The interplay of active and repressive histone modifications is assumed to have 
a key role in the regulation of gene expression. In contrast to this generally 
accepted view, we show that the transcription of genes temporally regulated 
during fly and worm development occurs in the absence of canonically active 
histone modifications. Conversely, strong chromatin marking is related to 
transcriptional and post-transcriptional stability, an association that we also 
observe in mammals. Our results support a model in which chromatin marking is 
associated with the stable production of RNA, whereas unmarked chromatin would 
permit rapid gene activation and deactivation during development. In the latter 
case, regulation by transcription factors would have a comparatively more 
important regulatory role than chromatin marks.