Can happiness change our gene expression?

Check out this great NYTimes blog describing a study published in the Proceedings of the National Academy of Sciences. 

What this finding indicates, says Steven W. Cole, a professor of medicine at U.C.L.A. and senior author of the study... is that "our genes can tell the difference" between a purpose-driven life and a shallower one even when our conscious minds cannot. Of course, genes cannot actually perceive or judge our behavior, so the shift in gene expression is very likely driven by an evolutionary strategy of working for the common good.