Evolution has become the major topic on this blog during the last couple of months. However, it seems that my readers who criticise it do not have a good understanding of the theory. Some of my creationist readers have the following misconceptions:
1) The theory of evolution requires that organisms must be able to predict the future in order to evolve.
2) Evolution has never been observed.
3) Evolution means that an animal of one species must give birth to an animal of a new one.
4) All mutations are harmful.
5) Evolution cannot explain bilateral symmetry.
I found the following simple introduction to evolution online and I would suggest that my creationist readers take a few minutes to read it.
How Evolution Works
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39 comments:
1) Actually, in order for the organism to evolve it does not need to be able to predict the future, it needs to be able to either alter itself on the genetic level to adjust to changes in environment, or an outside force needs to alter it. Such as what has been seen by some birds in the matter of only a few generations.
2) Macro evolution has never been observed.
3) The adjustment must be of the extent that it can be passed from one generation to another and be being done by multiples of the same species to have a lasting effect. Thus either there has to a common change being actively produced together by a group of the species, or an outside force has to be creating the change.
4) Almost all mutations are harmful. However, adaptation and adjustments to a changing environment are not necessarily.
5) I have no idea what bilateral symmetry is so i have no meaningful comment on this.
I realized about halfway through this list that you had posted a site to look at so i will have to do that now.
I'm glad you're reading it. I'll respond to what you've posted so far.
1) Actually, in order for the organism to evolve... it needs to be able to either alter itself on the genetic level to adjust to changes in environment, or an outside force needs to alter it.
There are many "outside forces" that play a role in evolution. Natural selection is just another way for saying "something killing everything which isn't suitably adapted." Also, radiation from the sun and a host of other "outside forces" cause mutations, which are essential for evolution.
2) Macro evolution has never been observed.
"Macroevolution" is a term that Creationists use to shift the goalposts. We show a species's evolution, you claim it's micro. We show speciation happening, you claim it's micro. The only way you would call it macro is if we showed you a huge leap in evolution, like ape to man, which nobody claims is possible on a short timescale. Therefore, your whole argument is a rhetorical ploy. Otherwise, you'd be satisfied by observed speciation, something I believe I've pointed you towards before.
3) The adjustment must be of the extent that it can be passed from one generation to another and be being done by multiples of the same species to have a lasting effect. Thus either there has to a common change being actively produced together by a group of the species, or an outside force has to be creating the change.
I'm not sure what you're referring to here. The "adjustment" is simply a gene. Genes are known to be passed down. Genes may be dominant or recessive. etc.
"Thus either there has to a common change being actively produced together by a group of the species..."
You only need one mutation in one individual for it to spread amongst a population. It'll take time, but you really only need to see a change once.
The term is "tautology" which I had to look up. It means explaining something by means of explaining itself. Therefore, a cat developed whiskers because of a mutation that made it more advantageous to have whiskers than not. Of course, any animals would benefit from the use of whiskers but hey, only cats had that mutation.
What you are doing is arguing backwards. We see a world that is so complex we need an explanation.
If you want to agree that evolution might be an answer you have to posit that there were zillions and zillions of sub- species that didn't develop eyes, lungs, fins, or opposable thumbs.
And where are their fossils?
What we can't find are animals in between species in the fossil record. The answer being the fossil record is not complete is a good one, even thought they've been digging up these tiny bones for the past 200 years.
And the beat goes on....
asher said: What we can't find are animals in between species in the fossil record.
Erm.... Archaeopteryx springs to mind here.... also the fossil record charting the changes from a land based mammal to the exclusively sea based whale is particularly well documented.
Google 'Transitionary Fossils'
Also, radiation from the sun and a host of other "outside forces" cause mutations, which are essential for evolution.
...which do not occur to the scale seen in birds over so quick a succession of generations as when they need to change to a changing environment.
That shows some intelligent forces at work. Either within the birds themselves, or by some outside intelligent force.
Macro evolution refers to the creation of entirely different genus' by the evolutionary process.
Micro evolution refers to a species adjusting to changes in the environment.
The only way you would call it macro is if we showed you a huge leap in evolution, like ape to man, which nobody claims is possible on a short timescale. Therefore, your whole argument is a rhetorical ploy.
Excuse me, you misrepresent myself and others here by saying that we say that evolution has never been observed. Then you turn around and criticse me for correcting you which in turn nullifys your planned argument. Yet, you accuse me of a ploy. Well, when you use a ploy to make your argument i suppose it is easy to assume that others are doing the same.
