Gombe Stream National Park, An excited whoop erupts from deep in the forest, boosted immediately by a dozen other voices, rising in volume and tempo and pitch to a frenzied shrieking crescendo. It is the famous ‘pant-hoot’ call: a bonding ritual that allows the participants to identify each other through their individual vocal stylisations. To the human listener, walking through the ancient forests of Gombe Stream, this spine-chilling outburst is also an indicator of imminent visual contact with man’s closest genetic relative: the chimpanzee.

Gombe is the smallest of Tanzania’s national parks: a fragile strip of chimpanzee habitat straddling the steep slopes and river valleys that hem in the sandy northern shore of Lake Tanganyika. Its chimpanzees – habituated to human visitors – were made famous by the pioneering work of Jane Goodall, who in 1960 founded a behavioural research program that now stands as the longest-running study of its kind in the world. The matriarch Fifi, the last surviving member of the original community, only three-years old when Goodall first set foot in Gombe, is still regularly seen by visitors.

Chimpanzees share about 98% of their genes with humans, and no scientific expertise is required to distinguish between the individual repertoires of pants, hoots and screams that define the celebrities, the powerbrokers, and the supporting characters. Perhaps you will see a flicker of understanding when you look into a chimp’s eyes, assessing you in return – a look of apparent recognition across the narrowest of species barriers.