How babies and young children learn to understand language

This is a fairly short book excerpt from "The Language Puzzle: Piecing Together the Six-Million-Year Story of How Words Evolved" by Steven Mithen:

How can babies possibly discover where a word begins and ends within a continuous sound stream? A breakthrough in our understanding came in 1996 in a three-page article in the journal Science entitled “Statistical learning by 8-month-old infants,” authored by the psychologists Jenny Saffran, Richard Aslin and Elissa Newport. This explained that infants use “transitional probabilities” (TPs) between syllables to identify which syllable strings recurrently go together, and hence are likely to constitute words, and which syllables have low probabilities of following each other and hence are likely to mark the break between words. The phrase pretty baby, for instance, has four syllables (pre-ty-ba-by) and three transitional probabilities between syllable pairs. In English the probability that ty will be followed by ba is lower than pre will be followed by ty, and that ba will be followed by by. That eight-month-old-infants can calculate and use such transitional probabilities came as a surprise.