The really big step was from cells without nuclei to cells with nuclei. Compared to that, sexual reproduction is a nit. There are dozens of intermediate forms of sexual reproduction still in existence, from bacterial conjugation through various forms and degrees of hermaphrodism, to heterosexual reproduction. We really don't need to speculate on the small steps required. They are still very much with us.
The big piece of complexity is not the changes from single cell to human. It's the basic machinery itself that interprets the genetic code.
Now there's an understatement:^)
Compared to that, sexual reproduction is a nit...We really don't need to speculate on the small steps required. They are still very much with us.
With all due respect I think the fact of the matter is, notwithstanding the existence of bacterial conjugation or hermaphrodism, nobody has the slightest idea how (and why) in an evolutionary paradigm such an inefficient and incredibly complex process such as meiosis ever got started or what mutations and/or adaptive advantages made it possible in the first place.
Cordially,