Why Sex Evolved: The Evidence

Pending the final announcement regarding the changes to be made to the forum, I am posting this in Origins & Creationism because it is likely to get the most views here. It may be better suited to the Science & Technology forum, however.

New Experiment Substantiates Evolutionary Theory of Sex

Sex has always been a puzzle for evolutionary biologists.

Reproducing asexually makes much more sense; there is no need for an organism to search and seduce a mate, fight off competitors, or risk contracting a sexually transmitted disease. What is more, given that an organism has survived long enough to reproduce, it is likely to have a first-rate set of genes under its pelt. Why run the risk of diluting these good genes with potentially poorer ones from another organism?

And yet sex exists; the vast majority of animals and plants reproduce this way.

The question has always been: why do they (and we) do it?

The answer, according to many biologists, is that sexual reproduction gives organisms an advantage against parasite infestation.

Parasites create a situation where, in spite of the disadvantages of sex, it is good for an organism to reshuffle its genome with that of another. This reshuffling creates offspring with new gene combinations that are potentially better than older combinations at resisting a parasite's advances.

Biologists know this as the Red Queen hypothesis. But there has been little experimental evidence for it. Until now, that is.

Worms’ sex life yields advantage over parasites at BBC World News

The researchers watched the worms gorge themselves on a lawn of a nasty bacterium, Serratia marcescens, which invades the worms' guts and from there multiplies into every crevice of their body, killing the worms from the inside. Across five different populations, worms that reproduced sexually fared well over the 20 generations, while all animals that cloned themselves died quickly.

This experimental result is of immense significance. One of the thorniest questions raised by the theory of evolution by natural selection is the evolution of sex. Now it appears that the scientifically proposed answer to the question is correct.

The mountain of evidence for evolution by natural selection has new pebbles added to it almost every day. But this is different; this is a giant boulder. Or rather, it is a missing keystone, which can now be slid firmly into the place science had been saving for it. The edifice is now complete.

Link to abstract of original paper published in Science.

What can one say except what a load of old bollygook

I don't think sex evolved. At least not on this planet. Genetically, it's a design that ensures a certain degree of genetic diversity in the population. Socially, it's a way of allowing more complex organisms to take care of young without disabling all the parent organisms. It's a half-way decent solution to a big design problem, though I think they could have done better.

reply to post by Astyanax
Obviously a great post Astyanax but honestly its not worth the effort anymore.

reply to post by uva3021


There are still some on ATS that don't have the mental capacity of a carrot, so any effort is praise worthy.

It's a good theory, I've seen it mentioned elsewhere and they can, over and over again, reproduce the results in the lab, namely that the worms engineered to breed sexually survived living within the parasitic enironment for 20 generations or more, whereas the worms that breed asexually did not even make it that far.

Originally posted by stumason
reply to post by uva3021

 

There are still some on ATS that don't have the mental capacity of a carrot, so any effort is praise worthy.

It's a good theory, I've seen it mentioned elsewhere and they can, over and over again, reproduce the results in the lab, namely that the worms engineered to breed sexually survived living within the parasitic enironment for 20 generations or more, whereas the worms that breed asexually did not even make it that far.

Yes I agree it is a good for nothing theory that probably would make sense to a carrot. What amazes me is that you 'carrots' linger where you obviously don't belong. Surely the garden plot beckons...?

Astytanax made a very informative post, but the belief has been firmly in place for about 40 years every since Hamilton and Williams established the significance of the link between parasites and their hosts. A great example of this relationship is the Duck-snail-nematode chain of sexual/asexual organisms in New Zealand. I suggest a google search. Examples such as these are just one out of a few thousand research projects completed on life histories of various organisms in a local ecosystem that all validate the sex and parasites theory.

Originally posted by Juran

Originally posted by stumason
reply to post by uva3021

 

There are still some on ATS that don't have the mental capacity of a carrot, so any effort is praise worthy.

