Humans’ most unique traits, such as speaking and abstract thinking, are rooted in the outer layer of our brains called the cerebral cortex. This convoluted sheet of grey matter is found in all mammals, but it is much larger and far more complex in Homo sapiens than in any other species. The cortex comprises nearly 80 percent of our brain mass, with some 16 billion neurons packed into more than 50 distinct, meticulously organized regions.
In an effort to explore the evolution of the human cortex, many researchers have looked to changes in the portion of the genome that codes for proteins. But a new paper, published in the journal Science , shows that protein-coding DNA provides only part of the answer. The new findings reveal that an even more critical component may be changes in the DNA sequences that regulate the activity of these genes.