Apologies in advance for this question being only indirectly related to the English language, but I find it fascinating.
I note with interest that the English words "mother" and "mama" have similar sounding equivalents in almost all languages, even those that appear to have no historical recent relationship.
Not even mentioned in that link is the Mandarin word "māmā", a language I always assumed had no relationship with English whatsoever.
This suggests to me that "mother" / "mama" could be one of the oldest surviving words, belonging to some lost parent language from which most modern languages derive.
My questions are:
Is this theory remotely plausible, or just fanciful thinking on my part? Are there any other "universal" words like this? (Could "OK" be considered such?)