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Author Topic: Speaking about plasticity @Cass/Dead or anyone.
xyyman
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Anyone want to look into this?

Why Europeans look so different from African and at the same time be a subset of Africans.


1.0 PHENOTYPIC ROBUSTNESS DETERMINES GENETIC REGULATION OF COMPLEX TRAITS
Anupama Yadav,

A balance between phenotypic variability and robustness is crucial for populations to adapt to multiple selection pressures. The plasticity of genetic pathways underlies this balance. We investigated this plasticity by studying the regulation of phenotypic mean and variance in a biparental recombinant population of Saccharomyces cerevisiae grown in a variety of environments. We found that the growth of this population was well buffered in most environments, such that majority of alleles regulated the mean value of phenotype, and only a subset of these alleles regulated phenotypic variance. This latter class of alleles allowed the other genetic variants to express a range of phenotypic values around a shifted mean. This shift depends on the population and the environment, i.e. based on the evolutionary history of a strain, buffering can result in either a superior or an inferior phenotype in an environment but never both. Interestingly, intricate coupling of the genetic network regulating mean phenotype and robustness was observed in a few environments, which highlighted the importance of phenotypic buffering in layout of the genetic architecture. For loci regulating variance, show a higher tendency of genetic interactions, which not only establishes a genetic basis of release of variance, but also emphasizes the importance of mapping robustness in understanding the network topology of complex traits. Our study demonstrates differential robustness as one of the central mechanisms regulating variation in populations and underlines its role in identifying missing heritability in complex phenotypes and diseases

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zarahan aka Enrique Cardova
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What does the full study say about Europeans as compared to Africans?

--------------------
Note: I am not an "Egyptologist" as claimed by some still bitter, defeated, trolls creating fake profiles and posts elsewhere. Hapless losers, you still fail. My output of hard data debunking racist nonsense has actually INCREASED since you began..

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xyyman
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^ @ TheReal

--------------------
Without data you are just another person with an opinion - Deming

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Thereal
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Thanks for the info.
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xyyman
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@TheReal. There was one other thread I am trying to locate on plasticity and the change in shape of the nose in African-American women. Cass/dead posted on it. That thread had a lot more details on plasticity.

--------------------
Without data you are just another person with an opinion - Deming

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the lioness,
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quote:
Originally posted by zarahan- aka Enrique Cardova:
What does the full study say about Europeans as compared to Africans?

quote:
Originally posted by xyyman:

https://www.youtube.com/watch?v=Re72di5phM0



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Tukuler
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quote:
Originally posted by zarahan- aka Enrique Cardova:
What does the full study say about Europeans as compared to Africans?

quote:
Originally posted by xyyman:
^ @ TheReal

Wait a minute. Is this a PM or
is it a public post? So, again,

What does the full study say about
Europeans as compared to Africans?

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xyyman
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@ Lioness, you got jokes.

On Europeans or plasticity on the whole the jury is still out. Why?

One study back in the 50's IIRC looked at the change in shape of the skull from new European immigrant and their offspring in the USA. The thesis is the change in the shape of the skull happens within one generation. The result was mixed.

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xyyman
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Got the old study


Reeanalysis of Franz Boas’s Immigrant Study
In 1910, Franz Boas published the first results from his classic study,


Changes in Bodily Form of Descendants of Immigrants. This landmark work became controversial almost immediately, as it challenged many prevailing ideas about human biology and race. The most striking finding at the time was that head shape—long thought to be a fixed, purely hereditary marker of race—was in fact sensitive to ***CHANGES IN ENVIRONMENT WITHIN A SINGLE GENERATION*** .


Boas’s most impressive response to the controversy was his decision in 1928 to publish 504 pages of raw, handwritten data from the immigrant study as Materials for the Study of Inheritance in Man. He explained: "It seemed necessary to make the data accessible, because a great many questions relating to heredity and environmental influences may be treated by means of this material." In the same spirit, here we provide the machine-readable data set that is the basis of our recent reanalysis of Boas’s data set. You will also find links to relevant publications and other sites of interest.


