Showing posts with label Eumelanin. Show all posts
Showing posts with label Eumelanin. Show all posts

Saturday, May 9, 2009

"Demic Diffusion" Dynastic models: R.I.P

Although by now intellectually relegated to a fringe-status [mainly radical Eurocentrist or affiliated cults] in the face of overwhelming & mounting evidence, there is still a crowd out there that is distressed by the prospect of the Dynastic Nile Valley complex being recognized, well, as autochthonous. The very idea that "sophisticated" or "advanced" complex culture(s) does not begin in Europe, but anywhere outside of Europe, upsets the white supremacist social "pyramid"; so, it comes as no surprise to see elements in this ideological bubble, whether they openly call themselves "gun-touting" conservative "patriots" or "liberal" humanity-loving "activists", cringe at the audacious nature of reality, that the very first sophisticated elaborate complex culture occurs just about anywhere outside of Europe, let alone Africa. The difference between the two camps of the white supremacist ideological bubble, is that the former is more forthright about their disquiet than the latter is.

The entity of "ancient Egyptian" social complex particularly presents a very unsettling situation in the white supremacist ideological bubble, because it has the distinction of being amongst the world's, and not just Africa's, earliest attestable elaborately sophisticated socio-cultural complexes, as well as being "aboriginally" African. Why is this? Well, the first reason had been already stated above, but second one entails the fact that white supremacy is hardwired in placing the darkest of people [skin pigmentation standpoint] at the bottom of their social ladder; think of it—though Eurocentrist elements would frown at such a deserved acknowledgment—as white supremacist "caste system". This is how said "caste system" works: at the top, is the lily white group, and from thereon, as groups progressively get darker, so is their position on the "pyramid" of this caste system determined accordingly—the darker a group gets, the lower its social status on the caste system's "gradient". It is for this reason that all sorts of rounds have been made at explaining away the "Africanity" of the 'ancient Egyptian' complex; including begrudging acknowledgments like,...

"well, yes it is African, but not black African" or "It was in Africa, but ancient Egypt's politics was more focused towards the Middle East, and should therefore more appropriately be seen as Middle Eastern", or "yes, ancient Egypt was physically located in Africa, but it's social complex was brought about by a horde of Middle Eastern immigrants", not to mention another common one: "they were a melting pot of all races [and so, ancient Egypt was brought about by this confederation of different "races"; "different races" presumably living in harmony back then than they are today]".

This one probably takes the cake, if not more forthright about its motivation by white supremacist agenda: "Western civilization history lessons places it [ancient Egypt] in the Middle East [and usually, as a prelude to western civilization history, and so it is], and that's that."

What the above is saying point blank, is that ancient Egypt should force-feedingly be "accepted" as "Middle East" or even "Western" because "we, westerners, say so; it doesn't have to have an ounce of fact to it, just needs to be accepted by those, who we [presumably] dominate". In other words, "we" use "geopolitical dominion" to assert and fabricate what should be accepted or not accepted; truth or reality never has anything to do with it. So, when reasonable people place "ancient Egypt" in its objective or true place, it upsets the white supremacist ideological bubble, because the said "geopolitical dominion" assertiveness is audaciously defied accordingly. Linked to this "assertiveness", the white supremacist "caste system" is defied by the condition of the darkest of groups developing elaborately sophisticated social complexes before the lily white European ones, which is what a "black African ancient Egypt" implicates.

Ideally, but harder to do intellectually, Eurocentrism would prefer just about every "meaningful" autochthonous development in Africa to be attributed to adjoining regions, which they'd prefer to call "outside" of Africa, like say, the portion of the Great Rift Valley of Africa in what they call the so-called "Near Eastern" side. This is not done out of any special Eurocentric love for "Near Easterners", but pretty much out of the necessity of upholding the usually unspoken white supremacy doctrine of Eurocentric-presumed "lighter" groups being on top of the Eurocentric-presumed "darker" groups in their "caste system". You see, from the Eurocentrist standpoint, the regions that they subjectively dub as the so-called "Near East", people with relatively lighter epidermal pigmentation are more prevalent in these areas than in the more southern climes of Africa; it matters not, whether these people are still generally considerably darker than most European populations. As far as white supremacy caste system is concerned, these groups are relatively nearer to "white" Europeans than the darker or darkest ones that them white Europeans are supposed to be naturally better than. This is why whenever archaeological finds in situ African continent come to the surface, which could potentially be indicative of some highly sophisticated—presumably quite ancient—social development at first glance, the Eurocentric doctrine is to first explore such findings in terms of demic diffusion models originating from adjoining "non-African" territories before exploring an autochthonous one; only if any number of demic diffusion models fail to sufficiently explain the findings, then is an autochthonous one begrudingly tolerated or accepted, well...at least until further down the road, new demic diffusion models come to mind. This is why for example, if one stops to think about it, notwithstanding what archaeology may say in tandem with say, linguistics and genetics, ideally Eurocentrism prefers to take for granted that any and essentially every animal domestication tradition in Africa must have initially been an imported trade from the so-called "Near East", the region that has become a Eurocentric propaganda entity of convenience, mainly because of its undisputed cases of more archaeological antecedents over that of Europe [otherwise, Europe ideally would be the first choice, as a "non-African" source].

Now, as many probably know by now, the "Near East" has been quite a fluid Eurocentric construct which has, depending on the occasion at hand, been used to cover portions of Northern Africa as well. Under this guise, huge chunks, if not all, of coastal Northern Africa cease to be part of mainland Africa, not out of geographical obscurity, but out of the information dissemination shroud, from repeated "western" mass media catchwords like the "Middle East", which is almost always used to include parts of coastal Northern Africa areas. This has happened so much so in the "western" world, that is not unreasonable to assume that some people in that part of the world are inclined to think that the so-called "Middle East" is its own continent. In this scenario, "Africa" becomes relegated to another Eurocentric-presumed catchword— for Africa's "darkies" bunch; at this point in the passage, we ought to know by now, how "darkies" fare in the Eurocentric "caste system". As soon as "Africa" is uttered, in the so-called "western" world, stereotypical images of these "darkies" come to mind at first instance, even though etymologically, the term traces its initial application on the continent in the coastal Northwestern African area.

Of course the Eurocentric dogma creeps in from time to time in "western" published journals, and as such, it boils down to a matter of the reading audience being sufficiently-researched in what they read, and thus, being able to sift out the objectively reasonable from the rest of the "noise" being radiated from these journals. Limb proportions for example, has been a recurring topic of science journals and book publications. One such that comes to mind for example, is Chris Stringer and Clive Gamble's publication, In Search of the Neanderthals: Solving the Puzzle of Human Origins. As the title suggests, the journey of investigation centers around Europe, for if one stops to think about it, the "search of the Neanderthals" is also linked to the search of "where Europeans came from" — their evolutionary journey. As a reader of this cite may know, within Eurocentric ideological circles, at one point Neanderthals were even considered as possible ancestors of contemporary Europeans; so putting this basic concept in mind, the 'western' fascination with Neanderthals becomes readily understood. In any event, limb proportions has become part of investigating the aforementioned evolutionary journey, and In Search of the Neanderthals explores this. Page 92 of the book for instance, provides us with average crural indices of sample candidates taken from different parts of the globe, and the respective temperatures of the prevailing or historic habitats of these candidates.

As a matter of basic intuition, one may know that skin or epidermal pigmentation is a function of the biological responsive measure to the level of the UV radiation, with diet playing a supplementary role; whereas in the case of body plan & limb proportions, the influencing factor is more a function of thermal regulation—optimized retention and loss of heat according to the temperature environment of the prevailing areas of habitat. In the tropics, not only are UV radiation levels higher, but so is temperature generally higher than those in temperate regions. So it should not be surprising to see a strong correlation between body plans and epidermal pigmentation.

