A little over 9,000 years ago, farming and rapid population growth led people to live close together in large numbers for the first time. At Çatalhöyük in Turkey, the oldest urban population we know about, people whose ancestors had been small bands of hunter-gatherers had to come to grips with living packed close together. The remains they left behind show that infectious diseases, environmental problems, and other curses of city living have been with us from the start.

Çatalhöyük may have hosted up to 8,000 people at its peak – even minimum estimates are 3,500 – after hundreds of thousands of years of living in bands of no more than 30. When first occupied around 7,100 BCE, Çatalhöyük may have been similarly small, but in 400 years it grew to reach a population the world had probably never seen before.

Professor Clark Spencer Larsen of Ohio State University led a 25-year exploration of this momentous step in human history. "Çatalhöyük was one of the first proto-urban communities in the world and the residents experienced what happens when you put many people together in a small area for an extended time," he said in a statement. "It set the stage for where we are today and the challenges we face in urban living."

With so many people crammed into an area of 13 hectares (32 acres), the population density was 10 times London today. This allowed infectious diseases to run rife, with a third of the site's early-period bones showing signs of infection, Larsen reports in Proceedings of the National Academy of Sciences.

Violence was shockingly frequent, particularly when crowding was greatest, with more than a quarter of skulls at the site having fractures from being hit with heavy objects, usually to the top or back of their heads. The majority of skulls damaged in this way belonged to women.

Just last month, a separate study showed parasites were another problem, with fecal samples showing signs of whipworm infestation. Nevertheless, Çatalhöyük's residents were healthier on this score than people living in other early human settlements.

Humans did learn some things with time, particularly in regard to sanitation, urban design, and transportation. Çatalhöyük never developed the concept of a street, with people entering and leaving the multi-story houses through ladders to the roofs, perhaps confining people with injuries or disabilities indoors.

Çatalhöyük residents had much higher tooth decay than their unsettled counterparts, which Larsen attributes to the shift to a cereals-based diet. The farming of wheat, barley or rye made Çatalhöyük's population possible. These cereals' distinctive ratios of carbon-13 relative to carbon-12 left a legacy in the city's residents' bones to show the food dominated their diet.

The importance of livestock can be traced from ratios of nitrogen isotopes, with sheep having been the dominant source of animal protein from the beginning, although cattle were domesticated later.

For all its problems, Çatalhöyük was heavily occupied for 1,150 years. Its decline was accompanied by changes to the leg bones of its residents, indicating they were walking ever-greater distances. "We believe that environmental degradation and climate change forced community members to move further away from the settlement to farm and to find supplies like firewood," Larsen said.

Regional climate change probably played a part, but this may also have been humanity's first encounter with the long-term degradation of resources through over-use.