Subject: How does one make a wild banana becomeb a domesticated banana?

I am had a discussion with someone about the domesticated banana. He mention 
that banana somehow changed form over time from wild banana to to the 
domesticated banana that we have now. I told him that that's not true, the 
wild banana has cultivated that way, it has not changed by it self. He then 
went on to ask me "if it's done by humans then can you give me an example of 
how this is done?" I beleive what I said but I have no idea how this is done 
today or thousands of years ago by people less technologically advanced than 
us. Maybe I'm wrong, but if so please inform me or tell me how this could be 
done. 

Thank you in advance.

P.S: It would be helpful if you could refer me to a credible source; I'd 
appreciated.

Re: How does one make a wild banana becomeb a domesticated banana?