"Tropical body plans" are thus strongly correlated with groups that generally have considerable epidermal melanin pigmentation, while "cold-adapted" body plans would be most expected of groups relaxed in epidermal eumelanin pigmentation [also see Allen's Rule for examples]. Of course, in some rather very rare occasions, some subtropical regions are known to sport high temperatures. In these isolated incidences, one might wonder if the correlation stands; well, it certainly depends on the biohistory of a population in said habitat, i.e. when they arrived, and their evolutionary status when said arrival took place, coupled with the UV radiation intensity [see previous posts: Skin pigmentation gene alleles & Skin pigmentation gene alleles — Part 2], the "openness" of the environment [ like forest, grassland, or desert] and the supplementary role of diet. Subtropical regions adjoining or not too far from the tropics are not expected to cause much or drastic change, though some change might well be expected depending on the duration of habitation in said environment and the accumulation of micro-evolutionary processes in tandem; one might for instance, expect to see an intermediary "mean" index of certain limb proportions amongst groups in temperate regions closer to the tropics than those in temperate regions of much far off latitudes, placing said groups between those of extreme tropic and sub-tropic climes. The "Bushman" groups of southern Africa for instance retain dark skin, albeit some relaxation of epidermal eumelanin pigmentation may have occurred as part of the micro-evolutionary processes, in consideration of long residency in mainly the southern hemisphere's lower-end tropical to sub-tropical areas of Africa. Their limb proportions, at least as indicated by the mean crural index [see C. Stringer and C. Gamble's In Search of the Neanderthals] may have undergone some change, but not too drastic to the point of displaying indices as low those seen in groups that historically reside(d) in far 'latitudinally'-distant temperate areas, including amongst Europeans. Consider the following crural indices, with purportedly associated mean annual temperatures indices of [some of which suggest "historically-associated"] environments of residency:



               crural     Mean annual temp C
              index

Lapps             79%           .25

modern Inuit      81.5%         4

Neanderthal       79%           -
[average]

Belgium           82.5%         10

S.African white   83.2%         8.5

Yugoslav          83.75%        8.4

American white    82.6%         9.8

Kalahari Bushman  83.4%         18

New Mexico Indian 84.6%         14

S.African black   86.4%         17

Arizona Indian    85.5%         18

Melanesian        84.8%%        23

Pygmy             85.1%         24.2

Egyptian          84.9%         26.1

American Black    85.25%        26 

Source: Courtesy C. Stringer and C. Gamble, In Search of the Neanderthals: Solving the Puzzle of Human Origins, pg 92.

The "Bushman" mean crural index is visibly not as low as groups associated with temperate regions [presumably in consideration of temporal divergence from ancestral populations] at greater latitudinal distances from the tropics; on the other hand, is it noticeably lower than groups accociated with latitudes that are in or much closer to the equatorial regions. The mean crural index of Neanderthal indicates that they likely displayed an extreme cold-adapted body build.

Crural indices are just one of the indicators of the likely inclination of the general body plan, and say nothing of the actual manifestation of the overall body build (body plan). Those percentages cited above are the mean values [of the leg's proximal section relative to the middle section without the feet segment], which hides the within-sample variability. The arm process [which includes the brachial index from the humerus to the radius & ulna; not in that table] has its own index to be taken into consideration, in the overall build of the body. These processes taken together, i.e. intermembral index, along with comparative measurements of its components in relation to the distal segments of the limbs, give a broader picture of the manifestation of the body build (plan), particularly in relation to the body's trunk; these indices together show that ancient Egyptians had what was dubbed as the "super-negroid" body plan. This is not surprising, considering that a portion of what is now called Egypt lies in the northern hemisphere of tropics, not to mention that Nile Valley populations were then relatively recent migrants from the tropical areas of the continent. Recalling Sonia Zakrzewski:

The nature of the body plan was also investigated by comparing the intermembral, brachial, and crural indices for these samples with values obtained from the literature. No significant differences were found in either index through time for either sex.

The raw values in Table 6 suggest that Egyptians had the “super-negroid” body plan described by Robins (1983). The values for the brachial and crural indices show that the distal segments of each limb are longer relative to the proximal segments than in many “African” populations (data from Aiello and Dean, 1990). - Sonia R. Zakrzewski, Variation in Ancient Egyptian Stature and Body Proportions

There you have it: As noted above, ancient Egyptians had longer distal segments relative to the proximal segments than many other African groups, thus giving ancient Egyptians that so-called "super-negroid" body plan.

It is interesting though that Zakrzewski cites Robins (1983), because notwithstanding what the results make all too obvious, Robins offers the sort of self-denial apologia towards the facts of the results her own tests bring to light, as exemplified above about other such denials in tandem with Eurocentric or white supremacy's imperialistic "assertiveness" to what should or shouldn't be accepted. Robins (1986) for instance, tells us:

Predynastic Egyptian stature and physical proportions

Abstract:

An attempt has been made to estimate male and female Egyptian stature from long bone length using Trotter & Gleser negro stature formulae, previous work by the authors having shown that these rather than white formulae give more consistent results with male dynastic material. Evidence is presented that the tibia length should include the spine in the later (1958) formulae and should exclude it in the earlier (1952) formulae. It is also shown that better results are obtained if the constants in the stature formulae are modified so as to conform more exactly with the basic data published by Trotter & Gleser. When consistency has been achieved in this way, predynastic proportions are founded to be such that distal segments of the limbs are even longer in relation to the proximal segments than they are in modern negroes. Such proportions are termed "super-negroid".

Introduction:

...Robins (1983) and Robins & Shute (1983) have shown that more consistent results are obtained from ancient Egyptian male skeletons if Trotter & Gleser formulae for negro are used, rather than those for whites which have always been applied in the past. This does not mean that ancient Egyptians were negroes; indeed, in their art they clearly distinguished between their own facial features and skin colour and those of people from further south. It does, however, suggest that their physical proportions were more like modern negroes than those of modern whites, with limbs that were relatively long compared with the trunk, and distal segments that were long compared with the proximal segments. If ancient Egyptian males had what may be termed negroid proportions, it seems reasonable that females did likewise.

Robins tells us that test results place them anatomically with "negroes", and yet, she seeks to moot this quantifiable fact with some subjective personal interpretation of what ancient Egyptian art supposedly communicates. In other words, her answer to defying the tangible results of a scientific test, was to turn to some intangible subjective personal opinion about Egyptian art; the two are worlds apart. It is akin to saying DNA revelation can be refuted by someone's subjective opinion about what some art may or may not be communicating, as a substitute for counter quantifiable DNA evidence. Furthermore, there is nothing moot about a finding that has been reproduced time and again, as for example, attested to Zakrzewski's reaffirmation. As for the supposition made about the ancient Egyptian female proportions as it relates to their male counterparts, this too had been confirmed in Zakrzewski's work.

Upon revisiting the above mentioned Zakrzewski study, we are told:

The ancient Egyptians have been described as having a “Negroid” body plan (Robins, 1983). Variations in the proximal to distal segments of each limb were therefore examined. Of the ratios considered, only maximum humerus length to maximum ulna length (XLH/XLU) showed statistically significant change through time. This change was a relative decrease in the length of the humerus as compared with the ulna, suggesting the development of an increasingly African body plan with time. This may also be the result of Nubian mercenaries being included in the sample from Gebelein.

Given the screwed up basis of "Nubian" in "western" discourse, one has to independently reaffirm what's actually being referenced. Now, if by 'Nubian', Zakrzewski is referring to people originating from beyond ancient Egypt's southern political border, and in what is now part of Sudan, then in the above, it appears that Zakrzewski is hinting on the so-called "super-negroid" body plan amongst them [so-called "Nubians"] as well. You know how it is; whenever anything is "increasingly African" in ancient Egypt, the presumed change has to somehow be attributed to an outside source preferably from south of Egypt, where a fictitious "black Africa" is "supposed to begin", according to dogmatic-preferences within Eurocentric circles. In any event, the results of Zakrzewski could not hide the fact that the rest of the Egyptian specimens tell the same story, aside from samples from Gebelein: the so-called "super-negroid" body plan! To reiterate from previous citation above,...

The values for the brachial and crural indices show that the distal segments of each limb are longer relative to the proximal segments than in many “African” populations (data from Aiello and Dean, 1990). This pattern is supported by Figure 7 a plot of population mean femoral and tibial lengths; (data from Ruff, 1994), which indicates that the Egyptians generally have tropical body plans.

The keywords: the Egyptians generally have tropical body plans.

...essentially meaning that this is so, even without considering any so-called "Nubian" presence, which is a too often used Eurocentric excuse to explain away any findings that render Egyptians too "negroid".

In other developments, relevant to the ongoing subject matter, the following was just recently been published:

Near Eastern Neolithic genetic input in a small oasis of the Egyptian Western Desert

Martina Kujanová 1 2, Luísa Pereira 3 4 *, Verónica Fernandes 3, Joana B. Pereira 3, Viktor erný

Abstract

The Egyptian Western Desert lies on an important geographic intersection between Africa and Asia. Genetic diversity of this region has been shaped, in part, by climatic changes in the Late Pleistocene and Holocene epochs marked by oscillating humid and arid periods. We present here a whole genome analysis of mitochondrial DNA (mtDNA) and high-resolution molecular analysis of nonrecombining Y-chromosomal (NRY) gene pools of a demographically small but autochthonous population from the Egyptian Western Desert oasis el-Hayez. Notwithstanding signs of expected genetic drift, we still found clear genetic evidence of a strong Near Eastern input that can be dated into the Neolithic. This is revealed by high frequencies and high internal variability of several mtDNA lineages from haplogroup T. The whole genome sequencing strategy and molecular dating allowed us to detect the accumulation of local mtDNA diversity to 5,138 ± 3,633 YBP. Similarly, theY-chromosome gene pool reveals high frequencies of the Near Eastern J1 and the North African E1b1b1b lineages, both generally known to have expanded within North Africa during the Neolithic. These results provide another piece of evidence of the relatively young population history of North Africa.

