Heredity Beyond the Gene
nautil.us
nautil.us
Heredity can be measured via twin studies - if twins are adopted into two different families or cultures: what commonalities can we still find, beyond random variability. The goal is to take culture out of the consideration and look at the biology. (You may argue how successful this can be, but it is the goal, and it is what is meant by ‘heredity’)
It’s reasonable to expect/have learned that all heredity must come through genes - which the headline illustrates - but we are starting to explore other mechanisms for heredity.
The article makes no comment on cultural transmission, which is entirely an independent concept.
And how often does this happen? It is about as common as a sighting of the Higgs boson - and you need a large sample group. Of "identical" twins separated at birth (identical twins are not genetically identical) and sent to two culturally/class-based different families, with little contact.
The Pioneer Fund (you can read about them https://en.wikipedia.org/wiki/Pioneer_Fund ) funded studies like the Minnesota Twin Family Study, but it was found to have many deficiencies, such as what I noted. Often twins in the cohort were only raised apart for a few years and so forth.
On occasion I watch television, and see wealthy heirs like the Hilton heiresses or Kardashian heiresses, or watch documentaries like Born Rich with various heirs and heiresses, and it's quite obvious why such a class spends its money on endeavors that says nature rules over nurture. Like the heir Wickliffe Draper did with the Pioneer Fund. That they are born superior without having to work or do anything. For the past ten millennia they said the gods favored them, like Socrates noble lie ( https://en.wikipedia.org/wiki/Noble_lie#Plato's_Republic ). The popes crowned them king. In our post-enlightened age this does not work so now they say their superiority comes from chains of amino acids. Of course, history tends to depose of them any how, the God-ordained superior genetics of the Romanovs were not as well adapted as the Bolshevik soldiers who rid the earth of them (tangential note - their inbreeding caused hemophilia which brought in Rasputin and hastened their downfall). It's an argument for laziness and parasitism - to not look at people by their work, but by the genetic superiority which they were supposedly born with. It's pathetic and parasitic.
Specifically about the twin studies this has been heavily criticized from their outset. Already Flynn (of the famous Flynn effect of IQ increase over time) put out the requirements for proper control of such studies in his 1980 book. Nevertheless in 30 years of conducting new ones it appears none improved the methodology to control more carefully for environment and for culture. Just one facet of their invalidity: adoptive families have been found to be exceedingly intelligent with IQ over 120 on average, which is obviously different than general average (Stoolmiller in Psychol. Bull. 125:392-409).
[0] http://www.abc.net.au/news/science/2015-09-23/masculine-face...
Something has to alter the baby's genotype (more specifically, the genes in germ line cells, which are the only cells whose genetic material gets passed on to offspring) in order to count as a method of heritability. Otherwise prenatal testosterone is the same as any other thing in the environment which can alter an organism's phenotype.
The term can have two meanings depending which part of the term you emphasize. I think it is important to be pedantic here.
EPI-genetics with an emphasis on "epi" really describes any mechanism that happens above the genotype level. Transcription factor binding is technically "epigenetic". It is a really broad term.
Epi-GENETICS with an emphasis on "genetics" describes inheritance of information outside of the genetic information. This is probably the more interesting use of the term.
It seems like most biologist use it as a catch-all term for methylation/histone modifications/polycomb-type mechanisms. All of these mechanisms are EPI-genetic, but not all have really been proven to be epi-GENETIC.
For human beings, culture, as a powerful multiplier of intelligence, is far more important than genes. Immigrant groups to the US, like Italians and Poles, increased their average IQ scores by about a whole standard deviation in about 2 generations in the early 20th century. Even hot-button topics, like the IQ scores of Black people in the US have data which suggest that it is culture which is both a source of great inertia/difficulty and a source of great hope. On the side of hope, one study found that the Black children of US service-people in Germany were the same as other children growing up in Germany. Likewise, evidence for cultural factors in the success of people in various fields is very strong. For example, Jewish immigrant communities have often dominated local tailoring industries in cities across thousands of years of history and several continents. However, it would be laughable to suggest the existence of a tailoring gene.
Information of the kind above has been suppressed by the Far Left in the West. It has also been taken up in a dishonestly distorted form by the worst fringes of the Alt-Right. However, the complete story demolishes both Far Left and Alt-Right ideological messages. In the power of culture, there is hope for the future. If the potato famine Irish could lift themselves to their current place in 21st century society, out of utter unemployable status, poverty lower than that of the contemporaneous American slave, and the sewage-smelling crime and terrorism-ridden slums of New York and London, there is nothing that cultural transmission can't do.
https://www.youtube.com/watch?v=WHr9GRgRw_M
https://www.youtube.com/watch?v=3w0X71d9Z08
(Also herein is a cautionary tale. History shows many, many examples of migrant groups who find themselves lagging behind. They are often kept in cultural isolation away from the mainstream of their local society, often, by their own elite, which uses this to maintain their status as group leaders. Culture is powerful, but its power can be harnessed to do great harm as well.)
