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De Loys' Ape

A geologist claimed to have discovered a new species of great ape in Venezuela in the early 20th century.  

by Brian Dunning

Filed under Cryptozoology, Natural History, Urban Legends

Skeptoid Podcast #302
March 20, 2012
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de Loys' Ape
de Loys' Ape
Public domain photo

Today we're going to point the skeptical eye at one of the many cryptids known from some scant evidence. Our subject is De Loys' Ape, also called Ameranthropoides loysi. It is said to be an unknown species of primate, walking bipedally through the jungles of South America like a hominid, having no tail like an ape, but bearing the physical appearance of a monkey. It stands one and a half meters tall (four and a half feet) and is known primarily from a single photograph, taken by an oil expedition in Venezuela sometime around 1920.

The world had known that Venezuela held vast oil reserves since the first Spanish conquerors arrived in the 16th century, but it wasn't until the early 1900's that the first modern oil wells were drilled. Following World War I, oil prospecting exploded in Venezuela, such that by 1929 it was the world's largest oil exporting nation. In 1917, swiss geologist François de Loys was only one of countless Europeans brought in by the oil companies to prospect. De Loys spent the better part of four years in Venezuela, traveling about and prospecting. It was during this period that something happened that would make de Loys famous forever.

If you do an image search for de Loys' Ape or Ameranthropoides loysi, you'll find plenty of results. The creature is known by a single old black and white photograph showing a dead specimen, propped up with a stick under its chin, posed in a sitting position on a wooden crate. The face is ugly; quite eerily so, in fact. Physically, the animal looks a lot like a spider monkey, but is said to have been substantially larger than any known spider monkey. According to the story, de Loys and his prospecting party were in the jungle. De Loys himself told the tale in a 1929 issue of the Illustrated London News, which was reprinted in The Washington Post and titled "Found at Last - The First American":

...The jungle swished open, and a huge, dark, hairy body appeared out of the undergrowth, standing up clumsily, shaking with rage, grunting and roaring and panting as he came out onto us at the edge of the clearing. The sight was terrifying...

The beast jumped about in a frenzy, shrieking loudly and beating frantically his hairy chest with his own fists; then he wrenched off at one snap a limb of a tree and, wielding it as a man would a bludgeon, murderously made for me. I had to shoot.

My Winchester got the best of the situation. Riddled with bullets, the great body soon fell on the ground almost at my feet, and quivered for a while. He gathered his arms over his head as if to hide his face and, without a further groan, expired.

De Loys examined the creature and discovered that it had no tail, which is characteristic of great apes and not of monkeys. He found that it had 32 teeth, which also differs from New World monkeys who have 36. From there, most versions of the story state that de Loys and the survivors of his party tried to preserve the head and hide of the beast, but that both were lost or abandoned during the group's subsequent misadventures and clashes with natives.

Knowledge of de Loys' ape story might never have reached the public consciousness were it not for the involvement of the French anthropologist Georges Montandon. Montandon's interest was race, in fact he later developed a racial taxonomy to classify and categorize many different races of humans. I was not able to find how and when de Loys and Montandon first met, but 1929 is when he first saw de Loys' photograph and heard his tale. As de Loys told the story to the public in the newspapers, Montandon told the story to the scientific community. He published an article in the Journal de la Société des Américanistes, and presented a talk to the French Academy of Sciences. Montandon declared that de Loys' ape was a new species, and gave it the name Ameranthropoides loysi.

Ultimately, Montandon failed to convince scientists, and Ameranthropoides loysi never made it into any taxonomy other than his own. But the more visible campaign, the public campaign waged by de Loys himself, was quite successful. De Loys' ape has been a pinnacle of cryptozoology ever since, and is featured in virtually every book on the subject.

Coming into this topic, the question I wanted to answer was how we should go about determining the truth of de Loys' ape. As with most questions like this, it's quite possible that we can never know the answer for a certainty, but we can at least get a pretty good idea. The three most likely possibilities are that it truly is a new species; that it was deliberately hoaxed somewhere along the line; or the third and most common possibility, that it was an honest misidentification combined with trumped-up reporting. This is the null hypothesis: that nothing extraordinary is proved to have happened, either a deliberate hoax or an actual new discovery.

By digging deeper into the histories of François de Loys and Georges Montandon, we can hope to find some additional clues into their motivations. Montandon appears to have been an ordinary anthropologist, and de Loys an ordinary geologist; for both men, the de Loys' ape episode is the only extraordinary event in their histories. But when it happened, both seemed to go to extraordinary (and unscientific) lengths to prove the creature was a new discovery. In fact, in de Loys' newspaper report, he even stepped far enough outside his geology background to assert this:

Until my discovery of the American anthropoid, we could only imagine that man migrated to these shores. But now, in the light of this discovery, it is obvious that the failure of the otherwise well established principle of evolution when it was applied to America was due only to imperfect knowledge. The gap observed in America between monkey and man has been eliminated; the discovery of the Ameranthropoid has filled it.