Am J Phys Anthropol, 2009

In response to the above, sure the small sample size is an issue [as apparent from the large margins of error], but look, the coalescence times simply tell us when the lineage itself expanded; it doesn't quite tell us when a lineage entered from locale A to locale B, without elaborate cluster information on how lineage 'X'—unique and respective in distribution pattern to locale A and locale B—could have entered say, locale B from locale A.

The present authors ignore Bovine-remains anthropology and DNA data, none of which is consistent with this:

"The complete mtDNA characterization of 35 unrelated individuals from el-Hayez revealed a local expansion in the last 6,000 years of two lineages belonging to the T1 Neolithic Near Eastern haplogroup. This suggests input of Near Eastern lineages during the Neolithic period in contradiction to the hypothesis that Northeastern Africa was an independent place of cattle domestication, as suggested by thee cultural context."

Human skeleton, Y or mtDNA is no substitute for actual cattle markers. It's just common sense. For instance, we have from previous analysis, which has been reaffirmed over and over again via lingustic examinations of domesticate terms, cattle DNA, and cattle remains [for example, also see: Fred Wendorf & Romuald Schild (Evolutionary Anthropology 3(4), 1994), Are the early Holocene cattle in the Eastern Sahara domestic or wild?],...

The Origins of African Cattle

The origins of cattle domestication and the dispersal of pastoralism in Africa have been contentiously debated in recent years. It has generally been assumed that domestic cattle were introduced into Africa from the Near East. Olivier Hanotte and colleagues [Science 296 [2002]], however, present genetic evidence of an indigenous origin for the earliest African domestic cattle, the humpless taurine [Bos Taurus]. They argue that cattle were domesticated in Africa prior to the introduction of two excotic domesticates: humped zebu cattle [B. indicus] from Asia and a genetic variant of taurine cattle from the Near East and Europe. Hanotte et al. used allele frequencies from 50 populations of modern cattle across the African continent to examine genetic variation. Their results reveal three ancient genetic signatures and each signature’s center of origin or region of entry. The native African taurine breed was independently domesticated in northeastern Africa, perhaps the eastern Sahara, and later migrated with pastoralist or crop-livestock farmers west and south. Asian zebu cattle were introduced along the east coast of Africa and in Madagascar and were most likely transported along a marine route from the Indian subcontinent. Finally, Near Eastern and European taurine cattle were primarily introduced along the shores of North Africa during the colonial period. These findings provide a genetic record of African cattle origins and migrations that have far-reaching implications for human migrations and the adaptive strategies used by African populations. They also require us to reexamine the models of domestication more broadly. - M. A. Kennedy

Archaeological attestations of the considerable distinct time frames of the Levantine agricultural Neolithic economy and that of the Nile Valley is also simply ignored, in lieu for an admittedly small sample of uniparental markers.

Predynastic Nile Valley human remains data is also ignored [as cited in Barry Kemp's publication - Ancient Egypt: Anatomy of a Civilization, Robins (1983), and Zakrzewski's Variation in Ancient Egyptian Stature and Body Proportions]...

Early Dynastic Periods. When the Elephantine results were added to a broader pooling of the physical characteristics drawn from a wide geographic region which includes Africa, the Mediterranean and the Near East quite strong affinities emerge between Elephantine and populations from Nubia, supporting a strong south-north cline.

2. Moving to the opposite geographical extremity, the very small sample populations available from northern Egypt from before the 1st Dynasty (Merimda, Maadi and Wadi Digla) turn out to be significantly different from sample populations from early Palestine and Byblos, suggesting a lack of common ancestors over a long time. If there was a south-north cline of variation along the Nile valley it did not, from this limited evidence, continue smoothly into southern Palestine. The limb-length proportions of males from the Egyptian sites group them with Africans rather than with Europeans. - Ancient Egypt: Anatomy of a Civilization

Anatomy of a Civilization has its own shortcomings elsewhere of course, but that's another topic for another day.

Linguistic indicators [as cited by Keita] shows that words for Levantine domesticates are not loan words from the so-called 'Near East'; recap:

Ovacaprines appear in the western desert before the Nile valley proper (Wendorf and Schild 2001). However,it is significant that ancient Egyptian words for the major Near Eastern domesticates - Sheep, goat, barley, and wheat - are not loans from either Semitic, Sumerian, or Indo-European. This argues against a mass settler colonization (at replacement levels) of the Nile valley from the Near East at this time. This is in contrast with some words for domesticates in some early Semitic languages, which are likely Sumerian loan words(Diakonoff 1981).

This evidence indicates that northern Nile valley peoples apparently incorporated the Near Eastern domesticates into a Nilotic foraging subsistence tradition on their own terms (Wetterstrom 1993). There was apparently no “Neolithic revolution” brought by settler colonization, but a gradual process of neolithicization (Midant-Reynes 2000).

As for the Y-DNA, Semino et al. 2004 gave a detailed layout of differentiation between Neolithic era J and post-Neolithic J dispersions; their data suggests that most of those J lineages in northern Africa which have counterparts in the so-called Near East, are post-Neolithic or recent dispersions. Much of the latter had been linked to Arab expansionist adventures into those areas.

To recap from above, the authors — i.e. Kujanová et al., of the work under study — say:

"Surprisingly, no other U-lineage (one U3b) is present, in particular U6, which is otherwise frequent throughout North Africa but more so in Western North Africa.

Indeed. Hg U6 seems to factor prominently in these "Neolithic" or else "Paleolithic demic diffusions into northern Africa" proposals [also see: Mitochondrial DNA M1 haplogroup: A Response To Ana M. Gonzalez et al. 2007], but time and again, its distribution pattern just doesn't seem to comply. Several different studies of the western oasis' populations tell the same story: the virtual rarity or absence of Hg U6, which is interesting given that this region is right on the path of the Sinai corridor through which any hypothetical so-called "Near Eastern" proto-U6 is expected to pass, in parallel with a hypothetical ancestor of Hg M1.

Is it possible that there were predynastic human movements into north Africa proper via the Sinai corridor? Yes, it's certainly possible and conceivable, but these events apparently didn't have the sort of impact, magnitude or oomph on the manifestation of autochthonous predynastic Nile Valley cultural development into the dynastic period that the usual "demic diffusion into Nile Valley" crowd would rather like to see. Prevailing and overwhelming evidence just doesn't bear it out, which is apparently a bad thing for business in the bubble of white supremacists, whatever stripes they come in, be it so-called 'liberals' or outright reactionaries.

Friday, October 10, 2008

An Interesting Encounter...

Several months back, in a forum discussion, the present author came across something quite interesting on the website of the owner of the said forum—going by the name of F. W. Sweet, and this is what it says/said:

"It seems that Dr. Shriver’s maternal grandfather moved from Pennsylvania to Iowa, then to California, leaving behind in the process most of his ties with his relatives.23 Dr. Shriver, it turns out, (see photograph above) is one of the 74 million White Americans with significant recent African genetic admixture.

In a coincidentally similar fashion, Dr. Rick Kittles, Shriver’s collaborator from Howard University in Washington, discovered that he carries the FY-null genetic marker at genome position 16q24.3. This marker is found in 998 out of every thousand Europeans but found in only one out of thousand Africans. Many of Dr. Kittles’s other ancestry-informative markers tell the same unexpected story. Dr. Kittles (see photograph above) is one of the many Black Americans with strong European genetic admixture. And yet, and there is no other way to say this, Dr. Shriver “looks White” and Dr. Kittles definitely “looks Black.” Why is there such a discrepancy between measured genetic admixture and physical appearance?" - by F. W. Sweet

At the time, this is what the present author posted in response to the extract:

Yes, I’ve seen both Dr. Shriver’s and Dr. Kittle's appearance, and I must say, it is hard to believe that either have low European or African recent ancestry respectively. If indeed the labeled sample belonged to either party, assuming that the said alternative coincidences did not arise from any probable technicality in the labeling, then I can only come to the conclusion that, the DNA sites examined as such, were made possible because those sites were kept intact in either one of their immediate parents, and if Shriver’s mum’s reaction is any indicator to go by, upon hearing the news, these markers would have been kept intact in her “white-appearing” father. Speaking of father, according to Mr. Shriver, how did he reach the conclusion that it had to be from his mother’s dad’s side, and not necessarily from his mother’s maternal side? Also, could it not have come from his father's side, and if not, why? Were many of the said ‘markers’ deemed to have been sex-biased in their genetic transmission?

