How did sex pop up? (Introduction)

by George Jelliss , Crewe, Saturday, September 19, 2009, 18:15 (5543 days ago) @ xeno6696

dhw in the "Revise this" thread (September 18, 2009, 15:07) wrote: "David has, for instance, asked the provocative question: How Did Sex Pop Up? Bearing in mind that it takes two to tango, and that if those two are to reproduce they will normally have to be male and female, the idea of simultaneous chance mutations puts a mighty strain on one's credulity." -I thought we had settled this agaes ago. However, here is a lucid account given by someone caling themselves "Sprite" on the RD Forum:-Sexual reproduction evolved before the separate sexes evolved. The first sexual organisms would have produced first just one type of sex cell and later there evolved the two types - eggs and sperm.
These would have been produced by the same body.
In time, some bodies specialized in producing either one or the other sex cell.
Then the body evolved to best serve its particular sex cell so males and female would have diverged to some degree within the same species.-Sex cells were first expelled into the sea.
Animals first on land would also have returned to water to spawn.
Some different ways evolved to transfer sperm more directly to females eg via a spermatophore or via a 'cloacal kiss' where the two openings briefly meet and sperm is transfered.-Once you have internal fertilization, intromittent organs in the male would have evolved to deposit sperm nearer to the eggs for a reproductive advantage over the sperm of other males.
Various intromittent organs and various internal female structures evolved across species.-Sprite also gives the following links. We've seen the first before.-http://pharyngula.org/index/weblog/comments/penis_evolution/-http://en.wikipedia.org/wiki/Intromittent_organ-http://pharyngula.org/index/weblog/comments/evolution_of_the_mammalian_vagina/-http://news.bbc.co.uk/1/hi/health/8250609.stm-The last relates to the sex-determination issue of the South African athlete in the news currently.

--
GPJ