We know a little about the lives of Palaeolithic humans from their remains. We can connect with ancient forms distilled into artwork, over 30,000 years ago. The earthen colours of ochre are still painted on cave walls. Many rare depictions of beasts – cave lions, leopards and hyenas – still exist at sites around the world, like the 13-species display in Chauvet Cave, France. Lines, dots, hand prints and stencils were visible there too, where pigment was blown over spread fingers, pressed flat against the rock. Etched markings were even used to denote movement and primal battles were recorded too, like a pair of woolly rhinos, butting heads, with locked horns.

In North Africa, 10,000-year-old Neolithic paintings were also found, which depicted a mysterious quirk in our ancestors’ behaviour. These were markings from a pastoral stage in our evolution – still, with the same focus on wildlife and hominids in different poses. In the late 1920s, the Libyan Desert had been a staging ground for many dangerous expeditions. The thirsty expanse of the Sahara was mapped by explorers, including the Hungarian, László Almásy, and an Englishman, Robert Clayton, who flew around a sandstone plateau and surveyed the landscape in his two-seat Gypsy Moth. Motor car and camel journeys also snaked off into the wind-blown hinterland, drawn to the secrets of southwest Egypt. While Clayton and Almásy searched hidden valleys in Gilf Kebir, above the Libyan Desert.

In 1933, Almásy made a surreal discovery, often cited by water-lovers around the world. During the Frobenius expedition, Almásy stumbled upon a system of painted caves in a shaded inlet, within the plateau. This site, not far from a dried-up lake, would later be known as the Cave of Swimmers (referred to in Michael Ondaatje’s book: The English Patient). Inside, Almásy saw ancient pictographs, painted on the walls. Figures lay suspended, their arms outstretched and knees bent. It was easy to assume, looking at these freefalling bodies, that they were not falling at all – they were actually buoyant swimmers. Their limbs seemed to be in motion, mimicking a primitive style of doggy-paddle.

Almásy reported what he’d seen in his 1934 book: The Unknown Sahara. Later, more evidence revealed the wet and green surroundings of the African Humid Period, before a climatic change chased away the wildlife. We know it was once wet enough for a hippopotamus to show up for a wallow. There were bodies of water, kept secret under the Saharan sands, like the massive Eman Ghoneim lake, which was discovered in 2007 and supplied by nine tributaries in Northern Darfur, Sudan. Still, not everyone was convinced that our early ancestors swam. Some argued these cave paintings might depict souls afloat in the waters of Nun. Or, souls arranged in some kind of metaphysical ascension.