Gian

Thanks Janus et al for all the above replies, ah well if I ever get to Titan I'll take my flippers and snorkel anyway.

Yep, Velocity Boy, 'Swimming on Titan' would make a great movie even if it's impossible! Dunno about finding Life, but it would be great if we did.

(1) I guess there's wind and tidal forces on Titan so maybe we can walk along the beach of one of the methane seas with methane washing up and down.

(2) If liquid methane has less than half the density of water, would it still be possible to have powered craft which could float on the surface?

(3) Thanks Janus and Airbrush for the hang-gliding idea. Or maybe even a nanolight powered by methane?

(4) Presumably with all the methane about, power won't be a problem. When explorers get to Titan I guess temperature suits would have to be powered (unless NASA has an insulation fabric which could withstand −179 °C?)

(5) As the atmosphere is mostly nitrogen, presumably explorers would only have to take oxygen with them and have a mechanism for mixing it to make breathable air?

(6) And given that there's water on Titan, would it be possible to mechanically extract enough oxygen to add to the nitrogen to make breathable air? altho I guess it would take a helluva lot of water....

cheers

GIAN

The atmospheric density as well as pressure at the surface of Titan is like being in about 15-20 feet of water here on Earth and surface gravity about 0.1G. If so, does anyone know if it would be possible with flippers and the right equipment to 'swim' through the atmosphere at the surface of Titan? ta

There seem to be only two palaeontology degrees in the UK. What's the best way in?

Also, what's a good starter book on evolution? (don't fancy Darwin at this stage)

The Universe has been expanding since the Big Bang ye? so we can see the 'red shift' in galaxies moving away. Does this mean literally that galaxies are getting further away from us in miles? or does 'stretching space' mean something else? I'm not a scientist so I need some assistance on this one

Actually, they would need a pressure suit. You can deliver oxygen to the lungs at sufficient pressure without a suit. The problem is that, on Titan, the air pressure is 45% greater than at Earth's surface. Our skin surface, like everything else about us, evolved in Earth's atmospheric pressure and is suited to that. If you increase the pressure 45%, you would get gas diffusion effects into the subcutaneous tissues and eventually the blood stream. Not a good thing when cyanide is one of the chemicals in the 'air'. Other chemicals like ethane permeate into the tissue - in this case at higher pressure - and exert changes to blood cell DNA. It is one of the causes of certain forms of leukemia.

 

well as I've said above I thought pressure at titan's surface was about the same as being in 20ft of water here on earth. But you'd sure need a temperature suit or presumably you'd freeze solid in seconds

You could fly on titan under your own muscle power much like that old guys who tried to use artificial wings on earth except it would work on titan.

 

You might be able to swim in the critical fluid CO2 at the surface of Venus, it's supposed to be dense enough to be comparable to liquid water..

thanks xxx

I think you confuse pressure and density.

good point

 

Indeed. Pressure is not the same thing as density, the latter of which accounts for buoyancy. The pressure on the surface of Titan is about ~1.5 atm, which is pretty much what you'd experience in ~20 ft. of water like the OP says. However the density of Titan's atmosphere is ~4x the density of Earth's, meaning it's only ~0.5% the density of water. That means the average person would experience a buoyant force of ~0.75 lb., which is completely negligible. You'd sink like a rock, just like on Earth!

i ain't got the mathematical knowledge to follow but im sure you're right. ye it's the difference between pressure and density. cheerz

Buoyancy works because of the balance between your weight and the weight of the volume of fluid you are displacing. If the weight of the fluid you displace is more than your weight, you float, if it is less, you sink. The fact that Titan's gravity is 10% of Earth's doesn't come into play because it effects both your weight and the weight of the fluid you displace equally. So instead we do a density comparison. At 1.5 atm, and 93.7K, Nitrogen has a density of ~5.6g/liter. Human's have a density of ~1000g/liter(being mostly water). So, as we can see, the weight of a human would be many times more than the atmosphere it displaces on Titan and he would not be buoyant enough to swim. The buoyancy of Titan's atmosphere would only be ~4 times greater than that of the surface buoyancy of the Earth's atmosphere.

thanks. im a newbie at all this but wanna be a scientist one day

Lack of buoyancy due to the low density of the air would men that you would still drop to the ground.

On the contrary, as I said the literature Ive read says the atmosphere is denser than ours, it's like being in about 20 feet of water, but with 10% of our gravity. You'd float to the ground eventually, but couldn't you just 'swim' along?

