The historical point can be summed up as Darwinism having undergone three stages of development.

Literal

Historical point [topic-は], Darwinism [subject-が] 3 [of-の] progress stages [object-を] has-gotten [quotative-ということ-で] can-be-summarized [probably-よう].

A formal academic sentence. 論点 ('point of discussion, argument'). The complex quotative-nominalization という+こと+で frames a proposition as the basis of a predication. 要約できる ('can be summarized') + よう (classical volitional/suggestive suffix, marking an estimation/suggestion). High academic register.