Like Francis Ford Coppola’s Apocalypse Now (1979), The Embrace of the Serpent, directed by Colombian director Ciro Guerra (2015), may at first sight be interpreted as a cinematographic adaptation of Joseph Conrad’s novel Heart of Darkness (1899). However, Guerra’s film is based on the travel journals of two real-life naturalists and explorers: the German-born Theodor Koch-Grunberg and the American Richard Evans Schultes (although, in the film, the character inspired by Koch-Grunberg is called Theodor Von Martius, and various geographical and historical details about his life and death in the Amazon have been fictionalised). Guerra’s film presents a parallel narration of these explorers’ journeys into the Amazon jungle, in a quest for a sacred, mystical plant called yakruna. Evans Schultes (Brionne Davis) carries a copy of Von Martius’ (Jam Bijvoet) journal. These stories, separated by approximately three decades, are connected by the character Karamakate, who is the last surviving member of the Cohiuano tribe. As a young man, Karamakate (Nilbio Torres) guides Von Martius, who is looking for the yakruna because this plant is supposed to be the only cure for an illness that he is suffering (which is never fully disclosed). Then, as an old man – played by Antonio Bolivar- he guides Evans Schultes, who claims to be looking for the yakruna because he has lost his ability to dream.

In the following paragraphs, I study a selection of scenes from The Embrace of the Serpent, and compare them to different journalistic and literary works that relate to an episode known as the Rubber Holocaust (or Holocausto Cauchero). In this analysis, I will focus on three narrative elements, which are a common feature in the stories that survive from this period. These are: (a) the figure of the civilised explorer, who steps into the jungle with an adventurous (and somehow optimistic) spirit, which progressively deteriorates as he is affected by the conditions of the tropical climate, and as he witnesses the atrocities perpetrated by the agents of the rubber industry; (b) the flourishing of this industry as a major element of the globalised economy of the early twentieth century; and (c) the use of narcotic and hallucinogenic substances in these stories.

Romantic explorers lost in the jungle

The Embrace of the Serpent opens with a quote from Theodor Von Martius’ journal, which begins with the following sentence: “No me es posible saber si ya la infinita selva ha iniciado en mí el proceso que ha llevado a otros a la locura total e irremediable” (“I cannot know if the infinite jungle has begun in me the process that drove so many others to incurable madness”). This line could also be used to describe the process of obscure decadence that ultimately defines the personality of Kurtz from Heart of Darkness. However, in Conrad’s novel, this feeling is compiled in a simple exclamation: the horror. The jungles that surround the Amazon and Congo rivers were the final frontiers in the process of global exploration and European colonisation, which remains as one of the central pillars of the modern, capitalist societies of the present. The notion that we currently understand as civilisation was built upon the partly heroic and partly murderous efforts of countless adventurers who, for centuries, explored and conquered remote and ruthless ecosystems.

At the time of Koch-Grunberg’s exploration, the rubber industry in the Putumayo region (located around the north-western basin of the Amazon River) was controlled to a great extent by the Peruvian businessman and politician Julio César Arana. He was the major shareholder of the Peruvian Amazon Rubber Company, which in 1907 was registered as a British enterprise. In 1909, the American engineer Walter Hardenburg wrote a series of articles for Truth magazine, where he exposed the abuses against thousands of indigenous inhabitants, who either were murdered or died because of the cruel treatment they received from the rubber barons (or caucheros) that worked for the Arana House1. Hardenburg witnessed some of these crimes as he travelled through the region the year prior to the publication of his articles. During this period, he was held captive by the Arana House. A few years later, he compiled the memories of his journey, together with the report written by the (then) British Consul in the Brazilian city of Manaus: Sir Roger Casement, in a book titled The Putumayo: The Devil’s Paradise2.

