by Aliya Whiteley

At the end of a long day, few things beat simple pleasures like watching a good film, eating a bar of chocolate the size of your head, or drinking a big glass of red wine.

By this point in the evening, most people don’t want to be told that they need to uncork the bottle and let the wine sit for at least 30 minutes before it becomes pleasantly drinkable. Yet that's (by the letter of the unwritten law) what you're supposed to do.

But why? Well, let's start with the assorted historical reasons.

Red wine has been around since the Stone Age. In fact, in 2011 a cave was uncovered in Armenia where the remains of a wine press, drinking and fermentation vessels, and withered grape vines were uncovered; the remains were dated at 5500 years old. Early winemaking often had a ritualistic aspect: Wine jars were found in Ancient Egyptian tombs, and wine appears in both the Hebrew and Christian bibles.

The concept of letting wine "breathe" is, historically speaking, relatively new and probably has its roots in the way wine was once bottled and stored.

Traditionally, sulfur is added to wine in order to preserve it for longer, and if too much is added the wine might well have an ... interesting aroma when first opened—the kind of "interesting aroma" that bears more than a passing resemblance to rotten eggs. Contact with the air may have helped to remove the smell, so decanting wine may once have been a way of removing unwelcome odors, as well as getting rid of the sediment that built up in the bottom of bottles.

It’s also possible that the concept springs from the early 1860s, when Emperor Napoleon III asked Louis Pasteur to investigate why so much French wine was spoiling in transit. Pasteur published his results, which concluded that wine coming into contact with air led to the growth of bacteria, thus ruining the vino. However, small amounts of air improved the flavor of the wine by "aging" it. In bottles, with a cork stopper, the wine still came into contact with a small amount of oxygen, and by storing it for years the wine was thought to develop a deeper flavor.

However, how much of that actually matters today?

Many experts agree that there is no point in simply pulling out the cork and letting the wine sit in an open bottle for any period of time; the wine won’t come into enough contact with oxygen to make any difference to the taste.

However, decanting wine might still be a useful activity. The truth is this: It entirely depends on the wine.

Nowadays we don’t really age wine anymore; we make it with the aim of drinking it quickly, within a year or so. But some types of wine that are rich in tannins (compounds that come from the grape skins and seeds) can benefit from a period of time in a decanter, to soften the astringent taste. These include wines from Bordeaux and the Rhône Valley, for instance.

If you really want to know if a particular wine would benefit from being given time to breathe, try your own experiment at home. Buy two bottles, decant one, and let it breathe for an hour. Do you notice a difference in the taste? Even if you don’t, it's an experiment that justifies opening two bottles of wine.

One word of warning: No matter where a wine comes from, it is possible to overexpose it to oxygen. So remember Pasteur’s experiments and don’t leave your wine out of the bottle for days. That, friends, would be one hell of a waste.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.