jp255

The point is that if we include extraterrestrial life into the equation and you do have a problem with it, then you need to redfine life it so that it does not include natural selection or darwinian evolution and can still accurately define the life forms we observe on Earth. You have not done this, and more importantly it has not been done as of yet (I have not come across such a definition). If you know of one, then I'd definitely be interested in reading it. It depends on whether or not you see replicating chemical systems (that are not under selection) as life or not, because without using natural selection then they can count as a life form. If you do see chemical systems as a life form then I have no problem with your statement, but if you don't then redefine life. Do you not think it is more appropriate to redefine life, without using natural selection or evolution, so that the definition is accurate, before you begin saying it is possible for life forms to arise that are not under selection/evolution? Do you not see the logic here? that the definition should be changed and still be accurate before you claim that extraterrestial life could arise without selection or evolution? If you are going to stick to these claims, that extraterrestrial life might not be under selection or evolution, then provide support for it? The definition of life we have can only hold with inclusion of selection/evolution. Until I see a definition which is accurate without selection/evolution, then there is not a problem. There are many things which may be a problem, but then again, they may not be. In the instance of the latter, you'd be looking a problem that does not exist to your knowledge, and this will be an everlasting problem. There may not even be extraterrestrial life, at least complex life forms. I think you are jumping the gun in a way. Is there a reason to think about potential scenarios in which life can arise without evolution/selection if the definition we have cannot hold without it's inclusion? If you do manage to then it's likely that you are wrong.

Your posts suggested that you do not know of the advantages to sexual reproduction. You shouldn't assume there are no advantages however, that's why I was griefing you a little . I will list them, but I don't have the time to go into them right now. Tomorrow. "Be critical of all ideas no matter how logical they might appear to be, and assess how likely you think it to be true". This is a great example of how you can benefit from this line of thinking as opposed to yours. If one was to be critical of your approach, you'd say "Do you at least realise that it is highly likely that sexual reproduction is positively selected for to a greater extent than asexual reproduction because the proportion of all extant species that display either type of reproduction are massively different? (with sexual much higher)). So, you should expect there to be some missing advantages you don't have knowledge of to account for this.

exclusion of natural selection or evolution to the definition of life causes it to breakdown and become much less meaningful for our observable life form, and if removing this aspect of the definition means the definition doesn't work for a life form which we do know exists and is observable, how can you even hope for the definition to work for something that might not even exist in the first place? This doesn't seem terribly logical to me. How do you propose the definition should be altered to appropriately define life without using evolution as inclusion criteria? Except evolution is not limited to DNA only. What aspect of replication are you referring to? and which allows for evolution? Such as? Also are you explicitply referring to the abiogenesis part of life, where the initial replicators might not be under darwinian evolution? Does this mean that the actual complex Alien (complex life form) might not be subject to evolution?

and there are no positives to having a male sex? you are only listing the downfalls. why? Sure there are bad aspects to having a male sex. Overall though, would you not agree that a species with two sexes is more advantageous for animals?

As I said in the other thread you posted this opinion. Sexual reproduction is the dominant form of reproduction, asexual species are in the minority. This suggests that sexual reproduction has been positively selected. So, you need to show that asexual reproduction is more positively selected than sexual reproduction in order to say sexual reproduction is not good. You know that there are differences between asexual reproduction and sexual reproduction other than the proportion of the individual's genes passed on to each of his/her offspring? Your quote thing under all your posts. "Be open to all ideas no mater how absurd, but also accept that most ideas are probably wrong.". Personally, I adopt this line of thinking "Be critical of all ideas no matter how logical they might appear to be, and assess how likely you think it to be true"

That is quite a statement! How exactly do you know that men being reproductively incapable is not beneficial? I can't remember the exact figure, but around 95%+ (It's a high number) of all extant species reproduce sexually. So if you make a statement that ultimately says "95% of extant species have an opposite sex incapable of reproducing, this is not beneficial", then provide evidence for this at the very least! because the mere fact that sexual reproduction is so abundant suggests that this is beneficial, no?

Well, we already know that you are homosexual (at least you claim to be). If we assume we did not have that knowledge, you think it is not possible for any us to not call you a fag or a gay upon looking at the video? You seem to be very sure that there is one way in which people can and do perceive your sexual orientation. Please explain why this is. You do know of genomic imprinting right? that partly disagrees with what you said there.