One major element in all the jungle odysseys mentioned in this article, is the portrayal of rivers, not only as the main – and in many cases only – route that the adventurers in these stories found to travel into the jungle; but as omnipresent, god-like figures, whose temperaments determine the fate of powerless and unsuspecting mortals. In The Embrace of the Serpent, this is emphasised by the fact the most relevant transitions (when the film jumps from Von Martius to Evan Schulte’s storyline and vice versa) are done through detailed, immersive shots of the texture of the water.

The Embrace of the Serpent
In the film, the character Karamakate is the narrative instrument that links the separate time frames of Von Martius and Evans Schultes’ stories. Similarly, Sir Roger Casement proves to be the historical figure that connects the universes of Conrad’s Heart of Darkness and Guerra’s The Embrace of the Serpent. The novel The Dream of the Celt (2012) written by the 2010 Nobel laureate in literature Mario Vargas Llosa, presents a literary account of Casement’s life. In his travels across the Congolese and Amazonian jungles, Casement witnessed and denounced some of the abuses committed by the Belgian colonial authorities commanded by King Leopold II and by the foremen and overseers employed by Arana. The main victims of such abuses were the indigenous populations who extracted the latex from the rubber plants that grew in these major rainforests, which are located at similar latitudes, separated by the Atlantic Ocean. As the nations of Latin America step into their third century of republican history, artworks like The Dream of the Celt and The Embrace of the Serpent appear as timely reminders of this obscure episode, along with the novels La vorágine (or The Vortex) by Jose Eustasio Rivera (1924) and Toá by César Uribe Piedrahita (1933).

As Conrado Zuluaga explains3, prior to the emergence of Gabriel Garcia Marquez in the mid twentieth century, there were two novels that stood out amongst the literature produced in Colombia. The first is the novel Maria by Jorge Isaacs (1867), which tells a tragic story of youthful love, portrayed within a romantic landscape of the serene and fertile fields of the Cauca Valley. This novel remains as one of the most lucid samples of artistic propaganda in favour of that Western impulse of civilisation, embodied in institutions of a centralist and aristocratic nature: like the Catholic Church, multinational corporations and the given national and regional governments that ruled (and still rule) the nation from the comfort of cities like Bogota, Medellin or Cali. These institutions implanted a Euro-centrist model of progress that, despite the series of failures that constitute the republican history of this and the rest of the Latin American nations, it is still considered the one and only valid interpretation of this rather equivocal term.

The second of these works is La vorágine, which presents an expressionist portrait of that other Colombia: dark and consuming, mysterious and heretic. In the novel’s narrative, central character Arturo Cova ends up famished, sick and enslaved by agents of the rubber industry.

Much of the story of La vorágine, is driven by the violent and corrupt practices of the caucheros. These concerns echo a scene in The Embrace of the Serpent where Von Martius’ expedition -which includes the young Karamakate, the German naturalist and his loyal companion Manduca suddenly finds an improvised burial ground, with a series of wooden crosses that stand under a field of rubber trees. These trees have been recently punctured and, by the base of their trunks, there are jars collecting the flowing latex. In the previous scene, Manduca is helping Von Martius carry his luggage (which include several suitcases where the German explorer is carrying all his scientific equipment) as the expedition is forced to walk along the shore while travelling against the stream of a torrential river. This effort drives Manduca, who is wearing western clothes (unlike Karamakate who only wears a waistcloth and ornamental necklaces) to take off his shirt and expose the lacerations on his back. Seeing this, Karamakate asks him if they were inflicted by the rubber barons. Manduca confirms Karamakate’s assumption and tells the story of how he escaped from the caucheros who enslaved him. Later on, when Manduca sees the rubber trees that have been recently punctured, he is filled with rage and spills the latex out of the jars. As soon as this happens, a mutilated indigenous man steps into the scene, crying hysterically. He first tries to rescue the latex that Manduca has spilled and, not being able to do so, asks him to kill him. Manduca points at the man’s head with a rifle (that until this point was hidden from Karamakate, who strictly opposes the use of fire weapons) and is ready to shoot at the begging man, but his travel companions end up convincing him not do so.