It's a good theory, I've seen it mentioned elsewhere and they can, over and over again, reproduce the results in the lab, namely that the worms engineered to breed sexually survived living within the parasitic enironment for 20 generations or more, whereas the worms that breed asexually did not even make it that far.

Yes I agree it is a good for nothing theory that probably would make sense to a carrot. What amazes me is that you 'carrots' linger where you obviously don't belong. Surely the garden plot beckons...?

Care to explain why your blind beliefs does not see this scientific evidence as valid? Until now you've just been trolling this thread. And quite badly at that.

reply to post by Thain Esh Kelch


Because evolution is a load of crock, that's why. And no I don't have to justify that fact. Let the carrots prove that I'm not right, that's what they profess to be good at. As for trolling I don't give a rat's ass about ridiculous points or whatever you are referring to. Thanks all the same.

reply to post by Astyanax


Asexual reproduction also carries another risk with it, since over the course of time the genetic integrity of the organism will be harmed, because of an increasing chance of genetic mutation.

reply to post by Juran

Congratulations, Juran. In three short posts you have done more to make creationists look like a shower of arrogant, infantile oafs than I or any other ‘evolutionist’ could ever have done.

Thank you assisting the march of science and secular reason so wholeheartedly.

reply to post by Zamini

Isn’t a deleterious mutation in a parthenogenic population unlikely to spread, since it places a selective handicap on all the mutants carrying it? Eventually, it should die out.

Originally posted by Astyanax
reply to post by Juran

 

Congratulations, Juran. In three short posts you have done more to make creationists look like a shower of arrogant, infantile oafs than I or any other ‘evolutionist’ could ever have done.

Thank you assisting the march of science and secular reason so wholeheartedly.

Look like what to who? To a bunch of carrots? oops sorry I mean 'evolutionists'. I would be interested to hear your theory on how sexual energy evolved because nothing happened until that turned up. Also, if parasites are so effective at destroying how did anything get past them; where did they, the parasites, come from, and which came first the parasite or its victim?

reply to post by Astyanax


And that is exactly what's happening to the Carausius morosus(wiki). They may go extinct because there hasn't been any sexual reproduction in 1.5 million years(recent study).

So yes, if one reproduces a-sexually then one is predestined to die out as a species. Makes sense.

reply to post by Juran


It's not only parasites. It's just another factor.

You don't have that in religion do you? Different factors. You only have one factor. Please stop ridiculing yourself

I regard Muller's ratchet as a rather logical reasoning for sex.

reply to post by rhinoceros
Its probably a combination between resisting parasites and purging deleterious mutations from the gene pool. The combination itself is probably selected for to an optimum ratio.

Originally posted by Zamini
reply to post by Juran

 

It's not only parasites. It's just another factor.

You don't have that in religion do you? Different factors. You only have one factor. Please stop ridiculing yourself

Oh yes, factors. You have lots of those don't you. Turn you on don't they. A pat response to any 'idiot' who asks a question that can't be answered with your bullsh#t, 'Its just another factor".
The only factor to be distilled so far is that your heads are full of crap.

reply to post by Juran

The answers to your questions are freely available on the internet. Google “Red Queen hypothesis” and “Müller’s ratchet”.

Again, thank you for your input.

reply to post by Zamini

if one reproduces a-sexually then one is predestined to die out as a species.

I looked at your link; it was quite interesting. Many thanks.

Sexual reproduction is an added string to evolution’s bow, but the vast majority of living things – algae, bacteria, sponges, many plants – reproduce asexually. Some fish, such as swordtails and platys, reproduce asexually through parthenogenesis in the absence of males. I once had a pond full of female swordtails and the population kept increasing. They did fine, except for the ones that got eaten by the kingfisher.

Life seems to have existed for at least a couple of billion years before sex was invented. That’s exactly why sex is such a puzzle. It is a complicated thing to evolve and it carries all kinds of reproductive penalties, which means there must have been a damn’ good reason to evolve.

This research suggests that the suspected reason, parasites, is the correct one.