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purely existing

It's neither intelligence or existing, it's a strain of thought and blood that flows through the veins within' the essence of the soul.

In other words if you think like a human or if looking at it in a spiritual way have that very blood/essence then your human.

Else wise your another species.

Though I have noticed people are trying to make other species into humans.....I still haven't forgiven that dentist for removing the Fangs I had been born with. =_=

To be considered human, it's biological.
Sure, there's the "higher-thinking", but other animals have been known to think as well as young humans, so they would count too under that: parrots, some dogs, apes.
Unless we're saying young human children aren't humans.

Apes are close to being human, or humans are close to being apes, but there is still a DNA sequence difference.

To Twisted:
When I was younger, I thought I was a collie, but that didn't make me one.
I even chased my friend around her kitchen and let her pet me afterwards on her couch.
Went on for years.
Didn't change the fact that I'm biologically human.

It was fun though.
:"3

Would totally do it over again~

Scientifically the only reason we are separated from animals is that we have thumbs and can think on a higher level of intelligence, other than that we are technically animals lol 3nodding

I define being human as being a Homo sapien. It is impossible for something else to be a human because that is what humans have defined it as.

Ohhhhhh symbol recognition is enormously important too. i think that comes down in a lot of instances to the developement/invention of abstract concepts ands significances. In the study semiotics (the study of symbology and significant imagery) the a symbol is broken into two parts, the sign; the image itself; the word cute for instance the written or spoken word itself is the sign. the second part is the signifier; what the idea that image or sign represents; in the word cute the signifier is the definition of the word, the abstract/intuitive idea of what cute means.

then the signifier is broken into two parts, the meaning as denotative; meaning directly what it means. and connotative; what subjective, or relative influences. In the case of cute, you have the dictionary deffinition of cute as the denotative meaning, and you have perhapse the idea of a kitten or a pretty girl as the connotative meaning.

anyway i digress, I feel that while symbol recognition is a development of property thought, (tho perhaps i dont know what you mean by that other than the concept of property ownership in ego) i feel that symbol recognition involves more an ability to categorize, organize and communicate a certain reality to the world around the Human. (tho symbol recognition is not exclusively a human experience, Chimps (even dogs) symbolize emotion (which is very a ellevated intelligence really) through body language gestures and calls. however vollentary or involentary those languages are to their consiousness the symbols are.)

also just to clarify Neanderthals are technically human beings, scientifically and biologically. Neanderthals scientific name is Homo Sapien Neanderthalensis, While modern man is Homo Sapien Sapien. The neanderthal and the modern man are actually two sub species of the same species. Like donkeys and horses, only perhapse Neanderthal man and Modern man are even more closely related than donkeys are to horses in that we might have even been able to reproduce between eachother and those children would not be sterile, unlike a mule.