What the New Caledonian Crows' Ability to Do Compound Tool Manufacture Teaches Us About the Theory of Primate Evolution

A few captive great apes can be trained to do some compound tool manufacture*; however, it is not spontaneously characteristic of the species. On the other hand, in the world of non-human species, such spontaneity is uniquely characteristic of New Caledonian crows. See https://www.nature.com/articles/s41598-018-33458-z

So, if hominid evolution were true, then what evidence do we have that some so-called hominid primates naturalistically -- that is to say, per a so-called co-evolutionary pathway -- obtained what natural selection theory says may possibly occur in a primate species in order for it to become more advantaged for survival than was true for its ancestors? Or, as respects all the putative primate "cousin" species (said to have evolved but then, as goes the just-so story, became dead-end, non-extant branches in primate evolution), were there not any besides Homo sapiens that would have been significantly advantaged had any of them also come to own enough mental prowess for ability to do compound tool manufacture? Apparently, anybody is justified in saying that the brain case size of New Caledonian crows gives convincing argument that a species' brain does not need to be the size of a human brain in order for it to ground ability to do compound tool manufacture. Seeing the thriving existence of so very many avian species having different brain sizes, then we can say that it is self-evident that the existence of all other avian species is convincing evidence that they are not significantly impaired/disadvantaged/threatened as though such a condition were caused by absence in their brains for grounding ability to do compound tool manufacture. Also apparent is the fact that ability to do compound tool manufacture does not necessarily correlate with ability to communicate by use of language. Only humans characteristically use language to communicate.

* "In Koehler’s emblematic study, the male chimpanzee, Sultan, made a useful compound pole, but only after being coached by a human demonstrator who poked his finger into the hollow bamboo element. According to Koehler, Sultan manipulated the tool elements for over an hour and then, after a short break (not long after the aforementioned demonstration), suddenly discovered the solution, as if overcome by an acute insight. In contrast, half of our 8 crows succeeded, similarly abruptly, but within only 4-6 min of engaging with the tool elements, and without any cueing by the experimenter. Also, Sultan did not immediately reproduce the constructive behavior the following day, while 3 of our 4 successful crows readily continued to produce compound tools in the trials that followed their first occasion. They also transferred to modified situations rapidly and demonstrated sensitivity to the need for tool construction."--See cited article.