How come we have so many words/phrases that share the same meaning?

I suppose the most obvious answer to this would be that through communication between people with accent/language A and B, new words/phrases were added from A to B and vice versa.

I find however that when we are writing longer texts, we are ensuring that we are not using the same word/expression too often and—if we do—replace them with something else that has the same meaning. In other words: It seems to me like we have an internal drive to use different expressions.

I was wondering if there was any (maybe evolutionary) explanation for this, as it kind of adds a lot of overhead to communication:

  • Time: unnecessary learning of new words whose meaning we're already capable of expressing with other words
  • Resources: necessity of a slightly bigger neuronal structure to accommodate those words/expressions
  • Complexity: more words need to be distinguished, which makes the understanding of the spoken word harder

How does this compare to animals? Do we know whether they also have several ways of expressing the same thing?

  • $\begingroup$ Okay maybe I didn't make myself clear then: I mentioned the dialect part to exclude it. What I was actually interested in is why we seem to have an internal desire not to use the same expression over and over again. This seems to me to be more related to cognitive science than linguistics.. $\endgroup$ Feb 1 '13 at 12:13
  • $\begingroup$ I'm not sure what is being asked here. It seems like you're asking "Why are there so many synonyms?" but this would be more appropriate for Linguistics than for us. If you're really interested in "Why are people motivated to avoid repeating themselves?" rather than a linguistic property, you should edit your post and restate your question as such. $\endgroup$ Mar 31 '13 at 11:32