The main reason for language is that the human brains are capable of generating it and the human vocal cords are capable of producing it. A lot of it has to do with abstract and symbolic thinking, again a capacity facilitated by brain structure.
There are many types of intraspecies communication seen throughout the animal kingdom, and even among humans there are non-linguistic communications in use, such as body language and paraverbal communication, such as the actual inflections used to convey different meanings with identical word combinations. For example:
"I stole your lunch." (falling inflection, assertion of fact)
"I stole your lunch?" (rising inflection, expressing denial and incredulity)
There are many types of intraspecies communication seen throughout the animal kingdom, and even among humans there are non-linguistic communications in use, such as body language and paraverbal communication, such as the actual inflections used to convey different meanings with identical word combinations. For example:
"I stole your lunch." (falling inflection, assertion of fact)
"I stole your lunch?" (rising inflection, expressing denial and incredulity)
