All of it is a matter of active research, as this relates to the evolution of sex/sexual reproduction, which, contrary to popular belief, is still an unsolved problem in biology. Classical evolutionary theory cannot explain sexual evolution. Any book about "why?" will either be highly opinionated, agenda-driven, out-dated, or simplistic (as are my comments here).
I am not a biologist, so I can not refer to or evaluate any meaningful recent papers on the matter. However, I can recommend the podcast 'Big Biology', which dives into current biology research, theory and philosophy, including sexual evolution.
You may start here: https://en.wikipedia.org/wiki/Evolution_of_sexual_reproducti...
Richard Dawkins' 'The Selfish Gene' is also an excellent read/audiobook. His specific theories of the evolutionary "unit" have been disproven, but his argumentation teaches a lot about "evolutionary thinking". I really wish he stuck with biology and science education instead of becoming this reactionary giga twat.
I am not a biologist, so I can not refer to or evaluate any meaningful recent papers on the matter. However, I can recommend the podcast 'Big Biology', which dives into current biology research, theory and philosophy, including sexual evolution.
You may start here: https://en.wikipedia.org/wiki/Evolution_of_sexual_reproducti...
Richard Dawkins' 'The Selfish Gene' is also an excellent read/audiobook. His specific theories of the evolutionary "unit" have been disproven, but his argumentation teaches a lot about "evolutionary thinking". I really wish he stuck with biology and science education instead of becoming this reactionary giga twat.