Although considerably less famous than La vorágine, the novel Toá, by César Uribe Piedrahita, is another major (contemporary) artwork that denounced the abuses of the rubber industry. Like La vorágine, Toá was mostly inspired by the author’s personal experiences in the Amazon. In the case of La vorágine, in the early 1920s, author Jose Eustasio Rivera was appointed by the Colombian government as part of the commission that aimed to define the national border with Venezuela. However, in the middle of this journey, he decided to abandon the commission (although he would later rejoin it), frustrated by the lack of support from the Colombian government. Therefore, he travelled south, all the way to Brazil, and in this journey witnessed some of the crimes perpetrated by the rubber industry and was greatly influenced by the work of the Brazilian journalist, sociologist and engineer Euclides da Cunha 4.  A few years later, Toá author Uribe Piderahita, who graduated as a medical doctor from Harvard University in 1922, was appointed as the director of the National Institute of Hygiene. In this role, he also got to travel along the Amazon jungle and witnessed the abusive behaviour of the caucheros 5.

The main character in Toá is the young doctor Antonio de Orrantía (a semi-autobiographical character), who has been commissioned to travel to the Putumayo region. The purpose of his journey is to write a report for the Colombian government, about the working conditions in the rubber plantations on the Colombian side of the border. At the time, these lands were disputed by the nations of Perú, Colombia, Brazil and Ecuador 6. It is worth noting that both Arturo Cova and Antonio de Orrantía are lulled into the heart of the jungle by a woman. The figure of sexual impulses that intensify within the tropical environment of the jungle is not, however, a driving argument in The Embrace of the Serpent. This may be explained by the age of the explorers. Unlike Arturo Cova and Antonio de Orrantía, who were still young when they stepped into the Amazon, Von Martius was already an old man, while Evans Schultes appeared to be in his mid-forties. Another interpretation may relate to the distinction between international (or northern) and national (or criollo) explorers. Although, as Martinez-Pinzon 7 explains, the adventurers who came from the central and more civilised Andean regions (like Cova and De Orrantía) were also regarded as foreigners within the Amazonian region. For this reason, the literary characters created by Rivera and Uribe Piedrahita (inspired by their own experiences as civilised agents in a rough natural environment) made an effort to project an image of toughness and overt masculinity, situated against the prejudiced view of men from urban backgrounds, who were considered soft and delicate by their rural counterparts. Meanwhile, the international explorers from The Embrace of the Serpent projected an image of wisdom and temperance. When Von Martius meets the young Karamakate, Manduca introduces him as a wise man from a distant land. Then, the only reference to a romantic or sentimental relation occurs in the scene when he is dictating a love letter to his wife in Germany, which drives him to tears and, because of this, he becomes the object of the young Karamakate’s mockery.

The Embrace of the Serpent
The absence of overwhelming hormonal impulses that affect the behaviour of both Evans Schultes and Von Martius, may simply be explained by the fact Guerra did not want to include another conflicting element in what already is a rather complex narrative. However, this lack of a sexual drive can also be related to the forces that led them to explore the Amazonian heart of darkness. The German, who originally travelled to the jungle pursuing a scientific goal, went to look for the yakruna because he was afflicted by a strange illness, which could only be cured with this mystical plant. The American claimed to have a similar motivation: that is, to find the yakruna hoping that it would allow him to recover his lost ability to dream (although his real purpose, which is revealed towards the end of the film, responded to larger macroeconomic and political forces). Nonetheless, it would be naive to believe that factors like having a European (or North American) background and being on a mission that respond to higher interests would protect an explorer from the temptations of the tropics. Regarding this, one may take into account how, in The Dream of the Celt, Vargas Llosa refers to the romantic encounters that Roger Casements allegedly had with men from both the Congolese and Amazonian regions, which (as Vargas Llosa narrates it) he registered in his personal diary and were later used by the British government to further defame his character during his trial for treason.

