I've been going through acrobatics trying to apply brain function to existing definitions of human nature, but the latter shouldn't be used to describe the former; these contortions shouldn't be necessary, and are in fact quite counterproductive to understanding, even my own. Instead we should be taking the brain function and categorising according to that: our brain function is the motivation that drives a behaviour, yet that motivation, even if it has the same source and goal, somehow becomes a 'different thing' between (social) topics.
Our brain's most basic function is 'recognising' situations and dishing out the 'right' chemicals (emotions) as a reaction to them: defensive and active for danger, and passive and soothing for reward, and our survival depends on our brain matching these correctly. Yet this recognition needs to be educated: in our first moments in the outside world, the only 'safe' situations we recognise are those we already know from the womb: the warmth of mother. When we see mother trustingly and fearlessly associate with others around her (namely father), our definition of 'safe' will spread to them as well. And the 'tree of trust' will spread to whoever they trust, and so on and so on.
That's just our most primitive 'danger detection' mode. Added to that are the lessons trusted people teach us: we tend not to accept any lessons from people not in this category, and although we may remember those 'lesson attempts', we will not integrate them into our 'knowledge repertoire' until we think about them ourselves at a later date - if we ever do - or until that person somehow later becomes part of the 'trusted' category. But still, if someone is not trusted as they give a lesson, they will not have a direct influence on our learning process.
In our younger years, if we are given an example of behaviour to imitate, we can only judge the 'success' with which we accomplish this imitation by empirical evidence (does the square peg fit in the round hole? No. The square one? Yes!) and the (emotional) reaction of the person making us do the exercise. I doubt that we even consider why we're doing that exercise in our younger years, we know only that we have to imitate 'older proof of successful survival trusted figure' in order to survive ourselves. Sometimes the lessons we are told to imitate, like learning words, have no physical aspects that we can confirm ourselves: we know only that, should we imitate a sound successfully, other humans will understand and provide an emotional response that is more or less the same from person to person. Yet, at a young age, we don't consider the why of those words, we know them only as successful methods of expressing our emotion and well-being, and the desires for and fears of the material things that effect these.
But as we grow older and the scope of our attention grows wider, we're going to notice functioning things and the behaviour of other humans (trusted or not), and we may want to try them out for ourselves without any prompting or guidance. For whatever reason, if a child chooses to act on their curiosity, their reward can only come from themselves.
This last bit is what intrigues me. In our society, it hard to tell what motivates curiousity and a desire to try (new) things out for oneself. Yet it is very easy to understand in a 'do or die' situation... survival is the 'reward', and if we have never encountered that situation before, we will educate our emotions to respond 'accordingly' if we survive it.
You see, in describing this basic function in this context, referring to my earlier post, we're talking about both critical thinking and morals here, or "recording an emotional response after testing". But it's more than that: this function is used in all aspects of our lives, but it is named differently for what motivates its use.
If we were to draw a diagram of 'human nature', we would have categories such as 'morals' and 'critical thinking' and 'learning' and 'feelings', but what we seem to be doing today is taking a single brain function and adding it, individually, as a separate entity, into each category. Instead, I propose making that common function a unique central 'thing', and linking the other categories to it.