I would say that the majority of what makes a given culture unique and different from other cultures is learned. But the elements of culture that are shared between cultures are probably based in genetics.
Also, regarding Darwinian vs. Lamarckian evolution: my reading is that epigenetics is mainly comprised of some interesting phenomena that, when taken together, don't really account for that much of the genetic variety that we see in humans and, thus, are more of a fleshing out, rather than a revolution, of our understanding of genetics.
Plasmids are genetic structures that can be acquired by a bacteria and then passed on to descendants or through the environment to peer organisms. Antibiotic resistance is one of the most common traits passed this way.
1) https://www.youtube.com/watch?v=w3310KWlDXg (especially the Q&A which is dominated by epigenetics).
2) This explains it in text -> https://westhunt.wordpress.com/2012/10/26/epigenetics/
He doesn't have any training as a geneticist or in biological research.
It's all in his LinkedIn: https://www.linkedin.com/in/gregory-cochran-48b51b79/
It is weird to expect only DNA to be used. The process is not that orderly. The special thing about DNA (and a few other mechanisms), it is invariant to phenotype changes. And that it will copy over information that has no direct influences on self-replication. That is what enabled unlimited heredity.
Cell also has more than just a single set of DNA - it also inherits mitochondria and maternal mitochondrial DNA.
Maternal phenotype is important only so far as it affects cell development very early in life or has strong effect on epigenetic mechanisms. Those mechanisms are indeed affected by conditions "in the womb".
As for paternal effects, sperm is an antigen and hormone too.
The article seems to be written to a person stuck in very old view of genome and heritability. I'm pretty sure no accrual scientist in the field believes the core thesis.
Genetic variation within a racial group is comparable to genetic variation across groups, making it incoherent as a biological concept even before you get into more-obviously-cultural constructs like the "one-drop rule".
So most serious geneticists have tended to move away from thinking of "race" as closely linked to genetics—the complicated contours of both population genetics and what we mean when we talk about race just don't fit together all that well, and coupled with a history of unethical policies justified by overly simplistic scientific knowledge in this field, it's best to be careful about the terms we use.
Also, what we think of as race typically has a lot to do with cutural & socio-economic traits. Race isn't a clearly defined concept and might mean slightly different things to different people.
>Frequent lack of repressive capacity of promoter DNA methylation identified through genome-wide epigenomic manipulation
tl;dr: they engineered a protein which methylates regions of the genome in human cells and checked how that affects gene transcription. In many cases where they showed that the gene's regulatory region was methylated were still transcribed, contrary to what many other studies are indicating.
>These findings suggest that promoter DNA methylation is not generally sufficient for transcriptional inactivation, with implications for the emerging field of epigenome engineering.
Perhaps methylation could be a footprint of something we don't know about yet.
And regarding status and wealth: genetics probably play more of a factor in these than you think.
How can you say what heritability means ontologically, when the only way of ascertaining it is through mathematical statistics that doesn't care about your distinctions between genetic or cultural origins of the effects. Unless very carefully controlled, which is apparently too much to ask form the crude tools used in these studies.
Specifically about height you are mistaken this is clear-cut. First there is influence if populace is not under closure. Immigrants and emigrants affect height. A study that controlled for this was taken on pretty stable populace of Norway. Since height is also perceived as attractive and matters in sexual selection it was no surprise that Norse rose 10 cm over a century, or 2.5 cm in a generation. For such an effect to work exclusively through selection though the average height of parents must have been several centimetre higher than the average height of populace! The magnitude of the effect is just too large to work solely through selection at that pace. Thusly it is to be concluded that height is not purely genetic but also an environmental adaptation, both captured in heritability.
https://en.wikipedia.org/wiki/Heritability
A trait, such as height, can be heritable without being 100% heritable. On the other hand, you have traits, like the language you speak, which are not heritable at all.
I am aware of the definition. I fear it is you who doesn't have the epistemological clarity. It is not words that define but procedures with which you arrive at your results. And they do not discern culture, environment, flesh unless you take an extra care.
How do you propose to measure heritability of the first spoken language? What would be the variable here? It is perhaps hard to define variance in the language you speak, no? Are you aware of any such study, proving as you say that language one happens to speak is not heritable at all (as opposed to obviously)?
To see about an obviously cultural trait you'd like the first spoken language to be, it would be perfectly possible to measure accent variance, and perform a GWAS or twin study on that to see whether this is heritable or not. I am not aware of such study.
