Translators play a vital role in saving the world's languages, allowing 6,000 to 7,000 spoken tongues to exist, and 3,000 rare dialects to survive.

"Without translation, there is no history of mankind," says linguist Astrid Guillaume, of the Sorbonne University in Paris.

"We know histories and cultures of the world only by way of translations," she adds.

The word "translate" comes from the Latin "traducere," which means "to carry across". Here are three examples of how translators serve linguistic diversity.

Saving rare languages

Born to a peasant family in Brittany, western France, where they spoke Breton, Rozenn Milin could have become a translator of French to that language.

She chose instead to champion the survival of the world's rarest languages through her Sorosoro project.

Sorosoro means breath, speech and language, in Araki, a nearly-extinct language now spoken by less than 10 people.

It is one of many tongues heard in the Pacific island republic of Vanuatu.

Sorosoro's goal is to preserve recordings of endangered languages by filming people who still speak them and storing the result, after translation, at France's national audiovisual institute INA.

Translators play an essential role in the project, transcribing hours of filmed stories, songs and ritual ceremonies, according to Milin.

"It is substantial and complicated work," she says, because it requires interlocutors who also speak French, English or Spanish well to translate the soundtracks.

Sign translation

There is no single sign language for those who cannot hear.

"There are as many sign languages as there are countries," explains Ronit Leven, vice president of the French federation of the deaf, FNSF, herself deaf and an interpreter of several sign languages.

An international sign language does exist - a sort of Esperanto that borrows from different, mainly European sign languages and is used for international gatherings.

"But nothing beats understanding and expressing oneself in one's own sign language," says Leven, who often works at such international events.

Even basic words differ from one language to another.

For example, the sign for "dad" in French points to the corner of the mouth, where a mostache would grow, whereas in U.S. sign language it is expressed with a thumb on the forehead.

Artificial intelligence

Interpretation errors and shoddy syntax are two reasons that automatic translation has had a bad reputation.

In her book "Google-moi" (Google Me), French philosopher Barbara Cassin wrote in 2007 of how the biblical phrase "And God created man in his image" was turned by Google Translate into German and back into French several times until a stabilized version was obtained. It came out as "And man in his image created a god."

That would not happen now. The result obtained from the same automatic translator is now "good, coherent and consistent," Cassin acknowledges in her latest work "Eloge de la traduction" ("Eulogy of translation").

The quality of translation should improve even more thanks to progress in artificial intelligence, in particular the mechanism of "deep learning" whereby a machine learns progressively by imitating how the human brain works with its own network of artificial neurons.

One such system was created by the French company SYSTRAN, a pioneer of automatic translation, which was acquired in 2014 by the South Korean group CSLi.

It maintains that the quality of translations, after several weeks of learning, is "close to that of humans".

"We are at the very beginning of a new era that offers excellent prospects in multilingual communication," predicts Jean Senellart, SYSTRAN technical director.