The "adjustment" is simply a gene. Genes are known to be passed down. Genes may be dominant or recessive. etc.
Correct, but to occur to the scale seen in birds at times and over so few of generations it becomes necessary for large numbers of the population to have the same gene adjustments that haven't been passed down. Which again points to changes that the birds are doing to themselves on a genetic level, or an outside force unrepresented by merely "natural" occurances.
Of course, any animals would benefit from the use of whiskers but hey, only cats had that mutation.
Exactly! If there were a designer, you'd expect more animals to have whiskers because they're useful. If it were due to random mutation and natural selection, you'd expect them only in some related creatures.
As for the missing links, be serious. The fossil record could only be complete if we had hundreds of thousands of fossils at neat intervals going back millions of years. There just aren't enough fossils. However, there are many so-called "missing links" fossils, like the ones between ape and human, reptile and amphibian, etc.
I'm still reading the article but this jumped out at me:
"As mutations occur, natural selection decides which mutations will live on and which ones will die out. If the mutation is harmful, the mutated organism has a much decreased chance of surviving and reproducing. If the mutation is beneficial, the mutated organism survives to reproduce, and the mutation gets passed on to its offspring. In this way, natural selection guides the evolutionary process to incorporate only the good mutations into the species, and expunge the bad mutations.
If this is true, why are there so many common birth defects like Down's Syndrome and retardation? According to natural selection, these defects should stop occuring as our ever evolving gene pools would select for these mutations to not be "beneficial" right? We would be seeing a steady decrease in the instances of these mutations, since they have been occuring since our earliest records of human history. For that matter--you can throw blindness and deafness in there too as those are not beneficial for optimum "survival".
If this is true, why are there so many common birth defects like Down's Syndrome and retardation? According to natural selection, these defects should stop occuring as our ever evolving gene pools would select for these mutations to not be "beneficial" right?
Because Down's syndrome is directly caused by a mutation of the egg or fetus (I don't remember which,) not by a mutation from a previous generation. If people with Down's syndrome regularly reproduced successfully, then it would be passed down, but they (as far as I know) do not. The rate of mutation is constant except for things like pollution and radiation, so there should be as many babies born with Down's syndrome as there ever were.
Natural selection does not affect the rate of mutation. It just kills organisms (or keeps them from reproducing) with the "bad" ones, where "bad" is defined as "the ones that keep organisms from successfully living and reproducing."
"If this is true, why are there so many common birth defects like Down's Syndrome and retardation?"
Sadie: These mutations are only common because of modern civilization. Because humans can and do save "the weak". If the Eugenicists had their way in the 19th century, there would be restrictions on the ability for those with certain defects to reproduce - thereby making the mutations that much more rare. Also, remember to talk about such things in per capita terms. There are something like 4 billion people on the planet. Out of those 4 billion, if a mutation happens to 1 million people, that's still only .025% of the population. That would be considered statistically rare.
If the mutation is beneficial, the mutated organism survives to reproduce, and the mutation gets passed on to its offspring.
That's what the definition of Natural Selection stated. With that being said, this definition does not explain why mutations are still being passed on to the offspring. Natural Selection does not explain dwarfism and the like. If a "small person" and a normal person get married, as they often do, they have a 50% chance of passing the mutation on to their offspring. According to Natrual Selection, that shouldn't happen.
Taken from a non profit Down's website:
The low points in Landgren's day come when she has to tell a couple that their unborn child carries a genetic abnormality. The high points come when further testing disproves the first results or when a fetus thrives in spite of problems.
In either case, Landgren is there to listen, inform and offer options.
"My principal role is to help patients understand the implications of genetic disease in their families," she said. "I help them understand what this means in terms of other family members and the reproductive options they have."
I'm convinced that Natural Selection is a weak theory. This shouldn't still be happening to our babies if Natural Selection was a working, functional way of life. Also, here's a question:
Why do infants need love and affection and skin to skin contact, to thrive? If evolution were true, this need for love and affection would be eliminated. As it is, infants that are in Romanian orphanages do not develop properly and sometimes die. They have food and water and the bare essentials but because they barely leave their crib and are not loved--they don't thrive. This doesn't sound like an evolutionary characteristic, the animal kingdom does not share this trait--
Down's syndrome in it's most common form is a primary nondisjunction, that is, of the four chromosomes present during miosis, instead of splitting into two sets of two, you get one with three and one with one. It is called trisomy 21, becuase the cell that contains the three chromosomes of chromosome 21 codes for the disease. There is no specific place on any gene that codes for the common form of Down's, it is the presence of three normal genes instead of two that causes the observed phenotype.
