The scientists from Washington highlights three genes which might have played an essential role in the history of human evolution. These three genes were responsible for the striking increase in the size of the human brain which further facilitated cognitive advances. The cognitive advances help to define what it to means to be a human being.

Such genes were found only in people who appeared three or four million years ago. This period marked its presence just before the period when dramatic brain enlargement was demonstrated by the fossil records. These demonstrations were observed in the ancestral species within the human lineage.

The three genes were nearly identical to each other. These three identical genes along with the fourth non-functional gene are collectively known as the NOTCH2NL genes. These NOTCH2NL genes arise from a gene family which marks its presence back to hundreds of millions of years ago. Also, they were heavily involved in the embryonic development.

The NOTCH2NL genes are active when they are present within the reservoirs of neural stem cells of the cerebral cortex. Cerebral cortex forms the outermost layer of the human brain. It is responsible for the majority of the brain functions inclusive of language, cognition, memory, consciousness, and reasoning. These genes were responsible for the delay of the cortical stem cell development into the neutrons within the embryo. As a result, it gave rise to the production of a higher number of the mature nerve cells.

Pierre Vanderhaeghen says, “The cerebral cortex defines to a large extent what we are as a species and who we are as individuals. Understanding how it emerged in evolution is a fascinating question, touching at the basic origins of mankind.” Pierre Vanderhaeghen is the developmental neurobiologist of Universit√© Libre de Bruxelles and VIB/KULeuven in Belgium.

David Haussler says, “It is the ultimate evolutionary question, and it is thrilling to work in this area of research.” David Haussler is the scientific director at the University of California, Santa Cruz Genomics Institute. He is also an investigator at the Howard Hughes Medical Institute.