Family and twin studies suggest that up to 50% of individual differences in human fertility within a population might be heritable. However, it remains unclear whether the genes associated with fertility outcomes such as number of children ever born (NEB) or age at first birth (AFB) are the same across geographical and historical environments. By not taking this into account, previous genetic studies implicitly assumed that the genetic effects are constant across time and space. We conduct a mega-analysis applying whole genome methods on 31,396 unrelated men and women from six Western countries. Across all individuals and environments, common single-nucleotide polymorphisms (SNPs) explained only ~4% of the variance in NEB and AFB. We then extend these models to test whether genetic effects are shared across different environments or unique to them. For individuals belonging to the same population and demographic cohort (born before or after the 20th century fertility decline), SNP-based heritability was almost five times higher at 22% for NEB and 19% for AFB. We also found no evidence suggesting that genetic effects on fertility are shared across time and space. Our findings imply that the environment strongly modifies genetic effects on the tempo and quantum of fertility, that currently ongoing natural selection is heterogeneous across environments, and that gene-environment interactions may partly account for missing heritability in fertility. Future research needs to combine efforts from genetic research and from the social sciences to better understand human fertility.
Showing posts with label evolution. Show all posts
Showing posts with label evolution. Show all posts
Gene-environment interaction for human fertility
Mega-analysis of 31,396 individuals from 6 countries uncovers strong gene-environment interaction for human fertility
Selection against Neanderthal introgression (two biorxiv preprints)
The Strength of Selection Against Neanderthal Introgression
Ivan Juric, Simon Aeschbacher, Graham Coopdoi: http://dx.doi.org/10.1101/030148
Hybridization between humans and Neanderthals has resulted in a low level of Neanderthal ancestry scattered across the genomes of many modern-day humans. After hybridization, on average, selection appears to have removed Neanderthal alleles from the human population. Quantifying the strength and causes of this selection against Neanderthal ancestry is key to understanding our relationship to Neanderthals and, more broadly, how populations remain distinct after secondary contact. Here, we develop a novel method for estimating the genome-wide average strength of selection and the density of selected sites using estimates of Neanderthal allele frequency along the genomes of modern-day humans. We confirm that East Asians had somewhat higher initial levels of Neanderthal ancestry than Europeans even after accounting for selection. We find that there are systematically lower levels of initial introgression on the X chromosome, a finding consistent with a strong sex bias in the initial matings between the populations. We find that the bulk of purifying selection against Neanderthal ancestry is best understood as acting on many weakly deleterious alleles. We propose that the majority of these alleles were effectively neutral-and segregating at high frequency-in Neanderthals, but became selected against after entering human populations of much larger effective size. While individually of small effect, these alleles potentially imposed a heavy genetic load on the early-generation human-Neanderthal hybrids. This work suggests that differences in effective population size may play a far more important role in shaping levels of introgression than previously thought.
The Genetic Cost of Neanderthal Introgression
Kelley Harris, Rasmus Nielsendoi: http://dx.doi.org/10.1101/030387
Approximately 2-4% of the human genome is in non-Africans comprised of DNA intro- gressed from Neanderthals. Recent studies have shown that there is a paucity of introgressed DNA around functional regions, presumably caused by selection after introgression. This observation has been suggested to be a possible consequence of the accumulation of a large amount of Dobzhansky-Muller incompatibilities, i.e. epistatic effects between human and Neanderthal specific mutations, since the divergence of humans and Neanderthals approx. 400-600 kya. However, using previously published estimates of inbreeding in Neanderthals, and of the distribution of fitness effects from human protein coding genes, we show that the average Neanderthal would have had at least 40% lower fitness than the average human due to higher levels of inbreeding and an increased mutational load, regardless of the dominance coefficients of new mutations. Using simulations, we show that under the assumption of additive dominance effects, early Neanderthal/human hybrids would have experienced strong negative selection, though not so strong that it would prevent Neanderthal DNA from entering the human population. In fact, the increased mutational load in Neanderthals predicts the observed reduction in Neanderthal introgressed segments around protein coding genes, without any need to invoke epistasis. The simulations also predict that there is a residual Neanderthal derived mutational load in non-African humans, leading to an average fitness reduction of at least 0.5%. Although there has been much previous debate about the effects of the out-of-Africa bottleneck on mutational loads in non-Africans, the significant deleterious effects of Neanderthal introgression have hitherto been left out of this discussion, but might be just as important for understanding fitness differences among human populations. We also show that if deleterious mutations are recessive, the Neanderthal admixture fraction would gradually increase over time due to selection for Neanderthal haplotypes that mask human deleterious mutations in the heterozygous state. This effect of dominance heterosis might partially explain why adaptive introgression appears to be widespread in nature.
More carriers of deeply diverged Y lineage (haplogroup A00) found in Cameroon
This possibly archaic African Y lineage was discovered a few years ago by hobbyists, and a project run and funded by hobbyists to collect and test additional A00 samples has started to report results:
There are some striking patterns in the results already. 85% of the A00 so far are from the Bangwa (Nweh) people, and 15% from the Nkongho-Mbo. This is despite the fact that nearly 57% of the samples collected were from Mbo, and only 37% were from Bangwa. Once all the results have been fully tabulated, we can provide more complete statistics. It will take a while to transcribe all the rich data from those handwritten sheets into electronic spreadsheets. [. . .]What's next? Matthew would like to head back to the field quite soon, in the second half of October, when the school where he teaches has a break. Our current plan is for him to visit the region of the Bamileke people. Matthew, an ethno-historian, has said "The similarity in names, language, dancing style and all other aspects of life suggest that the Bangwa are 90 percent Bamileke." By testing a good number of Bamileke, we'll be able to see whether the heritage they share includes A00, or not. It is possible that the A00 among the Bangwa comes from the indigenous people who originally inhabited the hills, before they arrived several centuries ago, or it could also have been present among the Bamileke earlier. Our results should give strong evidence to answer that question.
The next field trips should be even more exciting. One of our goals is to collect the most diverse samples of A00 possible, to uncover its internal structure. By sequencing the Y-DNA of A00 lines that have diverged and settled in different parts of Cameroon, we should be able to get a good idea of when those different lineages had a common ancestor, and understand better how the peoples among whom it's found are related.
One trip will take Matthew westward into the lowland regions close to Nigeria, where the Banyangi and Ejagham peoples live, toward the Cross River, home of the endangered Cross River Gorilla. These villages are also on the roads that led to the old Nigerian port of Calabar, where captives from Cameroon's highlands, including some Bangwa, were sold into slavery in the past. He has never before sampled in the western regions, and only 16 Banyangi have been tested in his past research, but there are versions of Bangwa history which say that these peoples make up a significant element of their founders. Members of the A0 haplogroup have been found in Nigeria, but we have no idea yet whether A00 are also found in that direction. The famed Iwo Eleru cave is in southern Nigeria, where a skull with archaic features has been found that dates to only 13,000 years ago, suggesting long survival of diverse humans in that region.
In his other trip, he'll seek to sample members of several of the different Pygmy communities of Cameroon, who live to the South and East. Among the Pygmy peoples, Matthew collected 53 samples in 2006, and two of them belonged to A00! These communities are far from the highlands where the Bangwa and Mbo live, so we can expect that their A00 will be quite distinct. This should be extremely interesting!
