May 31, 2005

Bones of Contention

TIME Asia has a wonderful story on the modern-day pygmies of Rampasasa:
"In those days we ate our meat raw, like animals." The speaker is Viktor Jurubu, an Indonesian farmer in his 60s, who, in his T shirt and sarong, looks little like the cavemen he's describing. Except for his height, which is about 140 cm. In the world of anthropology, Jurubu's small size is big news because he and his 246 fellow villagers of Rampasasa on the remote island of Flores say they are descended from a tribe of tiny, hairy folk whom they call "the short people." "We didn't have knives but used rocks," he explains. "We didn't even know how to make fire." Jurubu, a soft-spoken man with close-cropped gray hair, high cheekbones and deeply inset eyes, looks to the 30 or so villagers sitting in a circle around him for confirmation. They nod and grunt assent, and he proceeds to talk about the time their shy ancestors hid themselves from the outside world in Liang Bua, a high-ceilinged cavern scooped out of a limestone hill about a kilometer away. Again a chorus of agreement. "Tell how Paju left the cave and married one of the normal humans," calls out a voice from the crowd, "[and] how we came to live here in Rampasasa." Jurubu hesitates. After a pause, he opens his mouth to speak, but his words are drowned out by an impatient babble of voices competing to tell the story.

May 25, 2005

IQ falling?

The Flynn effect refers to the increase in IQ in recent history in several populations around the world. Several explanations have been proposed for this effect, but a new study from Denmark, replicating a previous one from Norway indicates that the Flynn effect has ceased in the 1990s, and indeed IQ has slightly dropped in recent years to early '90s levels.

Personality and Individual Differences (Article in Press)

A long-term rise and recent decline in intelligence test performance: The Flynn Effect in reverse

Thomas W. Teasdale and David R. Owen


In the 1980s reviewed evidence indicated that, through the preceding decades of the last century, population performance on intelligence tests had been rising substantially, typically about 3–5 IQ points per decade, in developed countries. The phenomenon, now termed the ‘Flynn Effect’, has been variously attributed to biological and/or to social and educational factors. Although there is some evidence to suggest a slowing of the effect through the 1990s, only little evidence, to our knowledge, has yet been presented to show an arrest or reversal of the trend. Substantially replicating a recent report from Norway, we here report intelligence test results from over 500,000 young Danish men, tested between 1959 and 2004, showing that performance peaked in the late 1990s, and has since declined moderately to pre-1991 levels. A contributing factor in this recent fall could be a simultaneous decline in proportions of students entering 3-year advanced-level school programs for 16–18 year olds.


Mental Energy

David Lykken has written an interesting editorial in Intelligence where he urges researches to consider the problem of mental energy as a predictor of intellectual achievement. He states his rule as follows:
Mental energy (e)–the ability to persist for long periods thinking productively about a problem, the ability to focus attention, to shut out distractions, to persist in search of a solution–is perhaps as important as general intelligence (g) in determining both successful performance and constructive achievement and the product of these two variables, g*e, provides the most valid predictor of success and achievement.
Drawing many examples from biographies of geniuses, he proposes that not only were they "smart" and able to solve complex problems, but they had an immense capacity to shut out their environment and work for really long periods of time.

Intelligence (online)

Mental energy

David T. Lykken


Biographies of great achievers, in science as well as other disciplines, suggest that those of genius caliber possess, in addition to their intellectual gift or gifts, an extraordinary abundance of mental energy. They can focus their attention on some task for long periods without tiring or becoming distracted from the problem at hand. It is plausible to suppose that intellectual achievement is a function of the product, rather than the sum, of mental talent and mental energy. It is therefore surprising that no standardized measure or method of assessing mental energy has been developed. One obvious approach would employ a variety of self-report items similar to those suggested. Perhaps other methods of assessing mental energy are feasible and might usefully augment current methods of predicting academic and occupational success.


May 24, 2005

Biracial Koreans

The Korea Times reports on the situation of biracial Koreans. Most biracials live -for historical reasons- in Caucasoid-founded nations, so it is interesting to see a different angle on the situation of biracials in a Mongoloid nation.

Biracial People Face Discrimination in Korea (excerpt):

In Korea, where everybody has black eyes, straight black hair and yellow skin, biracial Koreans face discrimination because of their appearance _ they look different.

Moreover, they are treated differently, with indirect words and in indirect ways, people are reluctant to accept them as members of our society, only because they are biracial.

With an increasing number of Koreans marrying non-Koreans, the number of biracial people is growing. But the inhospitality and discrimination against their children have not changed with the times, and Korea is still a country where biracial people face difficulties.

There are no statistics indicating the exact number of biracial people in Korea. But a figure can be estimated from the number of people registered with the nation's only biracial welfare agency, Pearl S. Buck International (PSBI), a foundation established by the Nobel laureate to assist children suffering racial discrimination.

According to the foundation's registry, there are about 4,800 Amerasians _ people born from Korean women and American men _ mainly U.S. soldiers stationed in Korea, and 12,000 Kosians _ people born from Koreans and other Asians, usually migrant workers.

The Peopling of the Americas

A new paper in PLoS Biology estimates the effective population size and time depth of Native Americans, using data on their genetic variation in several gene loci. Usual controversies in the subject of Native American origin revolve around the time of their first arrival, and whether there was a single or multiple Out-of-Asia movements into the Americas. This new paper, supports the idea that the Native Americans are a relatively recent offshoot of the Asian population.

This new research may explain many of the features of the Native Americans, who are undoubtedly Mongoloid, but often differ from Asiatic Mongoloids in having a much reduced frequency of the epicanthic fold, often prominent noses, and yet the familiar facial flatness and "Sinodont" dental pattern. Their appearance could easily be explained if they are descended from a Proto-Mongoloid population of small size, and hence did not partake in the subsequent evolution in Asia, which led to the formation of the complete Mongoloid racial complex.

PLoS Biology Volume 3 | Issue 6 | JUNE 2005

On the Number of New World Founders: A Population Genetic Portrait of the Peopling of the Americas

Jody Hey

The founding of New World populations by Asian peoples is the focus of considerable archaeological and genetic research, and there persist important questions on when and how these events occurred. Genetic data offer great potential for the study of human population history, but there are significant challenges in discerning distinct demographic processes. A new method for the study of diverging populations was applied to questions on the founding and history of Amerind-speaking Native American populations. The model permits estimation of founding population sizes, changes in population size, time of population formation, and gene flow. Analyses of data from nine loci are consistent with the general portrait that has emerged from archaeological and other kinds of evidence. The estimated effective size of the founding population for the New World is fewer than 80 individuals, approximately 1% of the effective size of the estimated ancestral Asian population. By adding a splitting parameter to population divergence models it becomes possible to develop detailed portraits of human demographic history. Analyses of Asian and New World data support a model of a recent founding of the New World by a population of quite small effective size.


May 21, 2005

Origin of Plasmodium parasites

A new study investigated the time depth of P. vivax and P. falciparum, two parasites implicated in human malaria.

Molecular Biology and Evolution (advance publication)

Mitochondrial Genome Sequences Support Ancient Population Expansion in Plasmodium vivax

Somchai Jongwutiwes et al.


