One-celled organisms evolved into multicellular colonies, elaborating their various parts into specialized organ systems.
(One-celled organisms; evolved; into multicellular colonies; elaborating their various parts into specialized organ systems) (One-celled organisms; elaborating; their various parts; into specialized organ systems)
One-celled organisms One-celled organisms
evolved elaborating
into multicellular colonies elaborating their various parts into specialized organ systems
their various parts into specialized organ systems