In October 2009, Stanford University geneticist Anne Brunet was sitting in her office when a graduate student came to her with a slightly heretical question. Brunet's lab had recently learned that they could lengthen a worm's lifetime by manipulating levels of an enzyme called SET-2. "What if lengthening a worm's lifetime using SET-2 can affect the lifespan of its descendants, even if the descendants have normal amounts of the enzyme?" asked Eric Greer.
The question was unorthodox, says Brunet, "because it touches upon the Lamarckian idea that you can inherit acquired traits, which biologists have believed false for years." The biologist Jean-Baptiste Lamarck theorized in 1809 that the traits an organism used during its lifetime were augmented in its offspring; a giraffe that regularly stretched its neck to eat would father calves whose necks are longer. The idea was largely discredited by Darwin's theory of evolution, first published in 1859. More recently, scientists have begun to realize that an organism's behaviors and environment may indeed influence the genes it passes to its offspring. The heritability of those acquired traits is not based on DNA, but on alterations in the molecular packaging that surrounds a gene. When Greer approached Brunet in 2009 with his question about worms and SET-2, such "epigenetic" inheritance had only been discovered for simple traits such as eye color, flower symmetry, coat color.
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