Extended Data Fig. 9 |. Mean enhancer phastcons scores partitioned by tissue activity.

Across all tissues, enhancers have a mean phastCons score that is slightly elevated above the genomic mean, indicating that these regions are slightly conserved over phylogenetic timescales. Fetal brain and neurosphere enhancers have a higher mean phastCons score than enhancers active in any other tissues. This result mirrors our findings on the landscape of recent purifying selection as measured by site frequency skew: fetal brain enhancers are more conserved than other regulatory elements, but fetal muscle enhancers are not.