Howthebrain learnstosee objectsand faces inan impoverishedcontext

596 NATURE | VOL 389 | 9 OCTOBER 1997 2. Kazakov, V. S., Demidchik, E. P. & Astakhova, L. N. Thyroid cancer after Chernobyl. Nature 359, 21 (1992). 3. Petridou, E. et al. Infact leukaemia after in utero exposure to radiation from Chernobyl. Nature 382, 352–353 (1996). 4. Lazjuk, G. I., Kirillova, I. A., Dubrova, Y. E. & Novikova, I. V. in The Chernobyl Papers Vol. 1, Doses to the Soviet Population and Early Health Effects Studies (eds Mervin, S. E. & Balanov, M. I.) 385–397 (Research Enterprises, Richland, WA, 1993). 5. Baker, R. J. et al. High levels of genetic change in rodents of Chernobyl. Nature 380, 707–708 (1996). 6. Dubrova, Y. E. et al. Human minisatellite mutation rate after the Chernobyl accident. Nature 380, 683–686 (1996). 7. Dubrova, Y. E. et al. Effects of radiation on children (reply). Nature 383, 226 (1996). 8. Satoh, C. & Kodaira, M. Effects of radiation on children. Nature 383, 226 (1996). 9. Hillis, D. M. Life in the hot zone around Chernobyl. Nature 380, 665–666 (1996). 10. Auerbach, C. Mutation Research (Chapman & Hall, London, 1976). 11. Dyck, J. in A Dictionary of Birds (eds Campbell, B. & Lack, E.) 472–474 (Poyser, Calton, 1985). 12. Møller, A. P. Sexual Selection and the Barn Swallow (Oxford Univ. Press, 1994). 13. Møller, A. P. Morphology and sexual selection in the barn swallow Hirundo rustica in Chernobyl, Ukraine. Proc. R. Soc. Lond. B 252, 51–57 (1993). 14. Falconer, D. S. Introduction to Quantitative Genetics 2nd edn (Longman, New York, 1989). 15. Siegel, S. & Castellan, N. J. Jr Nonparametric Statistics for the Behavioral Sciences 2nd edn (McGrawHill, New York, 1988). 16. Primmer, C. R., Ellegren, H., Saino, N. & Møller, A. P. Directional evolution in germline microsatellite mutations. Nature Genet. 13, 391–393 (1996). 17. Primmer, C. R., Møller, A. P. & Ellegren, H. Resolving genetic relationships with microsatellite markers: a parentage testing system for the swallow Hirundo rustica. Mol. Ecol. 4, 493–498 (1995). 18. Primmer, C. R., Møller, A. P. & Ellegren, H. New microsatellite markers from the pied flycatcher Ficedula hypoleuca and barn swallow Hirundo rustica genomes. Hereditas 124, 281–283 (1996). 19. Weber, J. L. & Wong, C. Mutation of human short tandem repeats. Hum. Mol. Genet. 2, 1123–1128 (1993). 20. Levinson, G. & Gutman, G. A. Slipped-strand mis-pairing: a major mechanism for DNA sequence evolution. Mol. Biol. Evol. 4, 203–221 (1987). 21. Ward, J. F. The yield of DNA double-strand breaks produced intracellularly by ionizing radiation: a review. Int. J. Radiat. Biol. 57, 1141–1150 (1990). 22. Strand, M., Prolla, T. A., Liskay, R. M. & Petes, T. D. Destabilization of tracts of simple repetitive DNA in yeast by mutations affecting DNA mismatch repair. Nature 365, 274–276 (1993). 23. Parsons, R. et al. Hypermutability and mismatch repair deficiency in RER+ tumor cells. Cell 75, 1227– 1236 (1993). 24. Fishel, R. et al. Binding of mismatched microsatellite DNA sequences by the human MSH2 protein. Science 266, 1403–1405 (1994). 25. Reitmair, A. H. et al. MSH2 deficient mice are viable and susceptible to lymphoid tumours. Nature Genet. 11, 64–70 (1995). 26. Saino, N., Primmer, C. R., Ellegren, H. & Møller, A. P. An experimental study of paternity and tail ornamentation in the barn swallow (Hirundo rustica). Evolution 51, 562–570 (1997). 27. Hanotte, O. et al. Isolation and characterization of microsatellite loci in a passerine bird: the reed bunting Emberiza schoeniclus. Mol. Ecol. 3, 529–530 (1994).