With this issue, Science kicks off its coverage of the 200th anniversary of Charles Darwin's birth and the 150th anniversary of the publication of On the Origin of Species. This issue contains an essay by Carl Zimmer on how life began and a review article by the Queen's University of Belfast's Peter Bowler on how Darwin's thinking was original, despite not being the first to come up with the idea of evolution. A group of scientists wrote in to urge the recognition of Robert Gallo's contribution for HIV/AIDS research. Gallo showed that HIV-1 causes AIDS and then developed a diagnostic kit. The 2008 Nobel prize in physiology or medicine for the discovery of HIV-1 went to Francoise Barré-Sinoussi and Luc Montagnier. "Given the enormous impact of these developments on the lives of countless thousands globally, Gallo's contributions should not go unrecognized," the authors write. Vadim Gladyshev and his colleagues report that one codon can code for two amino acids and which amino acid is incorporated is determined by a 3' untranslated region structure and where the codon falls within the mRNA. In particular, the researchers saw that UGA can specify either selenocysteine or cysteine in Euplotes crassus.