Jacob and the Spotted Sheep

Backon revisits an episode that geneticists have long dismissed as impossible. Earlier attempts to rescue it invoked selective breeding, while traditional commentators treated the outcome as miraculous, though several noted the detail that the peeled rods were placed in the animals’ drinking water. Drawing on research into heritable changes in gene expression that occur without any alteration of DNA sequence, and specifically on studies linking maternal diet to coat-color gene activity in mice and sheep, Backon proposes that substances leached from the bark of the three named trees could plausibly have acted on the flock prenatally. He extends the same logic to a puzzling talmudic tradition about the red heifer.