A very interesting new article in Science applies biological principles to the problem of evaluating how many ancient and medieval works have survived. Treating extant manuscripts as "fossils" of works, the author concludes that most of the technical literature even of Late Antiquity has survived. But, why were many older works from Antiquity lost? The author gives a reasonable suggestion:

But why then have so few actually survived from Antiquity? For instance, only one of seven works by Pliny the Elder and only a small fraction of the approximately 2000 works on which he based his Naturalis Historia (77 A.D.) (17), the foremost scientific encyclopedia of the Middle Ages, have survived. The answer may lie in copyists' changeover from papyrus to parchment during the third and fourth centuries (18). Surviving texts may be mostly those similar to Pliny's (19), which happened to have been in demand during and soon after the transition to the new and more durable medium.

Science, Vol 307, Issue 5713, 1305-1307 , 25 February 2005

How Science Survived: Medieval Manuscripts' "Demography" and Classic Texts' Extinction

John L. Cisne

Determining what fraction of texts and manuscripts have survived from Antiquity and the Middle Ages has been highly problematic. Analyzing the transmission of texts as the "paleodemography" of their manuscripts yields definite and surprisingly high estimates. Parchment copies of the foremost medieval textbooks on arithmetical and calendrical calculation closely fit age distributions expected for populations with logistic growth and manuscripts with exponential survivorship. The estimated half-lives of copies agree with Bischoff's paleographically based suggestion that roughly one in seven manuscripts survive in some form from ninth-century Carolingian workshops. On this basis, many if not most of the leading technical titles circulating in Latin probably survived, even from late Antiquity.

Link

By Abdullah Kilic
Published: Thursday 24, 2005
zaman.com

Invaluable pieces of mosaics, which have adorned the Hagia Sophia Museum's dome for over 1,500 years are being stored without any protection between the Hagia Sofia and Hagia Irene. The pieces dropped due to condensation and restoration work but have not been stored properly.

Experts are dismayed that pieces of mosaics portraying the Virgin Mary, Jesus Christ and Christian saints are being stored unprotected in boxes. Art historians criticize their continued storage despite the public outcry and say it is gross negligence and insensitiveness to leave them where they are. Saying that the Hagia Sophia is suffering serious problems from the mismanagement of its restoration, Professor Semavi Eyice says that the scandal is a national shame for Turkey. The monument has been called the "Eighth Wonder of the World", but pieces of its mosaics are being treated like rubbish, and Eyice has called on officials to take action. Professor Said Basaran, Chair of Istanbul University's Cultural Heritage Conservation and Restoration Department has said that the abandoned pieces are as valuable as the ones decorating the dome and that the mosaics should be transferred to a secure place.

Mosaic decorations on the dome of Hagia Sophia's dome, which was built in the sixth century A.D, are as valuable as the architecture of the construction. There are about 1000 square meters of mosaic inside the Hagia Sophia, within which, only a 60-meter-square part does not have mosaics. The size of the mosaics used in the Hagia Sophia varies from century to century. Mosaics from the sixth and the 10th centuries are 6 x 7 mm thick while the ones added in the seventh century are about 3 cm thick. The diameters of the mosaics on window frames also correspond to these numbers. Bits dropped from the 1,000 or 1,500-year-old mosaics on the dome of the Hagia Sophia, which is described as a "masterwork", are still waiting to be reset and are being stored without any attention to their valuable condition.

Link (Zaman)

Human Genetics (Online First)

Genes and human elite athletic performance

Daniel G. MacArthur et al.

Abstract Physical fitness is a complex phenotype influenced by a myriad of environmental and genetic factors, and variation in human physical performance and athletic ability has long been recognised as having a strong heritable component. Recently, the development of technology for rapid DNA sequencing and genotyping has allowed the identification of some of the individual genetic variations that contribute to athletic performance. This review will examine the evidence that has accumulated over the last three decades for a strong genetic influence on human physical performance, with an emphasis on two sets of physical traits, viz. cardiorespiratory and skeletal muscle function, which are particularly important for performance in a variety of sports. We will then review recent studies that have identified individual genetic variants associated with variation in these traits and the polymorphisms that have been directly associated with elite athlete status. Finally, we explore the scientific implications of our rapidly growing understanding of the genetic basis of variation in performance.

