Of course they do. To the extent that genes make you anything in particular, though the role of genetics in human behavior is pretty limited.
You’ve probably heard about the newly reported research in which a genetic link was found to homosexuality in a study of gay brothers. Kelly Servick has a good writeup on it here. The study looked at 409 pairs of gay brothers, and found a region on the X chromosome that was similar across the sample. This sort of shotgun approach, comparing a trait (in this case, gayness) with a bunch of DNA (I oversimplify) is very likely to get results that look real but are the result of random association. But, it is also possible to find real links. I am agnostic as to whether or not this study found something interesting. But I do have a few remarks to make about how you get to be gay.
Consider the following list of things:
<li>Sexual attraction (to whom you are attracted)</li>
<li>Erotic response (what is erotic, including physically, to you)</li>
<li>Attachment (with whom to you seek attachment, and of what kind)</li>
<li>Sex drive (do you have it and where is it driving too?)</li>
<li>Society norms (especially for your subset of society)</li>
<li>The details of social norms, i.e., what categories of sexual orientation exist around you.</li>
<li>Your relationship to social norms (your comfort level ... do you seek "normalcy" or prefer something else?)</li>
<li>Whom you know or encounter and where they are with all of the above things.</li>
<li>And many more things that ultimately may relate to sexual orientation.</li>
This list can be written in many different ways, and every item on this list really represents a number of other sub items. These things are not mutually exclusive and the list is not exhaustive of that which relates to sexual orientation. Feel free to provide your own lists in the comments, if you like.
Many, most, maybe all of these things have individual ontogenies for any individual. The ontogenies may start before birth. We are bathed (or not) in various maternal hormones in utero. We are bathed in our own hormones in utero. The effects the hormones have depend on the relationship between the amount of hormone and the abundance and distribution of receptor sites, and on the timing. The abundance and distribution of receptor sites itself is probably influenced by the process. It is very complicated. Differences between one individual and another may related to external or non-genetic factors. In fact that may be very common.
Hormonal effects and interactions continue after birth. Again, timing, relationships between kinds and relative amounts of hormones, and receptor sites, still apply. Causes may be numerous.
The above only applies to that related to hormonal changes, which may affect a number of somatic (body related) features including brain features.
Then there are the non-hormonal factors, including cultural and social ones. Again there are complexities to the ontogeny of an individual with respect to these factors. And, these complexities are dynamic; culture and society can change right underneath you. And the non hormonal and hormonal factors may interact.
Much of this can be thought of as a process of negotiation. One negotiates internally, one negotiates with one’s social groups, one negotiates with society, culture, even the law.
Here is a simplified model linking the DNA identified in this study to homosexuality. Various switches are turned on or off, buttons pressed or not, during a person’s development. They do everything in some individuals to “make a person be gay.” But there is one element missing. If you have the DNA profile associated with the sample of 409 brothers, you get to be gay. If not, you probably won’t be. But, the “yes-no” value (reminder: oversimplifying here) found in this DNA actually has another purpose. It has to do with how many hairs you have on the back of your hand. The variation across men in hand hair is accounted for by variation in these genes. But in some individuals (but not all) it also happens to be the final ontogenetic link in the chain to a particular sexual orientation that in the sociocultural context that the 409 pairs of men live in results in gayosity. In another society, another culture, at another time, it results in being more likely to be a blacksmith than a farmer.
Note: That was a made up example. But in the absence of a biologically, developmentally, sensible link between some DNA and a trait, we can certainly carry out amusing and instructive thought experiments.
This complexity of links between causes and effects is probably true for the vast majority of variation found in human behavioral traits. Not this exactly, but something like this. The steps involved can be characterized in a certain way with respect to a trait under study, but all or most of those steps actually relate as well to other things. Also, some of those steps might have multiple causes. A particular manifestation of sexual or erotic attachment may arise in one person for one reason, in a different person for a different reason. In other words, the list I provide above can take many forms, not just because I’m being vague about what is in the list. The list can simply be different for different people who end up with the same “trait” as we happen to define the trait for the moment.
