15 days ago
- Darwin found sex mysterious, questioning why intercrossing is necessary when asexual reproduction exists.
- John Maynard Smith proposed the 'twofold cost of sex,' highlighting the reproductive disadvantage compared to parthenogenesis.
- Theories like Muller’s ratchet and the Red Queen hypothesis attempt to explain sex's persistence but remain unresolved.
- Modern studies reveal diverse sexual behaviors in nature, challenging traditional views of fixed sex roles.
- Organisms like Tetrahymena thermophila exhibit complex mating systems, including conjugation with multiple mating types.
- Isogamy evolved into anisogamy, leading to distinct sperm and egg producers, driven by reproductive strategies.
- Species like jacanas and Neotrogla bark lice show reversed or unusual sex roles, with females sometimes dominating or evolving penis-like structures.
- Clown fish and earthworms demonstrate hermaphroditism, challenging the notion of fixed sex and gender.
- Bluegill sunfish exhibit multiple genders and mating strategies, including same-sex behavior and cooperative nesting.
- Spotted hyenas have unique female anatomy, with elongated clitorises used for birth, leading to high mortality rates.
- Same-sex behavior is common across species, observed in over 1,500 species, often for social cohesion or pleasure.
- Books like 'On the Origin of Sex' and 'Poking the Squid' argue against rigid definitions of natural sex, emphasizing diversity.
- Human sexual practices vary widely, from the Kreung's premarital liaisons to Simbari's ritual fellatio, highlighting cultural flexibility.
- While nature offers diverse examples, it does not prescribe moral norms, as behaviors include both cooperation and violence.
- The mystery of why sex exists persists, despite detailed mapping of its forms across species.