I've read that the gravity of Titan at the surface is about 10% that of Earth. Plus I worked out that the atmospheric pressure at the surface would be like being in about 20ft of water here on earth. So explorers wouldnt need a pressure suit (altho they'd sure need an oxygen and temperature suit!)

So presumably human explorers would be able to 'swim' along through Titan's atmosphere at the surface? Have I got this right?

GIAN

Is there a way we can estimate light (lux) levels in broad daylight on Titan? eg would it be like a cloudy day here on Earth, dusk or no more light than with a full moon?

Would the clouds be thin enough for an astronaut to see Saturn? Do the clouds ever part to give a clear sky? I've heard the sky would be orange with green methane rain. Would it always be foggy or could we see long distances?

I'm an art student and I want to do a landscape painting of the surface of Titan

cheerz

Gian x

Sexual reproduction, in the sense of exchange of genetic information between individuals with different code and using it to creating progeny with novel code, is found in almost all taxa at some stage of their life cycles or ecological reponses - it clearly has value even to organisms capable of reproducing without it.

 

There are many obligate sexual reproducers, especially in large organisms with longer life spans whose progeny are likely to face an accumulation of specifically adapted disease threats amid environments depleted or otherwise altered on a comparatively large scale over time by their large and long lived parent(s). There are very few obligate parthenogenetic organisms - one take is that an obligate clone producer will eventually produce progeny surrounded by specifically adapted enemies and specifically used up resource pools, in direct and specific competition with their parent without the parent's acquired defenses. The sequence of clones runs the genetic pool into a cul de sac of a disappearing niche with no exit, so to speak, and their advantage in numbers is obviated by their shared vulnerabiiities. This take is supported by the observation that many normally cloning organisms switch to sex when stressed and threatened.

 

Another take: one of the functions of sex is to vet and possibly repair the proposed string of progeny code before investing parental resources in it - reproduced code usually contains errors, and a series of clones suffers generations of accumulated copy mistakes. Sexual recombination can reveal and discard the worst of them immediately, before parental resources are wasted in attempted nurturing or development (the code has to successfully match the partner's, and function at least well enough to carry out the combination procedure, to produce progeny). The sexual combination can also replace or cover for bad stretches of code (the two combinitorial genomes are unlikely to have the same errors). Supporting this take is the observation that many incipient fertilizations fail in sexual reproducers, and cloning organisms such as bacteria in test tubes tend to produce noticeable percentages of crippled offspring, again partially obviating the numerical advantage of cloning's efficiency.

 

just a couple of thoughts.

Thanks. Will have to follow this one up

GIAN

PS any replies please keep as simple as possible. I aint a scientist (yet!)

GIAN

There may already be an answer here to this question, still looking through all the topics.

Why is there male and female, and why is there sexual reproduction? Presumably there must have been some evolutionary advantage over asexual organisms. Any ideas what those advantages may be?

thanks

GIAN

Selection does take that long. I wasn't arguing that inheritance doesn't happen, but using one individual doesn't mean selection is happening. Even if you have children who were equally quick to aggression you have to take into account the frequency of aggressiveness vs. non-aggressiveness in the entire population, not in a single family.

How do you not talk about societal/political dislike of homosexuals when you haven't showed evidence that there is any other kind?

I don't have any firm evidence that a repulsion about gay sex is endogenous I'm just thinking about it, that's why I originally put the question.

In the video clip I entered above some football players are asked about what they feel about gay sex and I felt their repsonses were somehow more fundamental and endogenous than something learned. This is something Ive seen myself. Still thinking about it and reading all the stuff people have posted. Cheerz

GIAN

I despise that thumbnail image. Could you at least

next time? Those types of links are an option in the advanced editor.

 

---

 

Does there have to be a dichotomy between endogeny and learning?

Thanks for the feedback still reading through it.

I don't like the image either, didnt know there was a way of concealing it.

I agree I don't know if the nature/nurture debate which comes up in so many different contexts is really very useful. The're all one and the same -except that alot of people treat the 'nurture' bit as a sort of behavioural problem. The gay guy talking to the footballers in the clip seemed to think they were just eing unintelligent. I think it's a bit more fundamental than that. But still reading through all your stuff and links

GIAN

Something to consider: the most common number one fear of young men as self-reported in research surveys is being perceived to be gay. The easiest way for someone who is afraid of being seen as gay to "prove" they aren't is to act visibly disgusted at homosexual acts.