1000 Genomes phase 3 papers
Both papers are freely accessible:
A global reference for human genetic variation
An integrated map of structural variation in 2,504 human genomes
"Male Homosexual Preference" and social stratification
I don't necessarily buy positive selection for genes predisposing to male homosexuality in stratified societies via pleiotropic effects in females. But I could easily believe that evolutionary mismatch leads to higher levels of homosexuality in denser (though population density is apparently not a significant predictor in their analysis) and/or more stratified societies, and that sexually antagonistic selection plays some role in slowing down selection against homosexuality.
Male Homosexual Preference: Where, When, Why? (PLoS ONE):
Male homosexual preference (MHP) has long been of interest to scholars studying the evolution of human sexuality. Indeed, MHP is partially heritable, induces a reproductive cost and is common. MHP has thus been considered a Darwinian paradox. Several questions arise when MHP is considered in an evolutionary context. At what point did MHP appear in the human evolutionary history? Is MHP present in all human groups? How has MHP evolved, given that MHP is a reproductively costly trait? These questions were addressed here, using data from the anthropological and archaeological literature. Our detailed analysis of the available data challenges the common view of MHP being a “virtually universal” trait present in humans since prehistory. The conditions under which it is possible to affirm that MHP was present in past societies are discussed. Furthermore, using anthropological reports, the presence or absence of MHP was documented for 107 societies, allowing us to conclude that evidence of the absence of MHP is available for some societies. A recent evolutionary hypothesis has argued that social stratification together with hypergyny (the hypergyny hypothesis) are necessary conditions for the evolution of MHP. Here, the link between the level of stratification and the probability of observing MHP was tested using an unprecedented large dataset. Furthermore, the test was performed for the first time by controlling for the phylogenetic non-independence between societies. A positive relationship was observed between the level of social stratification and the probability of observing MHP, supporting the hypergyny hypothesis. [. . .]
Autosomal DNA from Atapuerca pre- or proto-Neanderthals
DNA from Neandertal relative may shake up human family tree
The Sima people, who lived before Neandertals, were thought to have emerged in Europe. Yet their teeth, jaws, and large nasal cavities were among the traits that closely resembled those of Neandertals, according to a team led by paleontologist Juan-Luis Arsuaga of the Complutense University of Madrid. As a result, his team classified the fossils as members of Homo heidelbergensis, a species that lived about 600,000 to 250,000 years ago in Europe, Africa, and Asia. Many researchers have thought H. heidelbergensis gave rise to Neandertals and perhaps also to our species, H. sapiens, in the past 400,000 years or so. [. . .]Darren Curnoe points out:After 2 years of intense effort, paleogeneticist Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology has finally sequenced enough nuclear DNA from fossils of a tooth and a leg bone from the pit to solve the mystery. [. . .] They scanned this DNA for unique markers found only in Neandertals or Denisovans or modern humans, and found that the two Sima fossils shared far more alleles—different nucleotides at the same address in the genome—with Neandertals than Denisovans or modern humans. “Indeed, the Sima de los Huesos specimens are early Neandertals or related to early Neandertals,” suggesting that the split of Denisovans and Neandertals should be moved back in time, Meyer reported at the meeting. [. . .]
“It resolves one controversy—that they’re in the Neandertal clade,” says paleoanthropologist Chris Stringer of the Natural History Museum in London. “But it’s not all good news: From my point of view, it pushes back the origin of H. sapiens from the Neandertals and Denisovans.” The possibility that humans were a distinct group so early shakes up the human family tree, promising to lead to new debate about when and where the branches belong.
What are the broader implications of the research for understanding the evolution of living humans?First, the finding pushes the age of the shared human-Neanderthal ancestor well beyond 400,000 years ago, suggesting our species, H. sapiens, might also be at least this old.
Also, with the Atapuerca group living in Europe, it’s even possible that our species evolved in this or an adjacent region of Eurasia, and later migrated back into Africa.
And being close to the common ancestor, the Atapuerca fossils give us real insights into what it must have looked like and the ancestral body form of our own species.
The fossils from Europe, Asia and Africa from around this time are physically very diverse, with some researchers thinking they represent multiple species, only one of which could be the ancestor of living humans.
Question is, which one?
This new research suggests the European branch is closest among them all and deserves much more attention in this regard.
In contrast, we don’t know, and will doubtless ever know, whether Homo naledi had anything to do with the evolution of living humans, least of all whether its brain, mind or behaviour were anything like our own.
ASHG 2015: Population differentiation analysis of 54,734 European Americans
Population differentiation analysis of 54,734 European Americans reveals independent evolution of ADH1Bgene in Europe and East Asia.
K. J. Galinsky1,2 ; G. Bhatia2,3 ; P. Loh2,3 ; S. Georgiev4 ; S. Mukherjee5 ; N. J. Patterson2 ; A. L. Price1,2,3
Population differentiation is a widely used approach to detect the action of natural selection. Existing methods search for unusual differentiation in allele frequencies across discrete populations, e.g. using FST. Loci that are unusually differentiated with respect to the genome-wide FST or with respect to a null distribution of FST are reported as signals of selection. These approaches are particularly powerful for closely related populations with large sample sizes.However, population genetic data often is not naturally partitioned into discrete populations. We developed a test for selection that uses SNP loadings from principal components analysis (PCA). For a given PC reflecting geographic ancestry, under the null hypothesis of no selection, the square of the SNP loadings, rescaled by a scaling factor derived from the eigenvalue of the PC, follows a chi-square (1 d.o.f.) distribution. This statistic is able to infer selection with genome-wide significance, a key consideration in genome scans for selection. We confirmed via simulations that this statistic has correct null calibration under a wide range of demographies and is well-powered to detect selection at large sample sizes.We applied the method to a cohort of 54,734 European Americans genotyped on genome-wide arrays. PCs were inferred using our FastPCA software (running time: 57 minutes). The top 4 PCs corresponded to clines of Irish, Eastern European, Northern European, Southeast European and Ashkenazi Jewish ancestry, validated via PCA projection of samples of known ancestry. We detected genome-wide significant signals of selection at 4 known selected loci (LCT, HLA, OCA2 and IRF4) and 3 novel loci: ADH1B, IGFBP3 and IGH. 2 of the 3 novel loci could not be detected using discrete-population tests (or other existing tests). The ADH1B gene is associated with alcoholism (via the same coding SNP rs1229984 producing a signal in our selection scan) and has been shown to be under recent selection in East Asians (via a haplotype-based test for recent selection); we show here that it is a rare example of independent evolution on two continents. The IGFBP3 gene and IGH locus have been implicated in breast cancer and multiple sclerosis, respectively. Our results show that application of our PC-based selection statistic to large data sets can infer novel, genome-wide significant signals of selection at loci linked to disease traits.
ASHG 2015: The lingering load of archaic admixture in modern human populations
The lingering load of archaic admixture in modern human populations.
K. Harris1,2 ; R. Nielsen2,3
1) Stanford University, Stanford, CA; 2) University of California Berkeley, Berkeley, CA; 3) Center for Bioinformatics, University of Copenhagen, Copenhagen, Denmark.