Personally I am too doubtful of whether this evidence actually has any significant impact such that natural selection can detect it. Basically, to show there could be positive select for gay genetic factors I would rather read a study which had data that showed gay uncles have a significantly greater proportion of nieces/nephews that reach reproductive age. A study to show that gay uncles play with there nieces/nephews more often than hetero uncles is not good enough. Also, this needs to be shown over long periods of time for natural selection to raise the allele frequency of gay genetic factors anyway. This has not been done, and thus group/kin selection is still a big long shot. edit: duplicate thread! yay

How do you propose we do this then? Also, our definition of life does potentially define other lifeforms since the battle of the replicators was an instance in which different fundamental basic building blocks of life existed, all under selection. This is the best definition of life we have. Again, point out the problems with it. Suggest a new definition. Accept the one proposed. Take your pick. This was really aimed at andeh to begin with, but also extends to others claiming there cannot be a definition of life.

I understand your point, and it is true. Just because someone has acted in a homosexual manner once, does not mean that he falls in the homosexual category, and if he is placed in the heterosexual category then there is a failure to distinguish between those who are exclusively hetero and others that are not. All in all the definitions hetero, homosexual and bisexual are a social attempt to provide labels. In reality sexual orientation is a quantitative trait, as there are varying degrees to which a person is hetero, homosexual or bisexual. This is obvious. Also this is issue is accounted for, in part, in the heritability studies as the individuals are asked to say what their sexual orientation is. The terms heterosexual and homosexual were used in the study, it removes the social behaviour aspect as the individual themselves defines their own orientation, but it is far too early to begin to atempt to account for varying degrees of behaviour. I will say it again. The heritability is known. We know there is both a genetic component to homosexuality and an environmental component!!!. There are limitations to the heritability studies however. 1) there are social pressures/peer pressures that make some people hide/be ashamed of their sexual orientation (proof of this lies within this thread lol) so there could be people in the study which were gay but did not admit it. The confidentiality however should really cure this problem, but some people are weird and probably would still lie. 2) Dmaiski's theorised limitation, that the discordant MZ twin, because he is 100% genetically identical to his homosexual twin, tried being gay and then also found he liked it too. Leading to an increased number between DZ twin, giving an inaccurate heritability. This is valid. I frown upon this argument, can't imagine myself doing something my twin does just because I am genetically identical. Nonetheless I still think that a genetic component is likely from the multiple independent heritability studies that have been carried out, and the meta-analysis. Whether or not you discredit this evidence is due to point 1 or 2 is up to you. Many people are wrongly ignoring the estimated heritability without sound justification. Too many people here are using their own opinions as justification for their ideas on homosexuality. Remove your opinions from the equation and look at the evidence. There are a number of heritability studies, such as the one dmaiski posted. Whether or not it is a choice is much more difficult to answer, I have tried to answer that in the earlier pages. As for whether a gay gene can exist or not, this question also has some difficult aspects to it, but the answer is yes it can, by a few possible mechanisms. 1) genetic hitchiking 2) complex disease type model where gay alleles have low penetrance 3) people forget that some people enjoy both types of behaviour and those of course can reproduce 4) possible positive selection but doubtful.

I am just quoting all of the sentences which are absurd. You are ignoring all the evidence and using your own opinion and your own experiences to justify your ideas about homosexuality. Firstly, believing so strongly that you are gay because you have a genetic mutation and that the genetic mutation = 100% determinism will not ever help. Why do you believe this, even when the evidence does not suggest this? this is the obvious question to ask but even if we assume what you say is true, how can you ever hope to change? Seems to me that you are setting yourself up to be unhappy. As I said before, the heritability is within the region of 30-60%. It is not 100%!!!!!!! Therefore you can not say that a genetic mutation is the cause of your homosexuality, because you do not know for sure. Even if you do have a mutation, you cannot deny the possible influence of the environment either. So do yourself a favour and adopt the correct line of thinking. Just because it feels as though there is not a choice, does not instantly mean that x condition is genetic. How do you know that the environment cannot contribute?

Of course. Why should we make a definition to include other life forms which might or might not exist? I think it is more appropriate to make a definition which can be applied to all life forms we currently are aware of, and if we do come across other life forms then we modify the definition if neccessary. It is a little hard to make a definition for life forms we don't know about and might not exist.

What is wrong with the definition Jens provided then?

Why are you just guessing? you can determine the amount the environment contributes, which is what your theory is. 100 - ((52-22)x2). This study has quite a low sample size however. It still does show a genetic contribution to homosexuality though. You are right, that is a possibility. You think that sharing 100% of your genes would create such a powerful feeling of obligation though? DZ twins share 50% on average, the difference between 50% and 100% is enough to cause someone to feel obliged to try out homosexual behaviour such that 17 more people try it out in the MZ group? I would agree with you about the environmental factors contributing to homosexuality, but I don't think that sharing 100% of your genes with another person will make you do everything that he/she does. I suppose you have pointed out a possibility which casts doubt over whether or not this heritability observed is really genetic. That instead the heritability of homosexuality + peoples opinion on determinism is being assessed.

