There is a room in the Nairobi National Museum that resembles a vault designed to showcase jewels, tucked behind bulletproof glass.
In a sense that's exactly what it is. Although the room contains little more than bones, these fragments are just as precious as diamonds and even more rare.
For example, there is a skull of Homo habilis ("handy man"), found in 1973 by the research team of Richard Leakey, a skull of Homo erectus ("upright man"), and also Nariokotome boy, the most complete early human skeleton ever discovered.
These bones are divergent lines of evolution - or the remains of our ancient ancestors. Almost all were found at Lake Turkana, Kenya.
There is a diorama in the room that shows Turkana 1.7 million years ago: a lush landscape of thick grasses and trees, complete with mannequin hominids.
It looks idyllic for Africa, like the sort of place you'd want to build a log cabin and go fishing for tilapia.
Cue a time-lapse to the current era, though: the diorama lake disappears, filling with sediment in the shadow of volcanic Mount Kulal.
Vegetation bakes to death on a horizon of dust. Eventually a river returns, trickling into a basin 250 kilometres long and 30 metres deep, but the idyll is destroyed. This is a harsh landscape now.
Nilotic people migrate in and through, including the legendary Masai. In 1888, some Europeans arrive and name it "Lake Rudolf" as an odd tribute to the Crown Prince of Austria (it is renamed in 1975).
The British use Turkana as a buffer zone against expansionist forces. The Kenyans follow suit and let it languish as a backwater - out of sight, out of mind, far from the green comfort of the Ngong Hills near the capital.
At the same time, Turkana, now the largest permanent desert lake in the world, evolves into one of the last great African destinations in popular imagination.
Like Timbuktu in Mali, it has the quality of fable. People often dream about what they can't have, and Turkana is on a knife's edge of accessibility: two days' driving from Nairobi for the independent traveller, through a world of nameless rifts and phantom riverbeds.
Partly its romance is due to the challenge, the stark beauty, and the palaeontological evidence of human evolution - Turkana has earned the nickname "cradle of mankind".
And partly it's due to the work of Alistair Graham and Peter Beard, who came in 1966 to study the lake's 14,000 crocodiles and described it as "awkward to get to, uncomfortable when reached, and dangerous when meddled with".
With an endorsement like that, who could resist a visit?
The day I turn up in the township of Loiyangalani, on the eastern shore of Lake Turkana, it is 44 degrees. So I walk straight past the Cold Drink Hotel (not so cold), the Hilton Hotel (a shack), and the Curio Shop (selling "abarait" wrist knives and an alarming wooden pillow that doubles as a stool) - straight into the bar.
You hardly expect to find a drinking hole in Loiyangalani, but nor do you expect to find a fading estate built over a hot spring and run by an eccentric grey-haired German named Wolfgang Deschler. Welcome to the Oasis Lodge.
"How long have you been here?" I ask Deschler. "Too long!" he barks, downing a gin and tonic. Later he coughs up a number - 32 years - but his reason for coming remains a stubborn twinkle in his eye.
This is a landscape perfect to bury secrets in, just as it's suffused with a hazy surrealism. In the Oasis Lodge, for example, a sign beneath a cobwebbed crocodile skin commemorates the crossing of Lake Turkana by a windsurfer, somehow in aid of the (failed) Turkana Tree Planting Project.
And the first local who speaks to me was once an extra in The Constant Gardener and seems more interested in discussing acting technique than Turkana culture.
"Ralph Fiennes!" Angelo croons, as we step past spherical houses that look like enormous coconuts. "Ralph Fiennes was here. He told me he could shed tears just like that." He snaps his fingers.
"What did you do?" I ask.
Angelo did not believe Fiennes. So the actor in this tiny town on the edge of nowhere took off his sunglasses and began to cry on cue.
"What!" Angelo claims to have said. "Have you been bitten by a scorpion? This is not a manly thing to do here!"
Speaking of things to do, Lake Turkana is the sort of place that requires so much effort to reach that it seems enough to bask on the cracked shore, celebrating your own fortitude.
But there is a small Desert Museum, its thatch roof balding on a hill near Loiyangalani, that's worth a closer look: the curator Abdikadir Kurewa describes it as "a platform to show how the local communities live in a place of such hardship and retain their cultural attributes".
Exhibits give a brief overview of pastoralism and what's left of the local wildlife; the museum also surveys nearby rock art sites such as Marti where, on a stony promontory high above the lake, I find ancient etchings of giraffes.
Still, the main attraction of Turkana is undoubtedly the people. Which is why the best time to visit is during the Lake Turkana Festival every May.
In a place that is almost entirely marginalised, both culturally and economically, a place that faces tremendous challenges - such as an Ethiopian dam that threatens the survival of the lake, a planned wind farm near Loiyangalani, drought so harsh it kills acacia trees, and inter-tribal warfare - here is something miraculous.
"The Lake Turkana Festival gives the participating communities an opportunity for cross-cultural interaction, co-operation and exchange," the literature says. The main goal, besides development, is "promoting peace and reconciliation".
Twelve groups from the region take part in full traditional garb, which turns the town into a dazzling bazaar. The highlight comes late on a stifling afternoon, when a thousand people gather on a dusty open field.
Each group huddles together, whipping itself into a frenzy of rhythmic chants and undulating bodies.
Then there is the dancing, each group taking its turn: the marital strut of the Konso, dressed in blinding patterned reds; the hypnotic jump routine of the Rendille; the ochre-coated Dassanech, waving their arms above their heads; the Borana with their "elephant dance" after all the women pray for rain.
When the Turkana people take centre stage the crowd surges forward and the festival takes on the euphoric feeling of a desert rave.
Lake Turkana is not an easy destination. But not all travel is passive - sometimes it takes work. And the experience is sobering.
The rewards usually make it worthwhile, though. You come up against the pain of a forgotten place trying to modernise without losing its essence, and between its problems, dancing through floodlights, you glimpse a young troupe of El Molo women in handsome grass skirts, smiling before an adoring crowd.
The last speaker of the El Molo language died in 1999. But the village is still here, open to visitors any time of year, its people preparing for the next festival - their uncertain future - just north of Loiyangalani, on the shore of Lake Turkana, that fabled place.
The writer travelled courtesy of the Kenya Tourist Board.
- Sydney Morning Herald