Alcohol is a depressant that binds to GABA receptor, caused an increase in the main inhibitory neurotransmitter in the brain. This, in turn, raises the threshold for an action potential in post-synaptic neurons. Alcohol also acts to block certain excitatory neurotransmitters in the bran as well, such as AMPA. Alcohol (C2H5OH) contains only one major function group, a hydroxyl.
The first recorded cases of alcohol consumption in human history date back to the Sumerians, the first civilization to settle the fertile crescent of Mesopotamia. The Sumerians discovered that by fermentation, they could create beer from grains like barley, wheat and hops. Throughout times of antiquity, alcohol was the preferred beverage of choice for sanitary reasons. In the absence of modern scientific theory, those living in the ancient world lacked the knowledge with which to purify water and rid it of harmful microbes. The chemical properties of alcohol make it a much more harsh environment for bacteria, which is why it was considered safer to drink compared to water. There are numerous references and allusions to alcoholic beverages in a wide variety of ancient texts, including the Bible and Gilgamesh. In fact, wine is consumed during communion in the Christian faith.
In contemporary times, variant countries and regions of the world have different attitudes and laws regarding the fermentation, sale and consumption of alcohol. For example, in most European countries, the drinking age is arbitrary and citizens are permitted to consume alcoholic beverages at much younger ages compared to countries like the USA, where the drinking age is 21. The consumption of alcohol is even prohibited in some countries, as it is a violation of Islamic Law. America attempted a brief prohibition period, proscribing the sale and consumption of alcohol completely, but this law was later repealed. Ethyl alcohol, or ethanol, has a number of other pragmatic applications as well. It is sometimes used as a biofuel.