In Star Trek lore, the Vulcans are a logical, passive race with telepathic abilities. Because of this, they generally refrain from physical contact with strangers. The famous "Vulcan Salute" is a result of this, and is often used in situations where a human would shake hands or grasp arms.
However, prior to the reforms introduced by Surak, the Vulcans were a far more emotional race similar to the Romulans. Romulans also seem to utilize hand gestures in greeting, albeit in a different manner. For instance, Romulan soldiers salute by placing their fist over their heart.
No other race in Star Trek uses hand gestures like this (not even humans any more), so it leads me to wonder if the salute gesture originated with Surak's reforms, or if it is even older within Vulcan culture.
What is the in-universe origin of the "Vulcan Salute" within Vulcan culture?