I felt that dot answered that question with the link or at least gave launching points.
I feel that I agree with enkidu in that society defines human nature in a way thats convenient for the zeitgeist. I however feel that we have become so domesticated we may never know what true human nature was. Many studies on the domestication of mammals have shown that their brains significantly shrink and begin to fire less proficiently. Once taken out of their natural environment and their ability to control their own lives is removed they are no longer the same creature. I believe this gives us insight into our own lives as domesticated animals. For the most part as a species we don't decide anything in our lives that make us animals, or human. We don't decide what we eat, unless your privileged. we don't decide what we do, think, say, or believe, again unless your privileged; which is a very small percentage, and we can talk about privilege another time. For the most part we are given the illusion of being free thinkers that have mental sovereignty, but most of the population can not afford the time, and/or the information is not made available, or they are not in a place to receive it.
I'm not sure what human nature is but I'm pretty sure nothing existing in a imaginary world in which old men tell everyone how high to jump is natural.
I would be curious to hear some studies of prehistoric man, i don't know much other than what jared diamond had to say.