Man seems to be able to live in a wider range of climates than any of the other primates. If you traverse one of the canons that have been carved deep into the soft volcanic soil of Ethiopia, you descend from the temperate surface of the plateau to a level at which the canon is habitable for monkeys; but, before you reach the bottom, you leave the monkey’s habitat behind. You descend to a depth at which the canon is too hot to hold monkeys; but there is no altitude, from temperate plateau to tropical river-bed, at which Ethiopia is not habitable for Man.
What species is he noticing? Ethiopia’s most famous monkeys are geladas, which live at high altitudes in the Ethiopian Highlands. They only sleep lower down. How much lower? Was he seeing them as he descended into the canyons in the early morning? And why are there normally no monkeys in temperate climates? Wikipedia:
“Geladas are found only in the high grassland of the deep gorges of the central Ethiopian plateau. They live in elevations 1,800-4,400 m asl [above sea level], using the cliffs for sleeping and montane grasslands for foraging. These grasslands have greatly spaced trees and also contain bushes and dense thickets. The highland areas where they live tend to be cooler and less arid than lowlands areas. [...] Geladas are the only primates that are primarily graminivores and grazers – grass blades make up to 90% of their diet. [...] At night, they sleep on the ledges of cliffs. At sunrise, they leave the cliffs and travel to the tops of the plateaus to feed and socialize. When morning ends, social activities tend to wane and the geladas primarily focus on foraging. They will travel during this time, as well. When evening arrives, geladas exhibit more social activities before descending to the cliffs to sleep.”
The highest peak is Ras Dashen, at 4,500 metres.
In another book, he describes a journey from Gondar to Aksum in the far north, in early 1964, crossing the Tekezé Gorge – and, I think, the Semien mountains (any connection with simian?), where gelada live in particularly large numbers. Gondar was an Ethiopian imperial capital from 1635 until the middle of the nineteenth century. The Kingdom of Aksum emerged as a power in the first century and lasted for a thousand years. It was never conquered by Moslems.
The Kingdom of Aksum, in the northern part of present-day Ethiopia, had been converted to Christianity about half way through the fourth century. In the sixth century, Aksum, like Nubia, adopted Monophysitism, and the East Roman Imperial Government had to acquiesce. Aksum commanded the sea-route between Egypt and India, and its ruler was in a position to intervene in the Yemen in the Roman Empire’s interest. Constantinople could not afford politically to quarrel with Aksum over a theological issue.
Ethiopian Christianity is now predominantly Oriental Orthodox, which is quasi-Monophysite.
The road, which has kept more or less on one level so far, now gives way, without warning, beneath our wheels. The plateau breaks off short, and the road zigzags down the side of an apparently bottomless ravine. The descent is so steep that the sections of the road immediately below us are out of sight. Down we go and down and down again. A few more twists and turns and we have entered the monkey-zone. At our approach, these amusing creatures leap over the parapet with their children on their backs and hurl themselves into the abyss – a less formidable ordeal for them than coming to close quarters with their human cousins. A few more twists and turns, and the monkey zone has been left behind us and above us. Monkeys seem to be less adaptable than human beings are to differences of climate. The plateau is too chilly for them; the bottoms of the gorges are too torrid. Only human beings can make themselves at home in both these climates, and in the monkey-zone as well.
Gelada family (is the old one on the way to going grey?); sleeping on a cliff
Mankind and Mother Earth, OUP, 1976, posthumous (first two passages)
Between Niger and Nile, OUP, 1965 (final passage)