These are important advances in Linguistics, I was not aware of.
The debate over the extent to which language is learned or innate is one of the most enduring in linguistics. Most children start to speak around age 2, and within a few short years are proficient, often prolific, users of language. Do they simply listen and learn, or are they born with some language facility that is filled in by the specifics of their native tongue? Learning is obviously involved – children pick up the language(s) they are brought up with. But can this alone account for the complexity and creativity of language?
I saw this once myself. I knew an Italian family in NYC who had a young daughter who only knew English. They went for a vacation in Italy – and when they returned, their daughter could speak Italian!
When I asked her how she learned this, she said “I listened to them talk, and figured out what they were saying.”
Simple as that!