Clarence C. Gravlee, H. Russell Bernard, and William R. Leonard
7 April 2003

http://www.gravlee.org/research/boas/data/

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Tukuler
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And there were several challenges
disputing said claim. Surely skull
shape allows group placement
in the majority of cases either
when examining collections
as anthropologist do, or in
individual assessments
by forensic science.

No?


And there were several challenges
disputing said claim. Surely skull
shape allows group placement
in the majority of cases either
when examining collections
as anthropologist do, or in
individual assessments
by forensic science.

No?

quote:


Says Sparks, “Working from Boas's data, we found that some change had indeed taken place, but not much. After you factor out age, the amount of change is not statistically significant.” The reanalysis actually suggests an overall stability of the cranial index, even in a changing environment where people may
* abandon old cultural traditions,
* enjoy better nutrition,
* contract new diseases, or
* experience a lower infant mortality rate.

As Sparks and Jantz state in their PNAS article, skull differences between same-age related individuals born in Europe and America are “negligible in comparison to the differentiation between ethnic groups.” Says Sparks, “We found that the dominant force for all traits was genetic.”

Methodology is a real mutha 4 ya.
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xyyman
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Quote:
---
BOAS AND THE MEANING OF CRANIAL PLASTICITY

We turn now to the more fundamental discrepancy between our reanalysis and that of Sparks and Jantz—
namely, that we begin with incompatible understandings of what Boas actually said about environmental influences
on cranial form. From our perspective, it appears that Sparks and Jantz arrive at their conclusion by attributing
to Boas a position that he explicitly rejected. Sparks and Jantz argue that Boas got it wrong because
the differences in head form between families and between immigrant groups are generally larger than are the
differences between U.S.- and European-born children of immigrants. This finding, they argue, means that there is a
large genetic component to head shape and a relatively small environmental one.
In general, we do not dispute
their claim that there is a large genetic component to head shape, and we doubt that any human biologist would seriously
contest this point. More importantly, Boas himself never suggested, as Sparks and Jantz maintain, that “the
cranium can be shaped primarily by environmental forces” (2002:14636). Indeed, he repeatedly cautioned against
such a view and explicitly recognized the hereditary basis of cranial form.
---

--------------------
Without data you are just another person with an opinion - Deming

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xyyman
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I said the results were mixed.


quote:
Originally posted by Tukuler:
And there were several challenges
disputing said claim. Surely skull
shape allows group placement
in the majority of cases either
when examining collections
as anthropologist do, or in
individual assessments
by forensic science.

No?


And there were several challenges
disputing said claim. Surely skull
shape allows group placement
in the majority of cases either
when examining collections
as anthropologist do, or in
individual assessments
by forensic science.

No?

quote:


Says Sparks, “Working from Boas's data, we found that some change had indeed taken place, but not much. After you factor out age, the amount of change is not statistically significant.” The reanalysis actually suggests an overall stability of the cranial index, even in a changing environment where people may abandon old cultural traditions, enjoy better nutrition, contract new diseases, or experience a lower infant mortality rate. As Sparks and Jantz state in their PNAS article, skull differences between same-age related individuals born in Europe and America are “negligible in comparison to the differentiation between ethnic groups.” Says Sparks, “We found that the dominant force for all traits was genetic.”

Methodology is a real mutha 4 ya.

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xyyman
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Analysis of the African American female nose.
Porter JP1, Olson KL.
Author information

