This paper about the archaeological site of Gobekli Tepe is based on Ancient Depicted Sign Language that has been found to be in use globally in ancient times.
The question of when and where this ancient communicative system was invented is unknown. As far back in time as these signs have been found they seem to have already been part of a complete system. At the moment it seems that the system may be 40,000 years or more old based on the idea that aboriginal Australians appear to have brought the signing system with them in their migrations. The system was carried by various cultures in their migrations (the Image of the Deer based on its spirit- essence as browsers, a wanderer or nomad) ultimately ending up in the Americas. Gesture and depicted sign language was probably as much a part of their survival “toolkit” as flint napping, fire making, hunting skills, etc.
