Here, Darwinism seems to offer justification, for if all humans share common origins it seems reasonable to suppose that cultural diversity could also be traced to more constrained beginnings.
断句：
① Here, Darwinism seems to offer justification,
② for if all humans share common origins
③ it seems reasonable to suppose
④ that cultural diversity could also be traced to more constrained beginnings.
各部分结构：
① 状语(Here,)+主语( Darwinism)+谓语( seems to offer )+宾语(justification, )
② 原因状语连词(for)+内部条件状语从句( if all humans share common origins)
③ 原因状语从句：形式主语结构it seems reasonable to suppose
④ 真正的主语：that cultural diversity could also be traced to more constrained beginnings.
参考译文：此处，达尔文主义似乎提供了合理的证明，因为如果所有人类共有相同的起源，那么似乎有理由认为文化多样性也能追溯到更有限的起源。