The golden age of rubber

The flourishing and decay of the rubber industry in the Amazon comprises some of the most relevant episodes in the transition from the formal colonial order to the neo-colonial structure. First under the bipolar scheme of the Cold War and later under the neoliberal order that prevailed after the collapse of the Soviet Union, this transition has shaped the socioeconomic, environmental and political development of the world during the last century. In the following paragraphs, I present a contextualised analysis of this process, where I focus on the global, national and regional effects caused by a substance that got to be known as the white gold 8.

With the passage of time, and in part thanks to artworks like The Embrace of the Serpent, it has become evident that the two great wars of the first half of the twentieth century were part of the same historical chapter. Von Martius’ voyage, thus, may be presented as part of the prologue of this story, while Evans Schultes’ could be included in the epilogue. Von Martius’ trip occurs in 1909: in the midst of the golden age of rubber extraction in the Amazon. By the time of Evans Schultes journey (approximately three decades later) the white gold rush in South America had come to an end. This was caused by two main reasons: (a) the smuggling of rubber seeds by the British explorer (and so-called ‘bio pirate’) Henry Wickham -which allowed the British to grow the rubber plant in their colonies in Southeast Asia 9; and (b) the development of synthetic rubber (between 1909 and 1915) by the German chemical company Bayer 10.

Although the extraction of rubber from the rainforests of South and Central America began before the period of European colonisation (as, for example, can be seen in the case of the Ball Game that different Mesoamerican civilisations (including the Mayas) used to play with a ball made out of rubber 11) the golden age of rubber in the Amazon was originated by two (interconnected) economic impulses. These were (a) the arms race that broke down between the major political powers of the time; and (b) the invention of the automobile –and the effect that it had over urban development in the twentieth century 12. At this stage, it is important to remember that, beyond the feelings of fanatical nationalism that emerged during this period, the two World Wars were, above all, conflicts for natural resources. From a geographical perspective, one can mention three locations as the sources from where these impulses spawned. These were: the two largest European powers of the time – Britain and Germany  and the (then) emerging economic force of the United States,-which since (at least) the proclamation of the Monroe Doctrine in 1823, had been asserting their influence over Latin America (a region that it is still considered the US’s backyard).

Hence, the nationalities of the two explorers in The Embrace of the Serpent seem to be more than a circumstantial detail. Having said so, it is important to point out how Von Martius’ motives are not related to the Kaiser’s imperialistic desire. Instead, they may be attributed to the influence of other German naturalists, like Alexander Von Humboldt, who had previously explored these jungles.  Evans Schultes’ journey, on the other hand, turned out to hold a direct relation to the growing political and military power of the United States. Towards the end of the film, he reveals the real purpose of his trip which was to find a stem of the yakruna, extract it and ultimately grow it and use it to increase the purity of the rubber that the US industrial military complex was using in their fight against the Axis powers.

The Embrace of the Serpent
Just like the British Empire played a key role in the collapse of the rubber industry in South America, it was a (then) British citizen who prompted the downfall of the Arana House: the largest producer of rubber in the Putumayo region. As mentioned above, the trial against the Peruvian Amazon Company was (to a great extent) based on the reports written by the former British council in Manaus: Sir Roger Casement. Furthermore, it was thanks to Casement’s denunciations against the modern form of slavery suffered by the indigenous populations of the Congolese and Amazonian jungles that he was knighted. Therefore, there is a dark sense of irony in the fact that his experiences in Africa and South America led him to become an activist against British imperialism – and for the independence of Ireland – which in turn led him to seek an alliance with the Germans and ultimately be charged and executed for treason.

The rubber industry also influenced the establishment of the national borders, and the nationalistic feelings, of some of the young republics of South America. In the case of the Putumayo, it was the major cause of a series of conflicts that, for more than a century -between 1828 and 1933- erupted between Colombia and Peru 13. Such was the importance of these conflicts between Peru and Colombia, that it led  Gabriel Garcia Marquez and Mario Vargas Llosa (the only two Nobel laureates in literature from these nations) to plan a project to co-write a novel, which aimed to compile the Colombian and Peruvian reactions to the war that broke down between these two nations in 1932. This was, of course, before the infamous (and almost mythological) fight between these two authors, which kept them out of each other’s favour until Garcia Marquez’ death in 2014.

