Charles Darwin
Charles Darwin shattered centuries of creationist orthodoxy by demonstrating that all life is connected through descent with modification, driven by the relentless and unsentimental mechanism of natural selection.
The relentless competition for limited resources ensures that organisms possessing advantageous variations survive to reproduce, naturally selecting traits that gradually form entirely new species.
Faced with a fragmented and incomplete geological fossil record, Darwin relied heavily on historical biogeography to prove evolutionary descent.
Evolution operates as a branching process where diverse species diverge from common ancestors rather than progressing in a linear, purposeful ladder toward biological perfection.