Founder effects and bottlenecks can damage fitness by letting deleterious alleles drift to high frequencies. This almost certainly imposed a burden on Neanderthals and Denisovans, archaic hominid populations whose genetic diversity was less than a quarter of the level seen in humans today. A more controversial question is whether the out-of-Africa bottleneck created differences in genetic load between modern human populations. Some previous studies concluded that this bottleneck saddled non-Africans with potentially damaging genetic variants that could affect disease incidence across the globe today (e.g. Lohmueller, et al. 2009; Fu, et al. 2014), while other studies have concluded that there is little difference in genetic load between Africans and non-Africans (e.g. Simons, et al. 2014; Do, et al. 2015). Although previous studies have devoted considerable attention to simulating the accumulation of deleterious mutations during the out-of-Africa bottleneck, none to our knowledge have incorporated the fitness effects of introgression from Neanderthals into non-Africans. We present simulations showing that archaic introgression may have had a greater fitness effect than the out-of-Africa bottleneck itself, saddling non-Africans with weakly deleterious alleles that accumulated as nearly neutral variants in Neanderthals. Assuming that the exome experiences deleterious mutations with additive fitness effects drawn from a previously inferred gamma distribution, we predict that the fitness of the average Neanderthal was about 50% lower than the fitness of the average human, implying the existence of strong selection against early Neanderthal-human hybrids. This is a direct consequence of mutation accumulation during a period of low Neanderthal population size that is thought to have lasted ten times longer than the out-of-Africa bottleneck (Pruefer, et al. 2014). Although our model predicts some transmission of deleterious Neanderthal variation to present-day non-Africans, it also predicts that many Neanderthal alleles have been purged away, depleting conserved genomic regions of Neanderthal ancestry as observed empirically by Sankararaman, et al. (2014). Our results imply that the deficit of Neanderthal DNA from functional genomic regions can be explained without the action of epistatic reproductive incompatibilities between human and Neanderthal alleles.
Population genetic differentiation of height and body mass index across Europe
From Visscher and colleagues:
Population genetic differentiation of height and body mass index across EuropeAcross-nation differences in the mean values for complex traits are common1, 2, 3, 4, 5, 6, 7, 8, but the reasons for these differences are unknown. Here we find that many independent loci contribute to population genetic differences in height and body mass index (BMI) in 9,416 individuals across 14 European countries. Using discovery data on over 250,000 individuals and unbiased effect size estimates from 17,500 sibling pairs, we estimate that 24% (95% credible interval (CI) = 9%, 41%) and 8% (95% CI = 4%, 16%) of the captured additive genetic variance for height and BMI, respectively, reflect population genetic differences. Population genetic divergence differed significantly from that in a null model (height, P < 3.94 × 10−8; BMI, P < 5.95 × 10−4), and we find an among-population genetic correlation for tall and slender individuals (r = −0.80, 95% CI = −0.95, −0.60), consistent with correlated selection for both phenotypes. Observed differences in height among populations reflected the predicted genetic means (r = 0.51; P < 0.001), but environmental differences across Europe masked genetic differentiation for BMI (P < 0.58).
Collective violence in Early Neolithic Central Europe
With the recently examined LBK mass grave site of Schöneck-Kilianstädten, Germany, we present new conclusive and indisputable evidence for another massacre, adding new data to the discussion of LBK violence patterns. At least 26 individuals were violently killed by blunt force and arrow injuries before being deposited in a commingled mass grave. Although the absence and possible abduction of younger females has been suggested for other sites previously, a new violence-related pattern was identified here: the intentional and systematic breaking of lower limbs. The abundance of the identified perimortem fractures clearly indicates torture and/or mutilation of the victims. The new evidence presented here for unequivocal lethal violence on a large scale is put into perspective for the Early Neolithic of Central Europe and, in conjunction with previous results, indicates that massacres of entire communities were not isolated occurrences but rather were frequent features of the last phases of the LBK.Ancient mass grave reveals evidence of brutal massacre among Europe's prehistoric farmers
Archaeologists who painstakingly examined the bones of some 26 men, women and children buried in the Stone Age grave site at Schoeneck-Kilianstaedten, near Frankfurt, say they found blunt force marks to the head, arrow wounds and deliberate efforts to smash at least half of the victims' shins — either to stop them from running away or as a grim message to survivors. [. . .]Related:"What is particularly interesting is the level of violence. Not just the suppression of a rival community — if that is what it was — but the egregious and systematic breaking of the lower legs," said Scarre. "It suggests the use of terror tactics as part of this inter-community violence." [. . .]
"The LBK population had expanded considerably, and this increases the potential for conflict," said Meyer. "Also, the LBK were farmers, they settled. So unlike hunter gatherers, who could move away to avoid conflict, these people couldn't just escape. Add to this the fact that there may have been a period of drought that constrained resources, causing conflicts to erupt."
Meyer said the theory of conflict between different groups within the LBK is supported by the existence of an apparent ancient border near the Schoeneck-Kilianstaedten site. Archaeologists have found that flint was traded on either side of the divide but not necessarily across it — suggesting the two groups did not see each other as kin, he said.
The attackers, however, spared some members of the group, with victims skewed toward young children, adult men and older women.
"It's likely that the young women, who are missing in the grave, were kidnapped by the attackers," said Meyer.
- "Ancestral men probably competed for mates mainly by excluding competitors by force or threat"
- Sewall Wright on race differences, group selection, and cultural selection among humans (1978)
- More from Hamilton on kin recognition and intergroup hostility
With pleasure in cruelty as the motivation to punishment,62 and with cruelty to create terror, an individualistic argument sounds less plausible; but considering inclusive fitness, or group selection (which may be a really appropriate term for many human situations), there is no theoretical difficulty. For example, a priori, terror seems as good a weapon as false promises in bringing about the early submission or removal of a threatened tribe.
Sewall Wright on race differences, group selection, and cultural selection among humans (1978)
[From Evolution and the Genetics of Populations, Volume 4: Variability Within and Among Natural Populations, pp. 439-457]
Racial Differentiation in Mankind
The existence of conspicuous diversity among human populations in physical appearance has been common knowledge at least since the time of ancient Egypt. The subject is discussed at length in numerous books on physical anthropology and need not be considered here in detail.
There is no question that all mankind constitutes a single species in view of the absence of any physiological bar to hybridization between the most diverse races or of any recognizable loss of vigor in the first or later generations.
There is also no question, however, that populations that have long inhabited widely separated parts of the world should, in general, be considered to be of different subspecies by the usual criterion that most individuals of such populations can be allocated correctly by inspection. It does not require a trained anthropologist to classify an array of Englishmen, West Africans, and Chinese with 100% accuracy by features, skin color, and type of hair in spite of so much variability within each of these groups that every individual can easily be distinguished from every other.
[. . .] It has been indicated earlier that such an evolutionary process as that of man is much more understandable if it occurred by the shifting balance process. Simultaneous sampling drive at thousands of sufficiently neutral loci provides different material in innumerable localities without appreciable cost, material that can give the basis for effective interdeme selection.
Was the population structure of primitive man favorable to this process? There have been a number of studies of the few remaining peoples at the hunting and gathering level of culture that bear on this matter. Birdsell (1972), in an intensive study of Australian aborigines in western Australia, has described their population structure. The primary territorial unit is the band, consisting of a group of related families. Marriage is exogamous but largely restricted to the tribe, a group of bands in which the same dialect is spoken. He estimates the average total number in a tribe to be about 500, with a breeding population of about 185 and an effective number of about 100. This is small enough for the building up of considerable differences among large areas at each nearly neutral polymorphic locus merely by sampling drift. There is thus the basis for operation of the shifting balance process. [. . .]
