A question that seems to be unanswerable

That question is impossible to answer today, and there's no reason to think we will ever be able to answer it. Our species of Great Ape, Homo sapiens, was fully evolved by 200,000KYA. At that point the Modern Human brain was completely formed as it is today, with the speech center that makes possible language as we know it.

Nonetheless, this does not rule out the possibility that one of the transitional forms between Homo habilis, the earliest member of our genus, and H. sapiens may have had a sufficiently advanced brain to develop language, even if it wasn't quite as rich a language as those we have today. For all we know, the technology of spoken language could be more than one million years old.

The earliest evidence we have of the existence of a language only goes back 15,000 years. Just in the last few years linguists have found what appears to be a relationship between the Na-Dene languages of northwestern North America (including Tlingit, Navajo and Apache) and the Yeniseian language of Siberia. Since humans migrated from Siberia to North America around 15KYA, this implies that the common ancestor of all these languages goes back that far.

That leaves a gap of anywhere from almost 200,000 years to almost 2,000,000 years between the earliest language we have any knowledge of and the earliest possible invention of language. Without recordings or written records, we have absolutely no way of spanning that gap.

There are several possible ways in which language originated.

• The technology was invented once, when the human population was very small. It quickly spread throughout the entire species because it didn’t have far to go. This was probably the case with some of our earliest technologies, such as flint knives and axes.
• The technology was invented once, when the population was larger and widely spread. The tribe that developed it was so successful that neighboring tribes quickly borrowed the technology. This has happened with other important technologies, such as the domestication of horses.
• The technology was invented in multiple times and places. The idea occurred naturally and required no special conditions, so it happened more than once. This has happened with other important technologies, such as agriculture and metallurgy.

So we have two large and seemingly insurmountable obstacles to studying the origin of language: 1. We don’t know when it happened, and 2. We don’t know if it happened once or multiple times.

The study of existing languages isn’t much help. Except for the Na-Dene/Yeniseian link than I mentioned above, we can’t reconstruct any language, or analyze its relationship with other languages, beyond about 6000BCE. There are dozens of language families and we have no idea if they’re related. Indo-European, e.g. English, Latin, Russian, Sanskrit. Afroasiatic, e.g. Hebrew, Arabic, Berber, Amharic, Ge-ez, Ancient Egyptian. Finno-Ugric, e.g. Hungarian, Finnish. Sino-Tibetan, e.g. Mandarin, Cantonese, Tibetan. Malayo-Polynesian, e.g. Maori, Tagalog, Hawaiian. At least three families in the New World, many more in Africa and Australia.

Whatever the earliest language was, it was surely not one of the ones that is spoken today, or even one of the reconstructed ancestors of those languages. Furthermore, we don’t know if there was just one earliest language, or several that were invented about the same time.

Some linguists think that the first language(s) may have developed from hunting calls. This is a reasonable hypothesis, since several African languages still have clicks and whistles, the sounds we make to communicate with our buddies while we’re hiding behind trees.

Some suggest that language was invented shortly before our species’ migration out of Africa in 60,000BCE. We are such curious animals, such compulsive explorers, it’s hard to believe that nobody tried walking into Asia before then. Why did none of the earlier exploring parties survive and establish colonies? Could it be that without language it was difficult for them to plan and organize such a momentous project? Or that without language they had no way of passing on to their children all the knowledge that the people back home had, and without it they couldn’t survive?

 

The name "human" is reserved for species of the genus Homo, which came into existence two million years ago; H. habilis was the first species in the fossil record. Our species, H. sapiens, is referred to as "modern humans," and came into existence around 160,000 years ago.

Lucy lived three million years ago and was a member of an older species, Australopithecus afarensis. However, an even earlier species was discovered recently, Ardipithecus ramidus, and "Ardi" dethroned Lucy as the first ape that had broken off from the chimpanzee line to found the human line.

Lucy did not have a large enough brain to have a speech center. Like many more professional linguists, I'm willing to entertain the possibility that species before H. sapiens may have developed speech. All of the species in genus Homo have distinctly larger brains than the other apes. But it's unlikely that any species of the older genus Australopithecus, much less Ardipithecus, had a speech center; it's not clear that their mouths even had the flexibility to produce speech.

Look at our closest living relatives, the chimpanzees and gorillas. They have learned to communicate in a very small vocabulary of American sign language, but they cannot talk.

Ge'ez is Semitic language, closely related to Arabic and Hebrew. Semitic is a branch of the Afroasiatic family, which also includes the Amharic, Berber, Chadic, Egyptian and Omotic branches. They are all descended from a Proto-Afroasiatic language whose place of origin is unknown but may have been in or near Ethiopia.

Nonetheless, human migrations over the millennia ensure that the people who now speak Ge'ez are not direct descendants of the Africans who lived in Ethiopia 100,000 years ago. When North Africa became a desert, the people who lived there were forced to move south. Later on, when Neolithic agricultural technology was invented in Mesopotamia, allowing habitation of hostile regions, a reverse migration of humans from Asia back to North Africa occurred.

The tribe that lived in the northeastern corner of Africa 60KYA, some of whose members walked into Asia and became the ancestors of all non-African humans, are called the San. Today they live in southern Africa. (We know this through contemporary DNA analysis.) This illustrates the scope of the migrations within Africa.

The earliest written languages that we have evidence for are Egyptian and Sumerian, roughly 3000BCE.