Understanding the human mind in biological terms has emerged as the central challenge for science in the 21st century. We want to understand the biological nature of perception, learning, memory, thought, consciousness and the limits of free will. That biologists would be in a position to explore these mental processes was unthinkable even a few decades ago. Until the middle of the 20th century, when I began my career as a neuroscientist, the idea that mind, the most complex set of processes in the universe, might yield its deepest secrets to biological analysis and perhaps do this on the molecular level could not be entertained seriously.
The dramatic achievements of biology during the past 50 years have now made this possible. The discovery of the structure of DNA by James Watson and Francis Crick in 1953 revolutionized biology, giving it an intellectual framework for understanding how information from the genes controls the functioning of the cell. That discovery led to a basic understanding of how genes are regulated, how they give rise to the proteins that determine the functioning of cells, and how development turns genes and proteins on and off to establish the body plan of an organism. With these extraordinary accomplishments behind it, biology assumed a central position in the constellation of sciences, in parallel with physics and chemistry.