Examination of nucleotide diversity in 106 mitochondrial genomes of the most geographically widespread human malaria parasite, Plasmodium vivax, revealed a level of diversity similar to, but slightly higher than, that seen in the virulent human malaria parasite Plasmodium falciparum. The pairwise distribution of nucleotide differences among mitochondrial genome sequences supported the hypothesis that both of these parasites underwent ancient population expansions. We estimated the age of the most recent common ancestor (MRCA) of the mitochondrial genomes of both P. vivax and P. falciparum at around 200,000-300,000 years ago. This is close to previous estimates of the time of the human mitochondrial MRCA and the origin of modern Homo sapiens, consistent with the hypothesis that both of these Plasmodium species were parasites of the hominid lineage before the origin of modern Homo sapiens and that their population expansion coincided with the population expansion of their host.


May 20, 2005

The origin of M1

Here is the page of a doctoral student working on the origin of mtDNA haplogroup M1:
In addition, I am looking at a possible correlation between the presence of M1 in North and East Africa, and the Afro-Asiatic language family, which exists in a generally comparable region as M1. Further research in this area may help to understand more fully the relationship between genetic and linguistic change.

African Language Families: Illustrates the diverse linguistic families of the African continent. The Afro-Asiatic Language family may be related to the M1 mitochondrial haplogroup, as both are present in the same general areas of Africa and the Middle East.
I had referenced this work recently inspired by an abstract which appeared in the annual meeting of the AAPA:
The second great puzzle is mtDNA haplogroup M1 which occurs in East and North Africa, West Asia and Southern Europe, but not apparently anywhere else. M1 is a branch of the mainly Asian macrohaplogroup M, which is of great antiquity in Asia and likely originated there. According to a recent abstract, Holden et al. indicate that M1 is found at high frequencies in East and Northern Africa but not in Sub-Saharan Africa, and hint that it may be linked to the Afro-Asiatic language family. This suggestion is reasonable, and in my opinion the correspondence between M1 and Y-chromosome haplogroup E3b is quite remarkable throughout the broad peri-Mediterranean region, with E3b also reaching high frequencies in Afro-Asiatic speakers.

May 19, 2005

Dating of Mladec human remains

Nature 435, 332-335 (19 May 2005)

Direct dating of Early Upper Palaeolithic human remains from Mladec caron

Eva M. Wild et al.

The human fossil assemblage from the Mladec caron Caves in Moravia (Czech Republic)1 has been considered to derive from a middle or later phase of the Central European Aurignacian period on the basis of archaeological remains (a few stone artefacts and organic items such as bone points, awls, perforated teeth)2, despite questions3 of association between the human fossils and the archaeological materials and concerning the chronological implications of the limited archaeological remains4. The morphological variability in the human assemblage, the presence of apparently archaic features in some specimens, and the assumed early date of the remains have made this fossil assemblage pivotal in assessments of modern human emergence within Europe5, 6, 7. We present here the first successful direct accelerator mass spectrometry radiocarbon dating of five representative human fossils from the site. We selected sample materials from teeth and from one bone for 14C dating. The four tooth samples yielded uncalibrated ages of approx 31,000 14C years before present, and the bone sample (an ulna) provided an uncertain more-recent age. These data are sufficient to confirm that the Mladec caronhuman assemblage is the oldest cranial, dental and postcranialassemblage of early modern humans in Europe and is therefore central to discussions of modern human emergence in the northwestern Old World and the fate of the Neanderthals.


The importance of large genomic differences

The published sequence of the human genome is essentially a really long sequence of letters. Individual genomes differ from this sequence, and from each other, because they substitute one letter for another. However, these polymorphisms are quite rare, and hence humans are usually said to be genetically 99.9% the same.

However, two genomes may differ in other ways as well. Entire segments of DNA may be duplicated in some, or missing in others, or they could exist, but written "backwards".

Until recently, it was generally assumed that differences between individuals and populations were due to the really small changes in our genes. But, as reported in Nature, scientists are discovering that the large differences in which big chunks of DNA are duplicated, missing, or inverted, may be even more important for explaining human variation.
Two years ago, a group of researchers led by Michael Wigler at Cold Spring Harbor Laboratory found the first evidence that some of us have more copies of certain genes than do others (R. Lucito et al. Genome Res. 13, 2291−2305; 2003). And at last week's meeting, Evan Eichler of the University of Washington in Seattle reported that this is just the beginning: not only do we carry different copy numbers of parts of our DNA, we also have varying numbers of deletions, insertions and other major rearrangements in our genomes.

In fact, Eichler found at least 297 places in the genome where different individuals have different forms of these major structural variations. At these spots, some of us might carry a major deletion, for example, or an extra hundred bases of DNA.

But do such differences mean anything? Here, too, fresh evidence paints an intriguing picture. In January, scientists at the Iceland-based company deCODE Genetics found a long inversion — a stretch of DNA that is flipped around backwards — that is common in Europeans, but not in Asians and Africans (H. Stefánsson et al. Nature Genet. 37, 129−137; 2005). They also found that women who have this inversion bear more children than those who don't — a classic sign that the inversion confers an evolutionary advantage.

At the Cold Spring Harbor meeting, scientists presented more evidence that structural differences are important in human evolution. Duc-Quang Nguyen, a postdoctoral fellow in Chris Ponting's laboratory at the University of Oxford, UK, reported an analysis of areas where there are different numbers of copies of DNA stretches. Nguyen found that natural selection is actively working on these genes.

What's more, he found that many of these genes belong to groups that seem to help us interact with our environment. For instance, many work in the immune system, and affect how we fight off disease. These are exactly the sort of genes that could explain our diversity — why some of us get asthma when exposed to air pollution, or why some of us can eat plenty of cheeseburgers without gaining weight.

"We knew these variations existed, but this year we're asking, do they matter?" says Ewan Birney, head of bioinformatics for the European Molecular Biology Laboratory, based in Cambridge, UK. "The answer seems to be yes."

Out of Africa does not explain human genomic diversity

Eswaran, Harpending, and Rogers have written a new article in the Journal of Human Evolution which argues strongly against the simple Out-of-Africa model, according to which modern humans are exclusively derived from a relatively recent (i.e., tens of thousands of years old) population originating in Africa. It is, however, also different from the Multiregional model, according to which humans are descended from Homo erectus populations exchanging genes for a long time, as well as the Mostly out of Africa model, which sees that humans are descended from an expanding African population which hybridized with non-Africans to a limited extent.

The Eswaran et al. model does not postulate any particular process of migration, but rather the spread of a modern "gene complex" which emerged in Africa. This complex, consisting of a few co-adapted genes conferred a selective advantage, and gradually spread via gene flow from its original source. According to the authors, this model explains the contradictory stories of different genetic loci: some loci were part of the selective sweep that originated in Africa, and hence show a pattern of radiation from Africa, whereas other loci show no such pattern and represent the persistence of much older genomic ancestry.

