It's always been about ethanol...

Maybe we farm in order to imbibe.

Humankind's first encounters with alcohol in the form of fermented fruit probably occurred in just such an accidental fashion. But once they were familiar with the effect, archaeologist Patrick McGovern believes, humans stopped at nothing in their pursuit of frequent intoxication.
A secure supply of alcohol appears to have been part of the human community's basic requirements much earlier than was long believed. As early as around 9,000 years ago, long before the invention of the wheel, inhabitants of the Neolithic village Jiahu in China were brewing a type of mead with an alcohol content of 10 percent, McGovern discovered recently.
McGovern analyzed clay shards found during excavations in China's Yellow River Valley at his Biomolecular Archaeology Laboratory for Cuisine, Fermented Beverages, and Health at the University of Pennsylvania Museum.

The bearded archaeologist is recognized around the world as an expert when it comes to identifying traces of alcoholic drinks on prehistoric finds. He ran so-called liquid chromatography coupled with mass spectrometry on the clay remnants from Asia and found traces of tartaric acid -- one of the main acids present in wine -- and beeswax in the shards' pores. It appears that prehistoric humans in China combined fruit and honey into an intoxicating brew. [More]

Ethanol is a plausible energy source to rival fossil fuels for the same reason it has always been so valued by civilizations around the world: it is a concentration of energy (and consciousness-altering effects) that literally distills the power of sunshine into a transportable and usable form.

Early American settlers knew this.

The new Federal government, at the urging of the first Secretary of the Treasury, Alexander Hamilton, assumed the states' debt from the American Revolutionary War. In 1791 Hamilton convinced Congress to approve taxes on alcohol and carriages. Hamilton's principal reason for the tax was that he wanted to pay down the national debt, but he justified the tax "more as a measure of social discipline than as a source of revenue."^[1] But most importantly, Hamilton "wanted the tax imposed to advance and secure the power of the new federal government." ^[2]
Congress designed the tax so smaller distillers would pay by the gallon, while larger distillers (who could produce in volume) could take advantage of a flat fee. The net result was to affect smaller producers more than larger ones. George Washington, the president at the time, was one such large producer of whiskey.^[3] Large producers were assessed a tax of 6 cents per gallon, while small producers were taxed at 9 cents per gallon. [1] But Western settlers were short of cash to begin with and, being far from their markets and lacking good roads, lacked any practical means to get their grain to market other than fermenting and distilling it into relatively portable distilled spirits. Additionally, whiskey was often used among western farmers as a medium of exchange or as a barter good.^[4]

The tax on whiskey was bitterly and fiercely opposed among the Cohee on the frontier from the day it was passed. Western farmers considered it to be both unfair and discriminatory, since they had traditionally converted their excess grain into liquor. Since the nature of the tax affected those who produced the whiskey but not the people who bought the whiskey, it directly affected many farmers. Many protest meetings were held, and a situation arose which was reminiscent of the opposition to the Stamp Act of 1765 before the American Revolution.. [More]

This is also why cellulosic ethanol has such a steep hill to climb - it starts with thin energy-density feedstock.

It may also be that freaky mutations in the feedstock are reflected in modern alcohol reactions. Just as man was finding more stuff to ferment, he was being selected to tolerate the noxious potions being generated.

If your face turns red after drinking just one glass of wine, blame ancient Chinese farmers. Researchers are reporting that the "Asian Flush" mutation cropped up just as rice was first being domesticated, and it may have protected early farmers from the harms of drinking too much. But some other scientists urge caution, saying that the dates may not match up.

When you drink, enzymes in the liver known as alcohol dehydrogenases (ADHs) convert alcohol to an organic compound called acetaldehyde; another enzyme then converts acetaldehyde to acetic acid. But about 50% of Asians and 5% of Europeans have mutations in these enzymes that can increase the rate of alcohol metabolism up to 100-fold. This leads to a rapid accumulation of acetaldehyde, which can cause capillaries in the face to dilate�--and the face to turn red. Other unpleasant symptoms can include nausea and headaches. In 2008, a team led by geneticist Kenneth Kidd of Yale University found that one of these mutations--known as ADH1B*47His--may have been favored by natural selection in many East Asian populations.

A team led by Bing Su, a geneticist at the Kunming Institute of Zoology in China, set out to find the source of this selection. The researchers searched for the ADH1B*47His mutation in 2275 people across China representing 38 ethnic groups. They found that it was highly prevalent, up to 99%, in ethnic groups from southeast China; a bit less prevalent, 60% to 70%, in western China; and relatively uncommon, 14%, among Tibetans. Moreover, the team found a strong geographical correlation between regions with a high prevalence of the mutation and archaeological sites in China where rice had been domesticated thousands of years ago.

When Su and his colleagues calculated the age of the mutation, it came out at between 7000 and 10,000 years ago. That corresponds roughly to the earliest known evidence for rice farming, the team reports online this week in BMC Evolutionary Biology. "The [mutation] rose to extremely high frequency in a relatively short time, implying that the selective force was quite strong," Su says.

As for what the selective pressure was, the team concludes that the mutation was favored because it protected early farmers from the potentially fatal harms of drinking too much. The researchers cite two additional pieces of evidence for this hypothesis. First, recent archaeological evidence suggests that Chinese farmers concocted an alcoholic brew of rice, honey, and grape or hawthorn as early as 9000 years ago. Second, the drug disulfiram, which causes acetaldehyde to accumulate in the body, discourages alcoholics from drinking by causing nausea, vomiting, and other severe alcohol flush reaction symptoms. [More]

I have always been grateful for my inability to hold my liquor. Obviously it kept my ancestors from alcohol poisoning.

Speaking of which, isn't it about that time?