I had the result for two or three years before I even looked up the ID number of the person whom we tested. I looked at who it was and it was me! I checked myself and the rest of my relatives and tracked it through my family. I never considered that there were any African people in my family. There’s no real variation in my family. The admixture must have been pretty far back. It just so happens that we can detect it with the markers we have. My mom especially stood out as being surprised, maybe because I told her it was coming through her father. She still doesn’t believe it about her family! The part of Pennsylvania where my mother’s father came from is where the Underground Railroad ended. There are several towns right here in Southern Pennsylvania where there are very light-skinned African-American communities that are the remnants of the Underground Railroad. - by Shriver

So, not only would those markers have to be deemed “invisible” in terms of their impression on phenotype, but they would have had to remain intact to account for their genetic integrity throughout the parent-to-offspring transmissions for at least a few generations. For Dr. Kittles to retain that level of melanin, it occurs to me that he’d had to have been a product of a union between parents from families that had maintained endogamy for at least a few recent generations, likely of families that have had long enough tradition of socially identifying with the “black“ or “colored” community. I suspect, since I cannot say for certain without independent corroboration, that either of these two researchers would likely indirectly clue us in on this possibility through either paternal and/or maternal DNA markers, which by normal account, correspond to Y-chromosome markers and mtDNA respectively. Either that, or else more “AIM” would have been needed to be identified to account, if not *indirectly*, for the genetic component counterparts of their ancestors who were responsible for transmission of their phenotypic appearance - as is the case with skin color and hair texture for example. I realize these traits have their own markers, but I'm referring to the broader hereditary component of the parties who were primarily responsible for transmitting those traits. It is hard to imagine that only those 'visible' markers of those ancestors withstood the test of time, while every other component of their genetic transmission was swamped through the generations, particularly for 'immediate' family households who would swear that the maternal and paternal lines of the said family come predominantly from one ethnic endogamous group [be it "white" or "black"].


With regards to piece about Kittle’s ancestry, this was said:

In a coincidentally similar fashion, Dr. Rick Kittles, Shriver’s collaborator from Howard University in Washington, discovered that he carries the FY-null genetic marker at genome position 16q24.3. This marker is found in 998 out of every thousand Europeans but found in only one out of thousand Africans. - by F.W. Sweet

But in the tables provided, this location should have been associated with MC1R-314*, and not the FY-null marker, which is supposed to have been located at 1q23.2. Was this a typo, or something else is at work here?

And indeed, that was a typo, as the author himself admitted, upon my issuing of the notification above. If indeed the typo was in wrongly naming the loci, which it appears it is/was, then MC1R-314*'s — an allele known to prevalent in folks of recent African ancestry — location in Mr. Kittles' sample should come as no surprise.

Short of some extraordinarily rare situation of these two geneticists — aka Shriver and Kittles — being products of union between a) a parent heterozygous at certain loci linked to outward phenotype traits like skin color, eye color, hair thickness et al., which are generally observed predominantly in one geography than another or in one ethnic group than another, and a parent largely homozygous across said loci, b)OR else, between parents who happen to both be heterozygous at some or the other section of said loci, wherein the offspring [in this case, either Shriver or Kittles] somehow wound up being largely homozygous across said loci, from the look of things, there are very strong indications here that what Shriver was actually looking at as his own, might well have been Rick Kittles' DNA sample, and likewise, Shriver's DNA sample was mistaken for Kittles'. There might have been a technicality at the lab [could be labeling mishap for example, though some other yet-to-be-determined factor(s) could have been the cause] , which somehow escaped both Shriver's and Kittles' attention, and so, they took it for granted, no matter how awkward the results turned out to be, as their own, respectively. This would explain the seemingly reverse results for each candidate, who coincidentally, were partners on research work. Short of specific independent corroboration, obviously this amounts to conjecture on my end; let's just say that I'm throwing out there, a possible scenario for what could have accounted for the results we are told about, aside from considering one of those rare genealogical situations. One thing most of us would agree on, is that those results are certainly interesting!
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*Further reading:

—
Skin pigmentation gene alleles

— Skin pigmentation gene alleles — Part 2

Monday, September 1, 2008

Crania: Behind the "Generalized Modern human pattern" ...

Within 'Medi-centrist' circles, ideologues have sought psychological refuge in this anthropological catchword, in relation to cranial morphology; however, what is this term really a code word for? Well, let's examine from the language of a few anthropological publications, what this really boils down to...

The reactionary and outdated anthropological work of Colin Groves naturally comes to mind immediately:

...The implications of the Herto find for modern human origins are clear. Here were H. sapiens, more primitive than anyone now living but recognizably members of our own species, living in north-eastern Africa at a time when the Neanderthal people were in sole occupation of Europe. Even later than Herto, the only people for whom we have evidence were still non-modern - an enigmatic Neanderthal-like skull from Maba in China, and late H. erectus in Java. Just as predicted by the Out-of-Africa model, modern humans appear in Africa long before they are known from anywhere else.

There are implications for the origins of modern races, too. Herto (and Jebel Irhoud) are H. sapiens, but with primitive features. They are not, racially speaking, Africans. The later Omo and Klasies remains are more modern, but they too are archaic, and certainly show no traces of the features that characterize any modern races. Only Qafzeh and Skhul seem to lack these primitive features, and rate as “generalised modern humans”.

Our species seems to have existed as an entity long, long before it began to spread outside Africa or the Middle East, let alone split into geographic races.

When, then, did H. sapiens begin to split into races? The evidence indicates that modern racial features developed only gradually in each geographic area. The earliest H. sapiens specimen outside the Africa/Levant region is from Liujiang in China, whose dating was recently confirmed at 67,000 BP by a group led by Guanjun Shen of Nanjing Normal University. Like Qafzeh and Skhul, Liujiang is a “generalized modern”; it has no Mongoloid features.

The East Asian fossil record is not good enough to show when Mongoloid features began to develop. All we can say is that they must have developed before the end of the Pleistocene (12,000 BP) because this is when people began to cross what is now the Bering Strait (which was then a land-bridge); and Native Americans are Mongoloid.

H. sapiens began to enter Europe about 40,000 BP, but it is only at 28,000 BP that we get a fossil that shows any Caucasoid features - the Old Man from Cro-Magnon, in France.

Within the African homeland, the appearance of Negroid features is debatable. The skull from Border Cave, on the South Africa/Swaziland border, may be 60,000 years old and may show Negroid features, but both claims have been challenged.

And Australia? The earliest widely accepted dates for human occupation are of the order of 60,000 BP, not more, according to Bert Roberts of La Trobe University and the late Rhys Jones of the Australian National University. The claim that the Mungo Man skeleton is 62,000 BP has recently been challenged. According to a recent study led by Jim Bowler of Melbourne University, both Mungo Man and Mungo Woman may be only 40,000 years old (AS, April 2003, pp.18-21), but they are still the earliest skeletal remains we have from Australia. Are they Australoid?

Of all “major races”, Australoids have evidently changed least from the generalized modern human pattern, but the flat, receding forehead and angular skull vault that characterise many full-blooded Aboriginal people today are somewhat different to the Qafzeh/Skhul pattern. A 1999 study by Susan Antón and Karen Weinstein of the University of Florida, in the process of confirming that some of the Australian fossils (including most of the famous Kow Swamp series) had undergone artificial head deformation in infancy, found unexpectedly that most of the Pleistocene fossil Australian crania are rounder-skulled than modern ones. So racial features developed late in this part of the world, too.

In summary, the new discovery at Herto does not shatter any myths, but it extends the dataset, shifts the weight of evidence yet more decisively in favour of the Out-of-Africa model of modern human evolution, and helps to place modern racial variation very firmly into context.

Colin Groves is professor of archaeology and anthropology at the Australian National University.

© Control Publications 2003


Let's see what Groves says is not the "generalized modern human pattern":

— primitive features

...which Grove observes, is a feature of the Herto, the Omo and Klasies specimens; and to drive this point, Grove tells us that: The later Omo and Klasies remains are more modern, but they too are archaic, and certainly show no traces of the features that characterize any modern races.

Apparently, bespeaking of the outdatedness of his viewpoint, the Omo specimens that Grove deems more modern, are actually much older than the Herto specimen — that is, outside the fallacy of "human races".

What else is not generalized modern, according to Groves?

— Mongoloid features

...on which we are clued in, here: Like Qafzeh and Skhul, Liujiang is a “generalized modern”; it has no Mongoloid features.

What else?

— Caucasoid features

And we know this, because Groves tells us that: it is only at 28,000 BP that we get a fossil that shows any Caucasoid features - the Old Man from Cro-Magnon, in France.

