Larger brain size no guarantee of higher IQ: study

A larger brain size does not guarantee a higher intelligence quotient (IQ), according to a new study that contradicts the belief that a bigger brain meant a higher IQ potential, PTI reported.

Following the advent of brain imaging methods, (eg MRI, PET), reliable assessments of in-vivo, brain volume and investigations of its association with IQ were now possible according to the researchers.

An international team of researchers conducted a meta-analysis examining correlations between in-vivo brain volume and IQ and on the basis of data from 148 samples comprising over 8000 participants, they reported a robust but weak association between brain size and IQ.

This association appeared to be independent of participant sex and age, the researchers noted.

''The presently observed association means that brain volume plays only a minor role in explaining IQ test performance in humans. Although a certain association is observable, brain volume appears to be of only little practical relevance,'' said Jakob Pietschnig from the Institute of Applied Psychology of the University of Vienna.

''Rather, brain structure and integrity appear to be more important as a biological foundation of IQ, whilst brain size works as one of many compensatory mechanisms of cognitive functions,'' said Pietschnig.

The evolution of anthropoid primates, including monkeys, apes and humans, over the past 40 million years was largely driven by brain reorganization, and not brain size, according to new research from University College London (UCL). (See: Organisation trumps size in primate brain evolution).