The phrases "shame on humanity" and "shame to humanity" are both expressions used to convey a strong sense of disappointment or condemnation towards humanity as a whole, but they have slightly different connotations:
Shame on humanity: This phrase is often used when referring to actions, events, or behaviors that reflect poorly on humanity as a collective whole. It implies that the actions or events are disgraceful, and the speaker feels a sense of collective responsibility or connection to humanity. For example, someone might say "shame on humanity" in response to a large-scale environmental disaster caused by human negligence, indicating a feeling of collective responsibility for the negative consequences.
Shame to humanity: This phrase is used when referring to actions, events, or behaviors that bring disgrace or discredit to humanity as a whole. The focus here is on the specific actions or individuals responsible for the negative behavior, rather than humanity as a whole. It's as if these actions have brought shame or dishonor upon humanity. For example, if someone commits a heinous crime that gains international attention, people might say "shame to humanity" to express their condemnation of the individual's actions and to distance themselves from such behavior.
In summary, "shame on humanity" implies a collective responsibility for negative actions or events, while "shame to humanity" highlights specific actions or individuals that bring disgrace to humanity. Both phrases express a sense of disappointment or disapproval towards the actions in question, but they focus on different aspects of the situation.