The authors' final paragraph summarizes their perceived importance of the new model:
While each locus has its own history, the above reasoning suggests that African-dominated loci would all roughly tell the same story, while the others would each have its own—for assimilation would have varied in time and place in each case. Thus in the late 1990s, after a decade when most geneticists became convinced of the strict replacement recent African origin model, there was confusion when many nuclear loci—each in its own way—contradicted the patterns first seen in mtDNA. Yet, the following of that particular model remained strong, as there was no other theory that could explain the contrasting patterns. Now there is such a theory, and it tells us that while modern humans first emerged in Africa, living human populations carry within them a substantial genetic inheritance that had its origins in non-African archaics.

Journal of Human Evolution (Article in Press)

Genomics refutes an exclusively African origin of humans

Vinayak Eswaran et al.


Ten years ago, evidence from genetics gave strong support to the “recent Africa origin” view of the evolution of modern humans, which posits that Homo sapiens arose as a new species in Africa and subsequently spread, leading to the extinction of other archaic human species. Subsequent data from the nuclear genome not only fail to support this model, they do not support any simple model of human demographic history. In this paper, we study a process in which the modern human phenotype originates in Africa and then advances across the world by local demic diffusion, hybridization, and natural selection. While the multiregional model of human origins posits a number of independent single locus selective sweeps, and the “out of Africa” model posits a sweep of a new species, we study the intermediate case of a phenotypic sweep. Numerical simulations of this process replicate many of the seemingly contradictory features of the genetic data, and suggest that as much as 80% of nuclear loci have assimilated genetic material from non-African archaic humans.


Worse self-image, more eating disorders among gay men

Eating Behaviors
Volume 6, Issue 3 , June 2005, Pages 179-187

Body image, eating behaviors, and attitudes toward exercise among gay and straight men

Patricia L. Kaminski et al.


Gay men tend to be more dissatisfied with their bodies and may be at greater risk for symptoms of eating disorders compared to heterosexual men. However, the majority of research conducted with gay and heterosexual men has implemented instruments designed to assess eating disorder symptomatology in women. The present study assessed differences between gay and heterosexual men using the Male Eating Behavior and Body Image Evaluation (MEBBIE), an instrument designed to assess attitudes and behaviors related to eating, exercise and body image specifically in men. Analyses of MEBBIE scale means with body mass index (BMI) as the covariate indicated that, relative to their heterosexual counterparts, gay men diet more, are more fearful of becoming fat, and are more dissatisfied with their bodies in general as well as with their degree of muscularity. Gay men were also more likely than heterosexual men to hold distorted cognitions about the importance of having an ideal physique. Contrary to hypotheses, however, gay and straight men did not differ in the degree to which they exercised or felt guilty about missing a workout. Results are discussed in light of previous findings, and implications for clinical practice and future research are considered.


May 18, 2005

How to settle the question of the racial IQ gap

New technologies for measuring genetic admixture have made it possible to measure directly the percentage of ancestry that an individual has from two or more parental groups.

If two groups differ in intelligence due to the possession of private alleles, or the frequency of others, then we would expect that individuals of mixed ancestry would have a lower intelligence than the higher-achieving group, and higher intelligence than the lower-achieving group.

If, on the other hand, differences in intelligence are due to cultural factors, then we would expect proportions of genetic ancestry to have little explanatory power.

Therefore, to determine whether or not there is a racial character to intelligence, we must sample a mixed population, determine the IQ scores and ancestral proportions of its members, and see whether the two are correlated.

Previous studies have used skin color as a proxy for admixture proportions. Skin color has been found to be related to genomic ancestry in some groups, but not in others. Therefore, we must sample genomic ancestry directly.

Moreover, some previous studies have sampled from groups which are mixed, but also differ in other respects, e.g., the offspring of American blacks and German women after WWII, or of Americans from different parts of the United States; e.g., it is true that Southern blacks are ancestrally more Negroid than Northern blacks (on average), but there are other socio-cultural factors which separate the two.

The best study would sample from a single localized population, e.g., the black inhabitants of a town or city neighborhood; moreover, this population must be variable enough, i.e. have substantial variation in ancestral proportions.

Finally, individuals resulting from admixture between a Caucasoid and Black parent should be excluded, to avoid any possible heterotic effects.

If such an experiment were to be conducted, then the discovery of a significant correlation between IQ and ancestral proportions would be clear and unambiguous evidence for racial differences in intelligence. If the correlation is very weak, or absent, then this would argue against this dependence, although the experiment could and should be repeated multiple times and with many different groups known to have differences in IQ and for which ancestral proportions can be estimated.

May 17, 2005

Male and female migration rates

Proc Natl Acad Sci U S A. 2005 May 13; [Epub ahead of print]

Molecular analysis reveals tighter social regulation of immigration in patrilocal populations than in matrilocal populations.

Hamilton G, Stoneking M, Excoffier L.

Human social organization can deeply affect levels of genetic diversity. This fact implies that genetic information can be used to study social structures, which is the basis of ethnogenetics. Recently, methods have been developed to extract this information from genetic data gathered from subdivided populations that have gone through recent spatial expansions, which is typical of most human populations. Here, we perform a Bayesian analysis of mitochondrial and Y chromosome diversity in three matrilocal and three patrilocal groups from northern Thailand to infer the number of males and females arriving in these populations each generation and to estimate the age of their range expansion. We find that the number of male immigrants is 8 times smaller in patrilocal populations than in matrilocal populations, whereas women move 2.5 times more in patrilocal populations than in matrilocal populations. In addition to providing genetic quantification of sex-specific dispersal rates in human populations, we show that although men and women are exchanged at a similar rate between matrilocal populations, there are far fewer men than women moving into patrilocal populations. This finding is compatible with the hypothesis that men are strictly controlling male immigration and promoting female immigration in patrilocal populations and that immigration is much less regulated in matrilocal populations.


Medical journals have become a marketing branch of drug companies

Medical Journals Are an Extension of the Marketing Arm of Pharmaceutical Companies:
“Journals have devolved into information laundering operations for the pharmaceutical industry”, wrote Richard Horton, editor of the Lancet, in March 2004 [1]. In the same year, Marcia Angell, former editor of the New England Journal of Medicine, lambasted the industry for becoming “primarily a marketing machine” and co-opting “every institution that might stand in its way” [2]. Medical journals were conspicuously absent from her list of co-opted institutions, but she and Horton are not the only editors who have become increasingly queasy about the power and influence of the industry. Jerry Kassirer, another former editor of the New England Journal of Medicine, argues that the industry has deflected the moral compasses of many physicians [3], and the editors of PLoS Medicine have declared that they will not become “part of the cycle of dependency…between journals and the pharmaceutical industry” [4]. Something is clearly up.

Back-migration into Cameroon

The presence of R1* Y chromosomes in Cameroon is considered as evidence of a back migration from Eurasia into Sub-Saharan Africa. A new study of mtDNA in the region shows that Eurasian mtDNA is severely underrepresented, and hence either (i) there was biased male-mediated gene flow into the population, or (ii) the Eurasian mtDNA was lost due to drift.

An alternative explanation, not considered by the authors is that mtDNA, known to be involved in energy production, is subject to strong selection in different natural environments, and therefore, there may have been selection against Eurasian mtDNA after its initial introduction into the population.

American Journal of Physical Anthropology

Early View (Articles online in advance of print)

Brief communication: mtDNA variation in North Cameroon: Lack of asian lineages and implications for back migration from Asia to sub-Saharan Africa

Valentina Coia et al.