Abstract
The African American nose has been broadly classified as ethnic yet it differs significantly in morphology from that of other ethnic groups with which it is categorized. The objectives of this study were to (1) establish an objective protocol for analysis of the African American female nose using anthropometric measurements, and (2) determine whether subjective subcategorization schemes are a reliable replacement for anthropometry. African American women (n = 107) between the ages of 18 and 30 years consented to participate in this study. Photographs and 14 standard anthropometric measurements were taken of the face and nasal region, including nose length, nose width, special upper face height, intercanthal distance, mouth width, nasal bridge inclination, nasal tip protrusion, ala thickness, nasal root width, nasal bridge length, tangential length of ala, length of columella, nasofrontal angle, and nasolabial angle. Nasal indices including nose width-nose height index, nasal tip protrusion-nose height index, and nasal tip protrusion-nasal width index were calculated. In addition, photographic analysis was performed to evaluate nostril shape, nasal base shape, and nasal dorsal height. Proportional relationships and subcategorization schemes were evaluated. A new method of nasal analysis for the African American woman uses the proportional relationships of the anthropometric measurements. Proportional relationships included a columellar to lobule ratio of 1.5:1, a nasolabial angle of 86 degrees, and an alar width to intercanthal distance ratio of 5:4. The nasal dorsal height classification scheme was the most reliable for subjective analysis. The degree of variability found within this group of young African American women is illustrated by the following indices and their respective ranges: nose width-nose height index mean, 79.7 (range, 57 to 102); nasal tip protrusion-nose height index mean, 33.8 (range, 23 to 46); and nasal tip protrusion-nose width index mean, 42.8 (range, 32 to 61). The guidelines provided are a baseline from which to begin analysis and evaluation.

--------------------
Without data you are just another person with an opinion - Deming

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Tukuler
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And I said modern methodologies overturn
Boas. Check it from a .edu (reliability over .com)
http://news.psu.edu/story/140739/2003/05/01/research/boas-bones-and-race
quote:
Sparks and Jantz do not know why Boas concluded that the human skull was so fluid in response to environmental change.

“Boas had a strong statistical background,” Sparks says. “For his era, he was one of the most numerically intensive anthropologists around.

He pretty much did the type of analyses that people did back then. It was paper-and-pencil work—no computers.

After new statistical methods were developed in the twenties and thirties, Boas did not go back and recheck his head-form data.

You know quite well head shape is used to
successfully assign skulls, ancient or modern,
to "local" geographic breeding populations.

Seriously, have you never done that your
self, nor post from reports that do that?

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xyyman
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What is it with you and "who has the bigger dick". I have long past that stage. "I am what I am".

--------------------
Without data you are just another person with an opinion - Deming

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Tukuler
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Wtf r u talking about?

[Confused] [Confused] [Confused]


I'm presenting rational critique of Boas'
104 year old conclusions on skull
plasticity. What? The readership
are mushrooms to keep in the
dark and bullshitted on?

I bonestly expected you to come
back with Gravlee et all 2003 or
something.


Meanwhile Zarahan and me are waiting
on you to post from Yadav as he requested.

You're not trying to distract and divert
from that simple task are you?

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Djehuti
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quote:
Originally posted by xyyman:

Anyone want to look into this?

Why Europeans look so different from African and at the same time be a subset of Africans.


1.0 PHENOTYPIC ROBUSTNESS DETERMINES GENETIC REGULATION OF COMPLEX TRAITS
Anupama Yadav,

A balance between phenotypic variability and robustness is crucial for populations to adapt to multiple selection pressures. The plasticity of genetic pathways underlies this balance. We investigated this plasticity by studying the regulation of phenotypic mean and variance in a biparental recombinant population of Saccharomyces cerevisiae grown in a variety of environments. We found that the growth of this population was well buffered in most environments, such that majority of alleles regulated the mean value of phenotype, and only a subset of these alleles regulated phenotypic variance. This latter class of alleles allowed the other genetic variants to express a range of phenotypic values around a shifted mean. This shift depends on the population and the environment, i.e. based on the evolutionary history of a strain, buffering can result in either a superior or an inferior phenotype in an environment but never both. Interestingly, intricate coupling of the genetic network regulating mean phenotype and robustness was observed in a few environments, which highlighted the importance of phenotypic buffering in layout of the genetic architecture. For loci regulating variance, show a higher tendency of genetic interactions, which not only establishes a genetic basis of release of variance, but also emphasizes the importance of mapping robustness in understanding the network topology of complex traits. Our study demonstrates differential robustness as one of the central mechanisms regulating variation in populations and underlines its role in identifying missing heritability in complex phenotypes and diseases

