Emotional intelligence
Emotional intelligence is a skill or ability in the case of the trait EI model, a self-perceived ability to identify, assess, and control the emotions of oneself, of others, and of groups. Various models and definitions have been proposed of which the ability and trait EI models are the most widely accepted in the scientific literature. Criticisms have centered on whether the construct is a real intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....

 and whether it has incremental validity over IQ and the Big Five
Big Five personality traits
In contemporary psychology, the "Big Five" factors of personality are five broad domains or dimensions of personality which are used to describe human personality....

 personality dimensions.
The earliest roots of emotional intelligence can be traced to Darwin's
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 work on the importance of emotional expression for survival and, second, adaptation.