The evolution of language, Pre adaptation or a result of evolution?

Language is one of Homo sapiens’ distinct traits and distinguishes it from other species. Understanding the origin of language poses difficulties, since, unlike writing, spoken language leaves no explicit concrete evidence of its existence.
Spoken human language relies on the anatomical apparatus suitable for speech as shown here.
Read the end of this site for information about the evolution of speech.
The human brain has specific areas that support language as explained in this site.
These features may not have developed specifically for speech but could have been a preadaptation (use of an inherited preexisting anatomical structure for an unrelated purpose). So how can we be sure about how language evolved?

Here are some links I've personally thrown together, please take the time to read them, and post whether you think it was a pre adaptation or a result of evolution.

Spoken human language relies on the anatomical apparatus suitable for speech as shown here:http://www.bing.com/reference/semhtml/Vocal_apparatus

This websites identifies the different debates of this: http://www.bing.com/reference/semht...ed&qpvt=theories+about+why+language+developed

Idea on how language evolved : http://pandora.cii.wwu.edu/vajda/ling201/test1materials/origin_of_language.htm