It's one of the most common misconceptions about deaf people, and it seems logical: since signs are made through gestures, they should be understood everywhere. So, is sign language universal?
No, it is not. There are more than 300 different sign languages worldwide, each with its own vocabulary, grammar, and history.
This diversity is surprising, but it is easily explained. Sign languages are not codes invented to transcribe a spoken language. They are natural languages, spontaneously born within deaf communities, and they have evolved just like spoken languages: through contact, isolation, and transmission between generations.
One point deserves to be highlighted as it contradicts intuition. Two countries sharing the same spoken language can have radically different sign languages. Conversely, two geographically distant sign languages can be very similar if they share a common historical origin.
The kinship between sign languages follows its own genealogical tree, unrelated to that of spoken languages.
A second point worth knowing is that there is indeed an international system, used during meetings between signers from different countries. But it is not a language in its own right: it is a contact repertoire, limited and learned in addition to one's native language.
Finally, even within a single country, there are regional variations, just like accents and local expressions in a spoken language.
In this article, we explain why sign languages are not universal and what that implies.
How many sign languages are there in the world?
There are more than 300, and this number remains a low estimate since some are not yet documented. Here are the main ones.
ASL, American Sign Language, used in the United States and English-speaking Canada
LSF, French Sign Language
BSL, British Sign Language
Auslan, Australian Sign Language
DGS, German Sign Language
LIS, Italian Sign Language
LSE, Spanish Sign Language
CSL, Chinese Sign Language
JSL, Japanese Sign Language
ISL, Indo-Pakistani Sign Language, among the most spoken in the world
Libras, Brazilian Sign Language
RSL, Russian Sign Language
LSM, Mexican Sign Language
NGT, Dutch Sign Language
SSL, Swedish Sign Language
Among these languages, the comparison between ASL and BSL perfectly illustrates why universality does not exist. The United States and the United Kingdom share English, yet their sign languages are mutually incomprehensible.
ASL is finger-spelled with one hand, BSL uses both. Their vocabulary differs greatly, and an American signer does not spontaneously understand a British signer.
Conversely, ASL and LSF show a real closeness despite the geographical distance. The reason is historical: American Sign Language was built from French Sign Language in the early 19th century when a French deaf educator participated in founding the first school for the deaf in the United States.
This kinship shows that sign languages follow their own genealogical tree, completely independent of that of spoken languages.
One last point on this count. Some countries have several sign languages on their territory, and others share the same one. Belgium uses two, India and Pakistan largely share the same.
The exact number remains difficult to fix, as linguistic documentation is still progressing.
Why are sign languages different?
The answer lies in a reality that many ignore: sign languages were not invented. They naturally arose within deaf communities, just like spoken languages.
This origin explains everything else.
Everywhere deaf people have been gathered for a long time, a language has spontaneously emerged to meet their need to communicate. These emergences occurred independently of each other, on different continents and at different times.
There is therefore no reason for the signs to resemble each other, no more than French words resemble Japanese words.
Three factors have then shaped this diversity.
First, geographical isolation. Deaf communities have long lived without international contact, allowing each language to evolve separately for generations.
Then, schools for the deaf, which have played a decisive role. Each institution has been a hub where a language has stabilized and been transmitted. The relationships between sign languages often follow the historical connections between these institutions.
Finally, local culture. Signs reflect realities specific to each society: conventional gestures, cultural references, everyday objects, ways of designating family relationships.
One point needs clarification. Sign languages are not gestural translations of spoken languages. They have their own grammar, often very different from that of the spoken language of the same country.
This is precisely why two countries sharing a spoken language can have completely distinct sign languages.
Is there an international sign language?
Yes, but it is not a language in its own right. It is a contact system called International Sign, used during meetings between signers from different countries.
The distinction is important because it changes everything.
A language has a stable grammar, a fixed vocabulary, and native speakers who acquire it in childhood. International Sign meets none of these three criteria.
Its vocabulary remains limited and varies according to the participants in the exchange. Its grammar fluctuates, each signer adapting it from their own language. And no one learns it as a native language, since it is always acquired in addition to a national sign language.
Its functioning relies heavily on iconicity, that is, on signs whose form directly evokes the meaning. Signers combine descriptive gestures, mimes, and borrowings from their respective languages.
Its use is concentrated in specific contexts: international congresses, sporting events like the Deaflympics, meetings of representative organisations, and informal exchanges between deaf travellers.
A structural limitation needs to be noted. International Sign works well for concrete and factual exchanges, much less so for abstract, technical, or nuanced conversations. Its expressive capacity remains far inferior to that of a complete language.
One last point often surprises. International Sign is strongly influenced by Western sign languages, which disadvantages signers from other regions of the world and is a criticism regularly made within the deaf community.
It is therefore not a universal solution, but an imperfect contact tool.
Do sign languages also vary within a country?
Yes, and these variations are as marked as the accents and regional expressions of a spoken language.
The same concept can be signed differently from one city to another, and these differences have a name: regional variations.
They mainly affect everyday vocabulary. The names of colours, days of the week, foods, first names, and school vocabulary are among the most variable. However, the grammar remains stable across the entire territory, preserving mutual understanding.
Three factors explain this internal diversity.
First, schools for the deaf, and this is the main historical factor. Each institution has been a linguistic hub where signs have been locally fixed before spreading to the surrounding region.
Then, generations. Older signers and young people do not always use the same signs, particularly in technological or social vocabulary that evolves rapidly.
Finally, local communities, each developing its own uses and expressions.
A reassuring point for learners: these variations do not constitute an obstacle. Signers naturally adapt, ask for clarification when a sign is unknown to them, and understand the context without difficulty.
This flexibility is part of the normal functioning of the language.
However, a practical consequence should be known. If you learn and notice that a sign differs from the one you were taught, do not correct your interlocutor. Instead, observe the usages around you and adapt, as you would with a regional accent.