There are other trisomies, like Patua's syndrome, in which other chromosomes undergo a primary nondisjunction during sexual cell division.
With that being said, this definition does not explain why mutations are still being passed on to the offspring.
You ignored the statistics and that is highly significant. Natural selection doesn't say that things will not happen, it suggests that those that are not best suited for life will be phased out, or in the definition below they will be eliminated
"The process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated."
Next point
Why do infants need love and affection and skin to skin contact, to thrive? If evolution were true, this need for love and affection would be eliminated. As it is, infants that are in Romanian orphanages do not develop properly and sometimes die.
Here is why this is weak. The need for love and affection is not something that will kill an infant. It may emotionally stunt their growth, but it will not kill them.
The evolutionary question here is different from the way that you present it.
That's what the definition of Natural Selection stated. With that being said, this definition does not explain why mutations are still being passed on to the offspring. Natural Selection does not explain dwarfism and the like. If a "small person" and a normal person get married, as they often do, they have a 50% chance of passing the mutation on to their offspring. According to Natrual Selection, that shouldn't happen.
Why not? As long as nothing is out there killing dwarves, there's no natural selection against it. We should expect there to be more dwarves now than there were in the past because they're more likely to live and reproduce now.
Down's Syndrome isn't the kind of genetic disease you think it is. As the other posters have pointed out, it's not the result of inheriting a mutated gene, but rather a result of error in chromosome division.
As for babies requiring love, it was a tradeoff. Other animals have babies much more capable - able to walk around almost immediately. However, human babies have to be born so early in their development because their brains are so big. If they developed any more in utero, they wouldn't be able to get out of the womb. "Head circumference at birth is approximately 13-15 in. (33-38 cm) and by 12 months usually increases to approximately to 16-19 in. (41-47 cm). The rate of head circumference growth slows after 12 months."
Human babies are basically born premature (and therefore needing much more attention) as a tradeoff for having disproportionately larger brains.
Natural selection doesn't say that things will not happen, it suggests that those that are not best suited for life will be phased out, or in the definition below they will be eliminated
blindness is not best suited for life. Deafness is not best suited for life. Asthma is not best suited for life. And while a lack of love and affection does not "emotionally" stunt their growth. It stunts their growth period. It's called "a failure to thrive" and babies die of it in Romania and third world countries. Look it up, that's all I ask. I look up evolution stuff all the time, the least you guys can do is humor me.
"Nothing says "love" like a child's smile! In Tutova, you can help feed and care for babies who arrive at the "failure-to-thrive ward" shortly after birth. Each day, volunteers stimulate, love and nurture them in a way a parent would. Just playing with these children will make a huge difference in their lives."--from a Romanian volunteer clinic
As for babies requiring love, it was a tradeoff. Other animals have babies much more capable - able to walk around almost immediately. However, human babies have to be born so early in their development because their brains are so big. If they developed any more in utero, they wouldn't be able to get out of the womb. "Head circumference at birth is approximately 13-15 in. (33-38 cm) and by 12 months usually increases to approximately to 16-19 in. (41-47 cm). The rate of head circumference growth slows after 12 months."
then why doesn't evolution fix that? Why don't our bodies change to accomidate? It would benefit the babies to be less dependent at birth...
And while a lack of love and affection does not "emotionally" stunt their growth. It stunts their growth period. It's called "a failure to thrive" and babies die of it in Romania and third world countries. Look it up, that's all I ask.
I'm aware of this phenomenon. You're expecting too much out of natural selection. The need of babies for love wasn't weeded out because babies who didn't receive love probably didn't receive milk and died, so whether or not they thrived without attention wasn't relevant to their survival. It's not like prehistoric man had nurseries with formula for dozens of orphans.
then why doesn't evolution fix that? Why don't our bodies change to accomidate? It would benefit the babies to be less dependent at birth...
Unlike a designer, evolution can't step back, observe the situation, and come up with the best solution. Sometimes you get weird ones, like the optic nerve going through our retina or us having appendices or wisdom teeth or tail-bones. Evolutionarily speaking, it's probably easier to have 4 surviving children if you can have one a year and take good care of it than if you have to be pregnant for 2 years but have stronger babies.
