Emotional Intelligence & Interpersonal Skills

From early times there has been the conundrum of what makes a great leader. For every so often great leaders with no extraordinary traits, and certainly not having high IQ would appear to debunk the common psychological theories of their day. Conversely, why do some people with high traditional intelligent quotients (IQ) fail to reach their potential in either their personal or professional lives? Similarly there are occasionally those of average IQ who goes on to surpass their colleagues with higher IQ to reach stellar positions within their company.
Scientists have suspected since Darwin's era that our traditional view of a purely cognitive intelligence may not be the whole story. From that they surmised that we might actually have multiple levels of intelligence and one very intriguing one that may hold the answers to the puzzle - emotional intelligence combined with high interpersonal skills.