Within the plot of The Embrace of the Serpent, the decadence of the rubber industry in the Amazon Basin is most accurately portrayed in the scenes that take place in the rubber-collecting station of La Chorrera. This was the largest storage facility of the Peruvian Amazon Company. For this reason, it is a common reference in all the literary and journalistic works I have mentioned so far (i.e. La vorágine, Toá, The Dream of the Celt and The Putumayo: The Devil’s Paradise). In Guerra’s film, when Von Martius’ expedition arrives to La Chorrera, the station is ruled by a Capuchin priest, who has been left alone by the other members of his congregation. He is in charge of evangelising to a group of boys from the region. To fulfil this purpose, the priest often resorts to cruel and violent punishments (including flagellation) which he inflicts on the children in order to drive them away from what he considers the heretical behaviour they have inherited from their ancestors. Hence, when Karamakate meets them, he urges them to remember their heritage. This, in turn, leads to a conflict between the explorers and the Capuchin priest. When the old Karamakate returns to La Chorrera, while travelling together with Evans Schultes, the boys have grown into adults. Far from following the teachings that the Cohuiano shaman had shared during his first visit (when he liberated them from the yolk of the Capuchin priest), they are now following an obscure character that they call The Messiah. In a review of Guerra’s film published in The Guardian, Jordan Hoffman  describes this scene as “a surreal Apocalypse Now scenario”, where the (former) children’s society had “pieced together scraps of Catholicism and their forgotten indigenous culture creating, as a demoralised Karamakate puts it, the worst of two worlds.” 14

At first, The Messiah mistrusts the explorers, but then he accepts them as his guests, as he believes they are the Biblical Magi. For this reason, he asks Karamakate to cure his wife (a young indigenous woman) who is afflicted by an undisclosed illness. When The Messiah sees that her wife has been cured, he urges his congregation to celebrate. This, in turn, leads Karamakate to prepare and give them a strange hallucinogenic drink that drives them (even more) insane. Thus, the sequence ends with the two explorers leaving La Chorrera, as a delirious Messiah invites his disciples to eat him (in a bizarre, cannibalistic reference to the sacrament of the Holy Communion). This is one of many instances where Guerra uses the figure of mystical hallucinogenic substances as a narrative element in his story.

The narcotic factor

Beyond the symbolic and historic significance that the characters of The Embrace of the Serpent possess, the central element of the story is not a person but a plant. The yakruna has two fundamental characteristics that explain why foreign explorers like Von Martius and Evans Schultes were willing to risk their lives in order to find it. The first one, which drives the arguments presented in the previous section, is that it is supposed to increase the purity of the rubber latex. The second one is that it has both healing and hallucinogenic attributes.

Amongst the plants that the indigenous people of the Amazon have traditionally used for medicinal and spiritual purposes, the ayahuasca (or yage as it is commonly known in Colombia) has become quite popular because of its narcotic and cleansing (or laxative) effects. As Hill 15 explains, during the past 25 years, thousands of people from all over the world have learned about and experimented with the consumption of the mystical beverage, which local healers (or curanderos) prepare with this plant. The ayahuasca phenomenon does not only include the visits of travellers to Amazonian cities and towns in countries like Peru, Colombia, Ecuador or Brazil. It has also led to the organisation of drinking rituals in Andean cities like Bogota or Cusco, as well as other, more distant, destinations like Europe and the US 16.

