The species that made Kanapoi famous is Australopithecus anamensis, and this is its type-site - the place where the species was first defined for science. Its fossils here date to between 3.9 and 4.2 million years ago, making it one of the earliest known members of the human lineage. The most telling find was a shinbone. Its structure shows that A. anamensis already walked on two legs, settling a question that had haunted paleoanthropology: bipedalism, that defining human trait, came early - long before the large brain, the stone tools, or anything we would recognize as a face. Kanapoi has yielded the largest sample of this ancestor in eastern Africa, and many researchers consider it a likely forebear of the more famous Australopithecus afarensis, the species of the skeleton known as Lucy.

Hominins were only one thread in a crowded tapestry. The sediments at Kanapoi preserve a startling diversity of life from between 3.4 and 4.2 million years ago: fish, turtles, crocodiles, and other primates, alongside elephants, giraffes, rhinoceroses, hippos, pigs, rodents, ancient horses, and a full cast of grazers and predators. These remains were laid down along lake margins, rivers, and deltas, then sealed beneath layers of clay, silt, and volcanic ash. The rock itself records the changing water. Lower layers belong to an ancient lake; higher up, the deposits shift toward river channels, complete with fossil mussel reefs, before a final band of green claystone marks the return of standing water around 3.5 million years ago. Reading these layers is how scientists reconstruct the vanished landscape that A. anamensis called home.

The story of finding Kanapoi is its own saga of explorers and false starts. The Hungarian count Sámuel Teleki and the naval officer Ludwig von Höhnel became the first Europeans to reach the great lake in 1888, naming it Lake Rudolf after the Austro-Hungarian crown prince. A French expedition under Bourg de Bozas turned up rich fossil beds around the lake in 1902 and 1903, work that eventually drew the paleontologist Camille Arambourg to mount his Omo expeditions in the 1930s and 1940s. Louis Leakey and the team that would become the National Museums of Kenya probed the deposits in the 1940s, until the upheavals following the Second World War interrupted the work. Fossils were first recovered at Kanapoi itself in the 1960s, by a Harvard expedition - and the digging has continued, decade after decade, ever since.

Kanapoi is not an isolated marvel. It sits within the Turkana Basin, one of the richest hunting grounds for human origins on the planet, where the restless geology of the Rift has done paleontologists an extraordinary favor. As the earth pulled apart, it dropped the land into a deep basin that trapped sediment and the remains of whatever died there. Volcanic eruptions periodically dusted the ground with ash that can be dated with precision, giving each fossil a reliable age. Erosion now strips those buried layers back open, delivering the dead of deep time to the surface. Walk this scorched ground and you walk through a four-million-year archive - the long, patient story of how a small upright ape on a Kenyan lakeshore set out on the road to becoming us.