That’s an excellent question, and one that’s provoked no shortage of debates in our meetings. The thumb-hole you describe is actually called a punt, and there’s a huge discourse regarding its origins and significance… check out this page for more information than you’d ever care to know about the punt debate.
What we do know is that it probably doesn’t exist solely so waiters can show off by pouring wine with their thumb up in it… although it can’t be denied, some punts are really conducive to such things. Check out this photo of Jesse wrangling the 2005 Papillon (note: any bottle that I can actually balance on my massive thumb definitely possesses a punt to be reckoned with).
Back in 2006, our erstwhile member Sofia sent us a list of punt-related theories. Verbatim, straight from the archives:
A punt, also known as a kick-up, is the term used to refer to the dimple at the bottom of a wine bottle. There is no consensus as to the reason why wine bottles today have punts, though everyone seems to be adamant that their explanation is the correct one. The more commonly cited explanations are:
The punt as a historical artifact
–They are an historical remnant of old-fashioned glass-blowing techniques.
–They once had the function of making the bottle less likely to topple over. A bottle designed with a flat bottom only needs a small imperfection to make it unstable. In the past, it may have been safer to give the bottle a dimpl to allow for a margin of error.
–They once had (and may still have) the function of strengthening the bottle, particularly useful in the case of sparkling wine.
The punt as having a function
–They allow bottles of sparkling wine to be turned upside-down and then
stacked (depending on their shape).
–They allow waiters to pour wine in a fancy way.
–They can make the bottle look bigger.
–In aged wines, sediment deposits at the bottom or side of the bottle (depending on how the wine was stored), which the punt can help to consolidate.
–They help to sell wine to people who believe that a deep punt is an
indicator of a high-quality wine.
–They lessen the chance for breaking bottles when cases are stacked on top of one another.