Together with Montandon's aggressive promotion of the discovery in the scientific community, it does appear that both men went out of their way to prove something which wasn't well supported.

We also want to look at the actual primate population in South America to see if something like de Loys' ape might exist. So far, there are no other reports of anything like it. Some cryptozoologists have looked for local legends that might serve as a candidate match for de Loys' ape. One has been consistently mentioned, the didi. Most didi stories are reminiscent of Bigfoot; a large, hairy man-beast, often fierce or aggressive. There are virtually zero bibliographic references to the didi in the English language outside of the cryptozoology literature. It's certainly not a creature for which any empirical evidence exists, and thus it would be premature to characterize it as a possible explanation for de Loys' ape. In order to suggest that creature X matches creature Y, we have to know the characteristics of each. Didi stories differ widely from one another, so it's not logical to say that it has any established characteristics.

Another way we can evaluate de Loys' story is to look at all its details, and compare them with known history. Does his story pass fact checking? Does it fit well into the context of what was happening in Venezuela around 1920? The story does comes under suspicion. Notably, in his newspaper article, he claimed that no fewer than seventeen of his men had been killed by the arrows of native tribesmen, and that he himself had been shot in the thigh, and was still lame from this wound at the time. The place where he says he was attacked by the creatures is only about 15 kilometers west of La Fría, a city founded in 1853, capitol of the municipality in which oil was discovered. La Fría and other towns in the area are where the oil companies based their expeditions. In short, de Loys' location simply wasn't as remote as most modern retellers indicate. It's often said that he spent four years in the jungle, as if it was a single long expedition, but it wasn't. He spent four years making much shorter prospecting trips into the jungle.

How likely is it that a geology party would allow seventeen men to die without simply making the short return trip to La Fría or some other town? How likely is it that de Loys would have continued prospecting if any men had actually been violently killed on the job? The job simply wasn't worth men's lives, and at no time was de Loys in so remote a position that he could not easily have returned to civilization. In short, his story, as printed, is almost certainly a gross exaggeration in the style of the popular adventure fiction of the day.

There are also conflicting accounts of the famous photograph's history. In 1962, a Dr. Enrique Tejera read an account of de Loys' ape in a magazine called The Universal, and wrote to its author. The letter was published. Tejera said that he'd been in Venezuela with de Loys, working for the oil companies as a doctor, and the monkey photograph had a very different history. According to him, de Loys had been something of a practical joker, and had been given a local spider monkey called a Marimonda (white-fronted spider monkey, Ateles belzebuth), whose tail had become infected and been cut off. While they were in the city of Mene Grande in 1919, the monkey died, and that's when de Loys propped it up on the crate and took the photograph.

Of course we don't have any way to know which of these two stories is true (or even whether both are false), but the Tejera version is certainly more consistent with the photo. The monkey is sitting on a crate which would have to be very large if the monkey was as tall as de Loys said, and it's sitting in a clearing on a riverbank, among the stumps of plants that have obviously been cut away. Yet in de Loys' story, he and his men had only stopped there briefly to rinse off from "the day's struggle across the jungle", hardly consistent with well-prepared clearings and large heavy crates.

In conclusion, I'm satisfied that there's enough wrong with de Loys' story to assert that it was, at least in large part, fabricated; but I wouldn't say that this can be proved. Regarding Montandon's involvement, my own assessment is that he may or may not have been deliberately deceptive. The story he promoted was in line with his normal research, and he worked in a science that was in its adolescence if not its infancy; but he was willing to put his professional reputation on the line. I would probably camp in the jungles of Venezuela and not be worried about marauding ape-men; but I might just tip my turn-of-the-century flask in applause of François de Loys and his pet spider monkey with the infected tail.

By Brian Dunning

Please contact us with any corrections or feedback.


Cite this article:
Dunning, B. "De Loys' Ape." Skeptoid Podcast. Skeptoid Media, 20 Mar 2012. Web. 30 Nov 2015. <>


References & Further Reading

De Loys, F. "Found at Last - The First American." The Washington Post. 24 Nov. 1929, Newspaper: SM14.

Heuvelmans, B. On the Track of Unknown Animals. New York: Hill and Wang, 1959.

Lieuwen, E. Petroleum in Venezuela: A History. Berkeley: University of California Press, 1954. 18-32.

Montandon, G. La Race Les Races. Paris: Payot, 1933.

Silverberg, R. Scientists and Scoundrels: A Book of Hoaxes. New York: Crowell, 1965. 178-187.

Urbani, B., Viloria, A. Ameranthropoides loysi, Montandon 1929: the History of a Primatological Fraud. Buenos Aires: Libros en Red, 2008.


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