Answer to Question 1
Jung and Haier originally proposed the P-FIT model in 2007. P-FIT stands for
Parieto-Frontal Integration Theory. This theory proposes that intelligence comes from a distributed and integrated network of neurons in the parietal and frontal lobes of the brain. Individual differences in intelligence are seen as individual differences in brain structure and function. Neuroimaging studies provide support for the P-FIT model.
Answer to Question 2
Higher socioeconomic status, exposure to stimulating environments, taking advantage of cultural and educational resources throughout one's life, and not being lonely have all been associated with better cognitive functioning. Loneliness, for example, is associated with greater cognitive decline and with mental health problems in later life. Although social and lifestyle variables are associated with intellectual functioning, it is still debatable whether these factors slow cognitive changes in late life. Research evidence on these factors is mixed. For example, decreases in social engagement and cognitive decline are related, but what is the directionality? Are declines in memory the result of lower social engagement, or are memory declines the reason for lower rates of social engagement? Correlational data cannot determine directionality of effects.
The endosymbiosis theory
Intelligence and Education
Fluid and Crystallized Intelligence
Four kinds of evidence supporting the theory that species evolve.
Animal Intelligence
Multiple origins of replication on a single chromosome from Drosophila melanogaster