Numeracy begat prose. Writing originated with accounting records. Tokens of tallies provided proof of quantities involved in transactions.
With practice, symbolic systems were extended to convey any message. Invariably the form and structure of a written language mirrored its spoken progenitor.
Various accounts date the origin of Chinese logograms. A logogram is a symbol representing a word or its portion. A morpheme is the smallest semantic language unit.
Isolated pictures and graphs have been found in China that date back 8,000 years. According to legend, Chinese characters were invented by Cangjie ~2650 BCE: a bureaucrat for the legendary Yellow Emperor, who is credited with initiating Chinese civilization.
By the 6th century ce the Japanese had adopted Chinese ideograms. With their cultural inclination toward refinement, by 712 the Japanese had trimmed the ideograms to a more manageable number – from 10,000 to around 2,000 – and overlaid a phonetic system, where each symbol represents a syllable.
Cuneiform script, which emerged in Sumer around 3600 BCE, started as complex pictographs, which were iteratively simplified into fewer and simpler strokes via abstractive subtraction.
By 2800 BCE, the Egyptians had a set of 24 hieroglyphs to represent syllables with a single consonant of their language. Vowels went unwritten. Egyptian trade exposed others to their hieroglyphs. This begat experimentation into simpler script systems.
That early writing systems comprised ideograms owes to the mind processing written words as pictorial representations (pictograms). The later evolution of letter alphabets thus represents an advance in language abstraction.
Proto-Sinaitic script emerged in the Sinai 1850 BCE. It was an intermediate between Egyptian hieroglyphs and the Phoenician alphabet to come.
By 1200 BCE, the Phoenicians were using an alphabet with 22 letters. Being a maritime trading culture meant the alphabet was dispersed.
The Phoenician alphabet was adopted in Greece during the 1st millennium BCE. The Greeks added vowels, which the Phoenician phonetic alphabet lacked.
The legacy of Alexander the Great was cultural diffusion, especially the Greek alphabet. His empire abetted the spread of the alphabet throughout southwest Asia, all the way into India.
The influence of ancient Greece upon neighboring Italy was profound. The Greek alphabet was adopted and modified by the Etruscans who ruled early Rome. The Etruscan alphabet was adopted and further modified by the ancient Romans. Colonial expansion spread the Latin alphabet throughout the Roman Empire: whence the Romance languages, all with the same alphabet.
Except for the Chinese, the earliest written languages were dropped in favor of borrowing another. In the 1st century ce, the Egyptian ditched hieroglyphs for an alphabet derived from the Greeks (whence Coptic script), even as the grammar remained much the same.