Link

Human Genetics (Online First)

The 8818G allele of the agouti signaling protein (ASIP) gene is ancestral and is associated with darker skin color in African Americans

Carolina Bonilla et al.

Abstract Skin color, a predictor of social interactions and risk factor for several types of cancer, is due to two contrasting forms of melanin, the darker eumelanin and lighter phaeomelanin. The lighter pigment phaeomelanin is the product of the antagonistic function of the agouti signaling protein (ASIP) on the α-melanocyte stimulating hormone receptor (MC1R). Studies have shown that a single-nucleotide polymorphism (SNP) in the 3primeUTR of the ASIP gene is associated with dark hair and eyes; however, little is known about its role in inter-individual variation in skin color. Here we examine the relationship between the ASIP g.8818A>G SNP and skin color (M index) as assessed by reflectometry in 234 African Americans. Analyses of variance (ANOVA) were performed to evaluate the effects of ASIP genotypes, age, individual ancestry, and sex on skin color variation. Significant effects on M index variation were observed for ASIP genotypes (F(2,236)=4.37, P=0.01), ancestry (F(1,243)=37.2, P<0.001), p="0.05).">A polymorphism exhibits a dominant effect leading to lighter skin color and that variation in the ASIP gene may have been one of several factors contributing to reductions in pigmentation in some populations. Further study is needed to reveal how interactions between ASIP and several other genes, such as MC1R and P, predict human pigmentation.

Link

Finds in 141 tombs add to picture of ancient Macedonia

Bronze helmet with gold decoration from a mid-sixth-century-BC warrior’s grave. Many Macedonian officers were buried in full armor, together with swords, spears and knives.

By Iota Myrtsioti - Kathimerini

The gold of the ancient Macedonians still gleams on the soldiers’ uniforms being unearthed by excavations in the ancient necropolis of Archontiko in Pella.

Fully armed Macedonian aristocrats, gold-bedecked women in elaborate jewelry, faience idols and clay vases of exceptional beauty had lain concealed for centuries in 141 simple rectangular trench graves that were discovered recently in the ancient settlement.

For Charon

In their tombs, Macedonian officers wore armor and — in the late Classical and early Hellenistic periods — were equipped for the journey after death with coins for Charon, copper utensils made by local metalworkers, and rare incense or oil containers with the war of the giants depicted in relief.

These are not the first discoveries of gold-embroidered uniforms at Archontiko. Archaeologists Pavlos and Anastassia Chrystostomou from the 17th Ephorate of Prehistoric and Classical Antiquities found the first warriors in full armor four years ago while excavating the cemetery.

The contents of the latest 141 tombs to be discovered were presented recently at the ephorate’s archaeological conference.

The typical Archontiko tomb contained gold masks, gold breastplates, clothes and shoes adorned with gold strips, helmets, shields, swords, spears and knives embellished with gold strips or rosettes.

Though only 2 percent of the 20-hectare cemetery has been excavated, the harvest has already been rich.

The dozens of finds help form an image of the socioeconomic organization, burial rituals, high living standard, aristocratic origins and leading role of the families in one of the most significant urban centers of ancient Macedonia from prehistoric times until the end of the fifth century BC.

As the Chrysostomou couple explained, the ancient settlement built in the middle of the plain of Bottiaia, close to the ancient route connecting East and West — later name the Egnatia Road — was one of the most important urban centers before the foundation of the capital of Pella.

This is confirmed by the 541 tombs dating from the Iron Age, through the Classical period and up to the early Hellenistic era (seventh century BC - 280 BC). This year’s investigation of a family cluster (in the broad sense of a clan) produced rich finds, as important as those of previous years.

A trove of grave ornaments was found in the 25 male and 17 female tombs dating to the Archaic era (first half of the sixth century BC to the beginning of the fifth century BC).

The men were mostly in full armor, with helmets adorned with incised gold strips, steel swords with gold on the handles, spears and knives. Gold foil sheets with embossed ornamentation adorn the leather breastplates, clothing, footwear and hand coverings of the warriors. Apart from gold and silver jewelry, numerous other objects, such as bronze and clay vases, clay idols, metal likenesses of farm carts, furniture and spits accompanied the male burials.

