A Little exemple :
Upper paleolithic : The food is getting scarse in the current settlement of this hunting gathering group. A woman is sick and people are getting very nervous and stressed. The hunting group finally came back with a big piece of meat. They (the hunters) agreed to share the meat and give a bigger portion to the weak woman. But the rest of the group (that remained to work on the camp) does not agree and start yelling.
As you can see here, with a simple conflict, we have the left/right (progressive/reactionnary) dichotomy at work. The group who hunted the beast decided to share food with equity, but the group who stayed back and is hungry as fuck wanted the same size, thus ignoring the needs of the weak one in the group.