The hypervariable region-1 and four nucleotide positions (10400, 10873, 12308, and 12705) of the coding region of mitochondrial DNA (mtDNA) were analyzed in 441 individuals belonging to eight populations (Daba, Fali, Fulbe, Mandara, Uldeme, Podokwo, Tali, and Tupuri) from North Cameroon and four populations (Bakaka, Bassa, Bamileke, and Ewondo) from South Cameroon. All mtDNAs were assigned to five haplogroups: three sub-Saharan (L1, L2, and L3), one northern African (U6), and one European (U5). Our results contrast with the observed high frequencies of a Y-chromosome haplogroup of probable Asian origin (R1*-M173) in North Cameroon. As a first step toward a better understanding of the evident discrepancy between mtDNA and Y-chromosome data, we propose two contrasting scenarios. The first one, here termed "migration and asymmetric admixture," implies a back migration from Asia to North Cameroon of a population group carrying the haplotype R1*-M173 at high frequency, and an admixture process restricted to migrant males. The second scenario, on the other hand, temed "divergent drift," implies that modern populations of North Cameroon originated from a small population group which migrated from Asia to Africa and in which, through genetic drift, Y-chromosome haplotype R1*-M173 became predominant, whereas the Asian mtDNA haplogroups were lost.


Azoospermia and Y chromosome haplogroups

Hum Reprod Update. 2005 May 12; [Epub ahead of print]

AZF deletions and Y chromosomal haplogroups: history and update based on sequence.

Vogt P.

AZF deletions are genomic deletions in the euchromatic part of the long arm of the human Y chromosome (Yq11) associated with azoospermia or severe oligozoospermia. Consequently, it can be assumed that these deletions remove Y chromosomal genes required for spermatogenesis. However, these 'classical' or 'complete' AZF deletions, AZFa, AZFb and AZFc, represent only a subset of rearrangements in Yq11. With the benefit of the Y chromosome sequence, more rearrangements (deletions, duplications, inversions) inside and outside the classical AZF deletion intervals have been elucidated and intra-chromosomal non-allelic homologous recombinations (NAHRs) of repetitive sequence blocks have been identified as their major cause. These include duplications in AZFa, AZFb and AZFc and the partial AZFb and AZFc deletions of which some were summarized under the pseudonym 'gr/gr' deletions. At least some of these rearrangements are associated with distinct Y chromosomal haplogroups and are present with similar frequencies in fertile and infertile men. This suggests a functional redundancy of the AZFb/AZFc multi-copy genes. Alternatively, the functional contribution(s) of these genes to human spermatogenesis might be different in men of different Y haplogroups. That raises the question whether, the frequency of Y haplogroups with different AZF gene contents in distinct human populations leads to a male fertility status that varies between populations or whether, the presence of the multiple Y haplogroups implies a balancing selection via genomic deletion/amplification mechanisms.

Link (pdf)

May 15, 2005

More on the beachcomber hypothesis

John Hawks raises many alarm bells to the newer single coastal route Out of Africa hypothesis:
Okay, hmm...let me get this straight: modern humans had uber-technology to float across the Red Sea, kill mammoths, and outcompete every archaic human in every ecology they had occupied for a half million years or more, but they couldn't manage to move in 10,000 years across a semi-desert? And let's not forget the "modern" humans that get thrown under the bus in this scenario -- Skhul, Qafzeh, Liujiang -- either they don't qualify as "really" modern, or they've been misdated. Oh, and, there is the slight problem that no other locus provides any evidence of this pattern of population movement -- even the Y chromosome -- and many are not consistent with it.
John's entire post is interesting to read, and one wonders who reviewed this paper before it appeared in Science: the scenario proposed by the authors is certainly plausible, but mere plausibility is not science, nor does a study of the mitochondrial makeup of isolated Malaysian aboriginals establish that humans left Africa in a single migration that followed the coast at a pace of 4km/year.

Let's hope that there will be less of this in the future:
The Genographic Project is a major expansion of earlier work by Spencer Wells, a population geneticist and explorer-in-residence at the National Geographic Society, who used DNA from about 10,000 people to trace mankind's history to a tribe of hunter-gatherers in Africa 60,000 years ago.
and more attention to "details" such as this:
These indicate a more recent ancestry of the NRY at 59000 years (95% CI = 40000± 140000) than previously estimated at 134250-44980 years based on 13 mutational events and constant population size (Karafet et al. 1999).

May 14, 2005

The mitochondrial time depth of humanity

The supplementary materials of the recent article on the Orang Asli of Malaysia, include a very useful table of the time depth of various human mtDNA clades.

Free Image Hosting at

The most striking feature of these estimates is of course the close temporal agreement between the main Eurasian clades, N, M, and R at around 60-65ky, and their temporal proximity with L3, their parental clade at around 84ky.

The vast majority of living humans, including virtually all non-Africans are descended from L3. By contrast, the common ancestor of all humans has a time depth of 203ky, or almost 2.5 times more ancient.

This means, that e.g., an Australian, Korean, Indian, European, and many Africans have a common mitochondrial ancestor that lived 2.5 times later than the common ancestor of all humankind.

The situation with Y-DNA is similar, but the time depths are much shallower: most Africans and all non-Africans are descended from the M168 male, while all humans share an ancestry that is 1.5-2 times older.

It is common to distinguish between Africans and non-Africans, with the former being much more genetically diverse than the latter. But, the real "gap" in human origins seems to be between the really old Africans ("Paleoafricans") and the rest ("Afrasians").

The Paleoafrican element is entirely confined to Africa, while the Afrasian one is found in both Africa and Eurasia. Indeed, modern humans can be entirely split into two groups: (i) a group of "pure" Afrasians which includes all non-Africans, and (ii) a group of Afrasian-Paleoafricans which includes all non-Caucasoid Africans. Human groups of entirely Paleoafrican origin, unhybridized with the younger Afrasians are no longer in existence.

The Afrasians are a recent branch of humankind, and one which was for a great length of time separated reproductively from the Paleoafricans. This accounts for the reduced genetic diversity of Eurasians who are descended entirely from the Afrasian branch; by contrast, Sub-Saharan Africans and East Africans are the result of the intermixture of the Afrasians with the Paleoafricans, and this accounts for the high genetic diversity and antiquity of these populations.

The major human groups can then be described as follows:

Significantly Paleoafrican:

1. Sanids
2. Pygmids
3. Negrids


4. Aethiopids

Entirely Afrasian:

5. Australasids
6. Europids
7. Mongolids

May 13, 2005

Coastal migration theory

Two new papers in the new issue of Science are in support of the coastal Out of Africa migration hypothesis. According to this theory, the earliest Out of Africa members of our species followed the coastline of Asia, eventually reaching Australia, rather than heading towards the interior of the Eurasian landmass.

In Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes, Vincent Macaulay and colleagues sampled mitochondrial DNA from the Orang Asli of Malaysia. They found that these peoples possess a certain degree of admixture from other Southeast Asians, which was introduced in Holocene and subsequent periods, but they mostly have their own highly-specific, and very old subclades of macrohaplogroups N, M, and R. These macrohaplogroups, taken together, account for almost all non-African mtDNA. So, apparently the ancestors of all non-Africans were apparently involved in the very early migration Out of Africa from which the aboriginal Malaysians and also the Australasians are descended, and there was not a separate "northern" and "southern" migration Out of Africa.