To have heritability at all you have to have variance. People having hands and legs: heritability not defined. Has there been a language study around such immigrant children you mention to see if their language is heritable? Or do you rule out heritability here because <words>, which has nothing to do with how heritability is actually measured whenever it can be (there being underlying variance). Or have you made up that unconducted example like mine with accent? I would gladly accept my wrong if presented with actual conducted study you got that fallacious argument (language: 100% not heritable) from. Or was that just your personal understanding?
For instance, the United States has experienced waves of immigration from various European countries in the last several hundred years. Specifically, there have been large waves of immigration from Germany, Poland, Italy, and Sweden. Yet there is no meaningful population of German, Polish, Italian, or Swedish speakers, fluent or otherwise, in the United State. Also, most Caribbean islands feature extremely high degrees of African ancestry, but the language of these nations is whatever the language of the colonizer was (so Haitians speak French, Dominicans speak Spanish, Jamaicans speak English, etc.). Native Americans speak English and, as a result, their native languages are in danger of becoming extinct. American blacks do not speak African languages, despite being descended from Africans.
This is in stark contrast to skin color, which is highly heritable. So people descended from European immigrants have the same light skin as their ancestors. And people descended from Africans have the same dark skin as their ancestors.
I can't believe you wrote that. Have you been to Chicago? I encourage you to get out your bubble, while admitting failure to reason with you. Parting rhetorical question: what about Hispanics, Asians? https://en.wikipedia.org/wiki/Languages_of_the_United_States
This is of course totally apart from the asked question and the notion of heritability, which is dear sir a compound statistical and not a causal notion where you can handwave something away because obviously.
From my link on heritability:
> Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population.
As best as I can tell, you are pointing out that children often speak the same language as their parents, therefore the language spoken is heritable. But that is an exceedingly naive interpretation, because the result is confounded by the fact that children inhabit a very similar environment to their parents. Somehow you need to remove the environmental confound.
What I am saying is that there are natural experiments where this has happened, as I outlined above. Black Americans who are descended from slaves have very similar genetics to their African ancestors (despite some admixture with Europeans and Native Americans). Yet the prevalence of African languages among black Americans who are descended from slaves is 0. Therefore the heritability of African languages is 0, since African genetics has zero relationship to African languages once you control for environmental confounds.
Now lets look at the German language. According to this[0] Wikipedia article, there are 44 million American who trace their ancestry to German immigrants. Yet, according to the link you shared on languages in the United States, there are 0.91 million fluent German speakers, just 2% of those descended from Germans. In this case, again, it is clear that genetics play an exceedingly small role, if they play any at all, in the prevalence of spoken German. For Polish, there are 9.5 million Americans descended from Polish immigrants[1], but only 0.54 million fluent speakers of Polish. Again, that points to, at best, extremely low heritability of the Polish language.
The natural experiment was conducted by Omniscient Statistician? This was published somewhere?
You do realise that heritability has no sense outside particular time, particular controls and particular populace? There is no number to heritability (in particular not 0) unless you precisely specify on what probe (and that number is only valid to that specific probe). These are not constants but relative variables being measured.
Let me illustrate that with Flynn's effect of IQ increasing over the last century. A today's IQ test administered on 1950's populace would average below 100. In populace today heritability of IQ test-taking was measured to be something. If one were to combine these two populaces, the distribution's variance partition would change (the distribution would become bimodal, with new environmental factor: whether someone is from today or the 50's). Suddenly heritability would be severely diluted by the new environmental factor. Does that make existence of heritability suspicious? No. Does that invalidate your estimates? Yes.
For example, the statement that tall parents will always have tall children is incorrect, though there is a strong bias. I would be curious to see how the probabilistic linkage between parent and child height compares to that for language. My guess is that parent language has a stronger effect than 99.9% of SNPs identified in GWAS.
If you really think about the difference between the two inheritance scenarios you outlined, it's that one mechanism of influence occurs at a scale that readily admits direct observation and perturbation while the other doesn't.
I don't think we (humans) know anywhere near enough about how genes compare and interact with other factors to support an argument either for or against your final statement.
Heritability has a very specific meaning. The first sentence from that article: "Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population."
The key part in that sentence is "due to genetic variation between individuals in that population".
Yes, there is a very strong relationship between first spoken language of parent and first spoken language of child. But there is no genetic element to that relationship (Asian children adopted by American parents will speak English, not the language of their parents), thus first spoken language is not heritable.
> I don't think we (humans) know anywhere near enough about how genes compare and interact with other factors to support an argument either for or against your final statement.
There is a difference between knowing that an effect exists and knowing how an effect works. We know, via twin studies, that IQ and height are highly heritable (50-80% for IQ; 80% for height), even though we don't know all the genes responsible or the way in which they contribute. Similarly, wealth/financial status have been shown to be heritable. Siblings raised apart will have levels of wealth that are more similar than random strangers. Identical twins raised apart, even more so.