Orthography-based prescriptivism: The divergence of Sino-Tibetan grammar

Language is often thought of as a stream of sound, a fleeting thing that exists only in the moment of speaking. For centuries, linguists have operated under the assumption that writing is merely a tool to capture that sound, a secondary record of the primary spoken word. However, a new perspective suggests that the relationship might work in reverse: the way a language is written can actually shape how it is spoken and how it changes over time. This idea challenges the notion that writing simply follows speech, proposing instead that the visual symbols we use to record language can act as a powerful force, freezing certain parts of a word while allowing others to fade away. When two related languages adopt different writing systems, these visual constraints can push them down entirely separate evolutionary paths, turning a shared ancestral tongue into two grammatically distinct languages.

This is the central puzzle explored by researchers Liulin Zhang and Tszen Cizhen in their study of the Sino-Tibetan language family. This family includes some of the world's most widely spoken languages, such as Chinese and Tibetan, which share a common ancestor spoken thousands of years ago. Despite this genetic link, the two languages today look and sound very different. Chinese is known for being analytic, meaning it relies heavily on word order and separate words to convey meaning, with very little change to the words themselves. Tibetan, by contrast, is agglutinative, meaning it builds complex meanings by attaching many small pieces, or affixes, to the beginning and end of a root word. For a long time, linguists struggled to explain why two languages so closely related in their origins would diverge so dramatically in their grammar. The authors argue that the answer lies not in the spoken language itself, but in the scripts used to write them.

The researchers focused on how the specific nature of the Chinese writing system versus the Tibetan writing system influenced the survival of grammatical features. The Chinese script, which uses characters that represent whole syllables and carry their own meanings, acts like a coarse filter. It is excellent at preserving the identity of a single syllable, but it cannot easily show the tiny sound changes that happen inside a syllable, such as the addition of a small prefix or a change in the ending sound. Because the script could not represent these tiny internal parts, they eventually disappeared from the spoken language. In contrast, the Tibetan script is a segmental system, meaning it breaks words down into their individual sounds, much like an alphabet does. This script can clearly show every tiny prefix and suffix attached to a word. Because these small parts were visible and recordable in writing, they were preserved and continued to be used in the spoken language.

To prove this, the authors examined specific words that existed in the ancient common ancestor of both languages. They looked at a root word meaning "hook" and another meaning "large." In the ancient language, these roots could be modified by adding small sounds to the beginning or end to change their meaning, such as turning a noun into a verb or changing its tense. In Tibetan, the writing system recorded these modifications clearly. For instance, the word for "hook" could be written with a small prefix added to the front to indicate a specific grammatical function, and the script made this prefix visible. Over centuries, because the script showed the prefix, speakers continued to use it, and the language kept its ability to build complex words by stacking these small pieces together.

In Chinese, the story was different. The same ancient root for "hook" was written using a single character. The script treated the entire word as one indivisible unit. Even if the spoken language originally had a small prefix attached to the root, the writing system had no way to show it. The character represented the whole sound as a single block. Over time, as the spoken language changed, those invisible prefixes were lost because they were never reinforced by the written record. The language compensated for this loss by combining whole words together to create new meanings, a process known as compounding. Instead of adding a tiny prefix to a word, Chinese speakers began to put two separate words side by side. The writing system, by locking the language into single-syllable blocks, effectively forced the grammar to simplify and rely on word combinations rather than internal word changes.

The study also looked at how the loss of these tiny sound changes led to other shifts in the language. As the complex consonant clusters at the beginning of words disappeared in Chinese, the language developed a system of tones to help distinguish between words that were becoming too similar in sound. The researchers found that the writing system played a role here as well. Because the characters were fixed to specific syllables, the boundaries between words became very clear. This clarity encouraged the language to rely on these distinct syllables and their tones, rather than on the complex internal structures that had been lost. The authors note that while spoken language is fleeting and can change rapidly, the written word is permanent. This permanence creates a kind of pressure, or prescription, that stabilizes the parts of the language that can be seen and recorded, while allowing the invisible parts to drift away.

The researchers acknowledge that this divergence was not inevitable but was shaped by specific historical circumstances. The Chinese writing system was adopted across a vast area with many different spoken dialects. Because the characters represented meaning rather than sound, people who could not understand each other's speech could still read the same text. This made the written language the true unifier of the culture, allowing the script to exert a strong influence on the spoken language for thousands of years. In Tibet, the writing system was also influential, but the political landscape was different. After the collapse of the Tibetan empire, the spoken language in different regions began to drift apart, and the written language remained a classical standard. However, because the script could record the fine details of the sounds, the grammatical structures involving prefixes and suffixes were preserved in the written tradition and continued to influence the spoken language in ways that the Chinese script could not.

Ultimately, the study suggests that the writing system determines the smallest unit of language that can be standardized. If a script can only show whole syllables, then the language will evolve to treat the syllable as the basic building block, losing any smaller parts that cannot be seen. If a script can show individual sounds, the language will retain those smaller parts. This means that the choice of writing system is not just a matter of convenience; it is a fundamental force that shapes the very structure of a language. The authors conclude that the dramatic differences between Chinese and Tibetan grammar are not just a result of random changes over time, but a direct consequence of the visual tools used to record them. The script did not just follow the language; it helped to build it.