In “Chemical biology: Bring them back alive” by Michael Yarus (Nature 438, 40; 200510.1038/438040a), the references were jumbled. The reference list should read as follows:

1. Fusz, S., Eisenführ, A., Srivatsan, S. G., Heckel, A. & Famulok, M. Chem. Biol. 12, 941–950 (2005).

2. Yarus, M. Annu. Rev. Biochem. 74, 179–198 (2005).

3. Wilson, D. S. & Szostak, J. W. Annu. Rev. Biochem. 68, 611–647 (1999).

4. Lilley, D. M. J. Curr. Opin. Struct. Biol. 15, 313–323 (2005).

5. Tarasow, T. M., Tarasow, S. L. & Eaton, B. E. Nature 389, 54–57 (1997).

6. Helm, M., Petermeier, M., Ge, B., Fiammengo, R. & Jäschke, A. J. Am. Chem. Soc. 127, 10492–10493 (2005).

7. Yarus, M. & Knight, R. in The Genetic Code and the Origin of Life (ed. de Pouplana, L.) 75–91 (Landes Bioscience, Georgetown, Texas, 2004).

8. Lawrence, M. S. & Bartel, D. P. RNA 11, 1173–1180 (2005).

9. Yarus, M. Cold Spring Harb. Symp. Quant. Biol. 66, 207–215 (2001).