Man has tried to define a "golden barrier" a firm criterion to mark an unbridgeable gap between the mentality and behaviour of humans and all other creatures. Behaviour was tried such as the use of tools, or tools explicitly fashioned for particular use. Next was the distinction of mental attributes such as a moral sense or the ability to form abstractions. The development of culture - the complex behaviour of local populations passed through learning rather than instinct has persisted as a distinctly human attribute.
Darwin stated that "The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. Alexander Popes couplet: All are but parts of one stupendous hole, Whose body nature is, and God is the soul.
Alexander Popes observation of human nature being on an "isthmus of a middle state." Between bestiality and mental transcendence.
The representation of 151 years of study, including Jane Goodall's 40 years of research of chimps in the wild, published in a 1999 issue of the journal Nature, concluded that chimpanzees have distinct cultures within groups and that they learn behaviours through observation and imitation and are able to pass them on to other chimpanzees.
The evidence is overwhelming that chimpanzees have a remarkable ability to invent new customs and technologies, and that they pass these on socially rather than genetically.
The basic formulation of "them versus us" and the resulting search for a "golden barrier" represents a deep fallacy of human thought.
The true basis of distinction lies in topology and genealogy, not in any functional attribute marking our superiority.