I honestly don't know what a morally upright life is, it doesn't compute anymore. I just try to be good to people and do no harm. If that is simplistic then so be it.
The idea of sanctity evolving from learning not to eat tainted food is very interesting. Most things deeply entrenched in the human psyche are about basic survival.
When people ask 'is nothing sacred' I feel nothing is. Life is supposed to be sacred but this leads to refusing assisted death. We let humans suffer worse than dogs and cats. So no I don't think life or anything is sacred but I do understand the desire to be 'clean'.
This might be purely about hygiene and survival but I think we have an innate desire to feel that we are 'good'. Which again might be about social acceptance and therefore survival but I am not convinced of that. Guilt is a hugely destructive force in the human mind which leads me to think that there is more to feeling 'good' than mere social acceptance.