The essential, or instinctive morality is that of the small tribe of hunter-gatherers, each member accountable to and responsible for the rest. Each contributing what they can according to a stern law of group survival.

But this morality also includes the necessity of regarding those not of the tribe as a threat. The tribes' territory can support only the tribe. As such, it must be preserved and defended against the Other. The Other being anybody you don't recognise, and humans have only the capacity to recognise around 200 individuals.

Thus when, as a result of our imagination-driven progress, larger communities became established, it became necessary to artificially construct rules and establsh customs allowing us to interact in productive ways with people we do not know personally. The rules we call laws, the customs, morals. Laws and customs vary from community to community and from time to time. It was once considered moral, proper and indeed an obligation, to disembowel a stranger in an open field once a year in order to fertilise the crops. The Nazis who conceived and carried out the Holocaust considered it a supremely moral act.

Laws come and go as society changes, and so do morals. I was born in the 1950s and I've seen morals here in the UK undergo a massive change in my lifetime!