There is a reason for this vague connection, or in many cases, lack of connection, between inherited genes and behavior. A strong link between genetics and behavior has been shown to be very highly adaptive in some organisms. Here’s an old example. In a particular species of fruit fly, the larvae have a gene with two alleles. One allele causes the larvae to forage tightly in space, making a lot of turns in its search for food. The other allele causes the larvae to forage widely, to make few turns, and cover a larger area. Each allele is adaptive in a particular context and the fruit fly species has diversity at this locus. So, the fruit fly female mates with multiple males, produces a diverse batch of offspring, and the ones with a particular pattern of alleles at that locus have higher fitness. For now. In a different environment, maybe a few generations later (as the orange juice they are feeding on changes its characteristics as it rots in that glass you left on your desk) the genetic arrangement with the higher fitness changes.
But, humans are different. Humans are like the fruit fly, needing different traits at different times, but instead of those traits being programmed by genes, they are learned. Added on to the individual by enculturation.
This applies to some extent to all mammals because mammals have brains that matter to behavior. It applies very much so to primates, especially apes, and even more to humans. We have diversity in behavior, but we get it from our cultures. We learn to be a functioning adult; it is not pre-programmed. There probably are some pre-programmed behavioral features, but those are the features that would generally apply. But even those may be largely divorced from genetic inheritance on the grounds that behavior generally does not emerge from genes coding for neural structures. Genes in humans can’t code for neural structures at the level of the cerebrum, because of the way cerebrum develops, and that is where most of the relevant behaviors exist.
We can be pretty sure this is the case because of the huge cost we pay for it. Childhood. Childhood may be the most important human adaptation, and it may be the most costly. Human females can die in childbirth. That is nearly unheard of among mammals, outside of humans and our domestic stock. The babies can die in childbirth as well. That is because of our oversized brainy heads. Human babies are born helpless and spend several years nearly killing themselves at an alarmingly high frequency, and only survive childhood because of the adult humans taking care of them (or in some cases, wolves or ocelots, I suppose). This is costly to the adults. It limits reproductive output in the adults. Childhood also limits the reproductive output of the child, because it extend the time before reproduction, and decreases the chance of survival until reproduction.
Childhood, a brain that learns, the heavy reliance on the things the brain learns, and the long time it takes to make all this work demands a brain that is not overly programmed genetically, and results in a species with an extraordinary characteristic found in no other species: we are a multitude.
If you look at numerous species in most mammal families, you will find a wide range of behavioral and ecological repertoire. Measure body size, sexual dimorphism, typical system of mating, food getting, diet, defense, inter and intra species competition, etc. across all of the geomyids or voles, across all the species of dogs or all the species of cats, across the antelopes, across the African forest monkeys, etc. and you’ll find many features such as those mentioned that vary very little within species, but vary greatly across them within that taxonomic group.
Then look at humans. They look more like a taxonomic family than a species. Human cultures vary in these and other features as greatly as larger mammalian taxonomic groups.
But, when you capture an infant at birth from one human group and have it raised by another group, the infant grows up with behaviors typical of the adoptive group, not its natal group. That pretty much falsifies the idea that variation in our behavior is linked to variation in our genes.
By the way, if you move new born antelope, rodents, primates, etc. between species you may get some of the same effect. Cross species adoption does result in a bit of a behavioral chimera sometimes. But, it is only possible between some species and tends to work when the interactive parts of the system happen to be aligned. A parent bird will feed mouth-gaping carp for a while if they’ve lost their mouth-gaping baby birds. Within mammals, we’d expect a fair amount of post adoptive learning across species, because, as I noted above, learning how to be typical member of your species applies to some degree to mammals in general, more so to primates, more so to apes, and vastly more so to humans. Vastly.
Imma let you get back to finding links between genes and behavior. But first, remember, culture rules.
Final note. Part of the reaction to this new research, and this has happened with all prior research on homosexuality, is in reference to the sociopolitical outcome. If you are born gay, Conservatives can’t legislate against you, but if it is a choice, you might be a criminal. That sort of thing. This is balderdash. The Nazi’s killed all those people because of their genes. Many value free choice. Some will see being born gay as being born broken. People who are born a certain way, in many sociopolitical contexts, are vilified for it. You can’t win the sociopolitical game by claiming a certain human behavior or trait is built in or choice. You win that game on its own terms. And, lately, we mostly are winning.