It depends on what you mean by "subset" of Africans. ALL Eurasians or non-African populations in general descend from a sub-set of Africans. That said, are you aware that during the late Pleistocene during and even a little after the OOA migrations there were Africans who didn't look very similar to modern day Africans either (Hoffmeyer man of South Africa). In fact as recent as the Holocene there were still Africans who differed from modern Africans in cranial appearance (Mechta of Algeria). Even in east Asia there were certain groups who did not look like contemporary "mongoloid" east Asians like Liujiang man of southern China and Minatogawa man of southern Japan during the Holocene and even more recent crania like the Jomon era Japanese skulls.
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Elmaestro
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^This post reminds me of what I believe to be the problem in discussing population genetics or anthropology, etc. which is SCALE, whether temporal, spacial or characteristic. Often times on here people aren't clear on what time period or what traits and to which extent they wan't to describe relatedness. Also problematic is the selective reasoning in doing so, often imagining a single cluster for all SSA populations then intrinsically comparing them to a North or OOA sample population. or even worse, using a single population sample like YRI to define all of SSA in relation to other populations... It's imperative that we be more definitive in regards to scale, as of now all humans date back to two single individuals.

Now here's something I wan't to point out about this article (Yadav,).
quote:
1.0 PHENOTYPIC ROBUSTNESS DETERMINES GENETIC REGULATION OF COMPLEX TRAITS
Anupama Yadav,

A balance between phenotypic variability and robustness is crucial for populations to adapt to multiple selection pressures. The plasticity of genetic pathways underlies this balance. We investigated this plasticity by studying the regulation of phenotypic mean and variance in a biparental recombinant population of Saccharomyces cerevisiae grown in a variety of environments. We found that the growth of this population was well buffered in most environments, such that majority of alleles regulated the mean value of phenotype, and only a subset of these alleles regulated phenotypic variance. This latter class of alleles allowed the other genetic variants to express a range of phenotypic values around a shifted mean. This shift depends on the population and the environment, i.e. based on the evolutionary history of a strain, buffering can result in either a superior or an inferior phenotype in an environment but never both. Interestingly, intricate coupling of the genetic network regulating mean phenotype and robustness was observed in a few environments, which highlighted the importance of...
[...]

These guys are talking about phenotypic variation due to gene regulation, not polymorphisms, mutational repeats etc or genomic variation. Basically this is in the realm of adaptation and epigenetics. A mechanism as such can not explain the differences in lets say an Omotic individual and a Yemeni. However on a more interesting note, you can have a single population exhibit a phenotypic gradient based on geographic factors such as ...latitude "wink" even though the group is homogeneous, relatively speaking.

Basically, you can dig up the skulls of cousins located 1000Km apart and just by physical examination , not have a clue they were related. this is why genetics is important in this day and age, as well as oral and recorded history as complimentary constituents in piecing these things together.

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the lioness,
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quote:
Originally posted by Djehuti:

It depends on what you mean by "subset" of Africans.

xyyman's position is that many North Africans claimed to be heavily admixed are not a heavily admixed. They are in fact the ancestors of Europeans and he says the modern Europeans were living in North Africa less than 10,000 years ago. They migrated from Africa to Europe across Gibralter
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the lioness,
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 -
Iberomaurusian culture, (dark green)

The Iberomaurusian culture is a backed bladelet lithic industry found throughout the Maghreb.
The ancient Taforalt individuals carried the mtDNA haplogroups U6, H, JT and V, which points to population continuity in the region dating from the Iberomaurusian period.


xyyman, this seem like a no brainer for your theory the Iberomaurusians are indigenous Africans and are the ancestors of modern Europeans, not the Sterppe people

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xyyman
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"xyyman, this seem like a no brainer for your theory the Iberomaurusians are indigenous Africans and are the ancestors of modern Europeans, not the Sterppe people"

This is not rocket science.

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Old thread. Do you remember what I said about the AA female nasal index study? Cannot even remember.

