Astrocyte identity: evolutionary perspectives on astrocyte functions and heterogeneity

•There are conserved mechanisms for astrocyte differentiation between fly and mammals.•Similar gene expression profiles of fly and mammalian astrocytes are revealed by transcriptome analysis.•There is evidence of astrocyte diversity in vertebrates and invertebrates.•Inter-regional and intra-regional mouse astrocyte diversity follows the dorsal-to-ventral axis of the adult brain.