Sven

I hope that kingzfan2000 agrees with the title. He suggested to open a new thread here, to avoid derailment of the other thread. So here is our conversation again:

Hint: There's a continuum of asexually to sexually reproducing critters. Some can indeed do both. So its reasonable to assume that the first ones also could do both, and mated asexually until others were around which also could mate sexually. The ratio to sexually to asexually simply drifted slowly over time (as everything in evolution) until you got a new species which only mated sexually.

:huh: This displays your ignorance of evolution again. First, it's difficult to define "first humans" - where exactly do you draw the limit? Second, related to this, the emergence of the first humans was by no means abrupt, they could mate very well with the other creatures which were only 99.99999999% human.

lpetrich

I had started a thread on that subject not too long ago; here's the scenario I had outlined:

* Fusion and meiosis emerge as a way of surviving harsh conditions by recombining genes.

* Once a haploid/diploid alternation is established, suppression of inbreeding emerges with the mating-type mechanism. The sexes or mating types initially look alike (isogamy), something which is still common among protists and algae and fungi.

* In some organisms, the gametes become specialized (anisogamy), sometimes becoming full-scale eggs and sperm (specialized for food storage and motility, respectively).

perfessor

And the first person who spoke english - who did he talk to?

Justin Z

Hah! That is a great analogy. Nice work.

~Justin

Sven

As expected - he did not show up. :down:

kingzfan2000

I dont think its such a great analogy. Sexually reproducing creatures usually require a male and a female, so if you have a world void of sex and gender and filled with nothing but asexual organisms, how do you go from splitting in half or budding or whatever to reproducing sexually? Did mutations cause this evolution? If so, how did these mutations slowly change asexual organisms into sexually reproducing ones? Did it go from one method of asexuality to another, like fission or budding to parthogenesis or from splitting/fission to sexually reproducing?

I know that mutations are viewed as random unguided occurrences, and evolution takes millions of years. So is this a case of thousand or millions or billions of neutral mutations building up until the asexual organisms had some simple version of early reproductive organs or were the very first mutations found beneficial in some way? Where sperm and eggs the result of mutations? Did mutations create sperm and eggs first, the reproductive organs first or both at the same time? Did asexuality evolve into male and female in one organism and then later split into male and female, or did male and female evolve their reproductive systems independently of each other?

Mutations obviously didnt change the method of reproduction over-night, so what were the mutations for the first few thousands of years doing? Is there any empirical documentation of documented mutations even slightly changing the sexual nature of strictly asexual organisms? Was the change out of necessity or was it just chance? Some creatures can reproduce both asexually and sexually, so seeing as though each form of reproduction could be advantageous or disadvantageous in certain situations, why have so many organisms loss the ability to reproduce asexually when that method of reproduction could certainly be beneficial in certain circumstances?

Every time the evolution of sex is discussed, it is proposed that the reason sex evolved is because there are certain disadvantages to strictly asexual reproduction. So it would seem that in making note of the fact that supposedly all organisms were at one time asexual and you would probably have to go through thousands/millions of years of neutral mutations with these organisms still being strictly asexual, that evolution had a goal in going from asexual to sexual. Yet this is contrary to what is often said of evolution in that it has no purpose or goal. But how can you start from completely asexual, have millions of mutations that dont change the sexuality, end up with creatures that are strictly sexual, then you say the reason it happened was this or that and yet you still contend that evolution doesnt operate with purpose or goals? How many years and generations of mutations would it take to go from asexual to sexual? Lets take a thousand years; would a thousand years of mutations and natural selection be sufficient to remotely change from asexual to sexual? Doubtful. How about 10k, 100k, 500k? All these years and generations of mutations slowly creating sexuality while these creatures are still completely asexual and you will still say that evolution doesnt operate with purpose. I know its hard, but while answering these questions, please (Sven) try to keep the sarcastic and condescending remarks to a minimum. And dont be surprised when I dont respond when Im bombarded with 30 post every two minutes by a bunch of irate evos. Ill participate as long as you people can muster the patience to keep this civil.

kingzfan2000

Forgive me for not putting a message board discussion about the evolution of sex on the top of my to do list. Im sorry for having a life.

Faldage

The short and rough answer is that we start off with creatures that reproduce entirely asexually. Think amebae. Sooner or later some of them discover that if they bump into each other at just the right time, they can swap genetic material. No particular goal being headed for, they just do it. It turns out that it works a little better than just splitting. Think paramecia. Then, as lpetrich pointed out:
I'm sure there are some here who can polish this up, but that's the basic outline.

Sven

Sorry. I apologize.

I extrapolated your usual posting style to this thread. I was wrong.

Sven

Just follow the link lpetrich provided.

This is a nonsensical question. Everthing in evolution is caused by mutations.

Because reproducing sexually can be advantageous.

People with more knowledge than me will have to answer this.

Random with respect to fitness, yes.

Of course it's an adavantage if you can reproduce by different ways.

[snip - again, let's other people answer this]

This is something which happens often in evolution: When something isn't used for a long time, mutations which deactivate this function simply go unnoticed with respect to selection. Another example for this is the Vitamin C pseudogene, shared among primates.

Is it? :huh:
It's rather this way: Sexual reproduction has different advantages and disadvantages than asexual reproduction.

Only that this scenarios is wrong. Those mutations certainly were not (only) neutral.

Doesn't matter because it's wrong.

Why not? We could have had thousands of other outcomes - for instance species, which need three partners for reproduction. Who says that sexual reproduction is the end-all of evolution?

[snip - see above]

I didn't try until reading this, but looking above, my statements don't look that bad. I hope you see it the same way.

And I think you should look at the thread lpetrich linked to.

BTW, what about the other part? The one about who did the first human mate with? Was this answered to your satisfaction or do you want to continue with this later?