Mind you, this would be the same "Caucasoid" Cro-Magnons that Chris Stringer tells us: more like present-day Australians or Africans, judged by objective anatomical categorizations, as is the case with some early modern skulls from the Upper Cave at Zhoukoudian in China

And with regards to which, Brace says: oft-repeated European feeling that the Cro-Magnons are “us” (46) is more a product of anthropological folklore than the result of the metric data available from the skeletal remains

We are also clued in that generalized modern isn't exactly....

— modern racial features...either!

Yeap, you probably guessed it; he implies this to us, right here: When, then, did H. sapiens begin to split into races? The evidence indicates that modern racial features developed only gradually in each geographic area.

Yet even by Groves' own rationale, although he turns around and simply says that it has been challenged, the so-called 'Negroid' trait preceded the so-called Caucasoid:

Within the African homeland, the appearance of Negroid features is debatable. The skull from Border Cave, on the South Africa/Swaziland border, may be 60,000 years old and may show Negroid features, but both claims have been challenged.

For if the said 'Negroid' features are attested to 60 ky ago, then that would apparently predate the questionable appearance of the so-called 'Caucasoid' features at ca. 28 Ky ago among the discredited "Caucasoid Cro-Magnons" , wouldn't it?!

But perhaps the most instructive piece of Groves' racialist discourse, is this:

Of all “major races”, Australoids have evidently changed least from the generalized modern human pattern, but the flat, receding forehead and angular skull vault that characterise many full-blooded Aboriginal people today are somewhat different to the Qafzeh/Skhul pattern.

It doesn't take much of a stretch of the imagination to see that Australian aborigines are tropically-derived peoples, with considerable skin eumelanin, placing them well within the range of skin pigmentations found across 'sub-Saharan' Africans. In popular language, we all know the latter are known as "blacks". Indeed, Groves' ability to see closer phenotypic link between Australian aborigines and Upper Paleolithic "Eurasian" specimens of Qafzeh/Skhul and Australia, is consistent with the aforementioned Chris Stringer et al.'s assessment:

"Nor does the picture get any clearer when we move on to the Cro-Magnons, the presumed ancestors of Modern Europeans. Some were more like present-day Australians or Africans, judged by objective anatomical categorizations, as is the case with some early modern skulls from the Upper Cave at Zhoukoudian in China

Source: African Exodus: The Origins of Modern Humanity by Christopher Stringer and Robin McKie, Page 162

Stringer et al.'s observation is yet consistent with that of Neves et al. 2005:

"Increasing skeletal evidence from the U.S.A., Mexico, Colombia, and Brazil strongly suggests that the first settlers in the Americas had a cranial morphology distinct from that displayed by most late and modern Native Americans. The Paleoamerican morphological pattern is more generalized and can be seen **today** among **Africans, Australians, and Melanesians.**

Here, we present the results of a comparative morphological assessment of a late Paleoindian/early archaic specimen from Capelinha Burial II, southern Brazil. The Capelinha skull was compared with samples of four Paleoindian groups from South and Central America and worldwide modern groups from W.W. Howells' studies.

In **both analyses** performed (classical morphometrics and geometric morphometrics), the results show a clear association between Capelinha Burial II and the Paleoindians, as well as Australians, Melanesians, and Africans, confirming its Paleoamerican status."


Reminiscent of Groves' distancing of the generalized cranial morphology from the so-called 'Mongoloid pattern', Neves et al. tells us:

The increasing evidence that all late Pleistocene/ early Holocene human groups from South America are characteristically non-Mongoloid has major implications for the colonization of the Americas, as argued by one of us (WAN) since the end of the 1980s. Even if few studies with large samples from single sites have been carried out so far with Paleoindians (see Neves et al., 2003, 2004, as examples of these studies), it is evident by now that South America Central America and possibly North America, were populated by human groups with a more generalized cranial morphology before the arrival of the Mongoloids.

Like Stringer, they too see the generalized pattern as that akin to that seen in cranial morphology of tropical adapted groups like Australians, Melanesians and Africans:

— Since this more generalized morphology (‘‘Australo-Melanesian- like’’) was also present in East Asia at the end of the Pleistocene, transoceanic migrations are not necessary to explain our findings.

— As presented in detail elsewhere (Neves et al., 2003) the arrival of an ‘‘Australo-Melanesian-like’’ population in the Americas is easily accommodated under what is presently known about the place of origin and the routes taken by modern humans in their first long-distance dispersions (Lahr and Foley, 1998).

What Neves et al. tells us next, pretty much sums up why Upper Paleolithic African specimens show affinities with Upper Paleolithic 'Eurasians', as well as Paleo-Indians:

1) Accordingly, a population that began to expand from Africa around 70 ka reached southeast Asia by the middle of the late Pleistocene, carrying with it a cranial morphology characterized by long, narrow neurocrania and narrow, projecting faces.

2) We postulate that after reaching southeast Asia, this stem population gave rise to at least two different dispersions.

— 50 Ky ago
One took a southward direction and arrived at Australia around 50 Ka.


— Between 50 and 20 Ky ago
Sometime between 50 and 20 Ka a second branch dispersed towards the north, and arrived in the Americas by the end of the Pleistocene, bringing with it the same cranial morphology that characterized the first modern humans.

Neves et al.'s observations are apparently valid, and appears to be the consensus scientific finding, but even they fall victim to "idealized" typological constructs [as indicated by the need to refer to the term "Mongoloid" at all] — although to a much lesser degree than Groves — and it serves one to understand that when they speak of stronger phenotypic associations between Paleo-Indians and Paleo-Eurasians and contemporary dark-skinned tropically-adapted/derived groups like aboriginal Australians, Melanesians and Africans than other contemporary groups, that with regards to Africans, the comparison is being made with view to only a snapshot of African diversity. Take for instance, the following Neves et al. characterizations of the Paleo-Indian source populations:

Recap — Accordingly, a population that began to expand from Africa around 70 ka reached southeast Asia by the middle of the late Pleistocene, carrying with it a cranial morphology characterized by long, narrow neurocrania and narrow, projecting faces.

And then this — When the classical Mongoloid cranial morphology appeared in northeastern Asia, either as a local response to extreme environmental conditions, or as the product of a migration from northern Europe, a new expansion of northern Asians reached the New World, bringing with it a cranial morphology characterized by short, wide neurocrania and broad, retracted faces.

Although local microevolutionary processes in the Americas can not be precluded to explain the transition from a generalized to a very specialized cranial morphology (Powell and Neves, 1999), a model based on the entrance of two different morphological patterns from the Old World is much more parsimonious.

The two patterns are further described as follows...

The three different quantitative analyses undertaken in this study demonstrate that the first South Americans exhibit a cranial morphology that is:

1 — very different from late and modern Northeastern Asians and Amerindians (short and wide neurocrania; high, orthognatic faces; and relatively high and narrow orbits and noses)

2 — but very similar to present Australians/Melanesians and Africans, especially with the former (narrow and long neurocrania; prognatic, low faces; and relatively low and broad orbits and noses).

Source: Neves et al. 2005; Cranial morphology of early Americans from Lagoa Santa, Brazil: Implications for the settlement of the New World.

Clearly, the cranial patterns described in association with the Australian/Melanesian and African groups is only a snapshot of the actual overall diversity of Africans; the combination of traits described above is often invoked in what one might refer to as 'stereotypical Negro" — or as it has been referred to elsewhere — as "forest Negro". Certainly, these traits do not cover the full range of cranio-facial patterns observed across sub-Saharan Africans and Africans as a whole; they are just subsets of the said variation.

Revisiting that last 2nd point: 2 — but very similar to present Australians/Melanesians and Africans, especially with the former (narrow and long neurocrania; prognatic, low faces; and relatively low and broad orbits and noses).

It should be obvious from the above, that showing stronger phenotypic affinities with the above mentioned groups — Australians, Melanesians, and Africans, that this doesn't mean the said three groups show no inter-group differences; apparently, there are discernible phenotypic manifestations between them, with contemporary Australians and Melanesians perhaps showing somewhat stronger links to the aforementioned Paleolithic specimens than contemporary Africans, but relatively smaller distances between the three contemporaries and the Paleolithic specimens, than the case may be with other groups; this brings us to the:

Conclusion: Stronger phenotypic associations are observed between the modern tropically-adapted/derived groups like Australians, Melanesians and Africans and Paleolithic groups of Africa, Eurasia and America, because original modern humans were tropically-adapted Africans, who sported considerable skin pigmentation — that is to say, "blacks". Therefore, the 'generalized modern' is nothing more than a code word or just another euphemism for a variant(s) of the [naturally, dark-skinned] tropical African, otherwise also called "black African". This applies to their tropically-adapted Paleolithic descendant populations in the Levant, SouthAsia, Europe, and the Americas. The generalized moderns represent part of the then existing overall variation of tropical Africans, just as the "stereotyped" or "idealized" sub-Saharan African archetype constitutes just a part of overall phenotypic diversity of Saharo-Sub-Saharan Africa.

