Very important read in today’s times with people attempting to say biological sex does not exist and/or that people are not a sexually dimorphic species: Origins of Two Sexes
“Because male and female are fundamentally defined by the gametes they produce, understanding the origins of the two sexes means understanding why gametes come in two different sizes—many small motile ones (sperm) and few large sessile ones (eggs). Thus, we must trace the sexes all the way back to the origins of gametes—the primary biological vehicles through which sexual reproduction takes place.”
“Sexual reproduction is the mixing of genomes and the fusion of gametes, a process which forms a new genetically unique individual. It first arrived on the scene around two billion years ago with single-celled eukaryotic organisms. Despite heavy evolutionary costs, the stronger evolutionary advantages from sexual reproduction made it near universal among eukaryotes, with now more than 99.9% of named animal species reproducing sexually.” https://theparadoxinstitute.com/blog/2021/04/04/origins-of-two-sexes/?fbclid=IwAR3FsW0qs8LQ2GoUpD1kNQSApkrhOVSwHFNG95BxriGULifqLdESV4Tc3Fo
