http://www.larspenke.eu/pdfs/Deary_Penke_Johnson_2010_-_Neuroscience_of_intelligence_review.pdf
The neuroscience of human intelligence differences
by Ian J. Deary, Lars Penke and Wendy Johnson
Abstract: Neuroscience is contributing to an understanding of the biological bases of human
intelligence differences. This work is principally being conducted along two empirical fronts:
genetics -- quantitative and molecular -- and brain imaging. Quantitative genetic studies have
established that there are additive genetic contributions to different aspects of cognitive
ability -- especially general intelligence -- and how they change through the lifespan.
Molecular genetic studies have yet to identify reliably reproducible contributions from
individual genes. Structural and functional brain-imaging studies have identified differences in
brain pathways, especially parieto-frontal pathways, that contribute to intelligence differences.
There is also evidence that brain efficiency correlates positively with intelligence.

<my comment>
Ian Deary is one of the leading researchers on intelligence and wrote a book "Intelligence: A Very Short Introduction".

"To see what is in front of one's nose needs a constant struggle." - George Orwell