Ps — Some Eurocentric ideologues, as exemplified in Groves' work, unable to psychologically come to grips with their ultimate derivation from dark-skinned [tropical] African ancestors, conjure up pseudo-scientific "racialist" or typological discourse wherein they seek to mystify the fact by hiding behind code terms like "generalized modern", even if it means contradicting themselves in the process — again as Groves did — and overlooking it. For instance, from Groves, one almost gets the sense that he tries too hard to make a case that the generalized modern is a type which is spared so-called archaic features, yet distinctive from 'contemporary' populations which he divides and classifies into rigid types, while at the same time, acknowledging a relatively stronger association with the contemporary likes of aboriginal Australians. It doesn't take a genius to figure out that aboriginal Australians are considerably dark skinned peoples, whom like other tropical-affiliated groups like Melanesians, are in certain ways reminiscent of their dark skinned African brethren, not to mention sporting strong morphological affinities with both Paleo-'Eurasians' and Paleo-Africans, because they all emanate from autochthonous dark skin ancestral populations of tropical Africa — a fact which is relayed through cephalo-morphometric study, as just examined, and molecular genetics — wherein relatively deeper monophyletic units or markers are attested to in these groups [especially Africans] than those observed in their counterparts elsewhere!
____________________________________________________
*References:

— Colin Groves 2003

—Neves et al. 2005; A new early Holocene human skeleton from Brazil: implications for the settlement of the New World.

—Neves et al. 2005; Cranial morphology of early Americans from Lagoa Santa, Brazil: Implications for the settlement of the New World.

—Christopher Stringer and Robin McKie, African Exodus: The Origins of Modern Humanity.

— Brace et al. 2005, The questionable contribution of the Neolithic and the Bronze Age to European craniofacial form. Neat little link (clickable) to a discussion on the draft of the this paper before it went into publication!

Monday, January 28, 2008

Skin pigmentation gene alleles — Part 2

Reviewing H. Norton, R. Kittles et al, 2006 - Part 2:

Link to the part 1: Skin pigmentation gene alleles [clickable]

Additional notes:

For those who are curious, the authors of the aforementioned skin pigmentation study [Kittles et al.] don't specifically point out the TMRCAs for the identified genes in question, but apparently ancestral lineages were delineated from their derived counterparts. From extrapolation though, it makes sense that mutations that occurred after divergence of any given groups, would be relatively rare in the common ancestor of these recently diverged groups. On the other hand, certain mutations that were present within the common ancestor may be expressed more acutely later on in one or the other group that diverged from this ancestral population, while dying out or becoming relatively rare in another progeny group. Still these developments are able to assist one in delineating the frequency and mutational particulars of the genes controlled by natural selection and/or the pressure of genetic drift.

As for "Southwest Asian" populations, they generally fall into ranges contained within the Saharo-tropical Africans, while some northerly groups of this region apparently have relatively paler skin shades as a product of more recent migrations into the region. Kittles et al. at least in part, attribute such developments to gene flow from Northern Eurasia and perhaps, in some areas, East Asia. See again, from my last post:

Concerning the "derived" SLC24 A5 gene...

In contrast, the SLC24 A5 11*A-derived allele is found at low frequencies in several sub-Saharan populations including the West African Mandinka and Yoruba, the Southern African San, and South West Bantu.

The relatively **high frequencies** of the derived allele in **Central Asian, Middle Eastern, and North Africa** seem likely to be **due to recent gene flow** with European populations.

Similarly, the presence of the derived allele (albeit at low frequencies) in some sub-Saharan populations may be due to recent gene flow from European and Central Asian populations. —Alternatively, the derived allele may have lost in the ancestors of modern East Asians but retained in the ancestral European populations. The allele then rose to high frequency in Europeans following the divergence of Europeans and East Asian ancestral groups.

Many places outside of Africa, for instance, harbor the 'derivative' counterparts of several "pigmentation" genes [a variety of which have been associated with relatively lighter pigmentation], while ancestral alleles [many of which have generally been associated with relatively darker pigmentation] are commonly found in Africa and amongst direct descendants of earliest out-of-Africa ancestors of modern non-Africans, as is the case with OCA2 gene...

In general, the derived allele (associated with lighter pigmentation) is most common in Europeans and East Asians, and the **ancestral allele** predominates in **sub-Saharan Africa** and **Island Melanesia.**

...and this quite likely applies to "southwest Asians"...in harboring "derived" OCA2 which has been associated with playing a role in lightening skin phenotype, for example.

Lightening effect was apparently a gradual process, as populations started expanding to low UV radiation latitudes. This is readily seen in the intermediary situations between adaptations on opposite poles of empirical tests; see for example:

High Fst values [concerning the three genes TYR, MATP and SLC24A5] between Europeans and darkly pigmented populations such as West Africans and Island Melanesians are not unexpected if these genes have functional effects. However, the notably elevated pairwise Fst values relative to East Asians (the population in our panel that is the most similar to Europeans in pigmentation phenotype) is striking. Populations intermediate in pigmentation (Native Americans and South Asians) also exhibit Fst values falling in the top 5th percentile of their relevant Fst distributions with Europeans for these three loci. In the case of SLC24A5 A111G, South Asian pairwise Fst values also fall in this top 5th percentile when compared to both Europeans (Fst = .389,  p < .01) and East Asians (Fst= .519, p < .01), but not when compared to any other population. At all three loci Europeans have the highest frequency of the derived alleles relative to the other five populations.

The South Asians being referred to here, comprised of east Indian samples, which are claimed to be 'intermediate' along with the Native American samples. The phenomenon described above, seems to suggest that the alleles at the three said loci in the said 'intermediate' groups predate those attained in both East Asians and Europeans; as noted, their Fst values are not quite as high when compared with any other population [which would essentially be the dark populations]. Apparently, the pigmentation distribution in these 'intermediate' groups reflect demographic events distinct from those that produced the more dramatic pigment-oriented phenotypic manifestations in Europeans and East Asians respectively; being that they possess alleles that post-date OOA migration events, and yet those that predate extreme pigment-related adaptations sported by Europeans and East Asians, they are bound to report intermediary patterns. One might recall that the Native American OCA2-derived allele frequency was said to be comparatively lower than that of East Asians...

Interestingly, derived allele frequencies at this locus are quite different between Native American (15%) and East Asian populations (45%), suggesting that perhaps the derived allele at this locus did not reach very high frequencies in East Asians until after the colonization of the Americas

And might also recall that KhoiSans on the other hand, reported high frequencies of OCA2-derived...

The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area.

So yes, the derived version of OCA2 likely predates the often-talked about Upper Paleolithic OOA migration in varying frequencies in different populations, but likely did not pick up in distribution dramatically in East Asian and European populations, until after a section of central-East Asian had left for America, in a wave(s) following that of the first Paleo-Americans. This suggests that one drift episode [perhaps amongst the earliest for this type] raised its frequency considerably in at least one African group [the Sans], another drift episode raised its distribution in vicinity of central and/or east Asia to reasonably visible levels, but yet another drift episode raised its distribution even further in east Asia at a later time. All this paints gradual evolution in skin pigmentation relaxation temporally, in tandem with territorial shifts amongst populations.

And recalling...

The discordance between our Fst -based divergence values and allele frequencies in the Melanesian CEPH populations at ASIP largely stem from the relatively low frequency of the ancestral allele in the 2 CEPH Island Melanesian populations relative to our original Island Melanesian sample. These discrepancies make it difficult to determine if ASIP truly underlies broad pigmentation differences between darkly and lightly pigmented populations or instead inter-population variation at this locus can largely be explained by differences between Africans and non-Africans…

The answer is rather obvious, no? It reflects the basal phylogenetic position of Melanesians, which is why they'd share ancestral ASIP alleles with continental Africans. The difference then here, would be one of the basal phylogenetic position of Africans vis-a-vis OOA-derived populations, with the deepest-clade bearers of all OOA-derived groups carrying over basal African alleles outside of Africa.

More on the "derived" SLC24 A5 gene...


On the above piece, in one personal encounter, a question had come up along the lines of:

...because one of the authors says not enough time has passed for mutations? And just how is it the author would know this? Since the author, or one of the authors didn't specifically say how much time
has to pass for mutations then I'm asking you...to explain to me what you know they meant by this.

The natural answer to that question, as the present author put forth, was this:

Yes, the authors reckon that "not enough time has passed for mutations" and don't specify "how much time has to pass for [new] mutations" to occur, nor need to, because they determined this from the fact that the DNA flanking the gene in question lacked variation in the samples they studied; the tacit idea here, is that the DNA locus in question not only indicates selective pressure of the gene SLC24A5, where by the flanking DNA in question must have been part of a selective sweep, but its lack of variation suggests that not enough time has accumulated since such a selective sweep would have occurred; otherwise, more variation, however modest, would be expected of a designated DNA locus that has been around for a considerable length of time. And oh, it must be suggestive of some linkage disequilibrium in the inheritance of this assemblage of DNA.

