How does social exclusion affect someone's mental and emotional health?

Self esteem: Largely we are social creatures by nature, and social exclusion leds many to feel like outcasts and/or less-than others. In my opinion, it greatly erodes self-esteem, as we need others to relate to and interact with as a safeguard against lonliness. One of the more interesting definitions of the purpose of life is to care for someone else. When this need is thwarted by whatever force, pain follows