[Ester]

I did a little research on this topic but what i’ve written is just a drop in the ocean! There are volumes of information out there which expound on this issue but of course cannot be summarized herein.

First, I think it’s important to differentiate between sex and gender. Sex may be defined as the biology behind our maleness and femaleness, whereas gender is the psychological and socio-cultural characteristics associated with our sex. It is my guess that the evolution of sex occurred before that of gender.

There are many theories out there which try to explain the “why of sex,“ and its benefits compared to asexual reproduction. I will list only three of them....

After all, asexual reproduction is quicker and more efficient. So why did a process so blatantly unprofitable to its earliest practitioners become so ubiquitous? If we all evolved from asexually-reproducing single-celled organisms, as evolutionists would want us to believe, then why was it set aside in favor of sexual reproduction?

1. The lottery principle

• The idea behind the lottery principle, first suggested by George C. Williams, was that sexual reproduction introduced genetic variety in order to enable genes to survive in changing or novel environments. Using the lottery analogy, he compared asexual reproduction to buying a large number of tickets for a national lottery but giving them all the same number. Sexual reproduction, on the other hand, would be like purchasing a small number of tickets, but giving each of them a different number. The essential idea behind this principle is that since sex introduces variability, organisms would have a better chance of producing offspring that will survive if they reproduce a range of types rather than merely more of the same.
  

• The lottery principle has been discounted by many since it hinges on the belief that sex would be favored by a variable environment. However, a close inspection of the global distribution of sex reveals that sexual reproduction is most common in stable environments. In contrast, organisms that live where the environment is unstable - for example archaebacteria that live in hot springs, salty lakes or cracks in the earth’s crust- reproduce asexually.

2. Tangled-bank hypothesis

• This hypothesis suggests that sex evolved in order to prepare offspring for the complicated world around them. In his book, origin of species, Darwin uses the phrase “tangled-bank” to describe the intense competition for space, food, and other resources in any environment that is divided into different niches. Since clones specialized for one niche can give birth to offspring that can also handle the same niche, sex introduces different genes that allow the resulting progeny to use resources in multiple niches.

• The Tangled-bank hypothesis has also suffered serious scrutiny and many of its proponents have fallen away. The theory would predict a greater interest in sex in animals that produce many, small offspring which are in competition with each other. In fact, animals that produce many, small-sized offspring propagate via pathogenesis; whereas sex is invariably associated with organisms that produce few, large-sized young ones.

3. Red-queen hypothesis

• This hypothesis first suggested by Leigh Van Valen suggests that the probability of organisms becoming extinct bears no relationship to how long they already may have survived. That no matter how well adapted an animal may become, it still has the same chance of extinction as a newly formed species. The thrust of this hypothesis is that sex is needed to fight disease. Parasites are able to infect cells by hijacking protein molecules that transmit information by binding to cell surfaces.
  
  In other words, hosts have to continually shuffle the ‘locks’ while parasites invent new ‘keys’ in order to break into cells. Hence sexual reproduction persists because it enables host species to evolve new genetic defenses against parasites that attempt to live off them.

Although the above theories give the benefits of sexual reproduction, it’s origin and maintenance cannot simply by explained by natural selection. Hence, one can imagine that the evolution of sex (and its accompanying reproductive capability), is not a favorite topic of discussion in most evolutionary circles.

To date, no one has been able to explain the origin of sex from an evolutionary viewpoint. Evolutionists want us to believe that the highly complex and intricate manner in which a cluster of cells develops into a human body is merely due to chance. Indeed, all theories so far fail to explain the origin of the first fully functional female and the first fully functional male necessary to begin the process.

“Is sex the product of a historical accident or the product of an intelligent creator? “

You decide.

References:
'http://www.trueorigin.org/sex01.asp
'http://www.pbs.org/wgbh/evolution/sex/advantage/page03.html

[ndigila]

That's great, but I'm more interest in the "how" than in the "why". Is there a plausible answer to the question I originally asked:

Originally Posted by ndigila

If at one point you had only asexual creatures, living in the same environment, eating the same food, having the same enemies, etc, etc, What would cause these asexuals to evolve having female reproductive organs, and others having male reproductive organs?

[Ester]

Originally Posted by ndigila
If at one point you had only asexual creatures, living in the same environment, eating the same food, having the same enemies, etc, etc, What would cause these asexuals to evolve having female reproductive organs, and others having male reproductive organs?

