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Please explain a curious statement in “A more perfect union.” The article paraphrases Jonas Sandstrom of Uppsala University in Sweden as suggesting that an “endosymbiont’s isolation may be a one-way ticket to extinction. Once the bacterium loses genes . . . it has no way of getting them back. It can’t, therefore, evolve away from its special function and back toward an independent life.” This statement seems to contradict the basic theory of evolution itself, since it makes the absolute assertion that loss of genes must be an irreversible process. Why wouldn’t it be possible for the endosymbiont’s evolution to reverse its course and once again begin to multiply its genes? Paul Schlueter III
Dallas, Pa. The endosymbiont has no way of getting versions of its genes back because it is isolated from other bacteria. These bacteria aren’t in the insect’s gut, where they’d mix with other organisms. They’re inside cells near the gut.–J. Netting