<Li> Syllabic: grapheme represents a syllable . </Li> <Li> Alphabetic: grapheme represents an elementary sound . </Li> <P> The best known picture writing system of ideographic or early mnemonic symbols are: </P> <Ul> <Li> Jiahu symbols, carved on tortoise shells in Jiahu, c. 6600 BC </Li> <Li> Vinča signs (Tărtăria tablets), c. 5300 BC </Li> <Li> Early Indus script, c. 3100 BC </Li> </Ul>

When did humans learn to read and write