Evolution is not directed. It's not trying to come up with the best solution. It's just certain things surviving and others dying.
I'm not convinced. I get hung up on the Natural Selection theory. I mean, why do we have two kidneys if we really only need one? A back up? Like you said, evolution can't step back and see a need for a second one "just in case". I see a designer who knows we could give each other our spare kidney and that it would be a great testament to compassion and ultimately--glory to God.
I also see other smart animals--like Dolphins--exibiting acts of love.
If natural selection were a reality--love wouldn't be a key to helathy, optimal survival.
I mean, why do we have two kidneys if we really only need one? A back up?
Why not? Our ancestors would have been susceptiple not only to injury, but to disease as well.
Evolution doesn't need to "see" that two are better than one. Making two of something isn't much harder than making one of it from a genetic standpoint. Look at the mutation which gives you an extra finger. Once an organism -- and it's descendants -- had two kidneys, they would have been more likely to survive attacks, illness, and poison. (The kidneys filter toxins.)
If natural selection were a reality--love wouldn't be a key to helathy, optimal survival.
Why not? Isn't it easier for animals to survive in a group than individually? Love forms the bonds that hold us together. It makes the mother look after her children and the children stay close to the mother. It makes people defend each other from wolves. It encourages the father stay with the mother to protect the young. It (usually!) keeps brother from murdering brother, which helps your genes thrive, since your brother shares some genes with you.
re: fossils
Consider what happens to anything that dies. Predation, biochemical breakdown,erosion, etc., and so forth. I buried a dead cat in my back yard last year. It's completely consumed by nature now. Gone.
That we have any fossil record at all is nothing short of a miracle (I don't like the word, but it conveys the feeling here.)
Also, skeletal remains only show us a limited number of characteristics. Skin color, hair, internal organ structure,or feathers could be vary between fossils of similar structure and be intermediates.
Kol Tuv
re: If natural selection were a reality--love wouldn't be a key to healthy, optimal survival.
Love is a chemical reaction associated with feelings of pleasure and safety. In an evolutionary sense, love is hard wired into our physiology, allowing us to form the social bonds that ensured our survival. Hormones and pheromones play a role as well, and all without our being aware of their influence.
Many animals display this sort chemical love and bonding. What separates human love from primate love is that we THINK about it.
kol tuv
(Sorry, I forgot to say this before.)
The most important factor in Evolution is LUCK. The right/wrong place, the right/wrong time, the right/wrong mating, and the right/wrong gene sequence. None these factors are within the control of the organism at any point in it's life.
Luck is something that many people cannot accept. This does not mean to imply there is no cause and effect process, only that nothing is guiding it. It unfolds at it happens.
"Evolution is where genetic predisposition meets environmental challenge." (T. Dobzhansky)
Many animals display this sort chemical love and bonding. What separates human love from primate love is that we THINK about it.
I wouldn't say many animals. I'd say it is a very select few that display acts of true, real love. We can watch movies like The March of the Penguins and get all emotional because the animals look like they "love" each other but it isn't anything like a human being's love for another human being.
I guess we're getting off track here, JA. Sorry about that. I just want to say that I appreciate the tone of these comments, for the most part, and the mutual respect.
We can watch movies like The March of the Penguins and get all emotional because the animals look like they "love" each other but it isn't anything like a human being's love for another human being.
Granted those penguins only are "faithful" for a single mating season, but how do you know from the outside how different it is for them?
I guess we're getting off track here, JA. Sorry about that. I just want to say that I appreciate the tone of these comments, for the most part, and the mutual respect.
Not off track at all. All of your questions have been important questions about evolution.
And as for the tone, no problem. ;)
This was from the Discovery Channel's Website:
Highs and lows
Joy is an emotion that's shared by many animals and is expressed freely and unambiguously. Dolphins chuckle when they're happy. When Shirley and Jenny, two female elephants, were introduced to each other at the Elephant Sanctuary in Hohenwald, Tennessee, both got very emotional, roaring loudly, touching one another and remaining in close contact, as if they were old friends - and they were, but no one else realised at the time. It turned out that Shirley and Jenny had lived in the same circus 22 years earlier, when Jenny was just eight years old and Shirley was thirty. Since being reunited, they rarely leave each other's sides and are clearly very happy to be back together.
