Intelligence (trait) in the context of Planning

Brain–body mass ratio, also known as the brain–body weight ratio, is the ratio of brain mass to body mass, which is hypothesized to be a rough estimate of the intelligence of an animal, although fairly inaccurate in many cases. A more complex measurement, encephalization quotient, takes into account allometric effects of widely divergent body sizes across several taxa. The raw brain-to-body mass ratio is however simpler to come by, and is still a useful tool for comparing encephalization within species or between fairly closely related species.

Charles Edward Spearman, FRS (10 September 1863 – 17 September 1945) was an English psychologist known for work in statistics, as a pioneer of factor analysis, and for Spearman's rank correlation coefficient. He also did seminal work on models for human intelligence, including his theory that disparate cognitive test scores reflect a single general intelligence factor and coining the term g factor.

Joy Paul Guilford (March 7, 1897 – November 26, 1987) was an American psychologist best known for his psychometric study of human intelligence, including the distinction between convergent and divergent production.

Developing the views of L. L. Thurstone, Guilford rejected Charles Spearman's view that intelligence could be characterized in a single numerical parameter. He proposed that three dimensions were necessary for accurate description: operations, content, and products. A Review of General Psychology survey, published in 2002, ranked Guilford as the 27th most cited psychologist of the 20th century.

The Dragons of Eden: Speculations on the Evolution of Human Intelligence is a 1977 book by Carl Sagan, in which the author combines the fields of anthropology, evolutionary biology, psychology, and computer science to give a perspective on how human intelligence may have evolved.

Sagan discusses the search for a quantitative means of measuring intelligence. He argues that the brain to body mass ratio is an extremely good correlative indicator for intelligence, with humans having the highest ratio and dolphins the second highest, though he views the trend as breaking down at smaller scales, with some small animals (ants in particular) placing disproportionately high on the list. Other topics mentioned include the evolution of the brain (with emphasis on the function of the neocortex in humans), the evolutionary purpose of sleep and dreams, demonstration of sign language abilities by chimps and the purpose of mankind's innate fears and myths. The title "The Dragons of Eden" is borrowed from the notion that man's early struggle for survival in the face of predators, and in particular a fear of reptiles, may have led to cultural beliefs and myths about dragons.