Discovering the Enigmatic Bili Ape

There have long been whispers of a fearsome primate unlike any other roaming the Congolese jungle; a lion-eating giant that uses fishing tools and howls at the moon. It came to be known as the Bili Ape or Bondo Ape, both references to local towns. But what is this enigmatic creature? A chimp-gorilla hybrid? Some sort of yeti? Or something entirely different?

Conflict and the difficulty of access kept scientists away for decades. But when the truth finally emerged, it was worth the wait, albeit for unexpected reasons. So read on as we demystify the Congo mystery ape.

In the northernmost province of Bas-Uele in the Democratic Republic of the Congo, a giant ape legend has been passed down through generations. It spoke of two types of apes in the jungle. The first were chimpanzees, nicknamed “tree beaters” for their tendency to nest safely high up in the branches. The second were referred to as “lion killers,” and if the legends were true, they very much deserved this moniker. Reaching up to 6.5 feet tall, fearless and formidable, they were said to be impervious to poison arrows, would howl at the moon, and, yes, eat lions.

It was only in the 20th century that the wider world became aware of stories of this Congo mystery ape. And it all started with some skulls in Belgium’s Royal Museum for Central Africa. Collected in 1908 near the town of Bili in the Belgian Congo, they were thought to belong to gorillas, perhaps even a new subspecies. The possibility of an undiscovered gorilla intrigued Swiss photographer Karl Ammann, and in 1996 he embarked on a mission to find them. Over the next two decades, other scientists followed, building up a picture of the Bili Ape, also known as the Bondo Ape. So, what were their findings?

Much of the work of scientists has been to debunk the myths surrounding the Bili Ape, many of which were reported as fact in the media. Some of the incorrect claims have included their supposed giant size, that they have flatter faces than other chimps with a prominent brow, known as a sagittal crest, and that female Bili Apes lacked the genital swelling seen in other chimpanzees. From a behavioural perspective, there was no evidence of Bili Apes hunting lions or howling at the moon. And then, there was the biggest question of them all: what species are Bili Apes?

There was much speculation that the Bondo mystery apes might be a new species of primate, perhaps a chimp-gorilla hybrid. This was largely due to the myths surrounding them, which created the impression that they had both chimp and gorilla characteristics. However, DNA analysis in the early 2000s revealed no such thing. Bili Apes are genetically identical to the Eastern Chimpanzee, classified as Pan troglodytes schweinfurthii, the same as other chimpanzees in the region. This finding was significant in demystifying the giant ape legend of the Congo mystery ape. But there was more. While their genes were the same as other chimps, they had a culture all of their own.

Field studies revealed that Bili Apes have unique, complex behaviours and habits distinct in several ways from other chimpanzee populations. These were found to be consistent across a vast area of approximately 2,700 square miles, indicating a shared culture within the population. These included:

• Ground Nesting: Unlike most chimpanzees that build nests in trees, Bili Apes are also known to construct nests on the ground, a behaviour uncommon among other chimpanzee populations. This gorilla-like nesting habit added to the mystery of the Bondo mystery apes.
• Advanced Tool Use: Bili Apes display sophisticated and selective tool use. They select sticks of varying lengths for different tasks, using long sticks to keep a safe distance from dangerous prey and shorter sticks when close interaction is needed.
• Dietary Habits: Bili Apes eat different types of termites than other chimpanzees, consuming species others ignore while ignoring those others favour. This selective diet suggests cultural differences within the group. Additionally, they’ve been documented hunting or scavenging unusual prey, including African giant snails.
• Foraging Techniques: They engage in smashing behaviours to access food, breaking open hard-shelled fruits, carrying termite mounds to rocks to break them apart, and possibly even smashing turtles for consumption.

Perhaps the most significant aspect of learning about the Bili Ape was the potential for insight into human evolution. In particular, it’s been posited that their complex use of tools echoes the early stages of human technological development. Documenting such behavioural diversity in great apes is seen as vital in studying the evolutionary origins of culture and technology in humans.

Sometimes, the truth can be more thrilling than legend. While the Bili Ape is not a new species, it demonstrates an extraordinary adaptation of an existing one. The Bili Ape, or Bondo Ape, embodies a unique blend of behaviours and cultural practices that continue to intrigue scientists and add fascinating layers to this giant ape legend.