My interpretation of the significance of the study this article is about was that it is a very longitudinal study, demonstrating the patterns you mention across

My interpretation of the significance of the study this article is about was that it is a very longitudinal study, demonstrating the patterns you mention across thousands of languages. Anecdotally speaking as a multilingual person, I've noticed some of the same patterns - but untested, anecdotal comments aren't worth much; I find it significant and interesting that (at least some of) these trends seem to hold across thousands of languages. This isn't my field, though - is my impression of the significance here correct? A second question: isn't it the currently held theory in linguistics that there is more or less a single "super parent" language - which my memory of my intro to linguistics class from ten years ago identifies as Proto-Indo European - and wouldn't that common linguistic ancestor provide a plausible alternative explanation for this common sound symbolism? A question tangentially related to the above: the sounds you mention are all vowels, which are easier for infants to make and which infants tend to learn to make first; it seems to stand to reason that sound symbolism tied to sounds made earliest by infants would be more likely to be unchanged over time. Is there anything that rules out this perspective? Building on this, I know that there are some patterns to the development of abstract reasoning in children; has there any work been done on correlating abstract reasoning development timescales with the development of phonetic production skills? Perhaps this sound symbolism has to do a parallel in the developmental timelines of these two?