Early tablets

One drawback of using tokens to stamp tablets was a lack of legibility in their impressions. This would have prompted the shift to manually pressing symbols into the tablets with styluses that had occurred by the end of the fourth millennium BC. Like their envelope predecessors, the vast majority of tablets recovered from this period were economic and administrative in nature, recording inventories of food, livestock, etc. via representative pictographic symbols (Schmandt-Besserat). We can refer to this as a proto-writing system–i.e. a limited system of writing where symbols are representative of semantic meaning but not yet linked to any phonological meaning (representative of actual spoken language).

However, the longer this system was in use the more stylized and abstract the symbols became. We can track this evolution by comparing symbols at different chronological stages (Rogers).