Then there's anger. In Tezpur, India, a troop of about 100 rhesus monkeys brought traffic to a halt after a baby monkey was hit by a car. The monkeys encircled the infant - who lay in the road, his hind legs crushed - and blocked all traffic. A government official reported that the monkeys were angry, and a local shopkeeper said: "It was very emotional... some of [the monkeys] massaged [the infant's] legs. Finally, they left the scene, carrying the injured baby with them."
Many animals display profound grief at the loss or absence of a close friend or loved one. Jane Goodall, who has studied chimpanzees in the wild for more than 40 years, observed Flint, a young chimpanzee, withdraw from his group, stop feeding and literally die of a broken heart after the death of his mother, Flo. Flint remained for several hours where Flo lay, then struggled on a little further, curled up and never moved again.
In the movie The March of the Penguins, a mother penguin lost her egg to the icy cold. She then tried to steal another mother's egg to adopt as her own but the other penguins wouldn't let her.
However, when the movie showed a big bird trying to attack a group of unattended baby penguins, the audience was upset that the adult penguins did nothing to stop the attack.
I find it interesting that there are definately some animals that display acts of emotion: Elephants, monkeys, dogs, etc. but I think they all pale in comparison to the depths of human emotion.
All of this still lines up with the idea of God. Why would evolution leave emotions intact? I think JA had some reasonable answers for this--but why would human require so much more than needed to survive? Humans even commit suicide over emotional situations...
then why doesn't evolution fix that? Why don't our bodies change to accomidate? It would benefit the babies to be less dependent at birth.
Evolution doesn't make radical changes overnight. So this could very well be changing right now.
Hey I think having 3 arms would be a great advantage...but hey..we would lose the symettry that is just luck
I think JA had some reasonable answers for this--but why would human require so much more than needed to survive? Humans even commit suicide over emotional situations...
How do you know that it's "more than needed to survive?" It is now, but 40,000 years ago? It was a harsh life for everybody.
I didn't want to make this discussion too complicated, but there is something else that comes into play here besides natural selection -- something called sexual selection. Basically, this is something that's obvious once you see it - that males either fight over females, in which case the males that are best at fighting each other will have more offspring, or females choose the males, in which case the most attractive males will have the most offspring. Peacocks are the most extreme example of sexual selection -- their extraordinary tails serve no practical purpose except to attract a female. The peacock tail is sort of the end of a really, really long arms race.
Anyway, maybe some of the more extreme displays of love, things that led later humans to do things like write sonnets or make dramatic gestures, arose from sexual selection in addition to natural selection.
That's right. Wouldn't asexual reproduction be more in tune with evolution? I mean, here we have to find a mate, fight for attention and then go through all that dating and pre-nup nonsence just to have sex. In fact, having two sexes is just silly. The male gets pregnant with seahorses, the male guards the penguin eggs....if it was just one sex we could do ourselves, raise our young, and not have all these divorce lawyers in between.
"male and female he created them"
Where did all those animals learn to fight among themselves in order to mate with all the females? Why not just let Al have Mary and Bert go with Sonya etc. Ah ha...it's survival instinct. They KNEW it was important that only the strong survive...that only the strong get to mate...they KNEW.
JA--
Sexual selection makes trouble for homosexuality, doesn't it?
Wouldn't asexual reproduction be more in tune with evolution?
Actually, sex makes evolution happen a lot faster because children get some random combination of their parents gene while asexually produced offspring are clones of their parents. The broader the gene pool, the easier the evolution.
Sexual selection makes trouble for homosexuality, doesn't it?
How homosexuality comes about is an interesting question. Nobody yet knows the answer, but there are some possible explanations. Perhaps, like sickle-cell anemia, having one copy of the gene (or genes -- homosexuality is probably not a single-gene charicteristic and may not be totally genetic at all but rather a result of hormonal fluctuations in utero although there is evidence that at least some of it is genetic) confers some reproductive advantage -- maybe "carriers" of the gay gene who aren't themselves gay simply do better with the ladies. Maybe they have a higher sex drive. Maybe they're better at getting along with the other males. I don't really know, to be honest, but it seems like there are some possible explanations.
JA said: How homosexuality comes about is an interesting question. Nobody yet knows the answer, but there are some possible explanations.
