Problems with Mutation and the Evolution of the Sexes

I am most definitely an evolutionist, to start out. Correction: life starts with single-celled organisms. More accurately, pre-cellular organisms. Honestly, it depends on what you identify as "life." Viruses, for example, are not cellular, and likely more closely resemble the first life on the planet.The phrase "we start..." casues confusion. You and I "start" as a fetus in our mothers' wombs. Many take such phrases and believe that evolution means we somehow "morph" from one form to another inside our own lifetimes, which is compeltely false (and its unfortunate that TV and movies tend to perpetuate this little brainbug). Specifically, we self-replicate imperfectly. As did the first forms of life. It's these imperfections in the copying process that allow mutation and evolution to occur - otherwise all life would simply be cloned duplicates of the first life form. ...kind of. The move from single-celled to multi-cellular life is very interesting. The first examples were less true multi-cellular organisms and more single-cellular organisms living in colonies. Think algea - technically algea is a single-celled life form, but it congregates in large colonies. Some jellyfish are also simply colonies of single-celled organisms.So it's not a sudden "wow, you have several cells instead of one" change in a single generation. It's a gradual shift in certain populations toward cellular colonies, wich eventually gave rise to what we now call multi-cellular life. The Earth's crust was already cooled down by the time life formed. Magma is not very hospitable, even for extremophiles. But you are correct in that, over a few million years, a single-celled life form can give rise to a multitude of individual species, some of which could be multi-cellular. It doesn't stop - we're still doing it today, having babies. You seem to be under the impression that you, as an individual, were once a single-celled life form a few million years ago. That's not true - that's exactly the same as saying that you were your father 20 years ago, and your grandfather 30 years before that.All life continues to self-replicate. Some individuals may not be able to reproduce, true - take the example of a person who is born sterile. Does an individual with a mutation that prevents reproduction have any effect whatsoever on the species as a whole? Not really. Remember, traits can only be passed down through reproduction, so a mutation that prevents reproduction dies along with the individual and does not progress. No, it doesn't. This is a common misconception, but that's not what it says.Evolution is not an individual process. It's a process that affects populations. The frequency of expressed genetic trats does not change within an individual over a lifetime. The frequency changes over entire populations.Let's take giraffes for an exotic example. They didn't start with long necks - their evolutionary ancestors were much different. Lets start with this population of giraffe ancestors, and imagine that one giraffe has a mutation that gives him a slightly (we're talking a centimeter, not a meter) longer neck than the average. He's able to reach just a bit more food than the average individual, so he's well-nourished, and survives to mate.Now, he does not need his mate to posess the exact same mutation. Quite the contrary - he just needs a mate of the same species, and that's not a problem at all. Some of his offspring will posess the same mutation passed down from him, and will also have new mutations of their own (you have up to a few hundred mutations yourself, for example). So, several of the next generation posess longer necks, and are better-nourished than the average individuals, so they survive to mate. In bad years where food is scarce, they'll survive becasue they can reach more of the little food there is, and many of their peers with shorter necks will die - increasing the frequency of the longer-neck mutation (this is what we call natural selection. Note that it's not really "survival of the fittest," but rather more "survival of the fit enough").Over a very, very long time and many, many generations, the longer-necked individuals have become dominant - they are now the majority of the population, rather than just a few individuals. The frequency of genetic traits has changed, by subtle mutations guided by natural selection. Over an even longer timescale, tens of thousands of years or more, we can see the cumulative effects of mutations - the population now has necks that are much longer than their ancestors, becasue each successful mutation builds on all of the previous ones. The population now may have even changed enough so that it could be considered a different species from their ancestors - but at no point was any generation unable to interbreed with the generation immediately preceeding or following. In fact, the differences over individual generations are so tiny that you won't notice much, any more than you notice that some humans are taller than others. The problem is that "self-replication" doesn't mean "cell division." Well, it includes cell division, but that's not all. Self-replication also includes, sexual reproduction, budding, etc. Survival of a population increases with diversity. Getting stuck too far in a specific niche means that, if your niche is destroyed by a natural disaster, you won't be able to adapt. I'm not really certain what you're getting at here. All living things reproduce in some way - it's even part of the definition of "life." Is this the reason for your belief in Creationism? Becasue really, it's just a series of misunderstandings about what the Theory of Evolution actually states. They're common misconceptions, and they spawn from poor biology classes and are furthered by TV and movies (for the love of all that is good in this world, Teenage Mutant Ninja Turtles have nothing to do with mutation in a scientific context).We can help you understand what the Theory actually states here, if you care to stick around and ask some questions, and you can make your decision (or even argue against us) from there.

