by cofty 96 Replies latest watchtower beliefs
Another aspect - cantleave
dodging the bullet eh?
Some evidence of this theory has been elucidated from a species of wild strawberry plants which appears to be transitioning from hermaphroditism to dualality of sexes.- cantleave
Strawberries or their plants do not have sex organs or brains, hence cannot feel pleasure. Your point is interesting but does not prove procreation and pleasure are not linked and did not evolve this way.
Kate xx
Kate - you wind-up merchant. You know as well as me that the sex organs, sexual dimorphism and sexual pleasure were evolutionary developments AFTER the genes for separate sexes evolved.
Strawberries or their plants do not have sex organs
So what are stamens and carpel?
or brains
Brains are not necessary for sexual reproduction.
dodging the bullet eh?
No bullet to dodge you are firing intellectual blanks
Oops double post
LOL!
evolutionary developments AFTER the genes for separate sexes evolved.-cantleave
The fact it is a process and pleasure came later, does not negate that God could have planned it that way to icrease the population rates of species. You may not agree it's probable, but my theory is possible. Would you agree? Kate xx
but my theory is possible
Please don't call it a theory Sam, it isn't even a hypothesis
Would you agree?
God must be total bastard then, making it so pleasurable and then inventing nasty sexually transmitted infections so that we can't enjoy the pleasure without risk.
If I was NOT a witness I would be a pornstar... O... wait a minute...
If I was NOT a witness I would be a pornstar...
If I were not a human I would be a Bonobo
God must be total bastard then-cantleave
I agree he is a total so and so isn't he?
So far - populations of organisms that reproduce without sex suffer from a gradual accumulation of detrimental mutations known as "Muller's Ratchet".
Many potentially useful mutations suffer from selective interference. They remain invisible to natural selection because they are stuck on chromosomes beside other genes that are not fit to take on the competition.
When a useful mutation does succeed in increasing the success of the host it leads to a serious loss of genetic diversity known as selective sweep. These problems are especially pronounced when the population is highly variable, the mutation rate is high and selctive pressure is strong. We will see how these three factors were important in the origins of sex.
We saw how sex solves these problems through the process of meiosis which cuts up chromosomes and recombines genes in novel sequences in eggs and sperm. This reshuffling of the genes brings together favourable combinations of genes and allows natural selection to eliminate unfavourable ones.
The contrast can be seen in the male Y chromosome which never recombines. As a result it is a pathetic stub of a chromosome with a few genes mixed up with loads genetic gibberish.
We just said that asexual populations are potentially in trouble when selection pressures are high so what were the pressures that may have led to the dominance of sexual reproducton?
The first thing that can be said is that the common ancestor of all eukaryotes had sex. A eukaryote is something built from complex cells with a nucleus a membrane and organelles. All animals and plants are eukaryotes as distinct from bacteria which are prokaryotes.
Sex is something that plants, animals, algae, fungi and protists have in common. That means that sex was invented a very long way back in evolutionary history.
It is now almost universally accepted that many of the organelles of eukaryotic cells were once free-living bacteria. Bacteria - prokaryotes - that originally lived in a symbiotic relationship were later incorporated into a cell to form a chimera. The story of how Lynn Margulis pioneered this theory deserves a thread of its own. Its an excellent lesson in how science works.
One of the organelles in our cells is the mitochondria which produce energy. Mitochondria are inherited on the female side via the ovum and contain their own DNA separate from the DNA in the nucleus. Sperm donate nothing except DNA which we will come back to later when we look at the question of gender.
But mitochondria donated more than energy to its host cell. The genes in eukaryotic cells are divided up into random sections. Imagine reading a book that contained a few lines of text followed by some lines of random letters followed by some more meaningful text and so on. These random bits of non-coding DNA are called introns and make up almost half of our genome. When they were examined in detail many of the sequences of text were found to be similar to the sequences found in mitochondrial DNA. Not only that but the same sequences are found in exactly the same place of the genomes of eukaryotes from amoeba to humans.
Our early eukaryote ancestor became infected with these parasitic pieces of DNA code - jumping genes - and had no machinery to deal with it. Some of these landed right in the middle of genes causing havoc and probably accounting for another difference between prokaryotes and eukaryotes. The former have a circular string of DNA while the latter have shorter straight sections, sliced up by ancient jumping genes.
This leads to exactly the situation that is lethal to asexual organisms - a highly variable population, high rates of mutation and strong selective pressure.
The perfect storm for the success of a new reproductive strategy - sex.
Its late tbc...........