As announced in a recent issue of the scientific journal Cell, two neurobiologists at the Austrian Academy of Sciences made slight genetic "manipulations" in some female fruit flies, inserting the male version of one gene into the brains of these teensy creatures. They apparently hoped to create a super-strong, crime-fighting Six Million Dollar Fly, but instead ended up with k.d. lang-like female flies that act just like males during courtship: they gently tap virgin females on the legs, play songs on their wings for them, and, when that seems to go well, they lick the females in all the right places. And that, says a New York Times science writer, is "all part of standard fruit fly seduction."
Predictably, trouble started when another scientist linked the fruit fly study to fruity humans. "The whole field of the genetic roots of behavior is moved forward tremendously by this work," said Dr. Michael Weiss, chairman of the biochemistry department at Ohio's Case Western Reserve University. "Hopefully this will take the discussion about sexual preferences out of the realm of morality and put it in the realm of science," Weiss told the Times.
So.... Maybe it could be a single gene (or more likely a combination of genes to be fair).. but there does seem to be mounting evidence that it has a (large?) genetic component...
I don't deny that homosexuality might have a large genetic component but what does that have to do with proving or disproving God's providence? I think some people suggest that if homosexuality is genetic than that would mean God is against homosexuality but also that God created the gene for it, right? A perplexing double standard. Yeah--so?
God is the author of all sorts of genetic issues that lead to sin. It's a trial that He provided as a means for that person to come to lean on Him for strength and perseverence over the trial.
Alcoholism runs in my family--does that mean God has it out for me because I was born to be tempted by drunkeness?
No. It is the same with homosexuality.
I don't deny that homosexuality might have a large genetic component but what does that have to do with proving or disproving God's providence?
Who said anything about proving or disproving God's providence? We were answering your question about homosexuality and sexual selection.
I guess I was jumping the gun. *blushing* I have run up against many people that argue if God created homosexuality--how could it be a sin?
Actually I agree with you that it's not a good argument against the concept of homosexuality as sin. It's entirely possible that people are born with impulses to be pedophiles, and that's a sin by almost every definition.
I don't believe homosexuality is a sin assuming everybody involved is consenting and no damage is done to anybody, since I don't believe in victimless sin.
...and we come full circle.
:)
I don't deny that homosexuality might have a large genetic component
Why do you believe that? Is it because society tells you this? Is it because research tells you this?
Looking at the last question first. More research into the topic supports the genetic aspect of homosexuality for a reason. In the 1970's the primary professional association in the counseling field, the APA (American Psychological Association), decided to give way to political pressure and took homosexuality out of the DSM (Diagnositic & Statistical Manual), aka. the guidebook on disorders. It stated that homosexuality is genetic in nature and thus could not be changed (severe problems and abuses in the field of "conversion therapy" had spurred this on). Since then, if any research journal wanted APA approval or acceptance they could not print any articles that supported environmental aspects of homosexuality, or that showed that homosexuals could change. No research that supported anything other than what the APA wanted could be presented in any APA sponsored conferences. Thus organizations such as NARTH (National Association for Research and Therapy of Homosexuality) were all but shut out of the field by the APA. As a result you will find almost no research that supports anything but the APA view in the mainstream research.
Also, since the media has been almost entirely liberal until just recently, this is a view that has been pushed onto the American population as a whole as well.
So since the mainstream research organizations have supported a view based not out of research or science but out of politics, and have thus produced research fitting those results. And since the mainstream media has pushed a liberal view of the topic. Ultimately it has created this idea that homosexuality is almost entirely genetic and anyone who disagrees with this is some sort of idiot or fool.
As a disclaimer, all of this information is a couple of years old and the APA may have changed it's stance on this since late 2003. However, knowing the APA, and since their ethical standards guide has not changed to regards to this, i'd say that it's pretty good assumption that it has not changed.
There is a difference between something determined by genetics and something influenced by genetics. One way to separate the two is by studying identical twins.
According to studies (http://www.worldpolicy.org/globalrights/sexorient/twins.html) only 50% of the time (roughly) are the identical siblings of gay men and women themselves gay.
This means that while genetics may predispose someone to homosexuality, it is by no means the sole determinant of sexual preference.
Gender, which is 99.9% determined by genetics alone stands in stark contrast.
Now, this does not mean that homosexuality is voluntary - environmental factors may strongly shape sexuality in ways that we do not yet understand.
And speaking of suppressed research - just the opposite thing happened in the world of zoology, where the vast amount of homosexuality that occurs in animals was suppressed for years and is only now coming to light.
http://news.nationalgeographic.com/news/2004/07/0722_040722_gayanimal.html
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