Today marks the third installment in a series of articles by HumanProgress.org called Centers of Progress. Where does progress happen? The story of civilization is in many ways the story of the city. It is the city that has helped to create and define the modern world. This bi-weekly column will give a short overview of urban centers that were the sites of pivotal advances in culture, economics, politics, technology, etc.

Our third Center of Progress is Mohenjo-Daro, a city in today’s Pakistan that pioneered new standards of urban sanitation. The city is thought to have been constructed circa 2500 BC, although the site has been inhabited since around 3500 BC. Mohenjo-Daro was the largest urban center of the ancient Indus Valley civilization, covering nearly 500 acres, and one of the world’s earliest major cities.

The people of the Indus Valley civilization invented new water supply and sanitation devices that were the first of their kind. They included piping and a complex sewage system. Tunnels under Mohenjo-Daro carried the city’s waste to a nearby estuary. Almost all of the city’s houses had indoor baths and latrines with drains, and the city also showed its dedication to cleanliness with a large public bathhouse used for ritual bathing. National Geographic has opined that their civilization enjoyed the “ancient world’s best plumbing,” in some ways surpassing even the plumbing system that the Roman civilization would later create.

Ever since humanity gave up hunting and gathering to live in permanent settlements, our species has faced health challenges related to hygiene and the proper disposal of waste. Since the advent of cities, humanity has been vulnerable to rapidly spreading illnesses, because disease propagates more easily in concentrated populations. That is particularly true without adequate sanitation, and water-borne illnesses—such as cholera, diarrhea, dysentery, hepatitis A, typhoid, and various gastrointestinal diseases—were once a common cause of death.

Advances in sanitation have allowed people to live near one another in cities with less risk to their health than in the past. In particular, safe disposal of effluent to spare the water supply from contamination has proved to be a truly game-changing innovation. It has been argued that plumbers are the unsung heroes of civilization.

Today, Mohenjo-Daro is a striking archaeological site in the Sindh province of Pakistan. The site’s name means “Mound of the Dead” in Sindhi. Only part of the ancient city has been excavated and much of it remains hidden. Mohenjo-Daro has been designated as a UNESCO World Heritage site. Located on the right bank of the Indus River, Mohenjo-Daro is the most impressive of the ruined cities remaining from the Indus Valley Civilization. Mohenjo-Daro’s surviving structures are made of bricks fashioned from red sand, clay, and stones, lending the ruins a ruddy hue.

The Indus Valley civilization arose in the floodplains of the Indus and Sarasvati rivers in what is now northwest India and Pakistan, around 5000 years ago. The rivers flooded twice a year in a predictable manner, making the land fertile and allowing the Indus people to farm everything from cotton to dates to support their growing population.

Their prosperity also flowed from conflict avoidance and from their vast trade networks. They established one of the first long-distance trade relationships in the world by exchanging goods with the Mesopotamians located nearly two thousand miles to the west, as early as 3000 BC. Indus exports included spices such as clove heads, luxury goods like carnelian beads artfully etched with acid, and possibly even livestock such as water buffaloes. Their imports from the Mesopotamians included textiles and various artistic motifs and legends⁠—including aspects of the legend that would come to be known as the Epic of Gilgamesh⁠. The Indus people also had what is thought to be a written language, now called the Indus Script, which has yet to be deciphered by scholars.

If you could have visited Mohenjo-Daro in its heyday, you would have seen an orderly city of dense, multistoried homes with flat roofs fashioned out of uniformly sized bricks, standing along a grid of perpendicular streets. The grander houses had up to twelve rooms. You would have seen people gathering water, in decorated pottery jugs, from the numerous public wells and chatting, perhaps discussing art. Archeological evidence suggests that Mohenjo-Daro’s residents enjoyed art forms ranging from metal sculpture to dance. You may have observed children playing games, including games with dice, which many historians believe that the Indus people invented.

The city’s population may have peaked at around 40,000 people, similar to the population of Annapolis, Maryland, today. The men probably wore a cloth around their waist, perhaps gathered in a way that resembles modern dhoti pants, while the women wore longer skirts or robes. Wealthy people of both sexes wore jewelry with ivory, lapis, carnelian, and gold beads, as well as elaborate hairstyles and headdresses.

