Evolutionary shift from purifying selection towards divergent selection of SARS-CoV2 favors its invasion into multiple human organs

•The time taken to evolve SARS-CoV2 from bat RaTG13 lineage appears to be in between 9-14 years.•Evolution of a critical entry-point residue at RBD domain SARS-CoV2 Y493Q needs two substitutions with an intermediate virus carrying Y493H (Y>H>Q), although such an intermediate virus has not been identified in known twenty-nine bat CoV virus.•Genetic codon analysis indicates that SARS-CoV2 evolution from RaTG13 lineage strictly follows neutral evolution with strong purifying selection.•Its propagation in human from December, 2019 disobeys neutral evolution as nonsynonymous mutations surpasses synonymous mutations with the increase of ω (dn/ds) value.•Increase of ω implies SARS-CoV2 is proceedings towards divergent selection predictably for its infection power to evade multiple human organs.