ArchaeoMan wrote on Feb 3
rd, 2012 at 9:05pm:
The earliest concrete evidence I know of is at Bagor, India where spherical pecked stones were interpreted as slingstones. The article only says that they were found in phases I and II of the site, which date from 5000-2800BC and 2800-600BC. Clay projectiles at Hamoukar - in modern-day Syria - date to around 3500BC.
That said, I agree that the technology would likely be around well before then, probably extending from the paleolithic.
Following up on that Indian sub-continent connection, there is a review article from 2004 in Evolutionary Anthropology volume 13 by Professor Emeritus Kenneth Kennedy of Cornell, in which he states that cave art from Bhimbetka in Madhya Pradesh illustrates the use of the sling. These images are impossible to correlate to an exact date, as the site was used continuously for a very long stretch of time, but the Mesolithic burials at the site have been conclusively dated to 4480-3290 years BP. The upper paleolithic layers have not yet been accurately dated.
This isn't as concrete as slingstones, of course, but the dates for the mesolithic burials certainly jive with the finds at Baghor. Interestingly, mesolithic burials at Baghor II go back to 10,646 BP. So, if there is cultural continuity within the mesolithic finds in the Baghor II site, it may indicate the presence of the sling within the culture for nearly double the period for which manufactured slingstones have yet been found.