The "mamas" and the "papas"

"Before I knew anything about language acquisition, I assumed that babies making these utterances were referring to their parents. But this interpretation is backwards: mama/papa words just happen to be the easiest word-like sounds for babies to make.  The sounds came first – as experiments in vocalization – and parents adopted them as pet names for themselves."

Presented at Sentence First in a post introducing a new crowdsourced language project (details at the links).