It doesn't really matter what the facts are. Simply asking "Who" suggests you already know that a creator is a requirement, that all other potential possibilities are not possible... the burden of proof falls on those asking "who" in the first place. Anyway, The definition of life I go by is "Something which can self-replicate and natural selection/evolution can act upon.". This definition, when applied to the abiogenesis theory, would mean that life began in the early stages when replicators were battling it out.

You are not the only one that has referred to "the gay gene" anyway, just look at the thread title . Not neccessarily. You raise a good point about accents/speech patterns being mistaken as heritable amongst families. However this problem doesn not occur in MZ DZ twin studies because the accents/speech pattern would be perfectly correlated in both MZ and DZ twins (just assuming for arguments sake), so the heritability would be 0 as the difference of correlation is 0 between MZDZ twins. This problem would occur if only MZ twins were studied, as any cultural/environmental traits would appear to be heritable in unseparated MZ twins. So that argument doesn't really hold, the heritability for homosexuality was done by MZDZ twin studies and found to be 30-60% ish. MZDZ twin studies are the next best alternative to the separated MZ twin approach for correcting for shared environment issues, and has to be used due to the rarity of separated MZ twins.

And how many heritability studies can get there hands on large scale separation study data? the answer is of course, not many. Which is why you'll find the most common way of trying to determine heritability (using twin studies) is by correlation between MZ and DZ twins (unseparated, since separated twins are too rare), the heritability is then calculated by doubling the difference of MZDZ correlation. There have been heritability estimates of homosexuality anyway. I can't remember the exact value, but 30-60% region sticks out in my memory. Anyway the important thing is it is not 100%, so the usefulness of a homosexality GWAS shouldn't be overexaggerated. There are environmental contributions. I believe most GWAS are inherently flawed in that they assume the genetic loci work alone and therefore assume an addivitive model, ignoring potential epistatic or genetic interactions. Identifying potential epistatic interactions for each loci found to be associated is difficult, so additive models are assumed. This creates phantom heritability, if associated loci are incorrectly assumed to have additive effects. Also, GWAS themselves are not done on all populations so you should take care when using data/conclusions from GWAS and then exdending those conclusions to other populations. Referring to "the gay gene" as the causative agent of homosexuality is inappropriate. This is an absurd assumption! justify yourself or change your wording.

People often ignore the contribution of crossing over/Homologous meiotic recombination to evolution. Which has some useful evolutionary mechanisms which allow for genome changes of varying size (mis-aligned crossing over), exon shuffling (crossing over within a gene), allele shuffling (crossing over outside a gene), and gene conversions (one allele is converted to other form, resulting in two of the same alleles). Recombination itself has tons of different types of recombination mutations within these categories that can lead to gross changes of the genome and alteration of genes/alleles by exon shuffling or partial gene conversion (leads to new allele). It is generally accepted that these are random events in regards to position in the genome at which they occur. Sure they are not random in terms of mutation rate due to chemistry/maths, but position wise they are considered random. There are non-random mutations though, such as crossing over, which is known to occur at hotspots. These hotspots give rise to Linkage disequilibrium. Also hotspot usage (in meiotic recombination) is largely controlled by genetic loci in humans, and varies between populations resulting in the different LD maps in Hap map. Since those Hapmap studies, it has been investigated further and the gene controlling meiotic recombination in humans is PRDM9. I believe this is one of few mutations are considered to be non-random in regards to position.

The terms oncogene and tumour supressor genes are, in many cases, a misleading description. When p53 is described as a tumour supressor gene, it is misleading because p53 is known to have oncogenic gain-of function mutations which gives the mutant p53 new oncogenic functions. There are many genes like p53 that display properties of both tumor supressor genes and oncogenes. So it entirely depends on the construct as Charon said. However Miriam described it as oncogenic, if she meant that she was handling an oncogenic p53 mutant then that isn't good news. I'm not sure if there is a term to describe cancer contributing genes that have both loss-of-function and gain-of-function mutations. It is important to remember that even though a gene might be described as a tumour supressor gene, it can still have oncogenic gain-of-function mutations and therefore be described as an oncogene also. I think p53 is primarily described as a tumour supressor gene because the mutation spectrum mostly consists of loss-of-function mutations, this is just a guess though. I think it could increase the risk for the cells which were infected, as long as the the mutation was a gain-of-function or a loss of function mutation in a construct which would replace the functioning one as Charon suggested.