In Reconstructing the Origin of Andaman Islanders, Kumarasamy Thangaraj and his colleagues studied the mtDNA of Andaman and Nicobar islanders. The former are Negritos physically, while the latter are Mongoloid. The Andamanese belong only in Y-haplogroup D and mt-haplogroup M, and the authors attribute this to a founder effect, as they are a very small isolated population. In contrast, the Nicobarese seem to descend from southeast Asians in more recent times, as their mtDNA sequences match those of people from China, Malaysia and Thailand.

May 12, 2005

mtDNA and ACTN3 of Finnish athletes

The ACTN3 genotype was previously associated with athletic performance. Individuals who are homozygous RR (wild-type) tend to excel in sprints, while those who are XX tend to excel in endurance. According to ACTN3 Genotype Is Associated with Human Elite Athletic Performance:
In addition, the frequency of the α-actinin-3–deficient genotype (577XX) varies from 25% in Asian populations to <1%>
A new study has investigated the ACTN3 genotypes in Finnish athletes, and has also studied their mtDNA composition. It turns out that two haplogroups (J2 and K) are lacking in endurance athletes.

European Journal of Human Genetics (advance online publication)

Mitochondrial DNA and ACTN3 genotypes in Finnish elite endurance and sprint athletes

Anna-Kaisa Niemi and Kari Majamaa


Differences in ACTN3 (alpha-actinin 3) genotypes have been reported among endurance and power athletes. Elite athletic performance in endurance sports should also depend on mitochondrial oxidative phosphorylation (OXPHOS) that produces ATP for muscle metabolism. We determined mitochondrial DNA (mtDNA) and ACTN3 genotypes in Finnish elite endurance (n=52) and sprint (n=89) athletes, and found that the frequencies of mtDNA haplogroups differed significantly between the two groups. Most notably, none of the endurance athletes belonged to haplogroup K or subhaplogroup J2, both of which have previously been associated with longevity. The frequency of ACTN3 XX genotype was higher and that of RR was lower among Finnish endurance athletes, and, in addition, none of the top Finnish sprinters had the XX genotype. Lack of mtDNA haplogroup K and subhaplogroup J2 among elite endurance athletes suggests that these haplogroups are 'uncoupling genomes'. Such genomes should not be beneficial to endurance-type athletic performance but should be beneficial to longevity, since uncoupling of OXPHOS reduces the production of ATP, reduces the release of reactive oxygen species and generates heat.


Season of birth influences menopause

Season of birth influences age of menopause, say Italian researchers
A study of nearly 3,000 post-menopausal women showed that the earliest age of menopause was found in women born in March and the latest among those born in October. On average there was around 15 months' difference, with women born in October reaching menopause at over 50 years compared with under 49 years for women born in March.


"Our present data seem to indicate that women born in autumn develop better during their prenatal life and are born with a higher number of oocytes than women born in spring," said Dr Cagnacci. "An alternative explanation may be that early mortality is highest among children born in autumn, thus selecting the fittest for survival, although other studies do not support this hypothesis."

May 10, 2005

mtDNA and disease

The latest issue of Nature Reviews Genetics has an interesting summary of our current knowledge of mtDNA mutations contributing to disease. An interesting tidbit from the article:
Data on a single-point mutation (3243A>G) in Finland indicate that approximately 1 in 6,000 individuals are affected, whereas estimates from the British population intimate that about 1 in 3,500 people either have mtDNA disease or are at risk of developing it
Nature Reviews Genetics 6, 389-402 (2005)


Robert W. Taylor & Doug M. Turnbull

The human mitochondrial genome is extremely small compared with the nuclear genome, and mitochondrial genetics presents unique clinical and experimental challenges. Despite the diminutive size of the mitochondrial genome, mitochondrial DNA (mtDNA) mutations are an important cause of inherited disease. Recent years have witnessed considerable progress in understanding basic mitochondrial genetics and the relationship between inherited mutations and disease phenotypes, and in identifying acquired mtDNA mutations in both ageing and cancer. However, many challenges remain, including the prevention and treatment of these diseases. This review explores the advances that have been made and the areas in which future progress is likely.


May 07, 2005

Haplogroup U and cancer

Haplogroup U is one of the oldest Caucasoid mitochondrial lineages, and a new study demonstrates that it may be under negative selection. There has been significant evidence for selection operating on mtDNA, even though in many cases the causal mechanism remains unclear.

Selection operating on mtDNA has important consequences: first, it throws into doubt all uses of mtDNA for assessing the time depth of the recent common ancestry of extant humans. Second, the distribution of mtDNA lineages in modern populations may not be shaped as much by the processes of mutation, migration, and admixture, but also from selection. Third, these results begin to exhibit medical significance, and may have implications about the future availability of mtDNA testing for the general public as a tool for investigating deep ancestry and genealogy.

Mitochondrial DNA variants linked to renal, prostate cancer

Anaheim, Calif. – It's often called the 'powerhouse" of the cell because this is where sugar is broken down to release energy required for cell function.

But mitochondria also contain a small amount of DNA that's used to manufacture 13 of the proteins needed for all these activities.

Now, scientists at Emory University have discovered that mitochondrial DNA contains signature sequencing that is associated with two times the risk for prostate and up to two-and-one-half times the risk for renal cancer.

"The inheritance of mitochondrial haplotype is important in cancer disposition," said John Petros, M.D., associate professor of urology at Emory University and The Atlanta VA Medical Center. A haplotype is a combination of variations in a gene.

Like an asterisk fixed alongside the human genome, mitochondrial DNA (mtDNA) contains additional inherited genetic information that is passed primarily from mother to offspring. Petros identified the U haplotype as a signal for increased risk of prostate and renal cancer.

"There is also inheritance of missense mutations in at least one mitochondrial gene that is important in prostate cancer," Petros said. Missense mutations in genes lead to amino acid substitutions in the protein encoded by the gene. Among mitochondrial genes, several missense mutations in the cytochrome C oxidase subunit I (COI) gene predisposed men to increased risk for prostate cancer as well, Petros' research indicated.

The U haplogroup is one of many segments of the human population that can be grouped according to the evolutionary quirks embedded with their mtDNA. The U haplotype developed among people migrating to northern and Eastern Europe thousands, or even tens of thousands of years ago. People who carry the U haplotype mtDNA belong to the U haplogroup.

Petros determined that among Caucasian Americans, the U haplogroup makes up 9.6 percent of the general population, but a disproportionate number of prostate and renal cancer patients are from the U haplogroup.

"We found that 16.7 percent of the prostate cancer patients and 20.7 percent of renal cancer patients are from the U haplogroup," Petros noted. "If you are a Caucasian American and are of haplogroup U, you have roughly twofold increased risk over other Caucasian American haplogroups.

For those who are U haplotype, Petros suggests extra vigilance in monitoring for prostate or renal cancer.

"If you are among the U group, there is a similarly increased risk comparable to having a positive family history or being African American," Petros said. "The most conventional, nationwide recommendations for screening suggest that high risk groups get screened earlier. That is the essence of what we suggest. We would begin screening with serum PSA and digital rectal exams say at 40 or 45 instead of 50. If you believe in screening for early detection and prevention, you would certainly want to be aggressive and early with it."

