Figure 1From: A four-column theory for the origin of the genetic code: tracing the evolutionary pathways that gave rise to an optimized codeTwo-dimensional visualization of the matrix of physical property distances, d W , obtained via multi-dimensional scaling. The clustering of the amino acids in the first three columns of the genetic code is apparent. The horizontal axis is related to hydrophobicity and the vertical axis is related to size of the amino acid.Back to article page