specialization
1. The act of specializing, or the state of being spezialized.
2. (Science: biology) The setting spart of a particular organ for the performance of a particular function.
(biology) the structural adaptation of some body part for a particular function; cell differentiation in the developing embryo.
Multicellular organisms evolved. The first ones were likely in the form of sponges. Multicellularity led to the evolution of cell specializations that form tissues. Another major event was the evolution of sexual reproduction. The emergence of sex cells in the timeline provided a means for organisms to further diversify. Know more about these crucial events in geologic time in this tutorial...