Why a person doesn't evolve in one lifetime

September 26, 2007

If [our cells were replaced] simply by replication of the various specialized cells in each tissue, our tissues would evolve: mutations would arise, and some would spread. In particular, mutant cells that don't do their specialized job so well tend to replicate more quickly than non-mutants, and so gain a competitive advantage, freeloading off the others. In such a case, our wonderfully wrought bodies could grind to a halt.

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