 

This doesn't mean that anyone who says they are disgusted or acts disgusted definitely isn't disgusted, nor does it mean that they are really gay, but it does mean that it's fairly likely that any show of disgust is going to be somewhat exaggerated from the true reaction of the person in a significant percentage of people simply because it's how they think they're supposed to react and they don't want the social stigma involved in people thinking they weren't disgusted enough, which does still exist in a lot of places even as wider acceptance of homosexuality has come about.

what really started me thinking about this topic was this;

I don't think these lads are afraid of being gay, or seen as such, nor do I think this is a learnt dislike. i think what they feel is endogenous.

 

Since homosexuality was, and still is, strongly repressed in many areas of society the idea that homophobia would undergo such strong selective pressures in such a short amount of time is extremely far fetched. Also, one would need to explain why male homosexuals are hated on a far greater scale than female homosexuals, as well as why homophobia is a predominantly male trait.

 

 

 

Well I don't know about such selection taking that long; I have personality traits which Im told I got from my grandad who dies b4 i was born; and I suppose if my gf were equally quick to aggression our kids would grow up violent! And I think most people would agree personality traits are very visible from generation to generation.

I emphasise again the societal/ political dislike of homosexuals is not what im talking about, i'm talking about phobia in the true sense of the word, an irrational aversion to gay sex the way some people are averse to spiders. I dont think that homosex-phobia, and the homophobia most people mean are the same thing. I know people who are totally gay-friendly, but if they were to see say gay porn go 'euuuggh!!!' (Personally it doesn't bother me in the slightest, dunno why, but it does bother alotta my mates.)

Thanks for the reference I'll check it out later

GIAN

Well you're creating a false dichotomy of homosexuality and reproduction, and of homosexuality and heterosexuality. There is no reason to assume that some levels of homosexual behavior would not convey a selective advantage or be selectively neutral. Those traits can could epistatically cause "pure" homosexuality (meaning total aversion to heterosexual behavior) which may cause selective disadvantage. But since the alleles can 'hide' in the population due to total aversion needed specific allelic combinations.

Perhaps not, but people at the time may have thought of them as such.

Eg if we went back to a town in say 12th century France, women may have felt (unconsciously) 'men who are averse to homosexuality are better than men who arent so I want that sort of man more.' This trait if it is genetic/enogenous may be advantageous economically and/or be part and parcel of lots of other traits conducive to social and economic prosperity and thus better survival.

So such men reproduce and survive just that bit better. The reality is immaterial; it's the way people in the said village may have seen it which would influence outcomes.

However, if such an aversion is no longer considered in today's society, homoerotic-phobia (aversion to the sight or idea of gay sex) I suppose may eventually breed itself out.

GIAN

Why do you think that makes it relevant to the thread topic? Your personal obsessions may indeed be widely shared in your culture or among your subgroup of it, but this thread is in an Evolutionary, Morphology, and Exobiology subforum.

 

We are attempting to discuss the nature and implications of a hypothetical genetic basis for homophobia - whether you think your own evident and quite convincingly described involuntary disgust at your culturally mediated perception of indications of your culture's stereoptypical homosexual orientation is "normal" for a member of your culture is a long way from evolutionary concerns, and you have not provided us with much of a map for the connections.

 

 

Mechanism, please.

 

It's just as likely on guesswork grounds that we would reproduce better - or at least more prolifically and/or successfully under ordinary evolutionary circumstances - in the absence of homophobia.

 

Sequestering breeding-age women in relationships with unenthusiastic sexual partners, depriving children of the extra protection and resources of related adult men with no children of their own, reducing the pool of unencumbered adult men available to step in upon untimely deaths of parents or step up to meet hazards without as directly risking children's welfare, and so forth, would be damaging to reproduction - yes?

 

And that objection grants the unsupported hypothesis that homophobia increases the prevalence of heterosexual activity in human males.

 

The notion that taking a moderate (less than, say, 80) percentage of adult males out of a human breeding pool reduces the baseline reproductive potential of that population overall is without support in theory or in evidence, as far as I know. When biologists calculate the basic reproductive potential of populations with large mammal biology, they usually don't even count the males. In the US after the Civil War areas that had lost 2/3 of their breeding age males (corresponding to an exclusive homosexuality rate of over 60%) saw normal reproductinve rates, regardless - the percentage of non-breeding women was essentially unchanged once the violence of war had ended.