Walking through the city, you would have observed that Mohenjo-Daro had no grand temples, palaces, monuments or royal tombs. The society of Mohenjo-Daro seems to have been far less hierarchical than the cities of the Mesopotamians with whom the former traded. The people in Mohenjo-Daro may have had no king or, if they had one, he had only little authority. The lack of any royal structures certainly suggests the absence of a powerful ruler, although it remains unknown what kind of system governed the city.

Instead of a palace, the largest structure in the city was an immense, elevated public bathhouse. The Great Bath of Mohenjo-Daro measured almost 900 square feet, with a maximum depth of around 8 feet. It was constructed of fine brickwork, with a pool floor made of three layers: sawed brick set in gypsum mortar, then bitumen sealer, followed by another layer of sawed brick and gypsum mortar.

The status of the bathhouse as the city’s biggest and most prominent structure suggests that the people of Mohenjo-Daro highly valued cleanliness. Their entire ideology may have been based on cleanliness, according to historian Gregory Possehl of the University of Pennsylvania.

The bathhouse may have been a sacred place, and scholars believe that it was likely used for ritual bathing. The people did not need to use the bathhouse for everyday washing, because the houses of the city each had what was then a remarkable, groundbreaking feature: practically every home in the city, from the largest to the humblest, had a washroom.

These rooms were typically small, and square or rectangular in shape. In each washroom, the brick pavement floor was carefully built to slope toward a corner containing a simple latrine and drain, as well as a drained washing area. The slanted floors helped to ensure proper drainage, and the bricks were set tightly together to prevent leaking. Around each drain-hole the bricks were so meticulously rubbed down and fitted together that the joints were nearly invisible. In some cases, the bricks were overlaid on a bed of pottery debris to further bolster the floor’s resistance to leaks.

Homes with washrooms on upper floors were fitted with vertical terracotta pipes that carried effluent down to the street-level. The pipes of fired clay were joined together with tar to make them watertight. The Indus were the first people to have indoor plumbing, perhaps as early as 3000 BC. The pipes were positioned so that wastewater flowed down into the drain ditches that ran along every avenue in the city, and then into underground tunnels. Thanks to the invention of drain ditches, the cleanliness of the city’s streets was remarkable for the ancient world.

As the city’s population grew and the amount of waste it processed increased, the people kept their drain ditches functional by raising the brick walls alongside the former—to prevent effluent overflow into the streets. Archeological evidence suggests that the walls grew gradually in size to meet the city’s needs. The ditches and connected underground sewage tunnels carried waste away from the city, protecting its well-water supply from contamination.

Just like modern washrooms, the washrooms of Mohenjo-Daro were used for multiple personal hygiene activities, including bathing. Surviving artifacts suggest that the Indus poured pottery jugs of water over themselves to shower, and utilized clay scrapers similar to Greco-Roman strigils to cleanse themselves. In these rooms they also used pottery rasp tools to remove cuticles and shape their nails. Some washroom ruins contain what may be oil residue, suggesting that the washroom was also where Mohenjo-Daro’s residents moisturized their skin with oils.

Some traditions appear to be timeless. For example, evidence suggests that Mohenjo-Daro’s children played with bath toys just like today’s children. Instead of rubber ducks and plastic boats, their toy figurines were made of pottery. “[T]o judge from the number of pottery models that have been found in the drains, it would seem that the childish habit of taking play-things into the bath has persisted for thousands of years,” according to the British archeologist Ernest Mackay, who led the excavation of Mohenjo-Daro in the 1920s and 1930s.

Children were arguably the greatest beneficiaries of Mohenjo-Daro’s dedication to hygiene, although the city’s washrooms and sewage system were essential to the health of all of its people. While it can be hard to remember for those of us lucky enough to be able to take modern sanitation for granted, standards of hygiene throughout most of human history have been appalling. Associated illnesses were responsible for high rates of mortality, especially among children.

Mohenjo-Daro’s advanced plumbing serves as a reminder that progress is not steady or linear. Many people who lived thousands of years later coped with conditions far less hygienic than those enjoyed by Mohenjo-Daro’s people in the 3rd millennium BC.

