Nobody is entirely sure who first had the privilege of sitting on a toilet. Evidence of advanced plumbing systems in the ancient world abounds, but it's a strange, meandering path from antiquity to checking your inbox on the can.
Ancient cultures were surprisingly adept at moving water around in a way that kept people from having to walk through pools of their own feces. (That was really more of a Medieval European thing.) Cultures as far back as 3000 BC were flushing away their problems—so who you callin' primitive? Members of the Harrappa civilization in what is now India had toilets in their homes that drained into subterranean clay chambers. The residents of Skara Brae, a 31st century BC settlement in what's now Scotland, were even clever enough to use a draining system that exploited a nearby river to automatically sweep out their dirty business.
Fast forward a few thousand years, and the Romans were at the forefront of whooshing away waste. Massive aqueducts—engineering feats in themselves—brought massive volumes of fresh water into Roman cities. Rome's famed public baths were well stocked with urinal-style toilets that drained into its meticulous sewage system—though private commodes were a rarity reserved for elites.
With the fall of the Roman Empire, the rudimentary latrine (and notions of public sanitation) were widely lost in the west. If being chased down by roaming Visigoths was the worst thing that happened to you on a given day, at least you didn't step in an open cesspool or have a chamberpot emptied on your head from above. At that point, the highest end of the defecation spectrum was the use of ornamental chamber pots, disguised to look like a stack of books or decorative box. But the basic bedpan-deposit remained the status quo—a decidedly low-tech approach.
So who ended the stinky terror of the Dark Ages? Many historians believe credit is due to John Harrington, godson of Queen Elizabeth I. Harrington, a notorious royal troublemaker, published a satirical pamphlet in 1596 that served as both a social critique against his peers and a detailed instruction manual for the assembly of the first flush toilet. Talented guy! Harrington's toilet (found only in a few royal homes) included a mechanical valve to seal off the toilet, as well as a tank of water to flush it—basic components still used in our modern thrones. It wasn't until a couple of hundred years later, in 1775, that the first patent for the flushing toilet was granted to Scottish inventor Alexander Cummings. Cumming's coup was the addition of a constant pool of water in the toilet, so as to suppress, um, really, really bad smells.
From here, the toilet's path is a gradual mixture of small innovations—no great leap forward to the john we all know so dearly now. 18th century inventors refined the flushing mechanism and flow of water, with their 19th century successors adding better drainage and valves that (thankfully) leaked less. English plumber Thomas Crapper—a coincidence, I promise—did much to popularized the private flushing toilet in Europe, leading many to falsely believe he invented it. The only great toilet innovation of the 20th was that of integrating the water tank into the seat itself, rather than attaching it to a wall. Beyond that, a hundred years of slight tinkering haven't advanced the basic design beyond this point.
So where's the toilet heading? It's hard to say they're progressing much farther than where they are now—unless you consider lavish design concepts and Twitter integration progress. And frankly, if I have to choose between the Dark Ages and an era when people are tweeting their poop, I might choose the former.