It is probably because our society and needs are considerably more complex than those of any other living thing on this earth.
Nature is incredibly complex, of course, but animal communication tends to centre on instinctive needs, rather than the complex emotional states, abstract concepts and conflicting desires that ours tend to focus on.
To what extent psychology influences animal behaviour is a (very loaded) question for another time. Factors like species, scenario and the old aphorism of ‘that which you study, you also change’ come prominently into play the further we go down that road, so we’ll save that one for a later date…
Of course, so much of Human communication is predicated not on what is said, but upon what remains unsaid.
This is before we get to the problems presented by lies, personal interpretations and manipulation of established fact. In addition, body language is actually more important than verbal communication and we also ought to consider even seemingly arbitrary things like fashion and the cultivation of our external image as forms of communication.
AND we haven’t even talked about the form and structure of languages yet.
So, yeah, your point is well taken, Human communication IS incredibly complex.
So why is this? Here’s a little piece (taken from CommunicationTheory.org) displaying some of the reasons that we communicate.
1. We communicate to persuade: It means that we want someone to do something and this desire of ours is communicated. The mother patting the child to stop crying, the advertiser displaying a model in a new T-Shirt and the politician haranguing (urging) his audience to vote for him are all having the same objective of persuading, while communicating it differently.
2. We communicate in order to give or provide information: The science teacher demonstrating an experiment, the bank announcing a reduction in interest rates and the finance minister, presenting the budget are all communicating to provide information.
3. We communicate seeking information: A passer by asking you the way to the post-office, the student asking the teacher for some clarification or the investigating policeman making discreet enquiries are all seeking information by using this communication skill.
4.We communicate to express our emotions like courage or fear, joy or sorrow, satisfaction or disappointment with appropriate gestures and words. Some people have unlimited skill to emote, (i.e., to display excessive emotion) to suit the occasion. Our politicians are capable of emoting well, which by itself is a communication skill.
So, our communication needs, the imperatives that lead us to communicate in the first place, are much more complex than hunting, mating or grooming (although we do a lot of that, too, in fact, watch TV or listen to people’s conversations and see how prominent those three concepts are in our lives – the results may surprise you!).
As mammals, our social structures are closer and our relationships with each other are more complex than, say, reptiles, fish or amphibians. In evolutionary terms, a major cause of this is the nursing of live young on a mother’s milk, something which bonds and endears the young to its community.
Psychologically speaking, we are all unconsciously processing (and sending out) an incredibly large and complex set of signals each time we do anything.
A word, spoken aloud, may affect people in different ways. The word ‘cancer’, for example, will likely affect the listener in a way specific to his/her own experience, as well as its denotation/connotation within the parent culture. Context, also, is interesting, if a comedian comes out on stage in a comedy club and says the word ‘cancer’ – some people will laugh, but others will become angry. They will also react that way for different reasons that are individually specific to each of them (one man may laugh because he fears being left out in a crowd, a remnant of growing up in a large family, or being bullied at school. A woman may become angry because her friend has cancer and so on).
With every word, every action and every deed, we mask our fears and insecurities in ways as subtle and baffling as the way we send out tiny beacons containing our hopes and dreams. Why is it that shy people are often desperate not to inform somebody that they find them attractive? Surely that’s not nature’s way?
Overall, our communication is complex because it has evolved that way. At first, it was out of necessity, when we were cold, naked apes living in a hostile world of predation and starvation that needed to group together in order to survive. Then later, it evolved again when we needed to come together in order to build tools, or cities, or when we decided to look to the sky and dream of ways to get there.
Like all primates, we need complex social systems to govern how we interact and communicate with one another; we’ve just taken it a few steps further is all.