Originally Posted by ndigila

That's great, but I'm more interest in the "how" than in the "why". Is there a plausible answer to the question I originally asked:

To date, no one has been able to explain the origin of sex from an evolutionary viewpoint. Evolutionists want us to believe that the highly complex and intricate manner in which a cluster of cells develops into a human body is merely due to chance. Indeed, all theories so far fail to explain the origin of the first fully functional female and the first fully functional male necessary to begin the process.

[Type R]

Originally Posted by Ester

Originally Posted by ndigila
If at one point you had only asexual creatures, living in the same environment, eating the same food, having the same enemies, etc, etc, What would cause these asexuals to evolve having female reproductive organs, and others having male reproductive organs?
...
To date, no one has been able to explain the origin of sex from an evolutionary viewpoint. Evolutionists want us to believe that the highly complex and intricate manner in which a cluster of cells develops into a human body is merely due to chance. Indeed, all theories so far fail to explain the origin of the first fully functional female and the first fully functional male necessary to begin the process.

The exchange of genetic material between organisms may have preceded the development of gender. Gender may have arisen as a result of this behaviour, and organs became more highly specialized to a pre-existing activity. Mant bacteria can now pass their genes to other bacteria.

"Gene transfer in bacteria is unidirectional from a donor cell to a recipient cell and the donor usually gives only a small part of its DNA to the recipient."

So, at the microbe level, we can see hints of sex.

[Ester]

Originally Posted by Type R

The exchange of genetic material between organisms may have preceded the development of gender. Gender may have arisen as a result of this behaviour, and organs became more highly specialized to a pre-existing activity. Mant bacteria can now pass their genes to other bacteria.

"Gene transfer in bacteria is unidirectional from a donor cell to a recipient cell and the donor usually gives only a small part of its DNA to the recipient."

So, at the microbe level, we can see hints of sex.

Type R,
I think you're referring to the process of conjugation- which involves the transfer of genetic information from one bacterial cell to another. One cell donates DNA, and the "mate" receives it.

First of all, conjugation is very different from sexual reproduction. It does not produce new organisms; and since it's not reproduction, conjugation affects the bacteria involved, rather than their offspring. All that conjugation accomplishes is to increase genetic variation between the bacteria involved.

To give a plausible explanation for the origin of sex, you have to show how asexual organisms were able to diverge to a fully functional male and female. Also, what were the intermediate stages (if any)?

[al-zalzalah]

Originally Posted by ndigila

I'm not trying to argue, just asking honest questions because I'm somewhat ignorant about this issue

it's an interesting topic.
i seem to remember that there are organisms which can reproduce both asexually and sexually (plants and animals both); and i don't know what category hermaphroditism falls into.

but anyway maybe the theory doesn't claim a direct jump from asexual to sexual. maybe there are intermediate phases in between, where both forms of reproduction coexist. and maybe sexual reproduction gradually won over as the more ideal form of reproduction coz it allowed for genetic diversity.

wasn't able to read everyone's posts. coz i'm rushing out. so maybe i've reproduced somebody else's response.

[Ndigila2]

Thanks guys for all your responses. More issues though.

When dealing the evolution of a species, I don't think it's enough to explain the theory behind one species evolving to another (although it's really hard to define what a species is nowadays). When you account for the gender issue, this thing becomes much more complicated.

I'll tumia the example of a human.

For a human to successfully evolve and survive. Both the male and female have to evolve, with the male's sperm being compatible with the female's eggs. Unless they evolved first then dealt with the compatibility issues (which gives a whole new meaning to the term "experimental sex"), and if this was the case, the compatibility issues would have to be solved really fast since they only have about a 40 year window (between early teenage and menopause).

Is it possible for a human to mate with it's ancestor, if they lived together for a while? (I think last year or the year before, in Kenya they found homo habilis and homo erectus in the same rock layers, I wonder if they "crossbred."). If not, then the male and the female had to have evolved at the same "rate" (for lack of a better word). If, theoretically that the female human evolved first while the male was still stuck as a Zinjathropus, then the species would have been doomed even before it completely evolved.

So now let's say that both the male and the female successfully evolved but we're off by about 50 years. This would mean that the female would hit menopause before the male hits puberty. The species is also doomed then.

So if the evolution of humans from it's ancestor took thousands of years, and assuming the male and the female evolved independently, then their evolution "rates" would have to be almost in synchronous such that the males and the females evolve with compatible sperm and egg within about 40 years (worst case scenario) of each other.

Random thoughts. Correct me if I'm wrong.