 

Reproduction in beings like us is seldom if ever limited by a shortage of willing males.

well i don't know, but i would have thought that more aversion to homosexuality would mean more potential reproduction. But of course it may not just be reproduction itself. Certainly there was a shortage of eligible men around for several years after WW1 although Im not clear how that affected reproduction levels

However it may be what is SEEN to be better potential reproductivene potential rather than what is ACTUALLY reproductive potential. Men with what was thought to be an aversion to homosexuality would have been seen as better potential breeding stock by society in, say, the early middles ages, or in the prehistoric whatever the actual reality. (In those days for example it was believed that older men were incapable of fathering healthy children.)

Thus natural selection of men who by a natural quirk were particularly averse to homosexuality -and seen to be- would cause them to survive that much better and so reproduce better, and thus become more dominant.

Feedback any1?

GIAN

 

 

To address a side issue, I just looked up some terminology for varying types of homophobia.

 

We need to keep in mind that "homophobia" is discussed in two different ways in the literature. #1 involves an irrational discomfort or anxiety around homosexuals, and #2 involves something more like a rationalized dislike. In addition, this thread seems to have introduced a narrower third definition, one involving a disgust in the presence of homosexual sexual behaviors.

I suggest that we call #2 heterosexism or sexual prejudice.

I suggest that we call #3 homoerotophobia, as #3 seems to align well with Wainwright's intended use of the term (Girshick 32-33).

Yes I agree. What is commonly called homophobia is anything but an irrational fear, it's usually very calculated and socially constructed.

My gf's mum is an arachnophobe. It's not that she hates spiders personally or goes on demos saying 'send spiders home.' But she screams and would probably jump through the window if a spider scuttles across the floor despite knowing the spider is probably far more scared of her than she is of it.

1. We have not quantified the extent (intensity, duration, and range[i.e.total numbers]) of aversion felt by some heterosexual men to gay sex. We have not established what percentage of that aversion may be concealing a suppressed homosexuality. Without these numbers it is impossible to tell whether this expressed aversion is a chance fluctutation, with no evolutionary significan whatsoever.

 

2. While the genetic element of homosexuality seems well established I continue to be puzzled by what may have been extensive homosexual practices in the Greek city states. So, contrary to consensus opinion and misapplied political correctness, I strongly suspect a cultural aspect to the inclination. And then, on the other hand, there are the bonobos. Since we cannot say with clarity why the gay trait arises, it is even more difficult to say what benefit a reaction to it would constitute.

 

3. Perhaps the simplest explanation is the best. If males were not averse to it our reproductive rates would fall.

 

 

Re- what you have described as "so much aggravation". Remember that this is a discussion forum. Your question has generated a boat load of discussion. Ultimately these threads are not about the OP or their question, but about the rough and tumble of debate it generates.

Thanks for a sensible answer.

I agree; if there were not that aversion yes we wouldnt reproduce so well. So it does imply something endogenous. If that's accurate, people should not dismiss aversion to gay sex as 'hate' not those who feel it as 'queer bashers.' As people often say about gays, homosex-phobes can't awlays help it.

Anyone knows of any research I'd be grateful. Cheers GIAN x x x x

Id no idea my simple question was going to generate such aggravation. Can we get back to the original point please? with the proviso that a phobia is NOT ( as far as I know) 'hate' -like racism- which is personal A phobia is an irrational aversion. Eg I know of no racist who has a phobia of ethnic difference, it is all nurtured

I just wondered if the irrational aversion to gay sex - and i emphasise gay sex not homosexuality per se- by some straight men (many of whom are not actually gay-haters and may be well disposed) has some darwinian-style survival advantage deep within us.

replies concise and to the point please. it's gonna take me weeks to read all the above.

GIAN x x x

With natural selection, it always boils down to what selection pressures they're under in that particular environment. A strategy that works in one palce may not work in another.

 

 

Sexologists have frequently made use of a technique called penile plethysmography. Here's a famous example, an experiment conducted by Adams, Wright, & Lohr, "Is Homophobia Associated With Homosexual Arousal?" I haven't read the full summary, but I've heard of the experiment.

I never considered that those results might be explained by population genetics. Such 'degaying' genes, if they exist, might appear in populations with more gay genes. However, I doubt such an hypothesis would prevail. Homophobia, in the typical sense of the word, seems to be a malleable trait that will change depending on environmental influences.

 

response to erotic imagery - - - - unchangeable, perhaps genetic

response to sexual interaction - - unchangeable, perhaps genetic

opinions about homosexuals - - malleable, probably environmental, probably not genetic

 

Of course, the fact that it's malleable doesn't mean it cannot be influenced by genetics. We are all influenced by the environment AND genetics. However, it may be a higher order phenomenon with many contributing factors, thus it may elude such simple descriptions.