It was not until the 19th century that urban sanitation became widespread. Those advances, along with the discovery of the germ theory of disease, are the primary reasons for the dramatic rise in human life expectancy, according to Nobel Prize–winning economist Angus Deaton. While more people now enjoy proper sanitation than at any other time in history, even today, in poor areas of the world, far too many people contend with inadequate sanitation and accompanying diseases.

Mohenjo-Daro is thought to have been gradually abandoned almost four thousand years ago, when the Indus river shifted its course and farmers could no longer rely upon it to irrigate their crops. Today, Mohenjo-Daro is best-known as the largest remnant of the enigmatic Indus Valley civilization. Because the Indus people’s writing system is currently unreadable, many aspects of that civilization remain a mystery. The religion and seemingly kingless government system of Mohenjo-Daro are unknown, as are the reasons for the Indus Valley civilization’s ultimate demise.

For developing plumbing and wastewater management, Mohenjo-Daro has earned its place as our third Center of Progress. Without washrooms and sewage systems, our lives would be far shorter and less hygienic.

Most of us take modern restrooms for granted, but proper sanitation is a relatively modern phenomenon and is still far too rare in the poorest regions of the world.

The need to keep human and animal waste away from human contact may seem obvious today, but for millennia that was not the case. Before the emergence of the germ theory of disease, and the subsequent public health campaigns and construction of adequate sanitation infrastructure in most of the world, people and waste commingled – with catastrophic results.

Countless millions of people got sick or died from diseases such as diarrhoea, ascariasis (a type of intestinal worm infection), cholera, hepatitis, trachoma, polio, schistosomiasis and so on.

In due deference to our ancestors, it has to be noted that some cultures, such as ancient Rome, paid due attention to cleanliness. The Romans built numerous public baths, which were accessible even to the very poor for a nominal fee, and a sophisticated system of sewers that enabled Rome to grow and reach a population of over 1 million people around the start of the first millennium. That feat would not be replicated in Europe until London and Paris in the 19th century.

In general, however, standards of hygiene tended to be very poor. A typical urban dwelling had a cesspit underneath the house or next to it. That’s where human and kitchen waste accumulated and fermented. Inadequate drainage, irregular emptying and heavy rains could make the cesspit overflow and seep into the house. While discouraged by the city authorities, people often emptied their chamber pots into the streets below.

As Johan Norbeg of the Cato Institute wrote in his 2016 book Progress: Ten Reasons to Look Forward to the Future, “When pedestrians heard the shout of ‘Gardyloo!’ they ran for cover. This phrase, taken from the French for ‘Look out for the water,’ was your only warning that someone was about to throw their waste out of the window.”

In rural areas, people lived with their animals, including chickens and cows, and used both animal and human waste to fertilise their crops – an extremely dangerous practice compounded by the fact that people could go throughout much of their lives without ever washing their hands. That led to epidemics of disease as well as other unsavoury consequences.

The Jews, who sometimes died at lower rates than the rest of the populace thanks to the frequent washing of hands that is prescribed by Judaism, were often accused of witchcraft, persecuted and even killed.

The Black Death, which killed between 30 and 60 per cent of the European population in the 14th century, complicated matters further. According to some medical experts of the day, “once heat and water created openings (pores) through the skin, the plague could easily invade the entire body.” As such, even the rich and powerful tended to avoid bathing. Elizabeth I took a bath once a month, “whether she needed it or not,” but her successor, James I, only washed his fingers.

The Journal de la santé, which was kept for Louis XIV by his doctors from infancy until a few years before he died, described the king’s daily life in microscopic detail, but mentioned bathing only once. His magnificent palace of Versailles had no proper waste facilities and people relieved themselves where they stood – in the hallways, behind the curtains and in the gardens.

One 18th century observer noted that Versailles was “the receptacle of all of humanity’s horrors – the passageways, corridors and courtyards are filled with urine and faecal matter.” All that filth was an excellent breeding ground for vermin and disease that periodically decimated the rich and poor alike.

Today, poor sanitation is mostly limited to very poor countries. In sub-Saharan Africa, for example, a mere 30 percent of the population had access to improved sanitation facilities in 2015. That was an improvement on 1990, when only 24 percent did. In other parts of the world, progress was much faster.

In South Asia, which includes very populous countries like India and Bangladesh, the share of the population with access to improved sanitation rose from 20 to 45 percent over the same time period. Globally, it increased from 53 to 68 percent. That should only improve with Prime Minister Modi’s ‘Clean India’ project to build some 111 million new toilets in the space of just five years.

