How stem cells reflect evolution

Carl Zimmer, the writer and blogger, presented a lucid essay on Sunday about the deeper truth of the contaminated stem cells story. All of the federally recognized lines of human embryonic stem cells have contamination from the animal ingredients used to culture them. The science behind this state of affairs is a splendid example of how evolutionary theory makes sense of strange data. Zimmer is just one of the jewels in my selection of geology-related blogs.