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Genes don’t make me gay: pizza makes me gay.
Yes, of course, but what KIND of pizza???
Thanks, Greg, for a wonderfully thought-provoking discussion! 🙂
I call BS. You start with a basic statement that is largely false, and call on cultural differences to support your thesis, but fail to note several important details.
First, genes DO have a great deal to do with behavior… our genes are why we talk, think, and have cultural information transfer across the generations. Genes are what make us homosapiens and not oak trees. Those genes do code for our brains and its structure.
Next, you misguide us by pointing to the cerebrum as the seat of behavior…. but this is not the only structure in the brain… and ALL parts of the brain are involved in producing behavior, either directly (motor control) or indirectly (perception and most importantly, by coding for what we find sexually arousing and affectionally rewarding (who and what we are attracted to and who we bond with and when and why)… Human find other humans to be sexually attractive, not oak trees (barring a very, very unusual paraphilia)… and the vast majoriy of us find the opposite sex to be far more arousing and affectionally rewarding, post puberty. That some of us find the same sex to be more arousing than the opposit, is an interesting scientific puzzle… and the final comment on social acceptability irrelevant to the paper being referenced. Some of us (at least me) do want to know just what gene variants may be at play in sexual orientation… as well as what is going on with the fraternal birth order effect… and possible random epigenetic effects.
But to lay this much emphasis on culture is to fail to recognize one central fact, it is not our cerebrum that is involved here, but more likely neural circuits in our hypothalmus, among others. Further, there are aspects to sexual orientation, co-existing behaviors, that strongly suggest that one’s sexual orientation AND other sexually dimorphic behaviors are correlated and easily observable in very young children, too young, and too stereotyped to be culturally transmitted. This essay came closer to the truth when it talked about hormones and receptors… and it is genes that code for both.
Finally, we have seen from epidemiological studies, that there appears to be recognizable causative factors, some of which appear to be weakly heiritable, others environmental (but not cultural).
All in all… this cultural discussion is a red herring and not germain to the basic question of whether certain genes and their alleles are associated with a higher probability of a male being predominately androphilic.
Kay, you are making a very fundamental error. I’ll use your first example to explain what it is.
Genes are why we talk. Well, no, if you take a proper view of evolution, the why question has a different kind of answer, but I’ll assume you mean that we would not be able to speak without genetically programmed developmental things happening. Assume for a moment that is true.
Genes could also be said to be why we have sex. Or at least, we are provided with the traits that facilitate this behavior, according to you. And, in fact, I implied that in my first statement which you strangely dismissed just before insisting it must be true (I have no idea why you did that).
Here is your error: What explains the variation. Is variation in the trait explained by variation in the genes?
In terms of talking, no. The languages we speak are not genetically programmed. In terms of our sexual orientation, this may be the same, or similar, though I strongly suspect, as I say in this post, that genetics has a much stronger role in sexual orientation than it does in whether we speak French vs. KiSwahili.
Your statement about the brain and the cerebrum totally misses, maybe I could have explained it better. But I’m pretty sure you are reaching to pretend that you don’t know what i mean there so I’ll drop it.
Yes, neural circuits in the brain outside the cerebrum probably have something to do with our sexuality. You are correct, and this post does not contradict that at all.
But no, the involvement of culture as an explanation for variation across beings in an essentially cultural species is not a red herring.
Again with the mischaracterization. The mere fact that we can talk, produce sounds, develop DIFFERENT languages, is because we have the genes that code brain structures that allow one to learn any specific language… but that language production is not from our genetic heretage as homosapiens, that evolution has differentially provided us with the tools to produce languange, is just not true. We start with our genetic, epigenetic, and celluarly machinary, and develop as humans, not as oaks.
Again, this paper was an exploration of what genes, and allelles might be contributing to just that variation in sexual orientation.
