As populations started to settle in towns and cities, they were faced with a huge problem. Sanitation of water was nearly nonexistent, and unfortunately, this was spreading typhoid and cholera. Europeans and Asians had different means of purifying their water. While the Europeans fermented their water into alcohol, which killed off microbes, Asians boiled their water and made tea out of it. The differing methods eventually put pressure on the Europeans to be able to process massive amounts of alcohol in their systems, which was not the case in Asia. As a result, Asians are not able to drink as much without having the alcohol flush response due to a certain genetic variation (ALDH2*2). This variation causes them to produce a much less effective
