Complex sentence: Without foreknowledge of the genotype of organisms, but with extensive and detailed knowledge of the biology and geography of species, Charles Darwin developed and debated his evolutionary theory starting from a rough sketch he shared in 1839, but did not intend for publication.
Split into simpler sentences: Without foreknowledge of the genotype of organisms, but with extensive and detailed knowledge of the biology and geography of species, Charles Darwin developed and debated his evolutionary theory. He first shared his ideas amongst his peers in a rough sketch he penned in 1839, but did not intend it for publication.