Looking back at your original essay, and your response to my comment, it appears that you are making the argument of human exceptionalism. That somehow out larger cerebrums overide any contribution to variation in brain structures that may influence sexual orientation… and that culture trumps such brain structrues. It may influence one’s expression (well duh) but does not change those underlying structures that generate the basics of sexual orientation and associated childhood behaviors that have been noted in all cultures over millenia (feminine boys becoming androphilic as adults – tomboyish girls becoming gynephilic as adults).
In animal experiments, researchers have been able to knock-out specific genes that partially code (many genes particapate, obviously) for specific sexually dimorphic behaviors, as I blogged about here:
http://sillyolme.wordpress.com/2012/12/22/etiological-conjectures/
To say that somehow humans are immune to these effects is silly.
” is because we have the genes that code brain structures that allow one to learn any specific language”
That is only part of the story. A human raised in the absence of any linguistic environment will not actually develop those structures. In the absence of the genes, you don’t get language. In the absence of the cultural environment that includes language, you don’t get language.
“Again, this paper was an exploration of what genes, and allelles might be contributing to just that variation in sexual orientation.
Yes. And they are probably onto it, as I suggest. My agnosticism about the paper specifically is because I need to evaluate it more. They are probably right.
“Looking back at your original essay, and your response to my comment, it appears that you are making the argument of human exceptionalism. ”
Yes, that is a good question. This is not human exceptionalism, it is human unique derived features. Our system of mating and related sexuality is distinct from our ape relatives. That is not exceptionalism, it is evolution.
“somehow out larger cerebrums overide any contribution to variation in brain structures that may influence sexual orientation”
This is something you’ve added to my argument.
“In animal experiments, researchers have been able to knock-out specific genes that partially code (many genes particapate, obviously)”
Yes, and in animal experiments non-genetic changes to developmental process result in changes in the animal’s sexual behavior.
I think what has happened here is that you have attributed a point of view (and quite a few details) to my argument that aren’t there, and are arguing with them.
All Things Considered did a series a few years ago following several families with gay children. Some of the families were choosing to try to “cure” their children of their sexual orientation. Other families were accepting and supportive of their children’s sexual orientation. It was a compelling series with several parts that have always stuck with me.
One key aspect I remember was how early most of these families realized their children were gay. Several mentioned they knew it from as early as 3 years old. The families were very normal in every other respect so it was clear that there was nothing about it being a learned behavior or having anything to do with their socialization. There was no capacity for these very young children to make a conscious choice to be gay. They were too young to even have a concept of what it meant.
I was left with the sense that, absolutely, being gay is just a natural, genetic trait.
The most touching stories in the series were listening to the parents who were supportive of the children. There was a story of a young boy whose mother took him to a store to purchase his first dress, which clearly brought immense joy into the child’s life.
The most tragic were those trying to alter their child’s behavior. One was a boy who had to close his eyes when he saw the color pink… because he loved the color so much. He ended up quietly stealing his sisters dolls and hiding in the closet where he could play with them where no one could find him.
Regarding this article “Do genes make you gay”.
I would like to point out that the opposite may in fact be the case. After all, if two men meet without having their genes on, then it might well be argued that these men are gay.
Nicholas
http://www.hy-ls.org/index.php/hyls/article/view/57/0.html – Dual-gender macro-chimeric tissue discordance is predicted to be a significant cause of human homosexuality and transgenderism
Brian, has there been any followup work on that?
No. I hope someone does. That’s why I outlined experiments, or at least some. There are more. Mostly big projects. Lots of NIH money. This isn’t CELL or Nature so it’s slowly getting known.
Epigenetics is a crucial science to understanding the function of genes. When a gene has epigenetic problems, it might as well have mis-spelled DNA. Without that protein, the stochastic probabilities change, and the phenotype is not as strongly, uniformly drawn into expressing primarily male or female heterosexuality.
Homosexuality has a base rate, stochastically, but when a key protein fails to amplify male hormones in utero, the number of different sexualities increases, as does the number of people who will stochastically fall into non-heterosexual, intersexual, bisexual, etc. phenotypes. http://onlinelibrary.wiley.com/doi/10.1002/bies.201300033/pdf
I am puzzled by what feels like a universal omission of known epigenetic mechanisms by genetics researchers and reporters from their thinking. PBS’ NOVA had an episode on epigenetics as far back as 2006.
