Chimpanzees live in equatorial and tropical Africa, i.e. the place where the first humans developed as a species. The map on the right (source) shows the different distribution of daylight hours in the world depending on the time of year. At the Equator, there is a balance of 12h of daylight and 12h of dark throughout the year, and in the adjoining areas the variation is low. The further we go north or south, the variation is higher. The extreme situation is obviously in the Poles, with either constant day or constant night.
It is difficult to know the sleeping patterns of extinct hominid species. If we think of Neanderthals, who were adapted to cold weather in the northern hemisphere, we might expect some kind of biological adaptation to the new environment. For us, humans the story is quite different, as our adaptation to those habitats is mainly a result of our technical ability (use of fire, clothing, etc.). Millions of humans live today in areas that we were not originally designed to inhabit. Our body and biological rhythm correspond to an equatorial or tropical environment.
Now, what does all this have to do with language? Let's see.
In previous posts, I have suggested that language was born in the context of a complex communication system that already had its own grammar. Maybe it was born as just a complement in an already rich communicative environment, but it certainly developed into something that gained relevance in human societies, as we can see today. Languages are at the centre of any human group, and are perceived as an independent communicative system. How did this happen? Obviously, using oral communication has some advantage of its own, as many authors have pointed out. One of these advantages is the fact that it can be used at night, i.e. in the absence of the whole world of perceptive stimuli and visual references that can be found in daylight. Communicating in the dark requires some additional effort, and it looks like vocal speech might be the best solution to overcome the difficulties.
Now, if you live near the Equator, as our ancestors did, you are possibly not much worried about how you fill your night time hours. There are about twelve of them each day, and you spend most of that time just sleeping. This is how our ancestors experienced life. Communication, including language, evolved in this scenario of balance. There was no special pressure for oral speech to surface as a particularly crucial element. It did evolve, but maybe at a slow pace.
|From my Flickr photostream|
Maybe the new conditions found by humans at northern latitudes added new pressures to the development of language. If we look at the languages of the world, we can see an enormous discontinuity. The languages of central and southern Africa look extremely different from the languages of Eurasia. Some examples of these radical differences can be seen in The World Atlas of Language Structures, available online. Fusional languages like the ones in the Indo-European or Afro-Asian groups seem to have taken the concept of language to a degree of formal complexity that is not present in many sub-Saharan languages. A lot of research should be carried out before any solid conclusion may be drawn, and also to avoid overgeneralizations, but I think it is not absurd to hypothesize that Eurasia was an innovative area in terms of language, and that these innovations may have spread to other parts of the world, including Africa. The distribution of day/night hours may have played its role in the accumulation of pressure for these developments to take place.
- Anch, AM et al (1988). Sleep: a Scientific Perspective. Englewood Cliffs NJ: Prentice Hall.
- Siegmund, R. et al (1998). "Activity monitoring of the inhabitants in Tauwema, a traditional Melanesian village: rest/activity behaviour of Trobriand islanders". In Biological Rhythm Research, 29:49-59. (abstract).
- Videan, E.N. (2005). Sleep and Sleep-Related Behaviors in Chimpanzee. Dissertation.