Repetition and its use in the Chinese language.

Recently I have been thinking about repetition and its use in the Chinese language. In spoken English repetition is usually only a feature of the old ( they are confused or forget) or the naturally loquacious. Since all communication originated through verbal sound ,can it be assumed that the use of repetition to emphasise a meaning as used in modern spoken Chinese is a remnant of a far older speaking convention?

For example : 你(nǐ)去(qù)看(kàn)看(kan)。  我(wǒ)随(suí)便(biàn)看(kàn)看(kan)。

How does this use of repetition link with the written use of repetition? For example there are many words in Chinese that separately and together mean the same thing. For example  朋(péng)= friend ;友(yǒu)=friend  and 朋(péng)友(you)=friend .

动(dòng)=to move ,运(yùn)=to move and 运(yùn)动(dòng)=physical exercise ,movement.

学(xué)=to study , 习(xí)=to study and 学(xué)习(xí) =to study.

So the questions are in the development of language what practical function could this phenomenon have served? Does it occur in other Asian languages, for example Japanese or in other ancient languages like Sumerian Cuneiform?

Is modern spoken repetition in Chinese now always just restricted to verbs like 看(kàn) or can you repeat nouns, adjectives?