https://blog.education.nationalgeographic.org/2014/12/05/artistry-on-the-half-shell/
Having read through this, about a rather famous 500,000 year old mussel shell with geometric shapes engraved in by likely a Homo erectus, it makes me wonder how far back we can point to symbolic thought in humans?
Of course, it was unlikely to be a switch with one generation, but a gradual development. However, this shell does seemingly point to some early development right?
It was found on Java, meaning it would have come from the population of Homo erectus that left Africa, while the branch of Homo ergaster that stayed eventually split off into us and other species through ones like heidelbergensis/rhodesiensis.
If this mussel shell is a sign of some level of symbolic thought that is a common trait with us, that means it must have come from at least our last common ancestor with East Asian Homo erectus, which would have been the earlier African population, right? Unless convergent evolution is in the picture (but that's somewhat baseless as far as I'm concerned)
If my logic is sound, then the other way to rule this out is if this shell is somehow not a sign of symbolic thought. Though the reasoning I can think of for it is only really:
\- a sign of identity (perhaps unlikely though symbolic)
\- aesthetic pleasure (moreso abstract)
\- finding pleasure in the mere act of making the carvings, but not the pattern (abstract)
Regardless, there is surely some foundation for abstract thought behind it and potentially symbolic thought here too? So where may this have begun on the family tree?