The actual process of interdeme selection may take different forms. At one extreme, the local appearance of a superior genetic system is followed by expansion of its territory accompanied by complete elimination of its neighbors until it occupies the entire range of the species. At the other extreme there is merely excess diffusion from the superior center. Neighboring populations are graded up until they reach the point (the crossing of a saddle in the surface of selective values) at which mass selection carries them autonomously to the new selective peak, or perhaps beyond, if they contribute something that improves on the latter. The locations of the population with the highest selective peak may shift from place to place in the course of time, as a group of neighboring populations step each other up to heights well above the general level.
Bigelow (1969) has emphasized the importance of tribal warfare in the operation of this process. A tribe that is generally successful because of superior intelligence, capacity for cooperation, and high frequency of the heroic virtues as well as physical prowess, tends to increase its territory and also to grade up what is left of the defeated group by hybridization. The process is illustrated by the incessant tribal warfare of the tribes of American Indians observed by the European settlers in America, in which some tribes such as the Iroquois expanded at the expense of their neighbors.
The heroic virtues, including willingness to sacrifice one's own life for the good of the tribe, are traits that can hardly be developed (insofar as they have a genetic basis) by purely individual selection. They may to some extent arise as a by-product of familial selection in which close relatives with heredities strongly correlated with that of an individual who gives his own life to save them. As noted earlier, the effectiveness of familial selection in general is testified to by the improvement of milk production in cattle and of egg production fowls, mainly by selection of males on the basis of the performance of close female relatives. The importance of this sort of intergroup selection in evolution has been emphasized as noted in chapter 7 by Hamilton. The increase in frequency of traits deleterious on the average to their possessors but beneficial to the deme may also, however, be increased by interdeme selection (referred to as intergroup selection in early articles) if the benefit to the deme sufficiently outweighs the damage to the individual. A more rigorous demonstration of this mode of evolution of "altruistic" characters as been given by Eshel (1972).
Not all interdeme selection in man has consisted of intertribal warfare. According to Birdsell, about 15% of marriage among Australian aborigines were intertribal; not enough as shown by the wide variability of gene frequencies to homogenize the whole population but enough to permit effective interdeme selection if exchange was asymmetrical, predominantly from the more to the less successful. That differences were not swamped was presumably due to the exchange being largely between neighboring tribes which differed little, as indicated by the semiclinal nature of the pattern of gene frequencies. The average effective immigration from the population as a whole, the m of formulas, was thus very much less than 0.15. [. . .]
Evolution Since the Origin of Agriculture [. . .]
We can form a better idea of the course of event than in any earlier period but the interpretation is confused by the exponential progress of a second evolutionary process, barely existent at all in any other animal, and little if any more rapid in the earlier history man than his biological evolution.
This is the evolution of culture with its line of transmission largely from speaker to listener, supplemented in the last three thousand years by transmission from writer to reader. It began to become of major importance with the origin of language, but during the hunting and gathering phase of human life the slow advance of culture is indicated by that in the fashioning of stone tools and weapons. It was probably accompanied by relatively rapid diffusion of knowledge of such advances as were made. The success of tribes thus probably depended to a greater extent on capabilities, determined by their genes, than on the possession of techniques not known to their neighbors.
The mode of evolution of culture is analogous to that of the genetic system. Invention is the analog of mutation. Diffusion of culture is the analog of gene flow. Cultural variation is continually subject to selection on the basis of utility. There is random cultural drift, exemplified by the breaking up of languages into dialects. Finally, the most favorable conditions for cultural advance is local isolation, providing the basis for simultaneous trial and error among many variants and the diffusion of the more successful ones in analogy with the shifting balance process in biological evolution. We think here of the multiple competing cultures in ancient Southwest Asia, the evolution of culture among the city states of ancient Greece, and in much divided Europe from the Dark Ages to modern times. The great empires of the ancient Southwest Asia of Alexander and of Rome constituted an overbalancing final phase in the process, giving widespread diffusion but less progress by trial and error.
There has undoubtedly always been a considerable but incomplete correlation between the two kinds of evolution. The state of the culture has been to a considerable extent an index of the rank of populations genetically in the distinctive human line of evolutionary advance, and reciprocally the demands of culture have been the primary selective agent in this advance in its later stages. Aspects of culture are continually being borrowed, but whether such borrowings are effectively integrated into the existent culture to form new peaks (as most conspicuously in the recent period in Japan), or are adopted only superficially and to the detriment of the previous culture, is also an index of genetic capability.
The treatment of either the genetic capabilities or the cultures of peoples as if they could be ranked on single scales is, of course, a gross simplification. If the multiple genetic aspects of mental ability could be measured more independently of culture than is the case, it would no doubt be found that each local race has its own unique combination of favorable qualities. At present only IQ seems to have a repeatability that permits evaluation of the contributions of genetic and nongenetic variabilities to its variability, discussed in the previous chapter, and this only within a particular culture.
On the other hand there have probably always been wide differences among the peoples of the world in average intellectual ability and cultural level from the standpoint of progress toward the situation in civilized man. This was presumably related to the environmental conditions. Men could not endure the northern winters without fire, the use of which is documented by hearths found in France dating back over half a million years and somewhat later in Hungary and in China but only about one-tenth as far back in Africa (Campbell 1974).
The capacity to anticipate and plan for the future is a mental attribute which would be favored under northern conditions and selected for insofar as it has a genetic basis. This would presumably have come to be more advanced in the temperate zone than in the tropics. [. . .]
Linguistic evidence indicates the establishment of an important center of diffusion in east-central Europe some 5,000 years ago from which wave after wave peoples moved in all directions. The Hittites carried an Indo-European language of the western (centum) type into Asia Minor and established an empire some 4,000 years ago. A thousand years later the Iranians, who had moved east into what is now southern Russia and Turkestan, brought an Indo-European language of the eastern (satem) type into the original cultural center and later established the Persian Empire. They also carried another Aryan dialect to India. Other tribes moving south from the east-central European center reached Greece in several waves which, after mixing with the indigenous people, produced classical Greek civilization.
Other waves moved to the southwest into Italy, giving rise to Latin and other Italic languages; to the west, giving rise to Celtic languages in what is now southern Germany, France, and the British Isles; and to the northwest into what is not northern Germany and Scandinavia, to give rise, in much altered form, to the Germanic languages. Subsequent migrations greatly expanded the areas occupied by derivatives of Latin and Germanic branches at the expense in Europe of the Celtic. All the tribal migrations were undoubtedly accompanied by much intermixture with indigenous peoples, but the diffusion of language also undoubtedly implies considerable gene flow.
[. . .] The history of Europe, especially western Europe, was thus prevailingly one of inflow of genes up to the relatively recent period in which it itself became a center of massive outflow.
