The brain can compensate for lack of tissue or, to some
extent, for loss of tissue. Some people who have little or
no cerebral cortex have great intellectual ability. There
are many anomalies in relationships between ability
and brain size, so no comparative conclusions can be
reached except in relation to grossly aberrant individuals or within small taxonomic groups. In contrast, studies of complexity of
brain function can give much information about ability
as well as about welfare.