Important groundwork in opsin evolution studies

The report by Charles Day (Physics Today, October 2008, page 20 ) highlights some important aspects of the study of opsin evolution. However, too much credit is given to Shozo Yokoyama’s publication and work. Many people have studied the selective pressures on the sequence of amino acids that confers the molecule’s function. For example, during his graduate work in the early 1990s, Wesley Toller realized the evolutionary implications and did the early studies on opsins found in squirrel fish that inhabit different depths in the ocean. Yokoyama’s work cites and builds on Toller’s early graduate work. Yet Day’s report does little to acknowledge the prior work and implies that Yokoyama was the first to realize the link between opsin sequence, function, and the selective pressures imposed by the environment. My intention is not to diminish Yokoyama’s work but to give readers a better picture of the breadth of the field and the sources of some key discoveries.