The division of labour between the two hemispheres and the lateralization of handedness in humans have puzzled researchers for many years. In this issue, Sun and Walsh (page 655) review recent genetic, imaging and neurological evidence on the molecular mechanisms that underlie anatomical and functional asymmetries of the brain. They argue that brain asymmetry results from interplay between intrinsic factors and extrinsic influences, and propose molecular mechanisms that regulate brain (but not body) asymmetry and handedness. For example, asymmetrical distribution of morphogens during neural tube formation seems to be crucial for initiating asymmetrical brain development.
The driving force behind the evolution of brain asymmetries in humans has also been an enduring question. The left-hemisphere dominance for language ability and handedness in most humans seems to be more than mere coincidence. These authors consider evidence that genetic mutations that favoured right-hand dominance might have facilitated the evolution of language, increased brain capacity and overall social cohesion.
This is a preview of subscription content, access via your institution
