This emoji was part of the proprietary / non-standardized emoji set first introduced by Japanese carriers like Softbank. These emojis became part of the Apple iPhone starting in iOS 2.2 as an unlockable feature on handsets sold in English speaking countries.
Maslow's (1943, 1954) hierarchy of needs is a motivational theory in psychology comprising a five tier model of human needs, often depicted as hierarchical levels within a pyramid. Maslow stated that people are motivated to achieve certain needs and that some needs take precedence over others.
First, most basic level: physiological needs, such as the need for food, water, safety, and security. Second level: needs for social interaction, such as the need to belong. Third level: needs for esteem, which include the need for respect from oneself and others. Fourth level: needs for self-actualization, or realizing one's full potential. Maslow believed people pay attention to higher needs only when lower needs are satisfied.