There is a passage in La vorágine that explains the change of attitude toward this substance experienced during the past century. At the beginning of the novel’s second part, when Arturo and his travelling companions decide to journey into the heart of the Amazon jungle, they have an encounter with an indigenous tribe that invites them to participate in a drinking ritual. When this happens, El Pipa is the only one who accepts the invitation and drinks the yagé. The other travellers (Arturo, Franco and El Mulato Correa) are frightened to do so. Thus, by drinking the yagé, El Pipa, who is regarded as a shady, untrustworthy character, asserts his position as a reliable guide, who knows his way across the jungle and understands the customs of the local population.
As it has happened with peyote, another hallucinogenic substance traditionally used by the indigenous populations of Central and Northern Mexico, the popularisation of ayahuasca may also be interpreted as the desecration of a mystical element of the Amazonian culture. This, in turn, has led to cases like the death of Matthew Dawson-Clarke, a 24 year old New Zealander who in September 2015 died after consuming a tobacco tea in preparation for an ayahuasca ceremony. Following this story, Australian journalist Hamish McDonald 17 travelled to the Peruvian Amazon, where he found out about the booming ayahuasca industry, which, besides the rituals organised by traditional curanderos, also includes fake shamans and foreign (or gringo) operators, who organise drinking rituals for a growing number of tourists.

The Embrace of the Serpent

The figure of a civilised profanation of a mystical Amazonian plant is also an important narrative element in The Embrace of the Serpent. This is most evident in the scene that marks the end of Von Martius’ storyline. After they leave La Chorrera the expedition arrives to another station, where they find a group of men getting drunk with the yakruna. When the young Karamakate sees this, he feels enraged and decides to burn what they believe are the last existing stems of the plant. While he is burning the yakruna, the station is seized by a platoon of the Colombian army. Thus, Von Martius’ story ends in anger and desperation, with the image of the German explorer screaming at Karamakate, as his last hope to find a cure for his illness vanishes in the midst of the flames and the chaos provoked by the invasion of the Colombians.

Another narcotic and mystical plant showcased in Guerra’s film is the coca leaf. In the Amazon, this substance is most commonly consumed in the form known as mambe, which involves a preparation process where the coca leaf is pulverised and mixed with the ashes of the yarumo leaf. When the old Karamakate meets Evans Schultes, he tells the American he has become a chullachaqui, which means he has become some sort of spectre (like a photocopy of his former self), devoid of memories and feelings. Therefore, in a subsequent scene, where Evans Schultes reveals he is carrying a bunch of coca leaves, Karamakate confesses he has forgotten how to prepare the mambe and, for this reason, the American (who in his exploration has learned some of the traditional practices of the Amazonian culture) ends up showing him how to do so.

The recent story of the coca plant – and the way it has been targeted and demonised within the context of the so-called War on Drugs- is perhaps the most obvious example of the systematic desecration and prosecution of ancient indigenous knowledge in the American continent. The criminalisation of this and other plants used for the production of narcotic substances like marijuana and the poppy flower, which have marked the recent history of countries like Colombia, Afghanistan or The Philippines has also led to a series of environmental problems that are currently threatening the survival of precious ecosystems like the Amazon.

Beyond the use of chemical herbicides to eradicate coca plantations, the so-called War on Drugs has caused an even more serious problem: deforestation. The prosecution of coca fields has led growers to move their fields further and further into the jungle (Handwerk, 2011). This, combined with other commercial practices like cattle farming and mining has led to an ongoing massive loss of endemic flora and fauna, and the contamination of water sources, throughout the entire Amazonian rainforest. During the first decades of the twentieth century, when novels like La vorágine and Toá were originally published, despite the appalling crimes against the indigenous population and the ecosystems of the Amazon committed by the rubber barons, the magnificence of these jungles made it impossible for these authors to foresee a future where they might disappear. As Zuluaga (1988) explains, in La vorágine, Cova’s real enemy is not man and his “insatiable cruelty”, but the “jungle and its malignity” and that “vegetable world more insatiable and cruel than man himself” 18. Nonetheless, the current rate of deforestation and the pollution of water sources, seem to be proving that Rivera’s premise might not stand throughout the twenty-first century.