These objects present the first impression of a warrior, while the other grave offerings reveal the deceased’s personal and social prestige, two centuries before the rule of Phillip II and Alexander III.

The women were bedecked in jewelry that reveals their high social status. The grave ornaments (clay and metal vases, more rarely of glass of faience, or metal likenesses of carts) are related to the funeral customs of the journey to Hades.

Impressive items among this year’s finds were large silver clasps with disk-shaped heads adorned with rosettes and an 85-centimeter braided chain decorated in a style that predates those of Ephesus, Rhodes, and Eleutherna in Crete.

The necklace went around the chest where it was fastened by pins onto the clothing. It has gilded snake heads, seated lions and the heads of the female divinity Potnia of Thera.

The funeral ornaments in the women’s graves seem to have come to Macedonia from distant places. Among them are faience idols, probably from workshops on Rhodes, and clay vases from Kerameikos in Athens and Corinthian and Ionian workshops.

Link (Kathimerini)

The recent discovery of the fraudulent behavior of a German anthropologist has upset our understanding of Upper Paleolithic prehistory, and especially the problem of Neanderthal-modern human co-existence. In an older post, I linked to a paper in Nature which casts doubt on the idea that modern humans initiated the Aurignacian technological revolution. That paper was also based on a redating of fossils which were once thought to be of Aurignacian age, but were found to be much newer. And recently, the older dates for Omo, a very old African sapiens specimen removed much of the excitement from the discovery of the idaltu hominid from Ethiopia.

Methinks, it would be a good idea for anthropologists to redate the major fossils in their collections, as our understanding of human prehistory should not fluctuate depending either on frauds or "preliminary" dates that persist for decades in the literature.

While humans differ from chimpanzees in approximately 1-2% of the "letters" (nucleotides) of their genome, a new paper shows that as much as 80% of human proteins are different from those of chimpanzees. This shows how a small degree of genetic difference may have large overall effects.

Gene (Article in Press)

Eighty percent of proteins are different between humans and chimpanzees

Galina Glazko et al.

Abstract

The chimpanzee is our closest living relative. The morphological differences between the two species are so large that there is no problem in distinguishing between them. However, the nucleotide difference between the two species is surprisingly small. The early genome comparison by DNA hybridization techniques suggested a nucleotide difference of 1–2%. Recently, direct nucleotide sequencing confirmed this estimate. These findings generated the common belief that the human is extremely close to the chimpanzee at the genetic level. However, if one looks at proteins, which are mainly responsible for phenotypic differences, the picture is quite different, and about 80% of proteins are different between the two species. Still, the number of proteins responsible for the phenotypic differences may be smaller since not all genes are directly responsible for phenotypic characters.

Link

Interestingly, the only Caucasoid haplogroups present in the Mongolian population are J and R1a1, with R1a1 found in the highest frequency (83%) in the Khoton.

Gene (Article in press)

Genetic features of Mongolian ethnic groups revealed by Y-chromosomal analysis

Toru Katoh et al.

Abstract

About 20 ethnic groups reside in Mongolia. On the basis of genetic and anthropological studies, it is believed that Mongolians have played a pivotal role in the peopling of Central and East Asia. However, the genetic relationships among these ethnic groups have remained obscure, as have their detailed relationships with adjacent populations. We analyzed 16 binary and 17 STR polymorphisms of human Y chromosome in 669 individuals from nine populations, including four indigenous ethnic groups in Mongolia (Khalkh, Uriankhai, Zakhchin, and Khoton). Among these four Mongolian populations, the Khalkh, Uriankhai, and Zakhchin populations showed relatively close genetic affinities to each other and to Siberian populations, while the Khoton population showed a closer relationship to Central Asian populations than to even the other Mongolian populations. These findings suggest that the major Mongolian ethnic groups have a close genetic affinity to populations in northern East Asia, although the genetic link between Mongolia and Central Asia is not negligible.

Link

It appeared to be one of archaeology's most sensational finds. The skull fragment discovered in a peat bog near Hamburg was more than 36,000 years old - and was the vital missing link between modern humans and Neanderthals.

