A field of boffins called "evolutionary pyschologists", who hang out with linguists in the uni cafeteria spend some of their time trying to work out what language and human speach is actually for.
The old-skool model says that it is primarly about improved detailed, more accurate transfer of information. Better information means finding better hunting grounds, passing on new skills and knowledge to the next generation, sharing new discoveries in medicines and health, generally just being more competetive, and better able to breed.
But perhaps its not so basic as all that. Actual field observations on people using language and interacting show that for the large majoriy of the time people spend talking only a minute fraction is spent on exchanging data that is in any way related to survival. (Oh, by the way we're talking scientists evesdropping on conversations in the most "natural" settings they could find - crowded cafes, trains, presumably hairdressers salons, making tapes then anyalysing them in a terribly rigorous manner back at the lab). Its mostly completely banal meaningless stuff....our Jason's new job, celebrity marriages, Sheena's dress for the wedding, re-itererating something they said 5 minutes before, what's on at work, Janette's trouble with the baby, the terrible aesthetics of the building going up down the road, the lastest internet flight deals..... you get the picture.
A biologist may deduce that you are wasting a load of precious carbohydrates and brain computing power with this constant drivel, and why on earth did such a giant brain develop in the first place that could cope with something as complex as language?
Well, dear reader, this mob reckon from their studies that the primary purpose of language is to build and strengthen human relationships. You may have noticed me touch on this subject before. Other beings are so fundamental to our survival that we are constantly chattering, sharing , reinforcing our relationships. As miss J notes - "I trust you, I am interested in you, I am connected to you". Possibly the actual information, while important, is secondary to the exhchange.*
Today I was subjected to a lot (and I mean a lot) of talk about cars. Car racing, car models, car performace, car manufacturing and distribution. My end of the table at the Aussie barbie had a higher ratio of middle aged blokes at it, and it the subject just kept coming back around like a bad penny. Having little experience or interest in pretty much all the topics on offer I felt a bit like one of these researchers. Since we've established that any exchange is likely to be totally removed from issues of day to day survival, perhaps so-called conversations like these act like a natural filter for who on god's green earth one is to form bond with. Ipso facto, boredom is clearly an evolutionary tool for weeding out people who you have no need for in life. Bear it in mind kiddies.
*note: complete lack of referencing indicates that this abstract is entirely formed from a sketchy memory of a bbc science doco. Of course.