Link (EurekAlert)

Armenian modal haplotype

The most frequent haplotype in a sample of Armenians was seen against the background of HG1 Y chromosomes. It occurred in all Armenian groups, at frequencies ~5-14%. According to YHRD, the same haplotype defined over more loci (14 13 29 24 11 13 12 11,14) was also the most frequent one, occurring in 3% of Armenians (*). According to Whit Athey's haplogroup predictor, this is suggestive of haplogroup R1b. A search for the haplotype in YHRD produced the following result:

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The geographical distribution of this haplotype is such that it is shared by Armenians and two other populations from the Caucasus. Moreover, it is lacking in most other populations from the Caucasus, as well as in the other populations from further east. On the other hand, it is more frequently found in Europe, where as we know, haplogroup R1b tends to have higher frequencies as well.

The Armenian modal haplotype is also the modal R1b3 haplotype observed by Cinnioglu in Anatolia. According to him, apparently it entered Anatolia from Europe in Paleolithic times, and diffused again from Anatolia in the Late Upper Paleolithic.

An alternative explanation may be that the particular haplotype may have been associated with the movement of the Phrygians into Asia Minor. The Phrygians were an Indo-European people of the Balkans who settled in Asia Minor, and the Armenians were reputed to be descended from them. It would be interesting to thoroughly study the populations of modern Thrace, Anatolia, and Armenia, and to investigate whether a subgroup of R1b3 chromosomes linked by the Armenian modal haplotype may represent the signature of a back-migration into Asia of Balkan Indo-European peoples.

(*) Since this is an extended haplotype which includes some fast mutating markers, it is expected that it would occur at a lower frequency than the 6-locus haplotype reported by Weale et al.

Gay men are 3.5 times- and lesbians 2.15 times more likely to be mentally ill

BRITISH JOURNAL OF PSYCHIATRY (2004), 185, 479 - 485

Rates and predictors of mental illness in gay men,
lesbians and bisexual men and women

Results from a survey based in England and Wales


Background There is a dearth of research into the mental health of gay men, lesbians and bisexual men and women in the UK.

Aims To assess rates and possible predictors of mental illness in these groups.

Method A comprehensive assessment was made of the psychological and social well-being of a sample of gay men, lesbians and bisexual men and women, identified using ‘snowball’ sampling.

Results Of the 1285 gay, lesbian and bisexual respondents who took part, 556 (43%) had mental disorder as defined by the revised Clinical Interview Schedule (CIS - R). Out of the whole sample, 361 (31%) had attempted suicide. This was associated with markers of discrimination such as recent physical attack (OR=1.7, 95% CI 1.3-2.3) and school bullying (OR=1.4, 95% CI 1.1-2.0), but not with higher scores on the CIS-R.

Conclusions Gay, lesbian and bisexual men and women have high levels of mental disorder, possibly linked with discrimination.

May 06, 2005

Neanderthal femur from France

In a new paper, researchers report on a recently discovered Neanderthal femur from France. Part of the mitochondrial sequence was retrieved, and it matches other ancient Neanderthal specimens in having specific substitutions which are lacking in modern humans.

I often wonder why the study of ancient DNA from Neanderthals seems to be proceeding at a fast pace, but with the exception of two Italian Cro-Magnons there seem to be little published research on modern humans of Pleistocene age. These two specimens were similar to modern humans genetically and different from Neanderthals, but it is possible that other ancient specimens may turn out to be more similar to Neanderthals, or even completely different. This might signify that human mtDNA has changed over the ages due to selection, which has eliminated some mtDNA clades in favor of others which survive today. If that turns to be true, then the distinctiveness of Neanderthal mtDNA compared to modern humans may be due to its antiquity, and not because Neanderthals belonged to a different species.

Proc. Natl. Acad. Sci. USA
(Published Online)

A late Neandertal femur from Les Rochers-de-Villeneuve, France

Cédric Beauval et al.

In 2002, a Neandertal partial femoral diaphysis was discovered at Les Rochers-de-Villeneuve (Vienne, France). Radiocarbon dated to {approx}40,700 14C years before present, this specimen is one of the most recent Middle Paleolithic Neandertals. The diaphysis derives from an archeological level indicating alternating human and carnivore (mostly hyena) occupation of the cave, reinforcing the close proximity and probable competition of Middle Paleolithic humans with large carnivores for resources and space. Morphological aspects of the diaphysis and ancient DNA extracted from it indicate that it is aligned with the Neandertals and is distinct from early modern humans. However, its midshaft cortical bone distribution places it between other Middle Paleolithic Neandertals and the Châtelperronian Neandertal from La Roche-à-Pierrot, supporting a pattern of changing mobility patterns among late Middle Paleolithic Neandertals on the eve of modern human dispersals into Europe.


Child molestations by homosexual foster parents

Psychol Rep. 2005 Feb;96(1):227-30.

Child molestations by homosexual foster parents: Illinois, 1997--2002.

Cameron P.

Do those who engage in homosexuality disproportionately sexually abuse foster or adoptive children as reported by child protective services? Illinois child services reported sexual abuse for 1997 through 2002. 270 parents committed "substantiated" sexual offenses against foster or subsidized adoptive children: 67 (69%) of 97 of these mother and 148 (86%) of 173 of these father perpetrators sexually abused girls; 30 (31%) of the mothers and 25 (14%) of the father perpetrators sexually abused boys, i.e., 92 (34%) of the perpetrators homosexually abused their charges. Of these parents 15 both physically and sexually abused charges: daughters by 8 of the mothers and 4 of the fathers, sons by 3 of the mothers, i.e., same-sex perpetrators were involved in 53%. Thus, homosexual practitioners were proportionately more apt to abuse foster or adoptive children sexually.

Gay parents tend to have gay children.

One of the arguments used in favor of the adoption of children by homosexual parents is that the children do not seem to be influenced by their parents in their sexual orientation, and supposedly seem to have the same chance of being homosexual or heterosexual as the general population. However, a new study shows that this argument has no factual basis, and that children of homosexual parents tend to have a much higher chance of being homosexual themselves.

Journal of Biosocial Science (Published Online)




Do the sexual inclinations of parents influence those of their children? Of 77 adult children of homosexual parents who volunteered for three different investigations, at least 23 (30%) were currently homosexual: twelve (55%) of 22 daughters and three (21%) of fourteen sons of lesbians; five (29%) of seventeen daughters and three (17%) of eighteen sons of gays; none of six sons with both a gay and a lesbian parent. At least 25 (32%) were currently heterosexual. Of the ten with transsexual parents, one of nine daughters was currently lesbian, one was currently heterosexual, and one was transsexual. The son’s sexual preference was not reported. These findings suggest that parents’ sexual inclinations influence their children’s.

