Nature and the body

How four chambers, four one-way valves and a built-in electrical spark keep blood moving to the lungs and the body, beat after beat, from rest to a hill run in Iten.

How the cornea, the pupil and a living lens throw an upside-down picture onto the retina, and how river blindness, once common along West Africa's rivers, is being beaten.

How a dome of muscle and a cage of ribs pull air down your windpipe into 480 million tiny air sacs, where oxygen slips into the blood and carbon dioxide slips out, even on a dusty harmattan morning.

How a talking drum's gliding notes become tiny pushes on your eardrum, a lever of three little bones, and a ripple in the fluid of the cochlea that peaks in a different place for every pitch.

How a nerve cell fires: gates in its skin let salts rush in and out, the signal jumps along a fatty sheath, and a puff of chemicals makes a muscle kick, in a few thousandths of a second.

How two fist-sized kidneys filter all your blood dozens of times a day, take back almost everything good, and decide how much water to let go, on a 40 °C afternoon in Kano.

How a mouthful of pounded yam and egusi soup is chewed, squeezed, dissolved and soaked up on its long trip through one tube, from the mouth to the toilet.

How 27 small bones, the joints between them and long tendons pulled by muscles in the forearm let a drummer's fingers curl, grip, pinch and slap.

How a tiny parasite passes from a mosquito to a person and back again: the bite, the hidden week in the liver, the waves of fever in the blood, and the ways to break the cycle.

How a colony of honeybees runs a wax city: a queen laying eggs, workers raising brood, foragers bringing nectar and pollen from the flowers, a dance that gives directions, and wings that keep the hive cool.

How millions of blind insects build a tower of earth that farms fungus, guards a queen and breathes with the daily swing of sun and night, an idea Harare borrowed for a building.

How a little yellow bird tears grass into strips and knots hundreds of them into a hanging nest, with its door facing down and its tree over the water.

How a baobab stores tens of thousands of litres of water in its swollen trunk, drops its leaves to survive the dry season, opens its flowers at night for fruit bats, and can live for well over a thousand years.

How a leaf turns sunlight, water and carbon dioxide from the air into sugar, and breathes out the oxygen we live on, inside a tea leaf from the green hills of Kericho.

How a hard, dry cowpea seed drinks up the rain, splits open, sends down a root and pushes a hooked shoot up into the light, living on its own packed lunch until its first leaves can feed it.

How a white stork's wing works, from the arm bones inside it to the feathers that open and close, and how it rides rising warm air over Kenya's Rift Valley on its long journey from Europe.

How warm, wet air off Lake Victoria builds a cloud taller than Kilimanjaro, how ice inside it splits electric charge, and how lightning and thunder are born.

How the wind builds waves, why the water in them goes round in circles instead of travelling, why waves break on the beach, and how the Moon and the Sun pull the tides in and out.

How melted rock rises from deep under the East African Rift into the lava lake of Nyiragongo, and why its runny lava is such a danger to the city of Goma below.

A globe with one slice cut away: the thin crust, the slowly churning mantle, the liquid outer core that makes the magnetic field, the solid inner core, and the rift that is slowly splitting Africa in two.

How bones, muscles, nerves, heart, lungs and the organs that refuel them work together in one sprint, peeled back layer by layer on an anatomical model.