(Exclusively) genetic researchers could not find one or more “gay genes”, because most often the gay genes aren’t misspelled – their punctuation is. The markers aren’t sitting on the DNA need to initiate transcription.
Some disrupted marker are inherited. Those epigenetics markers which are sex-specific will express genetic consequences with very different severity in males and females.
Epigenetics is very important, and a new enough science that many genetic researchers, who are singularly focused on their narrow niche, have sadly failed to realize that the tools and framework exist to prove:
– they have working on slightly the wrong version of their questions.
– the answers to the properly asked questions are epigenetic.
– those answers could be quickly reaped by the longtime genetic researchers.
If only they could transcend their thinking… until then, much time and many words will continue to be wasted, talking around an epigenetics blind spot.
Christian, interesting ideas. I’m not sure I’d call these “known epigenetic mechanisms” at this point, though.
Greg, omit the word “known” since my point was that epigenetics plausibly can account for much of the observed non-genetic inheritance in humans. Therefore, when epigenetics is entirely absent from the discussion, an oddly large blind spot has formed (most odd for the most avid, most relevant researchers).
I have no relevant credentials in the field of epigenetics, but I did take an on-line course last year, offered by an Australian university. The science was intense. That paper on canalization and homosexuality is challenging at my comprehension level, but following the reasoning seems very rewarding, for all the explanatory power these insights would unleash across many traits and genes currently being studied, “up the wrong tree” (apparently).
Very soon they should have epigenetic sequencing machines as fast and reliable as DNA sequencers. If, IF the science of epigenetics is approximately what it purports to be, it really only stands to reason that there should be a sudden landslide of insight, sometime soon.
There’s still time to jump on board while epigenetics is truly avant-garde; before it’s trendy and everyone wants in. Think back to what it meant to take a stand inside the early debates between Lamarckian vs. Darwinian evolution. You had to be bold, just to join in.
Until the day comes, I’ll be wondering, waiting for scientists to catch up to science.
I think epigenetics is great, and important. It will change our thinking. I’m not yet sure at what level, though. I hope the research progresses.
The author’s copy of my 2006 award-winning review is here:
The Mind’s Eyes: Human pheromones, neuroscience, and male sexual preferences http://www.sexarchive.info/BIB/kohl.htm
The journal article / book chapter followed from other published works and is based on our Hormones and Behavior review article section on the molecular epigenetics of RNA-mediated cell type differentiation in species from microbes to man.
From Fertilization to Adult Sexual Behavior http://www.hawaii.edu/PCSS/biblio/articles/1961to1999/1996-from-fertilization.html
Homosexuality serves the same role as abortion – its a form of population control.
KMFDM, I’m not sure if that was funny, obnoxious, or ignorant.
I realize my comment sounds callous but its not without logic. Controlling the population is extremely important.
I’m going to say this primitively, but here’s my instinct. Natural selection is mean, and serves to benefit the species; but that’s ancient history, and we’ve been reproducing, or not, by very different rules for many centuries.
Before society, pre-human and human evolution progressed in part by excluding people from the breeding pool, making them uninterested in competing for an opposite sex partner. That left more potential caregivers who aren’t parents to help the clan’s children, or in other ways. That benefit seems plausible enough, when you accept that natural selection is a jerk that exists to use individual organisms for interests not their own.
If non-heterosexualities can be explained by epigenetics, then that non-genetic inheritance may be passed on the future generations. The absence of those particular sex-specific epigenetic markers won’t have as much of an impact on the phenotype of an opposite sex child. Nevertheless, if the gene is inherited, the deficient epigenetic markers will also be inherited. When those pile up after a few generations of breeding, the genome that follows won’t transcribe normally or nominally.
I want to see the epigenetic data on biological children of gay people, who go on to have children themselves with either gay people, or the children of gay people.
There are epigenetic markers that have nothing to do with what sexual characteristics are expressed, but they still follow this non-genetic, sex-specific inheritance pattern. A child of opposite sex from the parent contributing the epigenetic anomaly will not be as severely affected, but the trait can appear again if the third generation’s child’s sex switches again – and if that child grows up to have children with someone who contributes their own epigenetic issues… I think that’s where we see certain conditions where the prevalence keeps rising generationally at a rate which suggests that the condition is not genetically inherited. Autism, schizophrenia and obesity may be on the rise in part because of such a scenario.
