Figure 1.

Gene number estimates. Shaded bars denote results based on completed genome projects. The error bars should be regarded as approximate indicators of uncertainty only, as statistically comparable values are generally not available. This is not a comprehensive summary of data from all available species. Current estimates for mouse (3, 21) and pufferfish (22) are not shown but fall within the range shown for human. The C. elegans estimate, 16,527 ± 260, is the most up-to-date figure as calculated by the method used in ref. 9. Other data are from refs. 3, 7, 20, 21, 23, and 24 and references therein.