To call a language “dead” is often an exaggeration. Languages seldom really die; they evolve, and sometimes they fade out of usage.
Latin, for instance, is usually deemed to be a dead language, but this is not the case. To begin with, Latin is still the official language of the Vatican, and while catholic functions have been in local languages since 1964, papal documents continue to be redacted in Latin to this day. Moreover, while there are no native Latin speakers, there are hundreds of millions of people whose native language is directly derived from Latin: Italian, Spanish, Portuguese, French and Romanian; these are usually called “romance” or “neo-latin” languages. The word romance has unfortunately nothing to do with feelings, and is rather a reference to roman. Ancient Romans did, in fact, spread the usage of Latin around the world.
The evolution of languages is usually caused by their speakers’ movement across the globe: as populations mix, so do their languages. The best example of this is probably Romanian, whose name betrays a Latin origin even though it’s geographically distant from the area where its cousins are spoken. Indeed, the novice might find it surprising that Romanian is indeed a romance language, considering how the Balkan area separates its speakers’ pool from Western Europe, but linguistic evolution, like any other cultural trait, requires taking into account the bigger picture. The area then known as Dacia was inglobated by the Roman empire in 106 CE, but stayed a Roman province until until 271 CE, when the Goths conquered it. During those 165 years, vulgar Latin set its roots in the area, but was then polluted by subsequent linguistic interferences. Modern Romanian shows a striking mix of Latin and Slavic traits, the most immediate of which are postfix articles: EN lake, ES/PT/IT lago, FR lac, RO lac — EN the lake, ES el lago, PT o lago, IT il lago, FR le lac, RO lacul.
The more a geographic area is conquered by different populations, the more intermixed the local language will become, as it draws from all of them. Even more fascinating than Romanian is Maltese, which inherits from Italian, Sicilian, English and Arabic. Written Maltese can look to the untrained eye like a mishmash of random letters. This is how the first article of the Universal Declaration Of Human Rights looks like in Maltese:
Il-bnedmin kollha jitwieldu ħielsa u ugwali fid-dinjità u d-drittijiet. Huma mogħnija bir-raġuni u bil-kuxjenza u għandhom igibu ruħhom ma’ xulxin bi spirtu ta’ aħwa.
The fact that languages differ over time as the distance increases can be proven by Portuguese, specifically its Brazilian variety. Whereas European Portuguese is very similar to Spanish, to the point that they are almost mutually intelligible in writing, its South American counterpart is so different that some consider it to be an entirely different language, much more so than American English is to British English. The most striking structural distinction is that most Brazilian Portuguese dialects lost the second singular pronoun tu in favor of você (originally vossa mercê, ie. “your grace”, akin to Spanish usted), which is conjugated with third singular person verbs but is used informally. Interestingly, a similar pronoun, vos, is also used in several South American varieties of Spanish, especially those in areas geographically close to Brazil.
Languages generally evolve by simplification, as can easily be seen comparing the complex case system of Latin with modern romance languages, none of which use cases other than for pronouns. Moreover, language evolve under one’s own eyes. When I went to elementary school twenty years ago, the informal yet very common construction a me mi, as in a me mi piace was considered a serious mistake because it implied repeating the same thing twice. While it is not something that one would use in writing, it has become accepted in all but the most formal settings. (Note that the correspondent Spanish construction, a mí me gusta, actually requires the repetition.) A similar thing has happened in English: until a few decades ago, substituting whom (accusative) with who (nominative) in phrases such as I don’t know was considered bad practice; nowadays, it is standard English. Of course, phrases usually used as “whole blocks,” such as for whom the bell tolls or to whom it may concern, are likely to retain the original inflection for much longer. Sometimes the simplification is done by law, usually in the form of spelling reforms. This has recently happened with Greek in 1982 to drop its ancient polytonic orthography, and to German in 1996; the latter wasn’t exactly a smooth transition. Many reforms have been suggested for English, but none has ever been attempted. It is worth to remember this satyrical piece, attributed to Mark Twain, about how such a reform could be carried out over the course of at least two decades:
For example, in Year 1 that useless letter c would be dropped to be replased either by k or s, and likewise x would no longer be part of the alphabet. The only kase in which c would be retained would be the ch formation, which will be dealt with later.
Year 2 might reform w spelling, so that which and one would take the same konsonant, wile Year 3 might well abolish y replasing it with i and Iear 4 might fiks the g/j anomali wonse and for all.
Jenerally, then, the improvement would kontinue iear bai iear with Iear 5 doing awai with useless double konsonants, and Iears 6-12 or so modifaiing vowlz and the rimeining voist and unvoist konsonants.
Bai Iear 15 or sou, it wud fainali bi posibl tu meik ius ov thi ridandant letez c, y and x — bai now jast a memori in the maindz ov ould doderez — tu riplais ch, sh, and th rispektivli.
Fainali, xen, aafte sam 20 iers ov orxogrefkl riform, wi wud hev a lojikl, kohirnt speling in ius xrewawt xe Ingliy-spiking werld.
In some cases, languages do however indeed die without evolving, but a more correct term in this case is “extinction.” Most scholars consider a language to be extinct when it’s no longer used and there are no direct derivatives. Language extinction is closely linked with the story of populations as a whole, and almost always to catastrophic events such as genocide. For instance, Many Native American languages are now extinct, as the people who spoke them were killed during the colonization. The few survivors eventually stopped using them (or were too young and were never taught to speak them) and began using the language of the colonists. In some cases, if the pool of speakers is already small, there may be no push to teach it to other people and they may eventually die and take the language with them. This is the reason behind the attempt, in the recent years, to revive languages and dialects at a concrete risk of disappearing.
As we have seen, language defines culture and identity. When a language becomes extinct, the loss for humanity as a whole is much bigger than a set of grammar rules.