May 05, 2005

Burial customs in ancient Greek colonies of Sicily

Oxford Journal of Archaeology
Volume 24 Issue 2 Page 115 - May 2005



Summary. There have been recent suggestions that an indigenous element in ancient Greek settlements in Sicily can be detected through funerary customs. This paper reviews the evidence for 'indigenous' burial methods in Greek cemeteries, concentrating on multiple, contracted and acephalous burials. It argues that such evidence is limited and open to various interpretations and that while it is highly likely that Greek settlements did incorporate an indigenous population, the funerary record cannot be used as a reliable identifier of such groups. The paper also briefly assesses the evidence for the presence of Greeks deriving from areas other than the historical mother-cities and suggests that such individuals are also very difficult to detect. It concludes that the general impression given by Sicilian Greek cemeteries is one of overall subscription to coherent burial systems, which may be viewed as part of an attempt to forge a unified and independent cultural identity.


May 04, 2005

Humans and Horses

Steve Sailer observes the fact that winning times in a horse race have not improved in the last fifty years, while humans have greatly improved their performance. Is this due to inbreeding, the fact that thoroughbreds are descended from vary few horses?

Inbreeding is harmful because it produces individuals which are homozygous for deleterious alleles. Each individual has many such alleles, but since each of us has several thousand genes, it is usually unlikely that a random pair of individuals will have a deleterious allele for the same gene. If an individual has at least one good copy of a gene, then in most cases there are no harmful effects. However, inbred individuals are derived from closely related parents, and these parents have a much higher chance of having bad alleles for the same genes, and therefore their children will tend to get two bad copies for many genes, and this will have harmful effects.

Populations that have praticed inbreeding for a long time have abolished many of their harmful alleles, because such alleles are expressed more often, the individuals which express them die or fail to reproduce, and the alleles are removed from the gene pool. On the other hand, by chance, it is possible that alleles with small harmful effects may in fact be fixed in the population, and this reduces the quality of the population.

Thoroughbred horses are both inbred and artificially selected. The genes of champions have a higher chance of passing to the next generation than the genes of average performers or losers. As a result, the quality of the gene pool of thoroughbred horses is very high, because inbreeding and artificial selection has essentially purified it of most harmful mutations.

This comes at a cost: thoroughbred horses have very little genetic variation, that is, they have very few differences from each other. Evolution works by exploiting differences, by favoring some alleles over others. Natural selection leads to evolution only if it has the raw materials of variation to work with.

Therefore, the curve presented in Steve's post is best interpreted as an improvement of the genetic quality of thoroughbreds until 1950 through inbreeding and artificial selection, which reached a plateau; further improvements are no longer possible, because there is very little room in the horse gene pool to create new variants with superior performance.

Why did human performance improve so drastically compared to that of horses? I think that four factors have played a role:
  • Better living conditions have greatly increased the fraction of the human population that is healthy enough to compete in sports.
  • The human population has grown dramatically, and hence there is a much larger pool of individuals competing at the right tail of the ability distribution.
  • The financial rewards of those going into sports have greatly increased, and this has led to many able individuals choosing sports as a career path.
  • There have been extreme improvements in sports science in the last decades. Humans can learn easily, and they can improve their technique, experiment with new training regimes and give feedback about what works for them and what does not. Unlike horses, humans use their minds to optimize the performance of their bodies.

May 03, 2005

Parents take better care of pretty children

Ugly Children May Get Parental Short Shrift


Published: May 3, 2005

Parents would certainly deny it, but Canadian researchers have made a startling assertion: parents take better care of pretty children than they do ugly ones.

Researchers at the University of Alberta carefully observed how parents treated their children during trips to the supermarket. They found that physical attractiveness made a big difference.

The researchers noted if the parents belted their youngsters into the grocery cart seat, how often the parents' attention lapsed and the number of times the children were allowed to engage in potentially dangerous activities like standing up in the shopping cart. They also rated each child's physical attractiveness on a 10-point scale.

The findings, not yet published, were presented at the Warren E. Kalbach Population Conference in Edmonton, Alberta.

When it came to buckling up, pretty and ugly children were treated in starkly different ways, with seat belt use increasing in direct proportion to attractiveness. When a woman was in charge, 4 percent of the homeliest children were strapped in compared with 13.3 percent of the most attractive children. The difference was even more acute when fathers led the shopping expedition - in those cases, none of the least attractive children were secured with seat belts, while 12.5 percent of the prettiest children were.

Homely children were also more often out of sight of their parents, and they were more often allowed to wander more than 10 feet away.

Age - of parent and child - also played a role. Younger adults were more likely to buckle their children into the seat, and younger children were more often buckled in. Older adults, in contrast, were inclined to let children wander out of sight and more likely to allow them to engage in physically dangerous activities.

Although the researchers were unsure why, good-looking boys were usually kept in closer proximity to the adults taking care of them than were pretty girls. The researchers speculated that girls might be considered more competent and better able to act independently than boys of the same age. The researchers made more than 400 observations of child-parent interactions in 14 supermarkets.

Dr. W. Andrew Harrell, executive director of the Population Research Laboratory at the University of Alberta and the leader of the research team, sees an evolutionary reason for the findings: pretty children, he says, represent the best genetic legacy, and therefore they get more care.

Not all experts agree. Dr. Frans de Waal, a professor of psychology at Emory University, said he was skeptical.

"The question," he said, "is whether ugly people have fewer offspring than handsome people. I doubt it very much. If the number of offspring are the same for these two categories, there's absolutely no evolutionary reason for parents to invest less in ugly kids."

Dr. Robert Sternberg, professor of psychology and education at Yale, said he saw problems in Dr. Harrell's method and conclusions, for example, not considering socioeconomic status.

"Wealthier parents can feed, clothe and take care of their children better due to greater resources," Dr. Sternberg said, possibly making them more attractive. "The link to evolutionary theory is speculative."

But Dr. Harrell said the importance of physical attractiveness "cuts across social class, income and education."

"Like lots of animals, we tend to parcel out our resources on the basis of value," he said. "Maybe we can't always articulate that, but in fact we do it. There are a lot of things that make a person more valuable, and physical attractiveness may be one of them."

Link (New York Times)

Resource scarcity does not imply valuing fatness in women

It was previously suggested that societies where resources (e.g., food) are scarce have a preference for fat women, because such women are better able to survive in times of crisis (e.g., a famine). A new study has failed to replicate this finding.

Evolution and Human Behavior
Volume 26, Issue 3 , May 2005, Pages 257-270

Valuing thinness or fatness in women
Reevaluating the effect of resource scarcity

Carol R. Ember et al.


Brown and Konner [Brown, P. J., & Konner M. (1987). Ann. N.Y. Acad. Sci., 499, 29–46] proposed that plumpness or moderate fatness is valued in most preindustrial societies because of fat's adaptive value during periods of resource scarcity. Using three measures of resource scarcity, we tested the hypothesis that societies with little or no such scarcity value thinness in women, whereas those with high scarcity value plumpness. In one cross-cultural sample, the evidence was significantly opposed to this hypothesis, and in a second, resource scarcity and valuation of fatness were unrelated. We explore possible reasons for the contradiction between these results and those of Anderson, Crawford, Nadeau, and Lindberg [Anderson, J. L., Crawford, C. B., Nadeau J., & Lindberg T. (1992), Ethol. Sociobiol., 13, 197–227], who reported a positive relationship between resource scarcity and plumpness being beautiful and conclude that their measure of scarcity was, in fact, a measure of food storage, which modulates the relationship: Resource scarcity and valuing fatness in women are negatively associated when there is little or no food storage and unrelated when there is moderate or high storage. Finally, we retest the possible effects of climate and male dominance suggested by Anderson et al., finding that some measures of male dominance indeed predict valuing fatness in women, but we suggest that considering these to be measures of “protest masculinity” rather than male dominance may better account for the results.


