything is shared.
"We had this sort of crackers and jam festival," he says. "Everyone was so happy, so content eating this food, which was for them so exotic."
Since his father's time, some of the Hasupuweteri have taken to wearing clothes and watches. While he was in the forest David gave away all his best clothes, thinking that a cheap pair of trousers or trainers meant nothing to him but would be treasured by the recipient of the gift.
When he returned to the mission downriver, his appearance had undergone a transformation.
"I looked so bad, so dirty, so raggedy that the missionary said: 'You're starting to look like a Yanomami,' and she gave me some clean clothes. It was kind of funny, that I was starting to become a Yanomami, needing donations."
On a separate visit to the mission - this time with his mother - David managed to establish a Skype connection with his father.
"My father said to my mum, 'You still look young and beautiful'. And she said, 'You look old!'"
Yarima was disturbed by Kenneth Good's baldness, since the Yanomami do not go bald. He had to run and get a baseball cap before they could continue the conversation.
David watched his father making his mother laugh - the two seemed to be getting on well.
"They just seemed so natural together," he says. "It was clear that my mum didn't want to talk about the past. She was telling my father that I was married and I had two wives. And she told him that she was going to take me back, I was going to be down here. She told him to tell me not to run away from my wives."
David spent three months in the Amazon, but he travelled around, making four separate visits to his mother. Yarima couldn't understand why he kept coming and going. David didn't try to explain that he was in the process of establishing a non-profit organisation and was conducting research across the region.
He knew when he left for the final time it would be hard.
"When you untie the knot that hangs your hammock - in their eyes that's the ultimate symbolic gesture that you're leaving. And as soon as I untied that knot, there were tears all over. It just moved me so much."
Yarima was devastated. It seems she really had believed David would settle in the village forever.
"I told her, 'I'll be back'. Unfortunately, it's been two years and a lot longer than I wanted it to be," he says.
He wants his organisation, called The Good Project, to help indigenous people find their way in the market economy, a process he sees as inevitable. He says that those who live in more Westernised villages near missions can struggle with their identity, just like he did.
"Today there are Yanomami who are becoming criollos - who are becoming Venezuelan. But just because they learn Spanish and are wearing clothes, they are no less Yanomami.
"Who am I? Am I Yanomami or am I nabuh? The Yanomami see me as a nabuh and the nabuh see me as Yanomami. I get caught in the middle.
"The person I am today is completely different from the person I was five years ago. I am now proud to be a Yanomami-American, I'm proud of my heritage. I love my mother and I look forward to being with her again and studying Yanomami ways.
"I want to create this bridge of friendship between the Yanomami and this world of the United States - and I want to bring to it the perspective of someone who is a family member.
"I am not an anthropologist, I'm not a politician, I'm not a missionary. I'm a brother and a son."