India, July 26 -- There's an uncanny resemblance between the hands drawn in a cave in Indonesia 10,000 years ago (see image at right) and the gesture we use to get our phones to take photos today. We have, for millennia, been attempting to record the moment. From art on stone, to glass plates, film and pixels, the journey to a world of #PicsOrItDidntHappen has been revolutionary. Here's how the earliest photos worked. By the early 1820s, French landowner Nicephore Niepce had invented the art of heliography. It used light to harden and darken the surface of metal plates coated with asphalt and placed inside a box with a small hole and lens. As the light hit the plate, the surface darkened to form an image. The "unexposed" parts were washed away with oil to reveal a scene crafted by light. These images were captured over several hours, but tended to be blurry. As he refined his methods, in 1826, Niepce took the world's first recognisable picture: of grainy rooftops and the countryside surrounding his estate. (See Image 3 above) Then Niepce died, in 1833, leaving his notes to the Parisian painter Louis Daguerre. For six years, Daguerre refined his friend's process until he had invented the daguerreotype, which used mercury vapour to render detailed images - in just 30 minutes. His Boulevard du Temple (1838; scan the QR code at left to see the image), taken on a seemingly deserted street in Paris, is considered the first photograph containing a human: a man pausing to have his shoes polished, who was captured by accident. (Most people moved in and out of these early landscapes too quickly to be captured.) That year, across the Atlantic, a 30-year-old American photographer in the US stood motionless and gazed at a makeshift camera for 15 minutes. Robert Cornelius had just taken the world's first selfie (Image 8 above). Portraits were now within reach. In a world of advances in printing, one man wondered: Could copies be possible? English scientist William Talbot invented the negative-to-positive paper process in 1840. Instead of a metal plate, he used silver iodide to make paper light-sensitive, and thus created the negative. Once a camera could be trusted to faithfully preserve a moment, it began to serve as witness to history. In the 1850s, Roger Fenton was commissioned by art dealership and prints publisher Thomas Agnew & Sons to document the Crimean War (1853-56; fought to keep Russia from expanding into the Ottoman empire). He travelled in a horse-drawn van fitted with a darkroom. Long exposure times meant there was little live combat recorded. An 1855 image titled The Valley of the Shadow of Death (Image 6 above), however, shows a ravine littered with cannonballs - and still has historians arguing about whether it was staged. Does a galloping horse lift all four hooves off the ground simultaneously? Legend has it English photographer Eadweard Muybridge was trying to settle a wager with a racehorse owner, when he shot his famous sequence of brief-exposure photographs, in 1878. (See Image 12) He lined a racetrack with boxy stereoscopic cameras and proved that the horse does indeed lift all hooves off the ground. Muybridge would later project those images at high speed, to create an illusion of movement so powerful that it laid the groundwork for cinema. The world's first point-and-shoot handheld camera was born a decade after the horse series, in 1888. It used a lens to project an image onto light-sensitive film, and required no skill or training to use. The device was invented by American entrepreneur George Eastman. He called it the Kodak. It came with preloaded paper-gelatin film. Once the 100-image roll had been used, customers mailed the camera to the company, which developed the pictures, reloaded the film and mailed it all back. By the 1880s, photography was being used as a tool for social reform. Images such as The Bandit's Roost (1888) by Danish-American photojournalist Jacob Riis, exposed the harsh realities of poverty largely hidden from public view. He used newly invented magnesium flash powder to illuminate the dark slums of New York, with their dank stairwells and overcrowded tenements. The images made headlines and eventually contributed to the passage of new affordable-housing laws. By the 1950s, the technology was helping turn people into brands. Elvis Presley's publicity team, for instance, used carefully curated press photos (posters, magazine covers and still from TV appearances) to craft his image as a star, in 1956. Six decades later, social media would hand the reins of such image-building to the star themselves. In 2017, Beyonce announced her second pregnancy with a single, Renaissance art-inspired portrait posted directly to Instagram. (See Image 5). It quickly became the most-liked photo on the platform. Instagram, of course, changed everything. Launched in 2010, its first-ever image, taken by co-founder Kevin Systrom, was a yellow-filter photograph of a dog near a taco cart in Mexico. It changed our ideas of what counted as documentation. In the collage above, trace how the lens has been present at humanity's seminal moments, from Earthrise in 1968 to the 9/11 attacks of 2001, India's 2011 World Cup win, American footballer Colin Kaepernick taking a knee in 2016, and the ongoing horrors of Gaza. Scan the QR code alongside for more: The Bandit's Roost view of New York; Atkins's cyanotypes; the horrors of the holocaust and the 2004 Indian Ocean tsunami. Meanwhile, in 2023, another first: An AI-generated picture (Image 10 above) won a photography prize. German artist Boris Eldagsen says he created it hoping to spark conversation about the use of such tools. When it won a Sony world photo prize anyway, he declined to accept. The women in the frame don't exist. It wasn't made using a camera. The jury thought that was an interesting use of the medium. He argues it isn't the same medium at all....