Bad habit of mine Good! My apologies - that wasn't clear from your initial post. But I strongly reccomend you take a look at Quetzal's post, above - he did an excellent job of explaining what's currently known about the evolution of sexual reproduction. That's certainly a great start, but from your OP (and this could simply have been the result of your initial sarcasm), it really sounded like you believe individuals evolve. For instance, it sounded like you believe that evolution says that you, personally, started out a few million years ago as a single-celled organism, and that you've "morphed" your way up the "evolutionary ladder" (we don't like that term - it's more of a giant bush, and being "higher up" doesn't necessarily mean anything). That's nothing like what the Theory of Evolution states, and it's actually identical to saying that you used to be your father, and you existed as your grandfather before that. Evolution is a process that occurs over many generations of populations, not single generations or individuals. I suggest then that, next time, use less sarcasm in OPs and try to be more directly clear regarding your topic of discussion. The title, for instance, is "problems with mutations." That says nothing about sexual reproduction. Then either you were taught incorrectly (not at all uncommon at the High School level, unfortunately) or you did not understand (also not uncommon given the incredibly short amount of time typically given over to evolution in High School).The "passed down survival trait" you speak of is essencially the definition of a beneficial mutation. Mutations are small genetic changes that, in their initial appearance, were not inherited from the parent(s), but rather appear as a consequence of the DNA strand being imperfectly copied. If the host of the mutation survives to reproduce, the trait will be passed down to its offspring, simple as that. If a mutation makes survival more easy, or better yet, happens to help those who have the mutation survive better than those without it when a disaster strikes, the mutation can actually become present in the majority of the population. Further mutations, whether they are similar (as in the ever-extending giraffe neck) or not, will build upon those already passed down. Realistically, practically every feature of every organism in existence is the result of a cumulative series of mutations.When you say "wouldn't it keep having to mutate with each passing generation," you're pretty far off the mark. The original mutation is simply passed down, and in future descendants, it's not really a mutation any more - it's an inherited trait.If you mean "wouldn't additional similar mutations be required in subsequent generations to make the neck longer than the small initial change from the first mutation," then yes - to end up with a neck as long as a giraffe's, multiple similar (and quite a few supporting but not neck-related) mutations are required. But these don't need to happen in each generation - they just need to happen eventually. And they don't really need to happen at all - we know the current "end result," but there is no "final form" or goal in evolution - it's not a guided process. A trait appears, or it doesn't. If it does, it either helps the organism survive, or it doesn't. That last bit is usually influenced by the environment (natural selection). It's a random process.I remember once seeing a randomizer machine that may be relevant. It was a tall case with a glass front with many, many wooden dowels poking out of the back towards the front. Rubber balls would drop from the top, bounce randomly from each of the dowels, and eventually land in one of the pockets lined up on the bottom. Mutations are like the path of the balls - they randomply appear, for no real reason. There's no goal. The ball simply lands in one of the pockets. Subsequent balls may or may not land on a previous one. Sometimes one pocket will wind up being full of balls, while another may only have one - it's just random. Mutations are similar. A "neck extending" mutation, for example, either appears or it does not, and subsequent mutations may or may not appear and build on it. Mutations with a direct, positive efect are more likely to be passed down, so the cumulative effect can become very pronounced.Sexual reproduction isn't really any different from any other series of mutations. It's not like two individuals of a population spontaneously "decided" to be male and female. It would of necessity be a slow, cumulative process, beginning with the simpler forms of genetic exchange Quetzal mentioned. The "debate" today mostly concerns how it may have evolved, not whether it did or not - the problem being simply that sexual reproduction appeared so long ago that it likely first appeared in organisms that don't fossilize. We have to take our examples from organisms that are alive today and extrapolate, which is why we can't give you a complete "this is how it happened" story. The organisms and methods Quetzal mentioned, however, are exactly what the Theory of Evolution would predict - sexual reproduction is not unique, but is rather a modified version of a similar feature already existing in other species. And I'm sorry, but it's completely and totally wrong. That's like saying amputees should have children born without limbs, or that my child may have a birthmark if I get a tattoo.Mutations and evolution work by genetic changes, which are already set before you're born. Disfiguring your body in any way will have no bearing whatsoever on your offspring. If