How did our distinctive brains evolve? What genetic changes, coupled with natural selection, gave us language? What allowed modern humans to form complex societies, pursue science, create art?
While we have some understanding of the genes that differentiate us from other primates, that knowledge cannot fully explain human brain evolution. But with a $10 million grant to some of Boston’s most highly evolved minds in genetics, genomics, neuroscience and human evolution, some answers may emerge in the coming years.
The Seattle-based Paul G. Allen Frontiers Group today announced the creation of an Allen Discovery Center for Human Brain Evolution at Boston Children’s Hospital and Harvard Medical School. It will be led by Christopher A. Walsh, MD, PhD, chief of the Division of Genetics and Genomics at Boston Children’s and a Howard Hughes Medical Institute investigator.
“To understand when and how our modern brains evolved, we need to take a multi-pronged approach that will reflect how evolution works in nature, and identifies how experience and environment affect the genes that gave rise to modern human behavior,” Walsh says. …
Starting in 2006, comparative genomic studies have identified small regions of the human genome known as Human Accelerated Regions, or HARs, that diverged relatively rapidly from those of chimpanzees — our closest living relatives — during human evolution.
Our genomes contain about 2,700 HAR sequences. And as reported today in Cell, these sequences are often active in the brain and contain a variety of mutations implicated in autism and other neurodevelopmental disorders. …
Five people with an unusual pattern of brain folds have afforded a glimpse into how the human brain may have evolved its language capabilities.
How the human brain develops its hills and valleys—expanding its surface area and computational capacity—has been difficult to study. Mice, the staple of scientific research, lack folds in their brains.
Christopher Walsh, MD, PhD, head of the Division of Genetics and Genomics at Boston Children’s Hospital, runs a brain development and genetics clinic and has spent 25 years studying people in whom the brain formation process goes awry. Some brains are too small (microcephaly). Some have folds, or gyri, that are too broad and thick (pachygyria). Some are smooth, lacking folds altogether (lissencephaly). And some have an abnormally large number of small, thin folds—known as polymicrogyria.
In 2005, studying people with polymicrogyria, Walsh and colleagues identified a mutation in a gene known as GPR56, a clue that this gene helps drive the formation of folds in the cortex of the human brain.
In a study published in today’s issue of Science, Walsh and his colleagues focused on five people whose brain MRIs showed polymicrogyria, but just in one location—near a large, deep furrow known as the Sylvian fissure, which includes the brain’s primary language area. …