In this article it talks about if animals have different language. It states that animal language is coded. When they switched a pair of puppies they could not understand the language they were switched to. That language comes with that breed.
In this article it says linguist, people who study language, only can make educated guess. One educated guess is they speak with sounds of nature. Another guess is they started with basic sounds with tools. The groups also could have merged and met and combined their languages. There are more educated guesses in this article.
This article says that the environment we live in may cause some changes in language. There was a study conducted by the University of New Mexico. They studied 628 languages. In the study they got that the environment has an affect on language because of the echo and things that usually affect sound.
This article speaks of the religious aspect of my question. It says we all once spoke the same language. Then we bragged and did not praise God and punished us. It also says there is no proof of the origin of language. It says there are theories but no proof . Then it talks one other theory.