Through all of human existence, the population had only reached one billion people at the beginning of the 1800’s. It took less than one hundred years for that number to increase to two billion, four billion in less than fifty years, and six billion in twenty five years. Finally in 2018, there are nearly 7.6 billion people. But why was it what the population remained under one billion until the 1800’s and why did the population grow so fast after. Before the 1800’s the population remained low not because no one decided to have children but in fact it is the exact opposite. Post 1800’s before good sanitation, healthcare and medicine, and food security, families would have much of their children die before reaching adulthood. In Europe The average number of children a woman would have was about six and only a third of them would survive long enough to reach adulthood. Europe before the industrial revolution was an example of a tier one country on the DTM, in fact more people died in cities than there were babies being born. The reason cities still existed was because of a constant stream of people moving into them. Cities were cramped and had unclean, streets were often littered with human waste and there was disease in every city. As the industrial revolution many major improvements to technology were made. Farmers could produce more food with less work meaning less people had to work on the farms. By not working on farms people were able to explore fields like science, improve medicine and the sanitation of cities. This is known as specialization. After the industrial revolution we saw that Europe moved from being a stage one civilization to a stage to civilization when there were improvements in medicine and the death rate dropped. After some time, Europe was able to move to stage three where their birth rate drops as well because there was no need for all the births if not as many people died. It was because of the industrial revolution that Europe’s population boomed, but this process in not only limited to Europe, all countries are going through if not already went through this transition. Take for example, the two most populated counties in the world, China and India. China, the oldest civilization that still exists today, had a huge population to start off with. This was partially because of China’s main staple food being rice and the geography of the region.