Few places on Earth are as magical, mysterious, daunting or beautiful as the seething ribbon of biodiversity that lies beneath the Equator. That invisible line stretches 40,076 kilometers around the belly of the planet, linking an extraordinary profusion of landscapes, animals, plants and people in a sultry, ageless climate. It is a region of dense jungle and volcanoes, of sandy islands, snow-covered peaks and tropical coastlines. It is a region inhabited by people with incredibly diverse cultures, that are connected in mysterious ways, and of an astounding profusion of exotic creatures -- all beneath a broiling sun that offers no real seasons and brings, twice a year, at the spring and autumn equinox, the strange spectacle of days without shadows.

Most incredibly, the Equator is, literally, the font of all life. As we shall see, it is the original Eden, where we and all other life forms began. And it is also ground zero for global warming. In our era, the Sun overhead has grown pitiless, forcing all creatures to flee to the north or south. An Exodus from Eden has begun.

It is a journey that begins with the sunrise over Galapagos on the morning of the autumn equinox and follows the light through 360 degrees, east to west, over the course of one day. Like a magic traveller on the grandest expedition imaginable, our audience moves with us as we restlessly but deliberately circle the world, hour to hour, pausing rhythmically for encounters with an endless variety of fascinating people, cultures and beasts. This is an adventure through a world of giant tortoises and komodo dragons, bizarre butterflies and birds in a kaleidoscope of colours; a world where we encounter the last rhinos of Kenya, the mountain gorillas of the Rwenzoris and humpback whales nursing in the Pacific. Theirs are wildly varied stories of survival and competition in a welter of land- and seascapes that cover every possibility Earth has to offer: the hottest deserts, the coldest mountains, the angriest volcanoes, the tiniest islands, the calmest ripples of the deep Pacific and the raging tides of the icy Atlantic.

Collectively, their stories are the foundation of the epic tale of Eden. For the Equator is, quite literally, the birthplace of life on Earth. Science now understands that an astonishing 75 percent of all species on the planet originated on the Equator. Perhaps more incredible still, that wondrous garden has hardly changed since the dawn of life. The Equator is the only place on Earth where most original species never went extinct. It is for this reason that biologists refer to it as both the cradle of life and the museum of life. That is why the Equator is, beyond compare, the most biodiverse place on the planet. It is from here that life set out to colonize the rest of the planet. The most notable of Equatorial wanderers is, of course, humanity. Homo sapiens first arose in Africa’s Rift Valley, which straddles the Equator, and from there we spread out to colonize Earth. So it is not an exaggeration to assume that the Equator region is the Eden that all peoples remember deep in their cultural memory. It is the paradise where our story began.

On our journey through the Equatorial region, we are constantly reminded of that long history as we encounter the ancient marks of humanity carved into hillsides and etched into cave walls. We are reminded, also, that we still are all that we have ever been – for better or worse.

The zero latitude line is full of contrasts, and yet everywhere on the equator is united by a unique phenomenon: the switch from day to night never changes. It is always day for twelve hours and night for twelve hours – all year long. The start of spring and autumn is only heralded by the sun being vertically in the sky at noon. It is the only place on Earth where our world has no shadows on two days of the year. On around 20 March and 21 September the sun rises exactly in the east, follows the equator for twelve hours and then sets exactly in the west.

On these days, the ‘equinoxes’, the sun above the equator is located at the zenith at noon. For the ancient cultures of this region, this brief time without shadows was such an extraordinary one that they erected monuments on the equator. It continues to be a special moment to this day.