Related posts:
- Sewall Wright on Coefficients of Inbreeding and Relationship (1922)
- Hamilton on inclusive fitness and social behavior in humans
- More from Hamilton on kin recognition and intergroup hostility
- R. A. Fisher on group selection in humans
- James Neel and early human population structure
- Massive migration from the steppe is a source for Indo-European languages in Europe
- More ancient DNA evidence of Indo-European mass migrations
- C. S. Coon on the endocrine system and racial differences in temperament
Sewall Wright on Coefficients of Inbreeding and Relationship (1922)
JayMan continues to misunderstand basic population genetics, and continues to respond to people who point this out to him by sticking his fingers in his ears and reiterating his misunderstandings:
@johan stavers:I attempt yet again to get across to JayMan that the table of coefficients of relationship he looked up on wikipedia in no way proves that "unrelated" members of a given race share no kinship relative to members of other races (if JayMan were correct, of course, observable racial differences would not exist; JayMan inadvertently assesses his own level of knowledge in an unrelated twitter comment: "according to people who don't know science, there's no such thing as race."). Sewall Wright explicitly noted in the 1922 paper in which he defined coefficients of relationship that values like ".50 for brothers" hold "in a random stock" and that individuals belonging to an "inbred subline" will share relatedness relative to the general population.coefficient of relationship is flawed, if a man fathers a child with his sister his child is more than 50% related, this extends to niece/nephew mating and therefore logically also to mating within ethnicity or even nationNo, coefficient of relationship is perfectly fine.
JayMan, the fact that the table of "coefficients of relationship" on wikipedia is not valid for the purpose you're attempting to use it is not some subtle issue that's open to debate, but a point that follows directly from the definitions of the relevant terms.
Thus, if we can calculate the percentage of homozygosis which would follow on the average from a given system of mating, we can at once form the most. natural coefficient of inbreeding. The writer3 has recently pointed out a method of calculating this percentage of honmozygosis which is applicable to the irregular systems of mating found in actual pedigrees as well as to regular systems. This method, it may be said. gives results widely different from Pearl's coefficient, in many cases even as regards the relative degree of inbreeding of two animals.Taking the typical case in which there are an equal number of dominant. and recessive genes (A and a) in the population, the random-bred stock will be composed of 25 per cent. AA, 50 per cent. Aa and 25 per cent. aa. Close inbreeding will tend to convert the proportions to 50 per cent. AA, 50 per cent. aa, a change from 50 per cent. homozygosis to 100 per cent. homozygosis. For a natural coefficient of inbreeding, we want a scale which runs from 0 to 1, while the percentage of homozygosis is running from, 50 per cent. to 100 per cent. The formula. 2h-1, where h is the proportion of complete homozygosis, gives the required value. This can also be written 1-2p where p is the proportion of heterozygosis. In the above-mentioned paper it was shown that the coefficient of correlation between uniting egg and sperm is expressed by this same formula, f 1-2p. We can thus obtain the coefficient of inbreeding fb for a given individual B, by the use of the methods there out- lined.
The symbol rbc, for the coefficient of the correlation between B and C, may be used as a coefficient of relationship. It has the value 0 in the case of two random individuals, .50 for brothers in a random stock and approaches 1.00 for individuals belonging to a closely inbred subline of the general population. [. . .]
If an individual is inbred, his sire and dam are connected in the pedigree by lines of descent from a common ancestor or ancestors. The coefficient of inbreeding is obtained by a summation of coefficients for every line by which the parents are connected, each line tracing back from the sire to a common ancestor and thence forward to the dam, and passing through no individual more than once. The same ancestor may of course be involved in more than one line.
Coefficients of Inbreeding and Relationship
Sewall Wright
The American Naturalist
Vol. 56, No. 645 (Jul. - Aug., 1922), pp. 330-338
http://www.jstor.org/stable/2456273Go ask Greg Cochran about this if comprehension continues to elude you.
From Wright's 1943 paper on "Isolation by distance" (pdf):
Study of statistical differences among local populations is an important line of attack on the evolutionary problem. While such differences can only rarely represent first steps toward speciation in the sense of the splitting of the species, they are important for the evolution of the species as a whole. They provide a possible basis for intergroup selection of genetic systems, a process that provides a more effective mechanism for adaptive advance of the species as a whole than does the mass selection which is all that can occur under panmixia. [. . .]Sewall Wright, incidentally, was of New England Puritan stock.THE INBREEDING COEFFICIENT
Departures from panmixia may be expressed in terms of the average inbreeding coefficient of individuals, relative to the total population under consideration. This coefficient has been defined as the correlation between uniting gametes with respect to the gene complex as an additive system. It has been shown that its value can be found for any pedigree by finding all paths by which one may trace back from the egg to a common ancestor (A) and thence forward to the sperm along a wholly different path. [. . .]
The inbreeding, measured by F, may be of either of two extreme sorts: sporadic mating of close relatives with no tendency to break the population into subgroups, and division into partially isolated subgroups, within each of which there is random mating. The latter is the case in which we are primarily interested here.
"Ancestral men probably competed for mates mainly by excluding competitors by force or threat"
An abstract of a paper by David Puts on Human Sexual Selection:
Related posts:Highlights
• Sexual selection has been stronger in humans than is often assumed.
• Ancestral men competed primarily through force and threat of force.
• Ancestral women competed mainly through mate attraction.
• Understanding sexual selection clarifies some human psychological sex differences.Abstract
Sexual selection favors traits that aid in competition over mates. Widespread monogamous mating, biparental care, moderate body size sexual dimorphism, and low canine tooth dimorphism suggest modest sexual selection operating over human evolution, but other evidence indicates that sexual selection has actually been comparatively strong. Ancestral men probably competed for mates mainly by excluding competitors by force or threat, and women likely competed primarily by attracting mates. These and other forms of sexual selection shaped human anatomy and psychology, including some psychological sex differences.
Reply to RCB on the evolution and adaptiveness of ethnocentric altruism
Continued from this discussion.
"you are unable to explain to a competent person why you believe what you believe."
I'm trying to be patient here, but I don't know how much better I can explain this. You either get it, or you don't. If you don't, you're not as competent as you believe; you either don't really understand the basic concepts we're talking about or have mental blocks when it comes to applying them to humans, and this is something you need to deal with yourself.
No matter how many times I explain this, you don't want to get it. Your starting point is that Salter can't be right; so when I explain to you how your reasoning is flawed, regardless of how many times we go through this or how many times I address a particular objection, your response is just to throw out additional confused reasoning, often forgetting things you previously agreed I was correct on and switching back to objections that have already been addressed.
The benefit of the ethnocentric altruism alleles comes from between-group selection, not within-group selection. Even in the first generation, an allele for ethnocentric altruism can potentially boost its odds of representation in future generations by, for example, reducing the chance of extinction of the group it's found in (whether by contributing to avoiding defeat and extermination by rival groups in an ancestral environment, or resisting replacement-level immigration in the modern world).
It makes no difference whether there is enough between-group relative to within-group competition at modern scales to maintain or grow this sort of variation in the long run (and certainly Hamilton speculated that self-sacrificing altruism would be found at higher levels in tribal people than in the long-civilized). In a particular instance of intergroup competition of the sort we're discussing, ethnocentric altruism alleles attuned to Hamilton's rule would by definition be adaptive.
This will always be true, regardless of scale, and regardless of how often the group is actually faced with the threat of intergroup competition. In the face of such a threat, the alleles (ones that enhance group competitiveness in a generalized fashion and are sensitive to cost, benefit, and relatedness) will be adaptive.
Your argument is somewhat analogous to claiming sickle-cell alleles can't be adaptive (or even exist in the first place!) in a malarial environment because their frequency would not increase in the long run in the absence of malaria. Even if malaria is nearly wiped out and the frequency of sickle-cell alleles begins to decline, this does not prove that if a mosquito with malaria does land on you you'd be better off not having a sickle-cell allele.