this is really the way your teacher explained it, he should be fired, and it's no wonder you have some severe misconceptions surrounding evolution. And again, that's compeltely and totally wrong. If I work out and become a body builder, my children will not be born with bulging muscles. If I break my arm repeatedly and force it to heal in a strange shape, my children will not be born with such a deformity. If I suffer burns on my body, my children will not inherit the scars.Mutations and evolution are genetic in nature, and have nothing to do with changes within your lifetime. Quite the contrary. You're taking the position that sexual reproduction needs to form spontaneously and suddenly, with both a male and a female gender evolving at the same time. That certainly is quite a jump, and it would be somewhat similar to a giraffe suddenly "evolving" a new head. You're right to ridicule that idea...the problem is that this has nothing to do with what the Theory of Evolution predicts.Evolution predicts that no feature should be unique, no feature should spring up fully formed like what you're describing. Instead, all features of all organisms should be slightly modified versions of the same feature in a pre-existing species. Giraffe necks did not spontaneously "mutate" in a day - they are slightly modified versions of the same feature in their ancestors. So too is sexual reproduction as humans experience it not unique, and it did not appear "fully formed" with a male and female present. It began, as Quetzal ponted out, as simple genetic exchange. In many species, all individuals are simultaneously both genders - hermaphrodites. The change to exclusively single-gender individuals would have been a mutation based on that.Imagine a mutation in a hermaphroditic species where one individual is born with a mutation that makes the female fetures either absent or nonfunctional. This individual could be said to be the first "male." He'd still be able to reproduce with the rest of the population using his male features and their female features - he just wouldn't be able to have it "both ways" any more. It's a small change for an individual, but many cumulative mutations along those lines can eventually lead to a full seperation of the sexes if selective pressure is applied. There isn't really a "why" in evolution. We can tell you why a feature is beneficial, but why a feature forms in the first place is really tied to random mutations. The only thing that keeps the whole mess from being total random chaos is natural selection, which ensures that primarily neutral and beneficial features are passed down, and lethally harmful mutations are removed from the gene pool. Evolution doesn't work that way. Mutations are small changes, and they are mostly random. There's no goal, and you can't really say "why don't I have four arms, that would be useful" as evolution doesn't simply add on whatever is useful - it's not an intelligent process, any more than the formation of ice crystals are intelligent. Evolution is the cumulative effect of random mutations working within the limits of chemistry, guided by natural selection.We use computer programs modeled after evolutionary processes to solve problems, by the way. They produce some very interesting solutions, very much like evolution in the real world. Continue to approach us this way rather than the sarcastic, insulting tone you used in your OP, and you'll get more reasoned posts. If you simply want to learn more about what the Theory of Evolution actually styates, you've definitely come to the right place.

This is the cause of your confusion. High School Biology is at best a very basic version of evolution, and at worst it perpetuates complete inaccuracies (like your "bone bending" example). I'm not nearly qualified to go into too much depth (I'm not a biologist, this is just a hobby for me), but I'd be happy to try to lay out the basic model to the best of my understanding in a way you might understand. We also have some real biologists here on this site who very much know what they're talking about - they actually use the predictions of the evolutionary model every day, in the lab.So let's start out this way: A theory is not just an "idea." That's closer to a hypothesis. In science, a theory is a generally accepted model of an observed process that can make testable predictions. For instance, the Theory of Gravity is our model of the observed process by which matter attracts matter. It makes certain predictions (how much a given object will weigh on a given planetary body by taking the mass of the body and the object, for instance) that can be tested. When these predictions are borne out as true, the theory becomes less tentative. When there is a slight inaccuracy, we repeat the tests and make adjustments to our model until it reflects reality with as much accuracy as possible. If the predictions are completely falsified, we basically throw out the model and start from scratch - again, the goal is to model observed reality with as much accuracy as possible.The Theory of Evolution is just like the Theory of Gravity. We have observed that allele frequency (basically the frequency of any given trait) in any population of biological organisms changes over time. The Theory of Evolution is currently the most accurate model we have of the process of allele frequency change. The primary mechanism for allele frequency changes in the Theory of Evolution is random mutation guided by natural selection. The model makes many, many predictions which have been tested extensively