Disclaimer: It’s a very loaded topic. What do I know? I’m speculating wildly, without any credentials or a safety net. I think that’s fine, as long as my ideas are grounded in science, entertaining, and labeled so it’s clear that I speak from no position of academic authority.
“Let’s talk about Abortion”
http://www.perkel.com/politics/issues/abortion.htm
Excerpt — “The planet is overpopulated. The population keeps growing. Overpopulation is our biggest threat to this planet and will be the issue of the 21st century. The number 1 environmental issue facing mankind is overpopulation. There’s no point in talking about global warming, endangered species, the rainforests, acid rain, or other environmental problems without dealing with overpopulation first. And it seems logical to me that in looking for solutions to global population problems, the place to start is to terminate unwanted pregnancies. I am therefore for making it possible for anyone who wants an abortion to be able to get one.”
“Gay People are necessary for the balance of World Population”
http://www.comicvine.com/forums/off-topic-5/gay-people-are-necessary-for-the-balance-of-world–654320/
Gay people have babies, tho.
@18, 20, 21 KMFDM :
Yes indeed. I agree that far and vividly recall reading Paul Ehrlich make some very powerful arguments for it in his The Population Bomb’ book :
http://en.wikipedia.org/wiki/The_Population_Bomb
Powerful and good ways to encourage zero-population growth include notably empowering and educating women esp. int the Third & Developing World, reducing the influence of extreme religion and improving the quality of life and social safety nets so that parents in poor nations don’t feel they have to have huge families to be supporting them in the old age with high infant mortality rates.
Plus yes, having more acceptance of same-sex families and definitely global rights and access to abortion plus contraception helps too.
As for funny obnoxious and /or ignorant its possibly to be a mix of all those things (& more) at once. Plus it can depend on how people take it and in what mood they are and so on.
Yes, gay families can have kids too – but admittedly less and more, um, planned in general, I think, than hetrosexual families with their “accidental” pregnancies.
Christian H., I would have liked to read more of your thoughts; but, when you wrote in the initial paragraph that, “Natural selection is mean, and serves to benefit the species; but that’s ancient history, and we’ve been reproducing, or not, by very different rules for many centuries”, I knew best not to continue. You have a fundamental misunderstanding of natural selection; and, you do something that is in pretty poor taste within science- which is how you anthropomorphize a biological process. Natural selection is not mean, is does not care about how much we reproduce; it does not do these things! To say natural selection is ancient history is patently absurd; natural selection is an on-going slow-moving mechanism by which, for example, a gene mutates in a specific organism, and if that mutation turns out to be helpful for the survival and reproduction of that organism then great. I get the feeling that you think natural selection is goal-oriented? It is most certainly not something that can have goals! What about when a mutation occurs that is harmful for an organism initially; but, over time the species is able to turn the mutation into an advantage? Can we agree that at its most basic level “evolution” is simply the change in allelic frequencies among a population, over time due to selective pressures? Capiché…I would like to read the rest of your thoughts; but, I think you may need a better understanding of what you are talking about. Finally, a question: have you ever taken a formal biology course at university, where the title of the course is “Evolution”? Or are you Google taught? It does not really matter, oh wait it makes the entire difference;-) Cheers mate, Drewsky
Christian H, I read the rest of your comments; and all is forgiven. You are up-to-date on genetic research; so who cares what your credentials are! Nice writing, do you think that Kay Brown got the upper hand on the author? I kind of feel like she did kicked him while he was down when she wrote, ” it appears that you are making the argument of human exceptionalism. That somehow out larger cerebrums overide any contribution to variation in brain structures that may influence sexual orientation… and that culture trumps such brain structures.” QED, Sorry if I was rude my earlier post to you:-( -Drewsky
Drew, that’s very kind of you to say. I’m not well in control of my own rudeness, frustrated for lacking a voice in many ways, for many years.
When I sized up this article, I saw the first part where epigenetics is perhaps the last important missing in our understanding – and the rest of the article, which becomes unmoored with epigenetics explanatory power, while simultaneously seeming to me riddled with possible unjustified presumptions. Not my minefield.