It is quite stupid to say that homosexuality is not natural when there are so many more instances of homosexuality than there are instances of homophobia in nature. I wish this were the case, I think you do too. However in this instance, it is more appropriate to lean more towards homosexuality not being a choice for a few reasons. Sexual attraction is, in many many animals, non-random. Genetic factors have been identified in many animals which alter preference of potential mates' traits. Most well known example of this is birds of paradise, but there are many other examples. So it is not such a stretch to think that sexual attraction in humans is also non-random. Although there are no genes which have have been discovered in humans which alter mate choice to date (at least none that I know of), There is evidence of non-random sexual attraction in humans by looking at the data from those dirty websites where users rate the appearance of people in the pictures shown to them. So there is more inclination to think that homosexuality is likely to not be a choice than the reverse. As charon said altruism is observed in many animals other than humans. Another point is that the comparison is ignoring other important differences. I think it is safe to say that most humans living in first world countries live in an environment where food, water and shelter are in plentiful supply and that there is a low probability that these basic needs will become difficult to obtain overnight. The same can not be said for the environment in which most other animals live. Do you think that we would still care for the old on the same level that we do today if we lived in an environment which was much harsher? where food, water and shelter were hard to come by? The cost of being altruistic is very small to humans in comparison to other animals and you are not taking this into account. In my opinion, based on the sexual attraction arguments and it's subtle nature, I think there is an illusion of freedom and choice in this case which causes the heterosexuals to think that "homosexuals choose to be gay". Do you completely understand your own preferences concerning who you are attracted to completely? Why do you prefer black hair over blonde hair etc? If not, why do homosexuals have to be in complete control of who they are attracted to and therefore choose to be gay?

Homosexuality is genetic. Definitely no question about that, there are multiple independent studies which have shown the heritability of homosexuality to be within the region of 30-60% (can't remember the exact value) and other studies which have shown the risk of recurrence between relatives being higher than control groups. To those who are saying it still has no genetic basis, explain why the studies are incorrect. That being said to say the environment has no effect, like one of the links I came across did, is not true. If it was true then the heritability would be 100%, but it is not. Homosexuality amongst monozygotic twins is also not 100% concordant. So what genetic factors and environmental factors contribute to homosexuality? I think that there have been very few, if any, loci/genes which have been discovered to contribute to homosexuality in humans. I don't think the environmental factors have been looked into much either. Assuming that there is one gay gene is stupid, all possibilities should be considered. If anything it is more likely to be a polygenic trait because there are no discrete phenotypes, a range of preferences are possible. If you imagine there is a scale from 0-100, 0 being homosexual and 100 being hetero, I think it is safe to say there would be a range of values amongst populations from 0-100. This points to homosexuality being a complex trait, where there are many genetic and environmental factors which contribute to the sexuality value. How many factors there are is unknown. For other complex traits, like height, it is estimated that there are 100's to 1000s of contributing factors. The way some have been thinking about the potential propagation of gay genes is not correct. "I can't see how a gay gene could survive" and other such comments. If you applied the same line of thinking to some genetic diseases you'd come to the same conclusion? that x genetic disease is not genetic? Some have been looking at survival of genes too closely at the level of the individual, saying the homosexual won't pass on his genes (this is not even true in all cases). This statement is wrong for two reasons, 1. the reason i just stated, some homosexuals do have children. and 2. brothers and sisters of the homosexual that do go on to have children will pass on their genes, and thus indirectly the homosexual passes on his genes because he and the sister share 50% of their genes on average. Sure if there was a 100% penetrant homosexual allele which accounted for all homosexulaity in a population then it would be weeded out fast, it is clearly not like that in reality. To add to potential ways in which Homosexuality genetic factors can propagate and increase in frequency. Homosexuality is quite prevalent considering it reduces the individuals liklihood of reproducing. So how could genetic factors survive? one possibility is that some of the factors could have hitchiked to higher frequencies by being close to other genes which are under strong selection. If, for example, a genetic factor contributing to homosexuality was nearby a gene under strong selection such as brain size genes, then the homosexuality gene would increase in frequency despite the negative selection against it because of the more powerful positive selection of the nearby factor. Linkage disequilibrium allows for hitchiking to occur, although there is a limit to how long this effect will occur due to breakdown of the Linkage disequilibrium after recombination events over time.