On Jablonski :

The weaker the ultraviolet light, the fairer the skin. Jablonski went on to show that people living above 50 degrees latitude have the highest risk of vitamin D deficiency. "This was one of the last barriers in the history of human settlement," Jablonski says. " Only after humans learned fishing, and therefore had access to food rich in vitamin D, could they settle these regions." — The evolution of race was as simple as the politics of race is complex, By Gina Kirchweger

And to that, the present author says:

"Absolutely"!

Side notes:
The very "relaxed" eumelanin concentration in the skin of 'pale skin' individuals is the expression of their relatively "recessive" alleles, vis-a-vis the more "dominant" counterparts of those that instruct for more production, to produce the considerable skin eumelanin concentration of dark skin individuals. The present author has come across comical claims about the aforementioned "recessive" counterparts "masking" the effects of the more "dominant" skin pigmentation alleles, no doubt from individuals who are in the dark about the basics of genetics. The case in humans, whereby one comes across skin tone gradients, from extreme dark to extreme paleness, can best be described as one of the interplay of "incomplete" dominance of the 'wild types' over their "recessive" counterparts in subjects of "intermediate" skin tones, via polygenic inheritance—wherein the individual effects of "dominant" or "wild" alleles that produce greater eumelanin dosage, will mask those of the relatively "recessive" counterparts in normal "heterozygous" [so to speak, for simplification purposes] subjects, while the "wild" or "dominant" allele types will simply instruct for considerable skin eumelanin in "homozygous" dark skin subjects, and that of the relatively "recessive" allele types instruct for little dosages in "homozygous" pale skin subjects. Now of course, common sense should tell one that these terms "recessive" vs. "dominant" are relative terms, for we know that even in individuals where 'pale skin' is product of natural selection, as opposed to genetic mishap or disorder, the alleles which instruct for only modest eumelanin dosage, if we had two copies of the same alleles from each parent, then neither is dominant or recessive to the other; however, one such allele in the presence of a "wild type" from a darker skin parent, will tend to be "recessive" relative to the said "wild type". All the said alleles in this case, will instruct for eumelanin dosage, but the 'wild type", and hence more "dominant" type, will instruct for bigger dosages than the other allele, the "recessive" counterpart. For those needing basic illustrative demostration, check this site out: http://waynesword.palomar.edu/lmexer5.htm

Gist: If one is recessive, it has to be recessive relative to another, and likewise, if one is "dominant", it has to be so over another. It is just common sense.

Skin pigmentation gene alleles

Reviewing H. Norton, R. Kittles et al, 2006:

Besides the variations in the “SLC24A5” gene, as mentioned in the intro article, the “TYR” gene, the “OCA2“, the “ASIP“, and to some extent those seen in the MC1R gene, Kittles et al. have noted other genes "MATP C374G", “ADAM17“, “ATRN“, and “DCT” the mutations of which are deemed to have to had influence in promoting paleness…

Taken together (with the results of previous admixture mapping studies), these results point to the importance of several genes in shaping the pigmentation phenotype and a complex evolutionary history involving strong selection. Polymorphisms in 2 genes, ASIP and OCA2, may play a shared role in shaping light and dark pigmentation across the globe, whereas SLC24A5, MATP, and TYR have a predominant role in the evolution of light skin in Europeans but not in East Asians. These findings support a case for the recent convergent evolution of a lighter pigmentation in Europeans and East Asians…

Pairwise Fst estimates for the ASIP A8818G and OCA2 A355G SNPs tentatively suggest a pattern of divergence between 4 populations (Europeans, East Asians, Native Americans, and South Asians) and the relatively more darkly pigmented populations of West Africa and Island Melanesia, or possibly only between West Africans and all other populations. At both loci, West Africans and Island Melanesians have higher frequencies of the ancestral alleles than the other 4 populations. Pairwise locus-specific Fst values falling in the top 5% of the empirical distributions are observed between West Africans and 3 other populations (South Asians, Native Americans, and Europeans) at ASIP A8818G. Fst values between West Africans and East Asians at this locus are elevated but do not reach our cutoff value of 5% (Fst = .489, P = .065). At OCA2 A355G, only West Africans and Europeans show Fst values falling into the top fifth percentile of relevant comparisons (Fst = .516, P<.05). The low pair wise Fst values and higher frequency of ancestral alleles at both SNPs studied in these loci between West Africans and Island Melanesians hint that dark pigmentation associated with both loci in these populations may have a common evolutionary origin (Mean Fst (WA-IM) = .182; ASIP A8818G Fst (WA-IM) = .260, P = .282; OCA2 A355G Fst (WA-IM) = .101, P=.525).

Continuing with regards to OCA2 gene, we are told…

In contrast, the ancestral allele associated with dark pigmentation has a shared high frequency in sub-Sharan African and Island Melanesians. A notable exception is the relatively lightly pigmented San population of Southern Africa where the derived allele predominates (93%), although this may be simply due to small sample size (n=14).

The distributions of the derived and ancestral alleles at TYR A192C, MAPT C374G, and SLC24A5 A111G are consistent with Fst results suggesting strong European specific divergence at these loci. The derived allele at TYR, 192*A (previously linked with lighter pigmentation [Shriver et al. 2003]), has a frequency of 38% among European populations but a frequency only 14% among non-Europeans. The differences between Europeans and non-Europeans for the MAPT 374*G and SLC24A5 111*A alleles (both derived alleles associated with lighter pigmentation) were even more striking (MAT [European] = 87%; MATP [non-European] = 17%; SLC24A5 [European] = 100%; SLC24A5 [non-European] = 46%). The frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%).


By way of negative Tajima D values, which when strongly negative, indicate selective pressure, or more specifically—“directional selection”, especially when taken into account with both high locus-specific branch length and strongly negative heterozygosity values, the authors continue...

These data confirm the unusual European-specific patterns at MATP and SLC24A5. Both genes display long range (consecutive windows) and significant indications of positive selection for all 3 statistics. In contrast, there is little evidence of a European-specific pattern in the TYR locus although the non-synonymous TYR A192C SNP does individually show a strongly significant CEU-LSBL (P<.003) in the HapMap data as in our original findings. The contrast may be explained by the limitations of our HapMap sliding windows analyses, whereby adjacent SNPs are averaged using a method that does not consider Haplotype structure.

East Asians showed relatively stronger selection for a different set of genes…

…In particular, 2 genes (ADAM17 and ATRN) showed East Asian-specific signatures comparable in strength with those observed for MATP and SLC24A5 in Europeans.

While…

The ADTB3A gene also shows a strong and focused signature of positive selection in Africans...

Many hypotheses predict that natural selection will eliminate genetic variants associated with lighter skin in the regions of high UVR as a protection against photo damage (e.g., sunburn, melanoma, and basal and squamous cell carcinomas) (Blum 1961; Kollias et al. 1991) and folic acid photo degradation (Branda and Eaton 1978; Jablonski and Chaplin 2000). The photo protective properties of a highly melanized skin and the recent African origin of modern humans suggest that the ancestral phenotype is one of the relatively dark skin (Jablonski and Chaplin 2000; Rogers et al. 2004). If dark skin is the ancestral phenotype, then we may assume that the first migrants out of Africa were relatively darkly pigmented…

There are 2 primary explanations for the evolution of lighter skin in regions of low UVR:

—1)The first suggests that light skin is merely due to the relaxation of functional constraint and that derived alleles associated with lighter pigmentation may have simply drifted to high frequency in the absence of strong purifying selection (Brace 1963).

—2)The second explanation suggests that in lower UVR regions, positive selection would have favored mutations leading to lighter skin as a way to maximize cutaneous vitamin D synthesis (Rana et al. 1999; Jablonski and Chaplin 200). Given the relatively recent arrival and divergence of humans in and across Europe and Asia, the most parsimonious evolution of light skin would involve such mutations arising in a proto-Eurasian population soon after humans left Africa.

Consequently, these mutations should be shared between modern Asian and European populations. Alternatively, if separate existing functional variants were driven to high frequency in East Asian and Europeans or independent de novo mutations arose and were selected in each population after divergence of Europeans and Asians, then these would be obvious as high allele frequency differences between modern European and East Asian populations. Reduced levels of heterozygosity surrounding the SLC24A5 A111G polymorphism in the European, but not East Asian, HapMap populations support the latter hypothesis (Lamason et al. 2005), as do reduced polymorphism levels based on full resequencing data from MATP in populations of European descent (Soejima et al. 2005).

So basically, while “SLC24A5, MATP, and TYR have a predominant role in the evolution of light skin in Europeans,” the ADAM17, ATRN, and DCT appear to play a dominant role in the evolution of light skin in East Asians.