Kay Brown probably explored that territory fruitfully. Truth is, I zoned out; or rather, kept my focus on the epigenetics angle.
Natural selection sure isn’t what it used to be, not the way it works on us. Might as well give them different names. Before language, culture, society there’s another kind of natural selection. Jane Goodall chimpanzee clans, genetics and epigenetics reflective of fitness in a wild, organic, human and protohuman ecosystem.
The principles aren’t the same later, and now they’re ever more different still. As we keep people alive and reproducing into advanced years, we produce increasingly epigenetically-damaged genetic lines. Or look at the ancient Indian caste system from an epigenetics point of view. The niche we now adapt to is no longer nature, but each other.
I should look for an amateurs’ forum on epigenetics specifically. I haven’t found a place where I might make a more coherent contribution. Blog comments and discussions aren’t as lasting or effective.
Chris
The principles are the same. Natural selection is a process that always works the same way. That one of the reasons it is such a powerful force.
Understanding how natural selection is the same for humans today as it was for frogs in the Eocene is how you understand what natural selection is! 🙂
Greg, you don’t understand; and I almost feel like you’re not really trying.
What is natural about selection once society enters the picture? What is natural once there are MRIs and pap smears? Natural selection, such as it now works on humans, does not have the same kind of epigenetic populations to work on, with our recent centuries of industrial toxins, radiation, older parents, accumulating epigenetic damage.
Genes don’t matter as much when you also have society and medicine and aged parental [DNA+epigenetic markers]. Natural selection “works the same way” in a very shallow sense of the phrase. The outcome is very different in a population with minimal, pre-history levels of toxins and epigenetic damage versus today’s population.
I’m no expert in terms like speciation, or concepts like homeobox genes (which I had to look up just now), but the point is, there was a progression, there were themes, a “logic” of sorts – of course, not the goal of an anthropomorphized evolution, instead try calling it a falling towards order, complexity, adapting to niches, competing against predators and prey.
I don’t know what we’re doing now, but today’s natural selection is as distant from the past, as progressive jazz is to the madrigal. Sure it’s all music, but what kind of dancers do we eventually become, when we dance to such unnatural selections?
Christian. I’m not trying? Wow. Do you know what I do for a living?
Honestly, I’m trying. I’ve been trying for decades. Made some progress.
I don’t have time to address your questions right now but I can suggest a few things I’ve written on the topic you may want to look at, and we can get back to it later.
First, some basics. Might seem too basic but really it isn’t:
http://scienceblogs.com/gregladen/2009/08/25/the-modes-of-natural-selection-1/
http://scienceblogs.com/gregladen/2009/08/25/the-three-necessary-and-suffic-2/
Then on humans specifically:
http://scienceblogs.com/gregladen/2009/08/21/falsehoods-has-evolution-stopp/
http://scienceblogs.com/gregladen/2009/08/24/humans-are-no-longer-subject-t/
Again, we can pick this up later.
Don’t we find today that education and wealth are negatively correlated with fertility?
Don’t we find Catholics and Muslims have a higher reproductive rate than Protestants and Confucians?
Do we still call this “natural” selection, when the factors that determine the changing allele frequency seem not to be particularly “natural”?
Not really. The link is quite labile. (see http://scienceblogs.com/gregladen/2009/08/31/the-poor-and-the-dark-skinned/ )
The problem here is in the presumed meaning of “natural” in “natural selection.” Instead of calling it “natural selection” call it “Darwinian selection.” Then you don’t have to worry about the word “natural”
defining what is natural vs. not is itself a problem. If one requires that that which is “natural” be only a certain set of things, and that only when these things, and not other things, can be involved to call it Natural Selection, then there are problems. Nobody uses the term that way, with the constraint on what is natural vs. not.
Artificial selection is sometimes called by people who have not thought it through an alternative to natural selection. But it is a subset of natural selection where the selecting agent involves purposeful breeding/etc by humans.
Very thought-provoking piece, think I’ll bookmark this one. And you just coin a new term with ‘gayosity’? 🙂
🙂