over the past 150 years, THe theory has been modified to include new information, but the basic model of allele frequency changes being the result of random mutation guided by natural selection has not changed much - it's proven to be an incredibly accurate model.Evolution does predict common ancestry, but it's deeper than that. The best way I know to explain the core prediction of the Theory of Evolution is this: no feature in any organism should be completely unique. It should be a slightly modified version of the same feature in a pre-existing species. Slugs, for instance, should never suddenly sprout wings. But existing features can be slightly modified and sometimes even used for something completely different from what the parent structure was used for.All of this, of course, is guided by natural selection - it's not an intelligent process, because there's no "goal" or "decision." But it does cull out the variants that plain don't work.Let's go all the way down to bacteria for an example - there's a simple experiment you could even do yourself with a few supplies, or in a college biology lab. I'm sure you've heard of the so-called "superbugs" in the news, variants of existing illnesses that are highly resistant to antibiotics.This is a mutation, and their appearance was predicted by the evolutionary model.Bacteria are, relatively speaking anyway, very simple - but I'm not a biologist. I'll try to explain as best I can, but any of our resident biologists should feel free to jump in or correct me if I'm at all inaccurate. The bacterial cell membrane is composed of proteins. Those proteins are, essentially, defined by one or more genes in the DNA of the bacteria. A mutation is essentially a copying error - the base pairs that make the double-helix chain of DNA can mostly be mixed and matched, so sometimes the wrong base pair is copied, or an extra one is added, or one is subtracted. Since bacteria reproduce via mitosis (the clone themselves, basically, making identical copies), we know that any changes in their DNA must be due to what amounts to copying errors in the DNA replication cycle. Very slight changes compared to the entire strand, but enough to change a protein. By purely random chance, one of these copying errors can make the cell membrane of a bacterial cell slightly different from its parents. Now, this could make the new cell die, or it could just be "different" and not matter much. If it dies, the mutation disappears - it was clearly a "negative" mutation. If it does nothing significant, that one cell will pass along the new cell membrane to its offspring, and they to theirs, etc.Now, let's add an antibiotic.There will be many tiny variants due to mutation in the population of bacteria. For most, this won't matter...but there will sometimes be one such variation that makes the antibiotic not work. The reason it doesn't work goes farther into the chemistry - suffice it to say that the specific protein the antibiotic attacks isn't present in our variant because of one of those very tiny copying errors that changed a protein.Now, the only variant that has survived the antibiotics is our mutated variant - the rest have been killed off. The mutated variant now gets all of the food, and divides - the frequency of this particular feature has changed from a very small percentage to now nearly 100%. This is evolution - the allele frequency (the frequency of the genetic trait) has changed due to random mutation (the copying error), guided by natural selection (the antibiotic).This specific experiment has been done countless times, and is even predictable - the mutation itself is random, but in a large enough population size, it's nearly inevitable. So evolution has been observed, directly. The process is a fact, period. The Theory of Evolution model is actually considered to be about as solid as the Theory of Gravity, in fact, because of so many different direct observations of the process.Now, our bacterial variant isn't really a new species, necessarily (the definition of "species" is very touchy - honestly, organisms within anything but a few hundred or even thousand generations of separation sort of blend together. You can see variations, but you can't see enough of a difference to really call it a new species). We have observed what we would define as a new species forming in the laboratory, so we know that speciation is the result of continual evolution and separation of populations (if a population is separated and the two new populations never inter-breed again, they will evolve in different ways due to the different environmental pressures they each experience).These observations lead us to predict that all organisms share common ancestry, and that the variety of life is best represented in something like a tree - like we do, categorizing each creature into different domains, kingdoms, phylum, classes, orders, families, genera, and finally species. The farther apart on the classification tree, the more time has passed since the given species had a common ancestor.So, that's a lot to swallow for a single post, and it's pretty long even for me...so after you get back, take a look, and let us know if you understand, or if you need us to clarify.

Please, please do not try to start the "it's just a theory" nonsense. Read through the posts already made in the thread before you start responding to each one of us - this has already been addressed, and it's an example of ignorance of science. The word "theory" in science means something very, very different from the way you're using it.

