A popular approach points to the similarities between the ontogeny and phylogeny of language. The ontogeny and phylogeny argument has force only if the parallels between primate and child language are genuine. Traditionally, children's language is believed to include abstract linguistic representations and processes even though their speech output may be constrained by nonlinguistic factors, such as working memory limitations.
INTRODUCTION TO LINGUISTICS & PHONETICS - LINGUISTICS ONTOGENY AND PHYLOGENY