"Yes, the behaviors are polygenic. But all genes have to start at low frequency, and you have not explained how they get to high frequency"
Again: positive selection will come from intergroup competition. If your argument is that all relevant variants would be snuffed out immediately, leaving no variation on which group-level selection could act, this is of course absurd. Yet again: we're talking about very large numbers of weakly-selected variants, and a large surface on which new mutations can arise.
Crow and Aoki modeled group selection for polygenic behavioral traits. Again, it boils down to Hamilton's rule.
Group selection for a polygenic behavioral trait: a differential proliferation model [pdf]
Group selection for a polygenic behavioral trait: estimating the degree of population subdivision [pdf]
Our general approach is to use molecular markers, which are selected very weakly at most, as neutral indicators of population structure. GST gives us an appropriate description of the relevant aspect of the structure. By using Eq. 3 we can state the maximum value of cost/benefit of a quantitative trait if that trait is to increase in average value or frequency in the population. GST describes the present structure of the population; it does not tell us how it got that way. If this value has been roughly stable in the past, we could expect that traits with c/b up to this value would have increased in the population, assuming of course that such traits exist and have heritability greater than zero.
Empirically, ethnocentrism exists, and no doubt has since before we were humans. Empirically, ethnocentrism has heritability greater than zero.
Nature, nurture, and ethnocentrism in the Minnesota Twin Study [pdf]
Common Heritable Effects Underpin Concerns Over Norm Maintenance and In-Group Favoritism: Evidence From Genetic Analyses of Right-Wing Authoritarianism and Traditionalism [pdf]
- Genetic evidence for multiple biological mechanisms underlying in-group favoritism [pdf]
Your issue is with reality, not with Salter or me.
"Of course, ethnic altruist genes could be maladaptive relics of the past, when groups were small. But Salter says they are adaptive now."
Again, see above.
And Salter never claims we are well-adapted to ethnic competition in the modern world. If he'd believed that to be the case, he would have had little reason to write the book. From the introduction:
On Genetic Interests is an attempt to answer the empirical question: How would an individual behave in order to be adaptive in the modern world? I adopt the neo-Darwinian meaning of adaptive, which is to maximize the survival chances of one’s genes. I begin by describing humans as an evolved species and thus as creatures for whom genetic continuity consists of personal reproduction or reproduction of kin. [. . .]Humans can no longer rely on their instincts
There is nothing immutable or necessarily perfect about adaptations or the understanding, appetites and preferences they organize. Natural selection is constrained by evolutionary history and environment. It shapes bodies and behaviours in small increments by modifying existing species. Much in nature is badly designed, if one examines it from an engineer’s viewpoint. [. . .]
Like adaptations that advance them, proximate interests can be imperfect in promoting genetic interests. The main problem is the slowness of natural selection compared to the rapidity of technological and social change since the Neolithic. The inertia of adaptations can cause them to continue to promote proximate interests that no longer serve fitness. For most of humans’ evolutionary history, adaptations tracked slow-moving environmental change, including technological advances. In the species’ distant hominid and pre-hominid past, proximate interests that reduced an actor’s fitness were valued less and less as the genes that coded for such valuation failed to reproduce. For this reason, at most moments in time proximate interests have correlated with ultimate interests because the environment has changed so slowly that physiology and behaviour could keep track with it. Proximate and ultimate interests have been in equilibrium except where rapid changes in environment occurred. The equilibrium applying to humans has been upset in recent generations, so that we can no longer rely on subjectively designated proximate interests to serve our ultimate interest. We must rely more on science to perceive the causal links between the things we value and formulate synthetic goals based on that rational appraisal.
Proximate interests, often reflected in consciously held values, have become increasingly fallible guides to ultimate interests because modern humans live in a rapidly changing world. Humans evolved in small bands consisting of a few families, sometimes grouped into tribes numbering in the hundreds. For most of their evolutionary history humans made a living by hunting and gathering in largely natural environments. They lacked formal organization and hierarchy. Adults coordinated activities by negotiating simple demographic role specializations — by age and sex — on an egalitarian basis with familiar band members. Most information was common. Humans now live in societies numbering in the millions where the great majority of interactants are strangers or acquaintances. They make their living through a great diversity of occupations resulting in radical asymmetries in information. They live and work in largely man-made urban environments. They are formally organized into states administered by extended hierarchies of rank and resources actuated by authoritative commands, impersonal contracts enforced by the state authority, and powerful forms of indoctrination performed by universal education, centralized media and entertainment.
However, to the extent we are able to correctly reason about what would be adaptive in the context of intergroup competition, and act in accordance with this, we have the equivalent of our generalized ethnocentric altruism alleles.
Related:
Evolutionary significance of Denisovan admixture in Oceanians
Investigating the Evolutionary Importance of Denisovan Introgressions in Papua New Guineans and Australians
Previous research reported that Papua New Guineans (PNG) and Australians contain introgressions from Denisovans. Here we present a genome-wide analysis of Denisovan introgressions in PNG and Australians. We firstly developed a two-phase method to detect Denisovan introgressions from whole-genome sequencing data. This method has relatively high detection power (79.74%) and low false positive rate (2.44%) based on simulations. Using this method, we identified 1.34 Gb of Denisovan introgressions from sixteen PNG and four Australian genomes, in which we identified 38,877 Denisovan introgressive alleles (DIAs). We found that 78 Denisovan introgressions were under positive selection. Genes located in the 78 introgressions are related to evolutionarily important functions, such as spermatogenesis, fertilization, cold acclimation, circadian rhythm, development of brain, neural tube, face, and olfactory pit, immunity, etc. We also found that 121 DIAs are missense. Genes harboring the 121 missense DIAs are also related to evolutionarily important functions, such as female pregnancy, development of face, lung, heart, skin, nervous system, and male gonad, visual and smell perception, response to heat, pain, hypoxia, and UV, lipid transport, metabolism, blood coagulation, wound healing, aging, etc. Taken together, this study suggests that Denisovan introgressions in PNG and Australians are evolutionarily important, and may help PNG and Australians in local adaptation. In this study, we also proposed a method that could efficiently identify archaic hominin introgressions in modern non-African genomes.
Chris Stringer on the possibility of a Eurasian origin for Homo heidelbergensis
H. heidelbergensis is a critical human species in the Middle Pleistocene (∼130–780 thousand years ago (ka)). We know from several beautifully preserved crania that this species had a large brain, within the lower range of modern human variation, and a less robust face than early fossil humans. We know from their long bones that they were tall, strong people. From their associated archaeology we know they were capable of producing beautiful tools such as the large handaxes found in huge numbers at Boxgrove in Sussex. But there are many unanswered questions: who exactly belongs to the species Homo heidelbergensis, where did they live, how do they fit into the human family tree, and are they a separate species at all? [. . .]Related:Are they our ancestors? African H. heidelbergensis material, such as Broken Hill, shares numerous features with European fossils such as Petralona, leading many to group them together. As long as Mauer is also included, this taxon can be named H. heidelbergensis. Proponents of this wide concept of H. heidelbergensis assert that the mosaic of primitive and derived features shared by this group of fossils is unique, with few traits linking them exclusively to either modern humans or Neanderthals ( Figure 1B). H. heidelbergensis is thus hypothesised to be the last common ancestor of both Neanderthals in Eurasia and H. sapiens in Africa. This scenario is probably the most popular and well supported at present. [. . .]
