The study challenges traditional interpretations of weak seismic anisotropy in the deep Earth by proposing that it results from dislocation creep in olivine-rich aggregates deforming with [001]/(h0) slip in the upper mantle. This mechanism explains the variation in anisotropy patterns of P and S waves with depth, even if the upper mantle deforms coherently with a dominant horizontal shearing component. The authors use numerical modeling to support their hypothesis, suggesting that the transition from [100] to [001] slip at high pressure may be responsible for the observed anisotropy variations.The study challenges traditional interpretations of weak seismic anisotropy in the deep Earth by proposing that it results from dislocation creep in olivine-rich aggregates deforming with [001]/(h0) slip in the upper mantle. This mechanism explains the variation in anisotropy patterns of P and S waves with depth, even if the upper mantle deforms coherently with a dominant horizontal shearing component. The authors use numerical modeling to support their hypothesis, suggesting that the transition from [100] to [001] slip at high pressure may be responsible for the observed anisotropy variations.