Hi again Lyston,If there is a single word that defines the goals and purpose of the scientific method best, it is the word "accuracy." We may not be dead-on 100% correct, and we may never be - but we strive to make the most accurate models of observed reality possible, and we change those models in accordance with new data to impprove their accuracy. We don't claim to have all of the answers, and we'll never be able to give you the entirety of the evolutionary tree that led from single-celled organisms to human beings - just a highly accurate model with its supporting evidence. Small inaccuracies in the current evolutionary model are likely, and probably even certain to exist. Large inaccuracies (ie, biblical Creation) are so unlikely in light of the evidence that one may as well resurrect the old "planets move because they are pushed by angels" model. The current evolutionary model, according to the evidence we have gathered over the past couple hundred years, is very accurate, and is damned close to the bullseye. Creationism and the like are so detached from the evidence that they are, to follow the dartboard analogy, not even on the same dartboard. Or the same room. Or the same bar. They aren't even in the same city. An inaccuracy that large that would refute the amount of evidence in favor of evolution (which, remember, includes direct observation) would actually require a deity to purposefully plant evidence and then continue to cover up the "truth" via additional undetectable miracles and so on. While it can be said that there is a teeny, tiny, infenitisimally small chance that this is the case...I can say with a great deal of confidence, really, probably not.So...there's my little generalized speech regarding Creationism vs. Evolution. Now, on to the specifics of your post. Mutations are part of an organism's DNA. When that organism reproduces, the mutation is passed on to its offspring. It's no longer technically a mutation at that point - it's no longer spontaneously occurring due to a copying error, it's an inheritable trait. The offspring will have a few new mutations of their own, of course. We can't "prove" much at all about life so long ago, unfortunately - single-celled creatures don't leave any fossilized remains for us to find a few million or billion years later. We can say that simpler forms of life, like viruses (who don't even use DNA - they use RNA, and yes, I understand that defining them as "alive" is fuzzy because they require host cells to reproduce) are asexual. We can also say that it's highly, highly unlikely that sexual reproduction would be able to exist with the earliest forms of life - the population size is simply too small, and you actually do run in to the "nothing to mate with" problem you originally mentioned. In the case of the very first cell, it would have nothing to mate with. There's also the fact that more "complex" forms of life (multicellular life, for example) seem to use sexual reproduction much more frequently than "simpler" forms like bacteria.Science doesn't deal much with "proof." It deals with evidence (which is different, proof implies too much certainty) and accuracy (which is not the same as correctness - it's not black/white, true/false). We deal with what the evidence suggests, and making an accurate model based on our observations. The evidence currently seems to suggest that sexual reproduction developed later than asexual reproduction. The Theory of Evolution is a single theory - it's the model of changes in allele frequency in populations over generations, guided by natural selection. It fits quite well with other theories and hypotheses, like abiogenesis (the hypothesis that life arose from non-living organic compounds), but it's compeltely seperate. For instance, the Theory of Evolution would be unaffected by the discovery that the earliest forms of life were brought here by an alien spacecraft, created by a deity, landed on Earth with a comet, or spontaneously formed from an abiotic "soup." The Theory of Evouton only describes the mechanism by which the variety of life we currently see arose from earlier forms of life - Darwin's Origin of Species, essencially. The reason people are "up in arms" is this statement you made earlier:

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That's exactly what I meant. As for the first sentence, it is a belief. Evolution is a theory, not a fact, as you all know. It has evidence, but you still need to believe in it, just as one needs to believe in the concept of atoms (something that my Chem teacher of all people brought up). No matter how obvious it seems, there is a possibility (no matter how slim) that it could be wrong. That's why we are in debate.

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Specifically, the sentence "Evolution is a theory, not a fact, as you all know," and the follow-up "you still need to believe in it." This is very reminiscient of a very large percentage of Creationists who say "it's just a theory" as if "theory" meant "an idea I had over lunch" in science the way it can in common usage, or the way some Creationists use the tu quoque fallacy to insist "evolution requires faith too, so our belief is just as valid." Because we've had to deal with these same arguments literally hundreds, possibly thousands of times, they can draw emotional responses.Evolution is a theory, which in a scientific context means that it is a highly accurate, widely accepted model of an observed process supported by a large amount of evidence in the form of verified predictions.When Creatonists say "teach both theories" and claim that Creationism, which has not proven to be in even the tiniest bit accurate, does not model any observed process, has no supporting evidence (aside from the Bible, which objectively is identical to any other form of mythological text until corroborating evidence is discovered) , and makes no testable predictions, is also a "theory," well, scientists tend to get upset. I suggest then that we move on past the arguing over the word "theory" or discussions over whether "sex" or "gender" is more appropriate for the discussion. Honestly, I don't believe it's intentional on your part, but you've basically laid some bait for some of us to bite. I'll admit, if you're here for an appreciable amount of time and continue to say what can be interpreted to be "it's just a theory" or "evolution requires faith, too," I'll get just as grumpy as Taz. So let's try to move back to where we've been making good progress - the actual mechanisms of evolution, and specifically scenarios by which sexual reproduction could have arisen. That makes a bit more sense then. The Theory of Evolution is very specific in its scope, and it's pretty broad. The theories you mention here (and I'd probably call them hypotheses myself, but that's me) are far less general and deal with the evolution of a specific feature.