The geographic origin of H. heidelbergensis is still unknown, but the early fossils from Asia suggest that continent is as likely a place of origin as Europe or Africa at the moment. An Asian origin for a species directly ancestral to our own would certainly shake up the current rather Afro-centric view of our evolution.
Inbreeding and inclusive fitness
Inbreeding avoidance, tolerance, or preference in animals?
The widespread presumption that inbreeding depression will inevitably cause net selection for inbreeding avoidance ignores the inclusive fitness benefit of inbreeding that exists because parents are more closely related to inbred offspring than to outbred offspring. This increased relatedness arises because inbred offspring, by definition, inherit alleles from one parent that are identical by descent to those carried by, and potentially inherited from, the other parent. Inbreeding thereby increases the expected proportion of alleles that any one parent shares with its offspring, including alleles favouring inbreeding [10,24,25]. This inclusive fitness benefit underpins extensive theory predicting the evolution of self-fertilisation in plants [10,25–27]. That this same benefit could also cause the evolution of biparental inbreeding was suggested three decades ago (Box 1) [28,29], but remained widely ignored by animal ecologists. The assumption that inbreeding depression inevitably causes selection for inbreeding avoidance continued to pervade hypotheses explaining dispersal, mate choice, and polyandry [3,5,6,11,30–32]. Recent theory has re-emphasised that biparental inbreeding could be adaptive, even given inbreeding depression, with the inclusive fitness benefit phrased as ‘helping relatives to breed’ and hence kin selection [12,13,33].What Happens after Inbreeding Avoidance? Inbreeding by Rejected Relatives and the Inclusive Fitness Benefit of Inbreeding Avoidance
The fitness costs associated with inbreeding, primarily inbreeding depression in resulting offspring, have caused a widespread assumption among animal ecologists that inbreeding avoidance must be adaptive [10, 21, 22]. Meanwhile, empirical studies have reported a lack of inbreeding avoidance [34, 42–47], or even an apparent preference for inbreeding [48–52], causing a mismatch between expectations and data [27]. This mismatch is partially resolved by basic conceptual models of biparental inbreeding that imply that the inclusive fitness benefit of inbreeding might cause inbreeding tolerance or preference to be adaptive even given inbreeding depression in offspring fitness, and that predict sexual conflict over inbreeding [24–28]. [. . .]Related:Our models imply that the inclusive fitness costs and benefits of inbreeding versus avoiding inbreeding will vary among individuals depending on their interactions with multiple different relatives of both sexes, and on the degree to which focal individuals are themselves inbred. Understanding these costs and benefits and their combined consequences for the evolution of inbreeding strategies therefore requires consideration of not only the relatedness of an individual to its potential mate(s), but also the relatedness between the individual and the subsequent mates of rejected relatives. Knowledge of the distribution of relatedness within a population is therefore likely to be critical for understanding the evolution of inbreeding strategies. This distribution will in turn depend on the distribution of relatedness in previous generations and on previously realised inbreeding strategies and inbreeding loads, thereby generating complex feedbacks between inbreeding strategy, load, and relatedness. [. . .]
Sexual conflict and interactions among multiple non-self relatives are particular to biparental reproduction rather than self-fertilisation, but both types of inbreeding increase the expression of inbreeding load causing inbreeding depression in offspring [1, 2, 7, 12]. Inbreeding depression may decrease inbreeding load by exposing deleterious homozygous recessive alleles to selection [9, 71]. Resulting purging of deleterious recessive alleles may in turn affect the inclusive fitness benefit of inbreeding versus avoiding inbreeding causing inbreeding strategy and inbreeding load to coevolve [12, 72, 73]. The consequences of this coevolution have been modelled extensively with respect to outcrossing versus selfing [12, 18, 72, 74–76], but have not yet been modelled for the evolution of biparental inbreeding strategies [10]. Future theoretical developments will therefore need to explicitly consider coevolution between biparental inbreeding strategy and inbreeding load.
Predictive models of biparental inbreeding evolution cannot be simple, but their complexity need not preclude generality [77]. Tractable approaches for developing inbreeding theory might include game-theoretic models, or individual-based models that explicitly track ancestry and inbreeding load, and thereby incorporate feedbacks among relatedness, load, and inbreeding strategy.
JayMan continues to talk about things he doesn't understand
In this episode, he's back to insisting "ethnic genetic interests" (which despite having been corrected multiple times he's still unable to correctly define) are "bunk" (emphasis in original):
However, common among people who have a superficial and/or selective understanding of heritable group differences is belief in conveniently inaccurate claims. One of these erroneous ideas that White nationalists in particular have latched on to is the belief in “ethnic genetic interests” – that is, that kin selection has led individuals to favor people of their own race/ethnic group over others. This of course is bunk. Natural selection doesn’t work that way, since individuals within an ethnic group aren’t closely related enough for this to work. This has been explained repeatedly, lately by Misdreavus:It is impossible for such a thing as a “race altruist gene” to evolve, because sacrificing yourself on behalf of strangers does nothing to increase the frequency of the gene under any set of circumstances. It doesn’t matter if the frequency of a such a gene “magically” originated with a frequency of 4 in 10 Chinese people. The Chinese who don’t have the gene, on average, would have a higher fitness, resulting in the frequency decreasing monotonically over time.He continues to argue there, which is worth a read for anyone seriously interested in the matter.
After anyone seriously interested in the matter gets done studying the confused rantings of JayMan's gay sidekick, I would recommend they at least take a few minutes to skim the work of the man who coined the term "ethnic genetic interests". Doing so would have saved JayMan and misdreavus at least some measure of embarrassment.
A copy of Frank Salter's On Genetic Interests: Family, Ethnicity, And Humanity In An Age Of Mass Migration is freely available online.
If you want to talk about ethnic genetic interests, read it.
The actual definition of ethnic genetic interests
Frank Salter defines "ethnic genetic interests" as:
The number of copies of a random individual's distinctive genes in his or her ethny, not counting the copies in kin. The size of ethnic genetic interest is relative to the kinship of genetic competitors. When competitors are closely related ethnies, the interest can be relatively small. When competitors are distantly related, especially from different geographical races, ethnic genetic interest can be many orders of magnitude greater than familial genetic interests.
To deny that ethnic genetic interests exist is to deny that human population structure exists (or to hilariously misunderstand basic population genetics). Ethnic genetic interests exist regardless of whether or not one believes group selection has played any role in human evolution and regardless of whether or not people naturally favor others from their own group.
The issue of the degree to which group selection or kin selection favored the evolution of ethnocentric altruism in humans has no bearing on the reality of ethnic genetic interests. It's a separate issue, on which JayMan/misdreavus are also wrong (one can debate the issue, but not on the confused grounds JayMan and misdreavus have attempted to debate it).
Misdreavus's confusion about coefficients of relatedness
One area of confusion for misdreavus in the linked thread:
The coefficient of relatedness between a Swede and a non-related Swede is zero. The coefficient of relatedness between a Swede and a black African is also zero. You simply do not seem to understand this.I replied at the time:
This is exactly the misapprehension I just got done correcting for JayMan: http://racehist.blogspot.com/2015/02/kinship-coefficients-and-ethnic-genetic.html
The coefficient of relationship is simply twice the coefficient of inbreeding between the hypothetical children of two individuals. Inbreeding is defined relative to some population. It’s often convenient to disregard non-recent inbreeding in calculating coefficients of relationship, but this only makes sense with respect to a particular [approximately random-breeding] population, and, holding the base population constant, a Swede absolutely does not have the same coefficient of relationship to a sub-Saharan as to another Swede. Nor is there any difference in kind between the type of relatedness indicated through Fst and the type shared by close family members.