 

 

Thanks for the reference, still reading it. The guys who were said to be homophobic but also aroused by homosexuality may simply be more highly sexed 'Alpha'males for whom ANY mention of sex arouses them. Plus you'd have to exclude the effect on sexual arousal of other emotions, eg fear or anger. But it may be that this is the point; maybe a potential and genetic response to homosexuality also triggers an equally genetic, endogenous response which is homophobic. Still doesn't show if homophobia is nature or nurture

For us to have evolved such an aversion to homosexuality, then wouldn't we be equally revolted by female homosexuality? I'll confess myself, I prefer not watching two men having sex with each other. But is that down to my immeasurable hatred towards gay people, or something else? And if so, can that "something else" have aided in building the social construct of homophobia?

 

Now, I don't have any numbers, but one claim I seem to hear a lot is that quite a lot of men are grossed out by homosexual male sex, while enjoying watching, for example, lesbian porn (or well, porn involving two or more women, which definitely isn't the same thing. But still!). How would you explain this in evolutionary terms? Sure, one can say that the men are still looking at female bodies, which excites us. But then, wouldn't male homosexuality just make us go "meh, whatever" instead of "kill the gays!"?

 

I've read we have also got sort of an inborn (so in this case evolved) sense of what food should look like. For example, slimy greenish/yellowish goo isn't all that appetizing. Apparently, this is due to the likeness of puss, which signifies infection and generally bad stuff. So assuming this is right, and we do have some idea of how the world works in this regard. Now, translate this to male homosexuality.

 

Is it too far-fetched to think that the strong aversion to male homosexuality is simply down to the "ick factor" of the act? After all, the homosexual male act involves putting the pee pee in the pooper. Perhaps our evolved wirings simply screams at us that "that place is dirty thus can kill you!". Not in the sense that "gay sex is wrong and God will strike you down", but simply down to the same evolved behavior that makes us not want to lick someone else's open wound.

 

Again, I really don't think there's much evidence for anything other than homophobia being a social construct. But if it isn't, I'm boldly throwing this out as some kind of alternative idea, fully expecting people to read it as me thinking homosexuality is unnatural or something (which I don't). But I'll take that risk.

 

Edit: Also, I apologize if this seems like a lengthy bit of a "personal theory". I'm just throwing it out as an attempt of an explanation, and while I'd be happy to have it criticized, I'm fully aware that I might be very wrong.

thanks

Well precisely, I think the sight of two men having anal sex may be the "euuuugh" factor we feel when we see unappetising food which is actually perfectly good to eat. That's why the guys in the clip i've indicated above react the way they do. But then the 'icky' reaction to food no doubt developed becasue it protected us from foodstuffs which may be bad for us. Similarly with homosexuality

Men being attracted to female homosexuality is different becasue it still involves heterosexual attraction to women which is what the reproductive intention of nature wants.

I don't know wether any of this is accurate, Im hoping someone can point me to some research which will indicate it either way.

 

If it were endogenous due to natural selection at the species level it would be found in the species as a whole. It isn't - there are entire geographical areas of the planet (the Pacific Islands around Papua New Guinea, regions in pre-Colombian Americas, the pre-Christian cultures around the Mediterranean, etc etc etc) in which homophobia is vanishingly rare if existent at all (it would be an individual's symptom of mental illness) and no cultures in which it is not socially constructed and closely mediated in its expression.

 

You can learn this from any elementary anthropology text, encyclopedia, decent television documentary on the topic, attention paid to the newspaper, etc.

 

That would be a possibility if homophobia improved the the reproductive capacity of the species. But it doesn't, at least not in any direct way that anyone can see.

well as far as I know we don't need to follow genetic impulses, but what Im talking about is repulsion at the actual sight of it.

This is an example of what I mean (from 03.55-06.44 and 09.33-end)

I suspect that what these rugger players are feeling at the sight of gay intimacy goes deeper than social construction. They don't seem particularly badly disposed to gay men. As the guy at 05.19 says while accepting it, the actual sight of it seems to awaken some sort of revulsion which runs v deep.

It depends on what you mean by rapidly, and I'm unsure of the examples you gave could you provide links? Things may be able to evolve relatively rapidly, the punctuated gradualism model of evolution explains processes of fairly rapid evolutionary change.Technically this isn't evolution, it's abiogenesis. Evolution only deals with things that are already alive and have a population.

These are just things ive heard, but i'll try to find some research for you