Articles and Papers

The not so silly Bili Ape

The Dark Continent may yet harbour secrets long after its opening up by Western explorers. Karl Shuker examines the evidence for an unknown species of great ape reported in the jungles of the Congo.

An aerial view of the forest and savannah landscape of the Bondo/Bili area.

Until very recently the possibility of an unknown form of great ape existing in some remote region of darkest Africa, yet still eluding scientific recognition, seemed ludicrous — but not any more. Thanks to some extraordinary discoveries, this remarkable prospect may soon be formally confirmed. Indeed, in stark (but also much-welcomed) contrast to the all-too-familiar cryptozoological scenario whereby reports of a mysterious creature are followed by searches that singularly fail to obtain tangible proof of its existence, the evidence collected in support of the Bali ape's reality is so plentiful and diverse as to be positively embarrassing — bearing in mind that its identity has still not been resolved.

This curious saga began over a century ago, when, in 1898, a Belgian army officer returned home from what is now the Democratic Republic of Congo with some gorilla skulls he had obtained near the village of Bili, on the Uele River in northern Congo's Bondo area — even though no other gorillas had been found within hundreds of miles of Bili before (or since). He donated them to Belgium's Congo Museum in Tervueren, where in due course they were examined by its curator, Henri Schouteden. He was sufficiently struck by their anatomical differences from other gorilla skulls as well as by their unique provenance (roughly halfway between the extreme edges of the western and eastern distribution of any gorilla populations) to classify them as a new subspecies of gorilla, which he dubbed Gorilla gorilla uellensis.

This video footage appears to show a female "mystery ape" with a baby.

Less convinced of their separate taxonomic status was mammalogist Dr Colin Groves, whose examination of these skulls in 1970 led him to announce that they were indistinguishable from western lowland gorillas. Thereafter, the Bili ape sank back into obscurity — until 1996, when Kenyan-based conservationist and wildlife photographer Karl Ammann, intrigued by its strange history and apparent disappearance, set out on the first of several Congolese quests to rediscover this mysterious primate.

And rediscover it he did, bringing back such compelling evidence for its presence that several other notable investigators launched their own searches, and returned with equally fascinating clues concerning the Bili ape's nature. Such researchers included primatologist Dr Shelly Williams from Maryland's Jane Goodall Institute, Dr Richard Wrangham from the Leakey Foundation, Dr Christophe Boesch frem Leipzig's Max Planck Institute for Evolutionary Anthropology, Dr Esteban Sarmiento from New York's American Museum of Natural History and Dr George Schaller from New York's Wildlife Conservation Society.

Large and elaborate ground nests located in riverbeds are only found north of the Uele River.

What makes their various finds so especially interesting is the ambivalent identity that they collectively yield for the Bili ape — because, uniquely, it deftly yet bemusingly combines characteristics of gorillas with those of chimpanzees, creating a shadowy anthropoid that is at once both yet neither. For instance: if the Bili ape is a chimpanzee, it is a veritable giant, because videos of living specimens and photographs of dead ones suggest a height of 5-6ft (1.5-1.8m) — a mighty stature supported by the discovery of enormous footprints, some measuring almost l4in (36cm) long, and therefore nearly 2in (5cm) longer even than those of the mountain gorilla! Also, very large ground nests constructed by Bili apes have been found that compare with those created by gorillas; normal chimps build smaller, tree-borne nests. Further evidence of the Bili ape's great size comes from local Bondo hunters, who distinguish two distinct apes — 'tree-beaters' (normal chimps) and 'lion-killers' (the Bili apes). The latter earn their name from their combined size and ferocity, a mix potent enough to ensure their terrestrial safety even in a jungle profusely populated by lions and leopards. Indeed, so unafraid of these great cats are the Bili apes that they hoot loudly when the moon rises and sets — an activity unknown among normal, smaller chimps, which avoid doing so in case they attract predators.

Equally noteworthy is the presence of a pronounced sagittal crest running along the top of one of the original skulls collected by the Belgian army officer and also on a Bili ape skull found by Ammann in 1996 — because this crest, normally an indication of powerful jaws as the jaw muscles are attached to it, is characteristic of gorillas, not of chimps. Conversely, the facial anatomy of the Bili skulls is decidedly chimp-like, not gorilla-like. In addition, hair samples taken from Bili ape ground nests have been shown to contain mitochondrial DNA similar to that of chimps, and the fruit-rich contents of examined faecal droppings is again consistent with a chimp identity although, perplexingly, the droppings themselves outwardly resemble those of gorillas.

Karl Ammann found this crested skull during his initial survey in 1996. The sagittal crest is not normally seen in chimpanzees but is characteristic of the male gorilla.

So what is the Bili ape — a gorilla-sized chimp (freak population?/new subspecies?/new species?), an aberrant form of gorilla (freak population?/new subspecies?/new species?) that has evolved certain chimp-like anatomical and behavioural characteristics, or even possibly a genuine chimpanzee-gorilla hybrid? No confirmed crossbreed of chimp and gorilla has ever been recorded, but the two species are sufficiently similar genetically to engender viable offspring. Mitochondrial DNA is passed down exclusively from the maternal parent, so if such interspecific matings are indeed occurring, they must involve female chimps and male gorillas, to explain why the mitochondrial DNA from the Bili ape samples is chimp-like.

Happily, however the mystery of the Bili ape's identity may soon be a mystery no longer. Since autumn 2003, full DNA analyses, including nuclear DNA (that will shed light on both the maternal and the paternal lineages of the Bili ape), have been taking place at Omaha's Henry Doorly Zoo, under the auspices of conservation geneticist Dr Ed Louis, and involving DNA comparisons with gorillas, chimps, and also bonobos (pygmy chimps). Ultimately, however a body, or at least some tissue and blood samples, will be needed for absolute verification of the Bili ape's true nature. Until then, the primate world waits, and wonders, and the Bili ape continues to haunt the Congo's Bondo rainforests, cheerfully oblivious to the stunning fact that it may yet be unmasked as the most sensational zoological discovery of the past hundred years. Not so silly in Bili after all.

From: Fortean Times [FT187], September 2004.