Is Evolutionary Theory Central to Molecular Cell Biology?

The recent “Happy Birthday, Mr. Darwin” issue of Science (6 February 2009) celebrates evolution, the most unifying theory of biology. At the same time, this issue shows that molecular cell biology remains relatively untouched by evolutionary theory. Consider the fascinating studies of the STAT3 protein (Myers, 2009; Wegrzyn et al., 2009). This protein appears to have a dual function, on one hand mediating cytokine signaling at the level of the cell, while on the other regulating mitochondrial respiration. Since mitochondria are remnants of bacterial symbionts, at least two evolutionary hypotheses are suggested by these data. First, STAT3 may have originally been mitochondrial and was co-opted into a new function of manipulating host signaling to the advantage of the symbiont. Second, STAT3 may have originally been cytoplasmic and was co-opted into a new function regulating symbiont respiration to the advantage of the host. Sadly, in these fine articles there is no indication of such evolutionary thinking even though it allows the dual role of STAT3 to be interpreted, and indeed predicted, as a vestige of ancient levels-ofselection conflicts. Changes in the way biology is organized and taught may be necessary for evolutionary thinking to permeate all of biology.