Found the following text on Reddit:
The greatest mysteries of languages in history
With all the posts on unsolved murders and disappearances, I thought something more lighthearted - but no less confounding - would be nice. As a linguist, I can present to you some of our great headscratchers.
Were Europeans writing as early as 6000 BCE? Archaeological excavations have discovered throughout Europe, but especially in the Balkans, a type of script we call Vinca symbols. They span a good deal of Europe and several thousand years of time. We believe they were typically inscribed on wood, which is why so few survive. In earlier decades, there was debate over whether the symbols represented writing or not, but with the discovery of the Dispilio Tablet (~5260 BCE, copy of the wood tablet here) and the Tartaria Tablets (~5300 BCE), it is becoming difficult to deny that this is, at the very least, a form of proto-writing. Related are the Gradeshnitsa Tablets which were from the same area and timeperiod but don't use the same script; could they represent a different prehistoric language in the same area?
What were the languages of the Negritos? This one will never be solved. The Negritos were the first men and women of the now-underwater world of Sunda. After the rising oceans gobbled Sundaland, the Negrito population was forced to live on highest grounds that didn't vanish under the seas, disconnected from one another. Thousands of years later, the Austronesian peoples immigrated from the north and took the lands over. The Negrito languages were lost forever.
The Phaistos Disc One of the most famous mysteries of history. It's bizarre and ancient, and represents a full writing system several hundred years before Linear A appears on Crete. Intriguingly, the writing on the disc has been shown to involve prefixing and suffixing - yet the pattern of prefixing does not match the pattern of Linear A. There are a million reasons why that may be, but all we are stuck with are our prayers of discovering future examples.
Linear A Sometimes called Minoan, the language of the semi-historical King Minos, Linear A represents the first writing of Crete (apart from the Phaistos anomaly). Thanks to Greeks that modified Linear A to write in the Greek language, we have a fairly good guess as to what Linear A's language sounded like. We have even deciphered bits and pieces. The mathematics of the language were the first to be deciphered. Later, loanwords from known languages were spotted. But that's where the fun stops. It has never been linked to another language and, like Sumerian and Elamite before it, is destined to be a language isolate that has disappeared forever.
What were the original languages of Europe? Aside from Basque, all the languages of Europe are either from the Indo-European, Uralic, or Semitic language families (we will exclude the Caucasus for now). All three language families are invasive language families. For example, you are reading this post in English, an Indo-European language. But if you can trace your parentage to the British Isles, you are not genetically Indo-European, most of your ancestors were part of the original paleolithic inhabitants of the island. In other words, the role of massacres and extinctions has been overemphasized in popular history. The Indo-Europeans came from the Southern Russian steppes at around 5000 BCE and brought with them a superior technological culture, and one with chariots. As they settled, their language became a prestige language - a language people learn in order to facilitate trade and rise in status (think people around the world learning English today to get ahead). The Proto-Indo-European language spread and broke into dialects, dialects became languages, and soon after those languages became new languages. The result is that, for example, the speakers of Germanic tongues (an Indo-European branch) are hardly Indo-European by blood, and are rather the descendants of the original inhabitants of the land. But what were the languages of Old Europe? What were the orginal tongues? In rare instances, we were lucky enough to have them recorded. Etruscan, Raetic, Lemnian, Sardinian, Iberian, Linear A, etc... All those languages were lost in time like... tears... in the rain. With Basque, we were even fortunate enough that it has survived to today. Many of these original languages have left loanwords in the living languages of today. When someone learned an Indo-European tongue, the brought with them baggage, words for particular items occaisionally made its way into the language and live on Shameless self-plug with more information on that.
Original culture of Europe (part II). These original peoples not only left vestiges of their tongues, but mysterious items in the soil have been discovered. The henges of England are probably the most famous, like Stonehenge and Woodhenge. But what about these ancient, badass hats discovered around Germany?. What about the breathtaking sculptures of the Iberians? What philosophy motivated their construction and the significant investment of time and resources in a neolithic society?
Rongorongo An undeciphered writing system of Easter Island. I don't study Austronesian languages so I hesitate to put it down. /u/1337_SAS is a linguisti of Austronesian languages so maybe he could tell us more. But the wikipedia page is worth a read.
Sumerians They come out of nowhere in history, speaking a language unrelated to any on earth, conquer their known world and create the first fully-fledged writing in history, and then slowly disappear - assumed into the later Akkadian culture (the Akkadians were Eastern Semitic). Their impact upon all the languages of the region was real - even the word eden (as in garden of Eden) ultimately comes from Sumerian edin "grazing land between two rivers." We know a great deal of the language, yet it has resisted any attempts to link it to other tongues. Like other languages in the region at the time, it shows split ergativity, also found in Caucasian language families and several Indo-European tongues.
Other language isolates of the Ancient Near East Russia may be the graveyard of empires, but the Near East is the graveyard of languages. Sumerian is the most famous, but let's skim through all the other languages that appeared in writing and then vanished. Who were they? What were they like? They continue to echo on today. Some left us troves of writings, others only whispers. Cypro-Minoan, Gutian, Hurrian, Hattic, Urartian, Kassite, Kaskian, Pre-Sumerian, Elamite. By the way, those languages I mentioned are simply the strange ones. The ones that have no relatives surviving today. The ones spoken by entire civilizations, people with their own lives and cares and problems, and then left us with a whimper. There are dozens of well-understood languages that died in the Near East as well that I am skipping over.