1. 1. Dobson, D. E., Prager, E. M. & Wilson, A. C. /. biol. Chem. 259, 11607-11616 (1984). 2. Stewart, C.-B. R. thesis, Univ. Calif., Berkeley (1986). 3. Kimura, M. The Neutral Theory of Molecular Evolution (Cambridge University Press, Cambridge, 1983). 4. Perutz, M. F. Molec. Biol EvoL 1, 1-28 (1983). 5. Hill, R. E. & Hastie, N. D. Nature 326, 96-99 (1987). 6. Laskowski, M. Jr et al. Biochemistry 26, 202-221 (1987). 7. Brown, A. L. Nature 326, 12-13 (1987). 8. Fleming, A. Lancet 216, 217-220 (1929). 9. Jolles, P. & Jolles, J. Molec. cell Biochem. 63, 165-189 (1984). 10. Bauchop, T. & Martucci, R. W. Science 161, 698-700 (1968). 11. Olivers, D. J. & Hladik, C. M. J. Morph. 166, 337-386 (1980). 12. Padgett, G. A. & Hirsch, J. G. Aust. J. exp. Biol. med. Sci. 45, 569-570 (1967). 13. Pahud, J.-J., Schellenberg, D., Monti, J. C. & Scherz, J. C. Ann. Rech. Vet. 14,493-501 (1983). 14. Prieur, D. J. Comp. Biochem. Physiol. 85B, 349-353 (1986). 15. Wilson, A. C., Carlson, S. S. & White, T. J. A. Rev. Biochem. 46, 573-639 (1977). 16. Goodman, M. Prog. Biophys. molec. Biol. 38, 105-164 (1981). 17. Sarich, V. M. & Cronin, J. E. in Molecular Anthropology (eds Goodman, M. & Tashian, R. E.) 141-170 (Plenum, New York, 1976). 18. Stewart, C.-B., Dobson, D. E. & Wilson, A. C. Am. J. phys. Anthrop. 63, 222 (1984). 19. Haas, O. & Simpson, G. G. Proc. Am. phil. Soc. 90, 319-349 (1946). 20. Zuckerkandl, E. & Pauling, L. in Evolving Genes and Proteins (eds Bryson, V. & Vogel, H. J.) 97-166 (Academic, New York, 1965). 21. Sneath, P. H. A. & Sokal, R. R. Numerical Taxonomy (Freeman, San Francisco, 1973). 22. Peacock, D. & Boulter, D. /. molec. Biol. 95, 513-527 (1975). 23. Weaver, L. H. et al. J. molec. Evol. 21, 97-111 (1985). 24. Creighton, T. E. Proteins: Structures and Molecular Properties (Freeman, New York, 1983). 25. Romero-Herrera, A. E., Lehmann, H., Joysey, K. A. & Friday, A. E. Phil. Trans. R. Soc. B283, 61-163 (1978). 26. Liao, H., McKenzie, T. & Hageman, R. Proc. natn. Acad. Sci. U.S.A. 83, 576-580 (1986). 27. Stewart, C.-B. & Wilson, A. C. Cold Spring Harb. Symp. quant. Biol. 52 (in the press). 28. Rodriguez, R., Menendez-Arias, L., Gonzalez de Buitrago, G. & Gavilanes, J. G. Biochem. Internat. 11, 841-843 (1985). 29. Pervaiz, S. & Brew, K. Arch Biochem. Biophys. 246, 846-854 (1986). 30. Hammer, M. F., Schilling, J. W., Prager, E. M. & Wilson, A. C. / molec. Evol. 24, 272-279 (1987). 31. Felsenstein, J. PHYLIP (Phylogeny Inference Package) Version 3.0 Manual (University of Washington, Seattle, 1987). 32. Jolles, P. et al. J. biol. Chem. 259, 11617-11625 (1984). 33. McKenzie, H. A. & Shaw, D. C. Biochem. Intl 10, 23-31 (1985). 34. Hunkapiller, M. W., Hewick, R. M., Dreyer, W. J. & Hood, L. E. Meth. Enzym. 91,399-413 (1983). 35. Hunkapiller, M. W. & Hood, L. E. Meth. Enzym. 91, 486-493 (1983). 36. Drapeau, G. R. Meth. Enzym. 47, 189-191 (1977). 37. Strydom, D. J. et al. Biochemistry 24, 5486-5494 (1985). 38. Huang, H. V., Bond, M. W., Hunkapiller, M. W. & Hood, L. E. Meth. Enzym. 91, 318-324 (1983). 39. Swofford, D. L. PAUP: Phylogenetic Analysis Using Parsimony, Version 2.4 (Illinois Natural History Survey, Champaign, Illinois, 1985).