Our structure changes as our experience changes. We are part of a lineage of living things, more particularly, the human lineage. This is characterised by its dependence on the emotion called love for relational, and therefore physiological, wellbeing. If love is absent, we become ill. Love is the domain of behaviours through which another arises as a legitimate other in coexistence with oneself.
Love is an emotion constituting a certain space in which relations occur - no more, no less.
Acceptance as a legitimate other changes us in our relations. Rational arguments can cultivate aggression, but not where love exists. We are neotonic animals, i.e. we are born relatively undeveloped and our childhood is greatly expanded compared to other species. In evolution nothing happens because it is necessary or because it is an advantage. What happens is that a certain manner of living begins to be conserved and then other things gradually happen around this.