The United Nations’ aim of ending open defecation by 2030 seems quite optimistic for regions like sub-Saharan Africa and South Asia, but there is no apparent reason why East Asia, Latin America and the Middle East should not be able to reach the European level of 93 percent or even the North American level of 100 percent by 2030.

As in so many areas of human development, what was once the preserve of the rich West is now becoming commonplace all over the world, helping ever more people live richer, healthier, more hygienic lives.

This first appeared in CapX.

Increasing urbanization may not sound like a particularly positive and newsworthy trend. In fact, cities are the engines of human liberation and economic growth. Urbanization is also good for the planet, for people in the cities have a smaller environmental footprint than people in the countryside. As such, it should be welcomed and encouraged.

Traditionally, between 80 percent and 90 percent of humanity lived in rural areas and worked in agriculture. As late as 1900, 40 percent of Americans, to give just one example, worked on farms. Today, less than 2 percent do. Prior to mechanization, farm work was physically exhausting and poorly paid, which helps to explain why people started to move from the countryside to the cities. At first, most found employment in manufacturing. Today, they tend to occupy better paid and physically less strenuous jobs in the service sector.

In the past, cities were the engines of liberation. In Medieval Europe, for example, serfs who escaped from their masters and lived in a city for “a year and a day” became free from servitude. Hence the German saying, “Stadtluft macht frei” or “city air makes you free.” Cities also offered better schools, leading to higher levels of literacy and political consciousness and, in time, democratization.

At first, cities were even less sanitary than the countryside. Unprepared for the huge influx of people from the countryside, they could not cope with overcrowding and the spread of contagious diseases. Over time, urban infrastructure caught up with population growth and today cities provide superior medical care, leading to life expectancy that is, typically, a few years higher than that in the countryside.

Urban centers have been more welcoming to different lifestyles and beliefs since time immemorial. That was of particular significance to sexual and religious minorities, who were more broadly tolerated in cities, such as renaissance Florence and early modern Amsterdam, than they would have been in more intimate rural settings.

Finally, cities offered and continue to offer a greater variety of amusements, leisure activities and intellectual stimuli. As Samuel Johnson famously put it in 1777, “Why, Sir, you find no man, at all intellectual, who is willing to leave London. No, Sir, when a man is tired of London, he is tired of life; for there is in London all that life can afford.”

For once, Karl Marx may have been right when he wrote in the Communist Manifesto, “The bourgeoisie has subjected the country to the rule of the towns. It has created enormous cities, has greatly increased the urban population as compared with the rural, and has thus rescued a considerable part of the population from the idiocy of rural life.” Harsh, perhaps, but true.

In many countries today, cities are the centers of innovation, engines of growth, and home to the richest segment of the population – just think of Delhi, London, New York, Shanghai, Seoul and Tokyo. In fact, the World Bank found that “No country has grown to middle income without industrializing and urbanizing. None has grown to high income without vibrant cities.” Yet as late as 1950, a mere 29 percent of humanity lived in the cities. In 2018, it was 55 percent. In 2050, it is projected, 68 percent of people on Earth will be city-dwellers. In sub-Saharan Africa, 40 percent of the population live in cities – a figure that will rise to 57 percent in 2050.

Many of the environmental advantages of urbanization are derived from living spaces being condensed. For example, electricity use per person in cities is lower than electricity use per person in the suburbs and rural areas. Condensed living space also allows for more of the natural environment to be preserved. In a suburban or rural environment, private properties are spread out, because land values are relatively low. So, more of the natural environment is destroyed. In cities, property values are higher and space is used more efficiently. That means that more people live in the same square mile of land than in the rural areas.

Another environmental advantage of cities compared to rural areas is a decrease in carbon emissions per person. In a rural or suburban area people normally use their own vehicles to drive to work or anywhere else. Due to congestion, the use of personal cars in the city is much less attractive. More people use public transportation instead and that means that less carbon dioxide gets released into the atmosphere.

None of the above advantages of urban life should be read so as to deny the loveliness of the countryside, which is made all the lovelier by having more animals and fewer people living in it.

A version of this first appeared in CapX.