The problem, of course, is that the general Theory of Evolution is a necessary prerequisite to understanding the evolution of a specific trait. It's like the need to understand addition before you can really grasp multiplication.If Lyston doesn't understand how a mutation, any mutation, can be passed from parent to child for instance, how can we really discuss the gradual evolution of sexual reproduction via cumulative mutations? If we haven't yet explained how mutations are "positive" "negative" or "neutral" based primarily on the environment and selective pressures, and that these affect the allele frequency of the population and are not tied specifically to an individual organism, how can we discuss his misunderstanding that male and female must simply evolve in a single generation in parallel?I think Lyston's initial sarcasm coupled with what appeared to be the "it's just a theory" argument later on has resulted in a lot of grumpy responses, like the way we would respond to ICANT or another long-term member after repeating the same refuted hogwash for the thousandth time. Lyston hasn't done that - he just got here. I'm willing to set aside his initial sarcasm and just treat him as a newbie who wants to understand the opposition rather than attacking the same old strawmen. I'm all for that, so I'm willing to cut him a bit of slack until and unless his curiosity and desire to learn about evolution prove to be a sham, and he turns into Generic Creationist #72364.

The definitions, like the definition of a "species," are fuzzy - it's not black/white, true/false. Yes, a virus requires a host cell...but there isn't really an "exchange" of genetic information. No information from the host cell is passed on to the viral progeny - the virus basically takes over the cell's mechanisms and forces it to make more virus particles.Real sexual reproduction would involve an actual exchange of genetic material, not what amounts to a hostile takeover of a cell and turning it into a sort of biological virus factory. Real, most accurate possible answer? "We don't know." We really have no idea - all we have are "likelihoods." We also have to work at defining exactly what would be considered "life," because if abiogenesis is the origin of life on Earth (again, this is not what the Theory of Evolution says, it's just one of several possible starting points for evolution), we're going to be talking about a progression of pre-cell self-replicating strands of proteins. Are those self-replicating molecules considered alive? They'd be a lot like viruses. Do we not consider it "alive" until it forms something that better resembles a cell? Honestly, we don't know, becasue organisms this small and simple don't fossilize, so we will never find any "record" of their existence.It is likely however, from observing the forms of life currently on Earth, that the "first" life was very simple compared to the variety we see today. What we know is that it had to be self-replicating, and that its copying process must have been imperfect - those are the prerequisites for evolution to start working, and since we see evolution working today (and plenty of evidence of it working in the past), it's most likely the same was the case from the start.I would personally say that it's very likely that the first "life" existed as a very simply self-replicating molecule, something akin to RNA. Given the right environment of organic chemicals (and we know such chemicals exist in an abiotic environment from such examples as Titan), such molecules could reproduce without a cell membrane or any of the other cellular structures we see today. Imperfect replication and environmental differences could allow such molecules to do all sorts of interesting things to make something closer to what we would recognize - conjoining two of the single-helix RNA strands to make the first DNA, for example, or coopting another protein structure as the first cell membrane, etc. A real biologist would be better at speculating in this area and explaining the current model, however.I think it's pretty safe to say that anything from a few billion years ago would be simpler than what we currently define as "bacteria."

The evolution of the eye is a very complex and well-researched topics. Eyes have evolved not once on this planet, but many, completely separate times (meaning multiple branches of the evolutionary tree have developed eyes independently, and in different ways).However, that would be completely unrelated to the topic of this particular thread, which regards the evolution of sexes. You're more than welcome to start a new thread about the evolution of eyes, though. Weve gone over it a few times, but I always find it to be a fascinating topic.(The reason we try to keep topics narrowly defined is that there is a 300-ish limit on the number of posts in a thread. Topic drift means that those posts get taken up by things unrelated completely to the title - creating a new thread for a new topic is generally the way we do things here)