Pronoun problems

pronoun problems
The passage below is from ‘the Blank Slate’ by Steven Pinker.

http://evolbiol.ru/blankslate/blankslate.htm

This branching and differentiation is easily visible in the evolution of languages, perhaps ?the clearest example of cultural evolution. And as Darwin pointed out, ?it has a close parallel in the origin of species, ?which often arise when a population splits in two and the groups of descendants evolve in different directions. As with languages and species, cultures that split apart more recently tend to be more similar. The traditional cultures of Italy and France, for example, are more similar to each other than either is to the cultures of the Maoris and Hawaiians.

In this passage I have three questions.
First, what is the semantic subject of ‘the clearest example’?
Second and the last, what do the underlined ‘it’ and ‘which’ stand for?

I have my solution as follows:
?The semantic subject of ‘the clearest example’ is ‘the evolution of languages.’
?it : ‘the evolution of languages’
?which : ‘the evolution of languages’

Can you check it out for me?

Regards.