Beyond the southern valley of the Zambezi river in Zimbabwe where buffalo roam under bleached skies and tsetse flies linger on human flesh...
Beyond the scattering of bamboo huts where river beds dry up and dirt tracks end and the nearest police outpost is hundreds of miles away...
Beyond musiga trees stripped of bark, high up in the Chiruwa hills, you will at last hear the far-off rumbling of drums that belong to a tribe known as the ostrich people because of their V-shaped feet.
They are the Vadoma, or two-toed tribe, and they provide an unmatched example of genetic effects in a small population, for they have the condition known as ectrodactyly in which the middle three toes are absent.
In reference books you will search vainly for all but the most cursory details of their mysterious existence. Only a handful of men have encountered pure-bred members of the Vadoma. The first white man to do so was reportedly Charles Sutton, from Banstead, and now he has decided to share his remarkable story.
It is a story that begins in 1951 when he decided to emigrate from Surrey. Eyes shut, the young Charles aimed a pin at an atlas and found it embedded in southern Rhodesia. After making extensive enquiries, he was recruited by British South Africa police then posted to several rural stations.
It was while policing villages lit by flickering paraffin lamps in the Zambezi escarpment, where crimes ranged from theft of old shorts to murder, that Charles first heard about the Vadoma.
He was entranced. Eventually he came across a tribesman from Mozambique, with good local knowledge, and set off for the Chiruwa hills.
Recounting his first glimpse of the Vadoma, he says: "My guide, having proceeded ahead alone, returned to say that he had seen an old man sitting on the ground outside a very impoverished grass hut, surrounded by a number of clay pots which contained wild beer.
"From the light of a burning fire I could see astonishment written all over the man's face, especially looking at myself, as he later revealed that I was the first white man he had seen, and the first to come to that area."
The Vadoma speak Chikunda (Portuguese) and KoreKore, the language of the Mkorekore tribe. Their features are distinct from other African tribes, and their preoccupations are hunting, trapping wild animals, fishing and gathering wild fruits, roots and honey.
The nomadic bushmen are said to be intensely curious but to flee at the sight of an intruder. The elderly man Charles encountered was strangely becalmed. He turned out to be the headman of the tribe, and offered the visitors some beer. It was made from wild fruits, boiled continuously for seven days.
"When he gained our confidence as we drank, he beat a drum and several of the tribesmen appeared from nowhere - they just arrived on all sides, men, women and children," Charles said.
"Some of the women were carrying babies on their back; they were wearing nothing more than a type of loin cloth, and they were the Vadoma.
"During daylight the next morning a number of them came to see who we were. I could see one of them with only two toes on each foot, in a V-shape similar to an ostrich's foot - others had web-like feet."
The condition in the Vadoma is caused by a mutation of chromosome number seven. What they tell us is that a dominantly inherited genetic mutation survives when it has beneficial effects - the tribe's deformed feet may help with tree climbing.
If they had ventured forth - and expanded their gene pool - it is unlikely the Vadoma would have maintained ectrodactyly.
Charles says: "I asked the old man, Mhoramasaka, why he and his followers wanted to stay in the hills, away from civilisation, and not move to the villages near the Zambezi River.
"He said that they were quite contented with their life, and the way in which they were living - this being the only life they knew.
"They were missing out on village schools and clinics but this did not seem to deter them." And, as he finished this thought, the old man reached for his clay pot and took another gulp of wild beer.