Anyway, you can look up heritability estimates for human crania. Overall h2 = 0.55-0.60 which is moderate (hence craniometrics can be used to determine genetic relatedness, provided enough measurements are used). Selection and phenotypic plasticity does not explain most the variation:

"Both population history/structure and natural selection appear to have shaped the among-region differences observed in the modern human cranium, as represented in these 10 populations taken from Howells' data set. Population history and structure seem to predominate in shaping among-region differences among the nine non-Siberian (Buriat) modern human populations. This is in close agreement with Relethford's (11, 12, 33) analyses. However, when the Siberian (Buriat) population is included in the analysis, cold-mediated natural selection appears to be primarily responsible for the large differences observed between the Siberian (Buriat) sample and the rest of the world." http://www.pnas.org/content/101/35/12824.long

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So if it isn't selection nor plasticity.... What is left, might I ask?
Epigenetics?
Speciation?
Creationism?

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quote:
Originally posted by Elmaestro:
So if it isn't selection nor plasticity.... What is left, might I ask?
Epigenetics?
Speciation?
Creationism?

Neutral theory of molecular evolution. Most genetic/phenotypic variation is explained by 'neutral' processes, i.e. genetic drift and mutations that are neither beneficial nor detrimental, so are not selected for or against.
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quote:
Originally posted by Cass/Dead/Krom/Atlantid:
quote:
Originally posted by Elmaestro:
So if it isn't selection nor plasticity.... What is left, might I ask?
Epigenetics?
Speciation?
Creationism?

Neutral theory of molecular evolution. Most genetic/phenotypic variation is explained by 'neutral' processes, i.e. genetic drift and mutations that are neither beneficial nor detrimental, so are not selected for or against.
Please log out
Or go to the 'Ancient Egypt' sections and remain there permanently.

[EDIT:
Y'know what, I take that back... if you are speaking about variation in general or within a single population as opposed to differences among various populations or variation based on location/climate etc.

But if you are referencing the latter as I initially wrongly assumed, then you make no sense.]

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Djehuti
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quote:
Originally posted by Cass/Dead/Krom/Atlantid:

quote:
Originally posted by Elmaestro:
So if it isn't selection nor plasticity.... What is left, might I ask?
Epigenetics?
Speciation?
Creationism?

Neutral theory of molecular evolution. Most genetic/phenotypic variation is explained by 'neutral' processes, i.e. genetic drift and mutations that are neither beneficial nor detrimental, so are not selected for or against.
Then what do you call HBS (sickle-cell) disease among primarily Africans as well as African descended Mediterranean Europeans?? What about fair skin in populations that live in areas with little UV such as Europe while albinism was almost non-existent in Africa until recent times where it has become more common due to medical treatments preserving the lives of carriers longer? Obviously there is selection taking place.
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xyyman
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Skull and limb morphology differentially track population history and environmental factors in the transition
to agriculture in Europe - Cramon-Taubadel and Ron Pinhasi


Quote:
“The postcranial phenograms (see electronic supplementary material, figure S2b,c) show that for both the lower
and upper limb data, the Mesolithic OTUs placed among the Neolithic OTUs rather than with the Epipalaeolithic OTUs, as
is the case with the craniometric data.
In the case of the upper limbs (see electronic supplementary material, figure S2c),
the Epipalaeolithic **Afalou** OTU is linked with the** Neolithic Nubian** OTU, reflecting geographical and climatic proximity
rather than population history.

associated with the onset of the Holocene. Recent research has suggested that limb segment lengths may be influenced
by ‘thrifty’ phenotypic mechanisms and exposure to environmental stress
. In this context, a decrease in body size
associated with the transition to agriculture could be a plastic response to dietary stress. Further research is required to
investigate whether the timing of changes in body size are associated with climatic and/or dietary transitions.

This evidence for long-term adaptation in limb proportions among past populations, however, sits
at odds with evidence demonstrating both rapid changes in limb proportions of migrant populations and mechanisms
of developmental plasticity that could underpin the variation we see in intralimb proportions”

--------------------
Without data you are just another person with an opinion - Deming

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