Despite all the negative elements: the violence and greed that, in many ways, define the universe of The Embrace of the Serpent, the film actually ends on a positive note. At the beginning, when the young Karamakate is introduced, he appears in the middle of a swarm of butterflies that fly around his body. Then, at the end of Evan Schulte’s story – after he reveals the real purpose of his journey and shows that, for this purpose, he is even willing to kill Karamakate (in order to steal the last existing steam of the yakruna and take it to the military forces of his country) – it is the American who is shown surrounded by butterflies. For this to happen, Evans Schultes has to go through a parallel journey (or rather a trip) on a mystical plane, which takes place when he drinks a potion that the old Cohiuano shaman prepares for him, with the last stem of the yakruna (which they find on top of a mountain that rises from the middle of the jungle). After drinking the potion, he recovers his ability to dream and this is represented with a series of colourful animations (which are the only bits in colour in an otherwise black and white film) that play along at the compass of an indigenous chant. When he wakes up on the following morning, Karamakate is gone. Thus, Evan Schultes steps down from the top of the mountain and, when he reaches the shore of the river, the film ends with the image of a swarm of butterflies surrounding the body of the American explorer. This imagery symbolises a glimmer of hope, which in turn is the ultimate moral left by this wonderful cinematographic fable. This is why, in my opinion, The Embrace of the Serpent is one of the most remarkable works of art produced in the twenty-first century. More than that, it is a necessary message for a generation that remains indifferent, as an ecosystem that may easily hold the origin of life, steadily disappears in front of our eyes.


  1. Survival International, 2016, Death in the Devil’s Paradise, in Survival International website,
  2. Hardenburg, W.E., 1913, The Putumayo: the devil’s paradise, travels in the Peruvian Amazon Region and an account of the atrocities committed upon the Indians therein, London: Fischer Unwin, in
  3. Zuluaga, C., 1988, Introduction to the 1988 edition of La vorágine, Arango Editores & El Áncora Editores, Bogotá, Colombia 1988
  4. Peña, I, José Eustasio Rivera, Procultura S.A., Bogotá, Colombia, 1989
  5. Cobo Borda, J.G., Introduction to the 1982 edition of Toá: Narraciones de Cauchería, Bolsilibros Bedout, Medellín, Colombia, 1982
  6. Wylie, L., Frontier Fictions: The Place of Amazonia in César Uribe Piedrahita’s Toá, in Bulletin of Spanish Studies, Volume LXXXVII, Number 7, 2010
  7. Martinez Pinzon, F., La voz de los árboles: fiebre, higiene y poesía en La vorágine, in Bulletin of Hispanic Studies, Volume 91, Issue 2, 2014
  8. Rogers, G.K., Yungjohann, J.C.,  Prance, G.T., White Gold, the Diary of a Rubber Cutter in the Amazon 1906-1916, in Annals of the Missouri Botanical Garden, 77: 605, 1990

  9. Peck, Ibid
  10. De Guzman, D., 2008, History of the synthetic rubber industry, in ICIS Chemical Business, 12 May 2008,
  11. Cartwright, M, 2013, The Ball Game of Mesoamerica, in Ancient History Encyclopedia,

  12. Barham and Coomes, 1994, Reinterpreting the Amazon Rubber Boom: Investment, the State, and Dutch Disease, in The Latin American Studies Association,
  13. Credencial Historia,, Las Guerras con el Peru, in Revista Credencial Historia, Edicion 191 Noviembre de 2005,
  14. Hoffman, J., 2016, Embrace of the Serpent review – dreamlike exploration of the Amazon’s imperialist pollution, in The Guardian, 17 February 2016,

  15. Hill, D., Peru’s ayahuasca industry booms as westerners search for alternative healing, in The Guardian, 07 June 2016,
  16. Levy, A., 2016, The Drug of Choice for the Age of Kale, in The New Yorker, 12 Sep. 2016,
  17. McDonald, H., 2017, Ayahuasca: Grieving parents issue warning to backpackers after son’s death on jungle drug retreat, in ABC News website,
  18. Zuluaga, p 11