29 June 2008

Out of Africa

The only massive human migration in pre-history about which there is no doubt is the one that took modern humans from Africa to the rest of the world. It is estimated that Homo Sapiens Sapiens appeared as a new hominid species somewhere in Central Africa approximately 200,000 years ago, and it started to spread around 100,000 years later. Nowadays, this theory, called the single-origin-hypothesis, or simply the Out of Africa model, is generally accepted among paleoanthropologists and in the scientific community in general. The alternative view, known as the multi-regional hypothesis, has fallen into oblivion, especially after strong evidence from genetics started to confirm the single origin of the human species in Africa. The study of the genes in our DNA can be used as a means of establishing the evolution and main parameters of human populations. The first research in this area was carried out in the 1960s by the Italian geneticist Luigi Luca Cavalli-Sforza. In the last decades new techniques for DNA analysis have been developed and many scientists have continued to provide new results, which confirm and refine the monogenetic theory and help to open new research horizons. An example of this type of research can be seen in the following article: UNDERHILL, P.A. et al (2001), The phylogeography of Y chromosome binary haplotypes and the origins of modern human populations. Annals of Human Genetics, Volume 65, Issue 1, Page 43-62.

The image below is a map of the world which shows the Out of Africa expansion of H. Sapiens at its various stages:

(click here for a larger image and full details).
This all comes to confirm a very simple fact: ALL HUMANS COME FROM AFRICA, a sentence that racists and xenophobes should be reminded of from time to time.

Now, what about language?

In the scientific community there is no general agreement about which human or hominid species was the first one with a speech capacity. Was it a specific development or a mutation of H. Sapiens, or did modern humans just continue a pre-existing speech capacity of H. Erectus or other hominid species? On the other hand, it is not clear whether human language originated at a single location (monogenetic hypothesis) or more or less simultaneously in more than one place (polygenetic hypothesis). There’s a variety of proposals about these issues and a huge amount of research is being conducted involving archaeology, linguistics, paleoanthropology, genetics, neuro-science and other scientific disciplines. The most recent developments in this research seem to point in the direction of monogenesis. According to this view, which I share, the human language capacity was born with Homo Sapiens in Africa and it started to develop about 200,000 years before present. We know nothing about the possible ‘languages’ of the other hominid species (H. Erectus, H. Sapiens Neardentalensis, etc.), and we can only try to guess what kind of relationship there was between their communicative systems and the language of H. Sapiens Sapiens. But as I said, there’s strong evidence suggesting that human language as we know it was born as an innovation of the only hominid species that has survived until today: ours.

The emergence and expansion of the various language families (Nilo-Saharan, Altaic, Sino-Tibetan, Indo-European, etc.) must be seen in the context of the Out of Africa migration of humans, that is, a process which began around 100,000 years ago. There is no evidence suggesting any other massive, transcontinental migration of humans at a later stage in pre-history, for example in Neolithic times. Traditional chronologies, like the one which sees the expansion of Proto-Indo-European in approximately 3,500 BC., are no longer tenable. They are based on wrong assumptions about language change and archaeology. Amazingly, this traditional chronology is still accepted in mainstream (historical) linguistics.

Further reading:
- BALLESTER, Xaverio (2002). Las Primeras Palabras de la Humanidad. Ediciones Tilde, Valencia.
- CHRISTIANSEN, Morten and KIRBY, Simon, eds. (2003). Language Evolution. OUP.
- SYKES, Bryan (2001). The Seven Daughters of Eve. W. W. Norton and Company.


JoseAngel said...

Well, some people contend that the existence of a widespread family of Indo-European languages is itself the evidence of that later migration and population spread. It is not clear from your article why this kinship among languages should not count as evidence. Could you explain this point further?

Jesús Sanchis said...

Criticism of traditional Indo-European theories and chronology is one of the main elements in this blog. I have already published some posts dealing with this topic, like the one called "The name of the bear" or the one about Scandinavian languages. There are a lot of reasons to reject the old paradigm, and I want to write more articles about it.