Current archeological evidence suggests human presence in Island Melanesia by at least 40ky ago and in other parts of Sahul by at least 45ky ago (O’Connell and Allen 2004). If the original migrants to Oceania arrived there via a corridor of relatively high UVR, then we might expect their descendants to share ancestral pigmentation variants with African populations. However, if the ancestors of modern day Island Melanesians spent a significant amount of time in low-UVR, then it is possible that mutations associated with lighter pigmentation could have accumulated and a readaptation to high-UVR conditions would have been necessary, leading to potential divergence between Island Melanesians and Africans at functional pigmentation loci. In actuality, both of these scenarios may apply, as we know that modern Island Melanesian populations are descended broth early migrants (arriving 40ky ago) as well as later proto-Austronesian-speaking peoples from a southeast Asian homeland ~ 3,200 years ago (Spriggs 1997).

The discordance between our Fst -based divergence values and allele frequencies in the Melanesian CEPH populations at ASIP largely stem from the relatively low frequency of the ancestral allele in the 2 CEPH Island Melanesian populations relative to our original Island Melanesian sample. These discrepancies make it difficult to determine if ASIP truly underlies broad pigmentation differences between darkly and lightly pigmented populations or instead inter-population variation at this locus can largely be explained by differences between Africans and non-Africans. The discordance between the frequencies of the ASIP ancestral allele in our original Island Melanesian sample and the Melanesian samples from the CEPH panel may be indicative of both the complex demographic history of Island Melanesia (involving several migratory events (Spriggs 1997) and probable extensive genetic drift (Friendlaender 1975, 1987) as well as the importance of multiple loci in determining pigmentation phenotype…

Thus possible further extensions of variations detected amongst Melanesians can be explained by successive demographic events After their African ancestors migrated over 40ky ago. The “original Melanesian sample” appears to have more ancestral pigmentation genes in common with tropical Africans, which is to be expected given that they are direct descendants of the earliest Eurasians, as demonstrated as follows with the OCA2 gene…

In general, the derived allele (associated with lighter pigmentation) is most common in Europeans and East Asians, and the ancestral allele predominates in sub-Saharan Africa and Island Melanesia.

The mutations in the OCA2 gene may well have implications on imparting paleness, as demonstrated in the south African San people…

The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area.

While it seems plausible that the “derived” OCA2 gene came to being before the out-of-Africa migration that give rise to modern Eurasians, it doesn’t appear that this derived allele was necessarily widespread, and may well have been later on selected for in European and East Asians…

Interestingly, derived allele frequencies at this locus are quite different between Native American (15%) and East Asian populations (45%), suggesting that perhaps the derived allele at this locus did not reach very high frequencies in East Asians until after the colonization of the Americas

Contrast the situation with OCA2 gene with that of the MATP 374*G allele…

The virtual absence of MATP 374*G-derived allele in the sub-Saharan African populations that we examined in the CEPH-Diversity Panel is consistent with the origin of this mutation outside of Africa AFTER the divergence of modern Asians and Europeans.

Contrasting that of the “derived” SLC24 A5 [as in the case with the “derived” OCA2 allele], where two possible scenarios arise…

In contrast, the SLC24 A5 11*A-derived allele is found at low frequencies in several sub-Saharan populations including the West African Mandinka and Yoruba, the Southern African San, and South West Bantu. *The presence of the derived allele (albeit at low frequencies) in some sub-Saharan populations may be due to recent gene flow from European and Central Asian populations...

—1)The relatively high frequencies of the derived allele in Central Asian, Middle Eastern, and North Africa seem likely to be due to recent gene flow with European populations.

—2)Alternatively, the derived allele may have lost in the ancestors of modern East Asians but retained in the ancestral European populations. The allele then rose to high frequency in Europeans following the divergence of Europeans and East Asian ancestral groups.

The different mechanism of the evolution of light skin in Europeans and East Asians apparent from genetic examination, supports the understanding that evolution of pale skin came very late, because if had occurred prior to the divergence of the Europeans and East Asians, then it seems highly plausible that they would share more in common with one another the dominating alleles in playing a role in skin lightening…but as demonstrated, different set of alleles play dominating role in the lightening effect of the skin in Europeans and East Asians…

These results simultaneously and strongly suggest that Europeans and East Asians have evolved lighter skin independently and via distinct genetic mechanism, as there is an absence of any unusual pattern of diversity at SLC24A5, MATP, and TYR in East Asians.

The interesting part of the study, is this about the MC1R gene about its…

The MCIR gene was the only locus examined in detail that did not show any signal of potential positive selection. Previous sequence-based studies have reached conflicting conclusions about whether or not MC1R has been subject to positive selection outside of Africa (Rana et al. 1999; Harding et al. 2000; Makova et al. 2001).

Although MC1R’s association with red hair, fair skin, freckles, and melanorma risk in European and European-derived populations primarily from the British Isles (Box et al. 1997; Smith et al. 1998a; Schioth et al. 1999; Flanagan et al. 2000; Bastiaens et al. 2001) clearly demonstrates the important regional role that it plays in pigmentation, MC1R may have (with some exceptions [John et al. 2003; Nakayama et al. 2006]) little effect on variation outside of Europe (Myles et al. 2006). Consequently, no signal will be detected using our approaches.

Although the 2 SNPs that we typed in MC1R are not strongly associated with the red hair and fair skinned phenotype for which MC1R is so well known (Sturm et al. 2003), both are polymorphic in global surveys of populations (Rana et al. 1999; Harding et al. 2000). In addition, the MC1r G92A SNP may have a ”mild” effect on pigmentation phenotype (Motokawa et al. 2006). The 92*A allele at this site is known to have a lower affinity for alpha-MSH than wild-type MC1R alleles (Xu et al. 1996), which suggests that it may contribute to **normal** variation in pigmentation. However, if positive directional selection has acted on MC1R, we would expect variation at linked sites to be affected. As such, even if have not assayed the relevant SNP, we should still have observed some signal selection, especially given the small size (~3 kb) of this gene.

So polymorphisms in the MC1R gene seem to have had relatively more impact in Europeans than other populations. Perhaps this might have something to do with the effects of MCIR mutations in Europeans having an "exacerbating effect", i.e. in addition to those of other “pigmentation”-influencing alleles therein…or maybe to some degree, tenuously linked to the effects of one or the other, or a few of those lightening alleles in Europeans.

Finally, the seem to be a strong case for the ASIP and OCA2 genes in playing a role as a tale-teller [by way of ‘ancestral‘ genes and their ‘derived’ counterparts ] of the derivation of non-Africans from Africans, the populations wherein polymorphisms at these loci could well have played a role in skin tone variation to some degree or another…

The pattern of diversity at ASIP 8818*G allele (the ancestral allele associated with darker pigmentation) indicates a role primarily in African/non divergence (sub-Saharan African frequency; 66%, all other populations; 14%) rather than between darkly and lightly pigmented populations. At OCA2 355, the derived allele (linked with lighter pigmentation) occurs at its highest frequencies across Europe and Asia, but is also relatively common among Native American populations (18-34%) and is present at much lower frequencies (0-10%) among Bantu-speaking African groups. In contrast, the ancestral allele associated with **dark** pigmentation has a shared **high frequency** in sub-Saharan African and Island Melanesians...

Observed patterns of global skin pigmentation diversity and their correlation with environmental UV exposure suggest an adaptive response. Although we cannot rule out a role for sexual selection, our results support multiple genetic mechanisms for evolution of skin color. We provide evidence that at least 2 genes, ASIP and OCA2, probably played a shared role in shaping light and dark pigmentation across the globe.

Aside from non-sequitur about the need for “uniformity” in dark hue in ancestral humans, considering that not even a single immediate family or household will necessarily pass for such a ridiculous test, all in all, Kittles et al.’s analysis lend strong support to the claims made by the likes of Jablonski, about dark skin being the original or default state of Homo Sapien Sapiens!

As a matter of fact, this paper discredits Frank Sweet's claim on his "Onedroprule" site, about the "default" human skin tone being light brown of the likes of Khoisan, and the "supposed dark tone of Bantus being more recent", as others and the present author himself have demonstrated in "Egyptsearch.com" discussions. There is no evidence that Africans in their ancestral skin tone state were uniformly dark skin, but preponderance of evidence does show that dark skin was the ancestral state of human skin pigmentation. As noted already, the ancestral alleles appear to be shared between dark skin populations like Melanesisans and tropical Africans.

This posting above, is itself a slightly modified repro of earlier posting in the following link: White race very young [clickable Egyptsearch link]

Referenced source: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians, by Rick Kittles et al. , 2006.

Link to part 2: Skin pigmentation gene alleles — Part 2 [clickable]