They reckon it is an evolutionary tradeoff - a chimp has to make rapid and complex decisions within a short time frame in the very competitive social hierarchy of a troop.

We are more on collaborating and thus evolved language.

In other words, we can remember those symbols, but only if they make sense in the form of a sentence.

There is a special link between language and memory for sure, evident, if not else, at least by our almost complete lack of memories about our years before language acquisition.

It is called infantile amnesia - our brain only figures out declarative memory storage by the age of 2 to 4 - some argue that is not linked to language as animals also experience this.

Cool, I didn't know that, if it happens in animals it probably has nothing to do with language.