NS has several articles on the topic in their new issue, like “What is it really?” and “Do IQ tests really work?” See the link to explore it. For example, from the first article:

“When researchers talk about intelligence, they are referring to a specific set of skills that includes the abilities to reason, learn, plan and solve problems. The interesting thing is that people who are good at one of them tend to be good at all of them. These skills seem to reflect a broad mental capability, which has been dubbed general intelligence or g. This seems to fly in the face of old ideas. In the early 1980s, Harvard psychologist Howard Gardner argued for the existence of multiple intelligences, including ‘bodily-kinaesthetic’, ‘logical-mathematical’ and ‘musical’. However, most researchers now believe these categories reflect different blends of abilities, skills and personality traits, not all of which are related to cognitive ability.”