Why humans are so distinct from other species?

[CapnAwesome]

Regardless, there are several competing explanations or potentiators in the history of human evolution to which is normally ascribed the selective pressures which resulted in our larger brains, and the specific topographical features. Among these are bipedalism, language, climactic instability, manual dexterity (opposable thumbs), and just a general adaptationist "more is better" explanation (which has serious shortcomings, as it doesn't explain why we have big brains, and say cheetahs don't). Of these, only climactic instability seems reliably suitable as a selection pressure resulting in generalized increase in intelligence. The back side of this is that there are animals with similar intelligence ratios (body to brain size) who haven't become "intelligent" in the way that we have. Regardless, if you are arguing that humanity is distinct, it would seem that the null hypothesis is that humanity is, perhaps modestly improved, but not in any sense distinct; if correct, then the notion that humans are distinctly intelligent bears the burden of proof, and I've yet to see any put on the table. (Beyond the rather insipid, "Lookee what I can do. Shiny!")

In regards to feral children: Yes humans can be brought down to the basic skills of an animal, but the reverse is simply not true. No animal can be brought up to the skill set of a human. Sure, animals can learn a comparatively small vocabulary of words, but try to teach one to read.

As for your dismissal of 'lookee what I can do.' Human accomplishments and abilities should far far exceed the burden of proof for greater intelligence. Almost any human being, baring genetic deformity, is capable of learning algebra. No animals are.