Even after having it explained to them again, Misdreavus (and apparently JayMan) still failed to understand this very basic concept.
Misdreavus's confusion about the viability of genes for altruism
This is another extremely basic issue: frequencies of genes harmful to an individual's fitness with respect to his group can increase globally if his group expands relative to other groups. If misdreavus had read and understood pretty much anything written about altruism and kin selection or group selection within the past half century, he would have grasped this.
If groups with high frequencies of ethnocentric people expand at the expense of groups with low ethnocentrism, genes for ethnocentric altruism can increase in frequency.
Even misdreavus's (anti-group-selectionist) idol understands this (or did at one point):
Imagine that in much of history, people lived in small groups that often fought with their neighbors. In that sort of situation, selection for group altruism is at least possible, since the group is full of close relatives, while the opponents are less closely related. Both sides are probably members of the same broad ethnic group or race, but that doesn’t matter : only the kinship coefficients matter.Related:
- Kinship coefficients and Ethnic Genetic Interests (JayMan embarrassing himself again)
- Remedial population genetics for Greg Cochran
- Hamilton on inclusive fitness and social behavior in humans
- More from Hamilton on kin recognition and intergroup hostility
- R. A. Fisher on group selection in humans
- Robert Axelrod on the evolution of ethnocentrism
- Gender and Politics Among Anthropologists in the Units of Selection Debate
Variation and signatures of selection on the human face
Variation and signatures of selection on the human face. [Open access]
J Hum Evol. 2014 Oct;75:143-52
Authors: Guo J, Tan J, Yang Y, Zhou H, Hu S, Hashan A, Bahaxar N, Xu S, Weaver TD, Jin L, Stoneking M, Tang K
Abstract
There has been much debate about why humans throughout the world differ in facial form. Previous studies of human skull morphology found levels of among-population differentiation that were comparable to those of neutral genetic markers, suggesting that genetic drift (neutral processes) played an important role in influencing facial differentiation. However, variation in soft-tissue morphology has not been studied in detail. In this study, we analyzed high-resolution 3D images of soft-tissue facial form in four Eurasian populations: Han Chinese, Tibetans, Uyghur and Europeans. A novel method was used to establish a high-density alignment across all of the faces, allowing facial diversity to be examined at an unprecedented resolution. These data exhibit signatures of population structure and history. However, among-population differentiation was higher for soft-tissue facial form than for genome-wide genetic loci, and high-resolution analyses reveal that the nose, brow area and cheekbones exhibit particularly strong signals of differentiation (Qst estimates: 0.3-0.8) between Europeans and Han Chinese. Our results suggest that local adaptation and/or sexual selection have been important in shaping human soft-tissue facial morphology. [. . .]
The Qpc values found in the nose and brow area between Europeans and Han Chinese approach the high differentiation reported for skin pigmentation (Relethford, 2004b). This suggests that strong local adaptation may have shaped these facial features (Myles et al., 2007). For the nose, strong correlations have been found between the nasal index and temperature/humidity, supporting climate adaptation as the major selective force (Thomson and Buxton, 1923, Davies, 1932, Weiner, 1954, Wolpoff, 1968, Hiernaux and Froment, 1976, Crognier, 1981 and Franciscus and Long, 1991). Models simulating airflow dynamics demonstrated that bigger nasal volumes, narrower shapes and downwardly pointing nares might enhance the airflow exposure of the mucosa and thereby facilitate the heating and humidification of the air (Churchill et al., 2004). The European nose shape thus may have resulted from adaptation to a colder climate. The relatively enlarged brow area in Europeans has also been noted previously (Russell et al., 1985). It has been argued that brow area size is positively correlated with the magnitude of the mechanical stresses resulting from mastication, so brow area shape differentiation (SOM, Fig. S11) could be the result of dietary differences (Russell et al., 1985). Adaptation to specific diets (Hubbe et al., 2009) and climate adaptation (Coon et al., 1950) have been hypothesized to explain the expanded zygomatics in Asians.
In addition to natural selection, sexual selection may also have played a major role in shaping interpopulation variation in the human face. Selective mate choice based on facial appearance in humans is well documented as a universal condition in global populations (Wells et al., 2009). However, whether and to what extent sexual selection shaped human facial morphology has rarely been investigated. Fisher's runaway sexual selection model suggests that a positive feedback loop composed of an arbitrary trait involving appearance, and the accidental preference of this trait in the opposite sex, could initiate a powerful sexual selection process (Fisher, 1958). It is therefore possible that some of the strong differentiation signals involving the soft-tissue facial form may have resulted from sexual selection. Further studies that combine high-resolution 3D face analysis, studies of human behavior, and genetic analyses are necessary to delineate the possible roles of local adaptation versus sexual selection in explaining the relatively large between-population differentiation that we find for soft-tissues of the human face.
Gender and Politics Among Anthropologists in the Units of Selection Debate
Gender and Politics Among Anthropologists in the Units of Selection Debate:
In recent years evolutionary theorists have been engaged in a protracted and bitter disagreement concerning how natural selection affects units such as genes, individuals, kin groups, and groups. Central to this debate has been whether selective pressures affecting group success can trump the selective pressures that confer advantage at the individual level. In short, there has been a debate about the utility of group selection, with noted theorist Steven Pinker calling the concept useless for the social sciences. We surveyed 175 evolutionary anthropologists to ascertain where they stood in the debate. We found that most were receptive to group selection, especially in the case of cultural group selection. The survey also revealed that liberals and conservatives, and males and females, all displayed significant differences of opinion concerning which selective forces were important in humanity’s prehistory. We conclude by interpreting these findings in the context of recent research in political psychology.Peter Turchin:
A particularly interesting recent study is the one by William Yaworsky, Mark Horowitz, and Kenneth Kickham, Gender and Politics among Anthropologists in the Units of Selection Debate, published a month ago in Biological Theory. It’s interesting because it addresses the question of group versus kin selection, which is of course one of the most dividing issues in evolutionary science.Related:Yaworsky and colleagues obtained 175 surveys from evolutionary anthropologists who served faculty in graduate programs in various universities (which means that they are training their own graduate students). Their analysis of the questionnaires showed that there were very striking differences between different groups of anthropologists. Liberals were much more likely to disagree with the statement that tribal conflict was a principal evolutionary force that shaped human behavior. Conservatives, on the other hand, thought that tribalism was a fundamental human trait. They also tended to agree with the notion that homicide was frequent in early human societies.
The differences between male and female evolutionary anthropologists were even stronger than between different parties. Women were very resistant to the ideas that tribal conflict was an important selective force and that homicide was common in prehistory. [. . .]
And I expect that the questions of the importance of between-group competition and the frequency of lethal violence in prehistory will eventually achieve the same level of consensus. It may take many decades, but my hunch is that it will happen more quickly than that.
In fact, it’s already happening. The data of Yaworsky and colleagues show that 80 percent of respondents disagree with Pinker’s assertion that group selection is a useless concept. A similar proportion thinks that group selection is an important process, and 55 percent consider group selection as a more important process than kin selection. In contrast, among the professors who trained this cohort of respondents, the previous generation, only 8 percent were strongly in favor or “leaned” towards group selection. We are winning!
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