Heterozygosity and attractiveness

According to a new study, men who are heterozygous at three loci of the major histocompatibility complex are judged to be more attractive by women. Such men may be more resilient to infection, and hence they might live longer, or infect their spouses and offspring less; therefore, women may have evolved a preference for the phenotypical cues of MHC-heterozygous males, and such males have come to be seen as more attractive.

Evolution and Human Behavior
Volume 26, Issue 3 , May 2005, Pages 213-226

MHC-heterozygosity and human facial attractiveness

S. Craig Roberts et al.


Females gain direct or indirect fitness benefits by choosing between males with traits indicating “good genes,” but we usually know very little about the nature of these genes. However, it has been suggested that genetic quality may often be defined as heterozygosity at certain loci. Here, we show that heterozygosity at three key loci in the major histocompatibility complex (MHC) is associated with facial attractiveness: Faces of men who are heterozygous at all three loci are judged more attractive by women than faces of men who are homozygous at one or more of these loci. MHC genes code for proteins involved in immune response. Consistent with this function, faces of MHC heterozygotes are also perceived to be healthier. In a separate test, in the absence of any other cues, patches of skin from the cheeks of heterozygotes are judged healthier than skin of homozygotes, and these ratings correlate with attractiveness judgements for the whole face. Because levels of MHC similarity can influence mate preferences in animals and humans, we conducted a second experiment with genotyped women raters, finding that preferences for heterozygosity are independent of the degree of MHC similarity between the men and the female raters. Our results are the first to directly link facial attractiveness and a measure of genetic quality and suggest a mechanism to help explain common consensus concerning individual attractiveness. In a relatively monogamous species like humans, evolutionary benefits from choosing heterozygous mates could include prolonged parental care and reduced risk of contracting disease for females and their offspring.


May 02, 2005

More on Y-chromosomes in Bosnia Herzegovina

The recent paper on Bosnia Herzegovina gives some new insights into the origins of the populations residing there, as well as their relationships to other populations of the region. According to the authors:

In the PC analysis (Figure 3), the first PC shows that the three populations are genetically extremely close to each other, and closely related to other populations of the Balkans. However, the second PC tends to separate the Croat group not only from both Serbs and Bosniacs, but also from the Croats of Croatia.
Here are some of my observations:
  • Haplogroups C and Q are lacking in Bosnia Herzegovina, indicating that the region was not affected by Central Asian descended groups arriving either from eastern Europe or Asia Minor. We can infer the absence of Q from the absence of P*(xR) in these samples; note that P*(xR) was found in mainland Croatians and two islands believed to have received it either from the Avars or the Ottomans.
  • Serbs have a frequency of about 7.5% K*(xP) which is lacking in Croats and is found in a frequency of 1.2% in Bosniacs (aka Muslims). It is not clear what this represents.
  • J-M267 is found in 2.4% of Bosniacs and is lacking in Serbs and Croats, indicating perhaps that this was brought by Muslims.
  • E3b dominates over the other "Neolithic" haplogroups G and J. This probably reinforces the association of J with more "coastal" migrations observed before, and this probably applies to G as well, which is found in higher frequencies in Greece and Italy than in these Balkan populations.
  • R1a1 is found at frequencies less than 15.3%, and this is much lower than the 34% observed in the Croatian mainland and closer to the 10% frequency observed in Greece.
  • Haplogroup I-M170 is found at frequencies comparable to those of the Croatian mainland, except in the Croatians of Bosnia where it is much higher, perhaps due to drift. These frequencies differentiate these populations from the Greeks and Albanians where I-M170 is lower.
It is quite interesting that haplogroup R1a1 seems to decrease in frequency from north to south, just as it was shown to decrease in frequency from east to west in Anatolia. Analysis of the phylogeography of R1a1 is still needed to resolve when, and from which sources, this widespread haplogroup reached the area. Post-Last Glacial Maximum expansions, the signature of the Kurgan culture, Slavic migrations, and invasions from Iranic and Turkic tribes of Central Asia could conceivably account for its presence.

New evidence challenges hypothesis of modern human origins

WUHAN, April 27 (Xinhuanet) -- Chinese archaeologists said newly found evidence proves that a valley of Qingjiang River, a tributary on the middle reaches of the Yangtze River, might be one of the regions where Homo sapiens, or modern man, originated.

The finding challenges the "Out-of-Africa" hypothesis of modern human origins, according to which about 100,000 years ago modern humans originated in Africa, migrated to other continents, and replaced populations of archaic humans across the globe.

The finding comes from a large-scale excavation launched in the Qingjiang River Valley in 1980s when construction began on a rangeof hydropower stations on the Qingjiang River, a fellow researcher with the Hubei Provincial Institute of Cultural Relics and Archaeology.

Archaeologists discovered three human tooth fossils in one mountain cave in Mazhaping Village, in the Gaoping Township of Jianshi County, western Hubei Province, and found pieces of lithictechnology and evidence of fire usage in Minor Cave in Banxia. There were similar findings in Nianyu Mountain and in Zhadong Cavein Banxia, all in Changyang Prefecture of the Qiangjiang River Valley.

A special research panel named the Jianshi Man research team has been set up to analyze the findings.

Zheng Shaohua, a member of the Jianshi man research team from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, confirmed the tooth fossils belonged to humans dating back between 2.15 and 1.95 million yearsago.

The archaeologists also found fossils of bone implements in thecultural strata at the ruins where the human tooth fossils were discovered.

The fossilized bone implements bear traces of human beating, testifying that humans, not apes, lived inside the mountain cave, said Qiu Zhanxiang, another member on the Jianshi Man research team.

The pieces of lithic technology and traces of human fire usage found in Minor Cave in Banxia were said to date back 130,000 years,the ruins of human fire usage in Nianyu Mountain were dated as 120,000 years or 90,000 years old, while pieces of lithic technology and traces of fire usage found in Zhadong Cave in Banxia, were dated as 27,000 years old, said Professor Zheng.

Before these latest archaeological findings, Chinese archaeologists had found fossils of what is now known as ChangyangMan in 1957 under the leadership of renowned Chinese paleoanthropologist Jia Lanpo. Changyang Man represents early Homosapiens dating back 200,000 years.

The latest archaeological findings together with the earlier discovery of Changyang Man all prove there was continuity in Homo sapiens' development in China, said Liu Qingzhu, head of the Archaeology Institute of the Chinese Academy of Social Sciences.

"They are also of great significance to research on Paleolithic era in China and East Asia, and theories regarding multiple origins of mankind," said Liu.

Link (Xinhua)

May 01, 2005

Christos Anesti and Happy Easter!

By means of Your Cross, O Lord, You abolished death.
To the robber You opened Paradise.
The lamentation of the myrrh-bearing women You transformed,
and You gave Your Apostles the order to proclaim to all
that You had risen, O Christ our God,
and granted the world Your great mercy.