This, at least, is what Professor Reiner Protsch von Zieten - a distinguished, cigar-smoking German anthropologist - told his scientific colleagues, to global acclaim, after being invited to date the extremely rare skull.

However, the professor's 30-year-old academic career has now ended in disgrace after the revelation that he systematically falsified the dates on this and numerous other "stone age" relics.

Full Story (Guardian)

This interesting new paper suggests that cognitive changes are triggered by changes in the economic significance of education. In other words, as society places greater cognitive demands, individuals must become smarter to deal with these demands, and they become smarter via education, i.e., by spending more time training their brains to perform in the more demanding environment. This theory sounds plausible. Better living conditions and better education probably account for the observed worldwide differences in intelligence.

Intelligence (Early View)

Educational and ecological correlates of IQ: A cross-national investigation

Nigel Barber

Abstract

The new paradigm of evolutionary social science suggests that humans adjust rapidly to changing economic conditions, including cognitive changes in response to the economic significance of education. This research tested the predictions that cross-national differences in IQ scores would be positively correlated with education and negatively correlated with an agricultural way of life. Regression analysis found that much of the variance in IQ scores of 81 countries (derived from [Lynn, R., & Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger]) was explained by enrollment in secondary education, illiteracy rates, and by the proportion of agricultural workers. Cross-national IQ scores were also related to low birth weights. These effects remained with national wealth, infant mortality, and geographic continent controlled (exception secondary education) and were largely due to variation within continents. Cross-national differences in IQ scores thus suggest that increasing cognitive demands in developed countries promote an adaptive increase in cognitive ability.

Link

A new article quantifies the African admixture in the population of Buenos Aires from Argentina. The admixture is estimated at 2.2% overall, but is concentrated on only 10% of the total population. These results indicate the great reduction of the black element in Buenos Aires, although it did not disappear entirely.

American Journal of Physical Anthropology (Early View)

African ancestry of the population of Buenos Aires

Laura Fejerman et al.

The population of Argentina today does not have a visible black African component. However, censuses conducted during most of the 19th century registered up to 30% of individuals of African origin living in Buenos Aires city. What has happened to this African influence? Have all individuals of African origin died, as lay people believe? Or is it possible that admixture with the European immigrants made the African influence invisible? We investigated the African contribution to the genetic pool of the population of Buenos Aires, Argentina, typing 12 unlinked autosomal DNA markers in a sample of 90 individuals. The results of this analysis suggest that 2.2% (SEM = 0.9%) of the genetic ancestry of the Buenos Aires population is derived from Africa. Our analysis of individual admixture shows that those alleles that have a high frequency in populations of African origin tend to concentrate among 8 individuals in our sample. Therefore, although the admixture estimate is relatively low, the actual proportion of individuals with at least some African influence is approximately 10%. The evidence we are presenting of African ancestry is consistent with the known historical events that led to the drastic reduction of the Afro-Argentine population during the second half of the 19th century. However, as our results suggest, this reduction did not mean a total disappearance of African genes from the genetic pool of the Buenos Aires population.

Link

In a new article in Science, researchers have genotype approximately 1.6 million single nucleotide polymorphisms (SNPs) in 71 individuals drawn from the 3 major human populations: Europeans, Asians, and Africans. A summary of the results frm EurekAlert..

Science, Vol 307, Issue 5712, 1072-1079

Whole-Genome Patterns of Common DNA Variation in Three Human Populations

David A. Hinds et al.

Individual differences in DNA sequence are the genetic basis of human variability. We have characterized whole-genome patterns of common human DNA variation by genotyping 1,586,383 single-nucleotide polymorphisms (SNPs) in 71 Americans of European, African, and Asian ancestry. Our results indicate that these SNPs capture most common genetic variation as a result of linkage disequilibrium, the correlation among common SNP alleles. We observe a strong correlation between extended regions of linkage disequilibrium and functional genomic elements. Our data provide a tool for exploring many questions that remain regarding the causal role of common human DNA variation in complex human traits and for investigating the nature of genetic variation within and between human populations.

Link

This story in Nature neatly summarizes the redating of the Omo skulls from Ethiopia. The two skulls have now been dated to 195+/-5 thousand years ago, which makes them the earliest known fossils of Homo sapiens. This new discovery comes to upset the recent discovery of the Homo sapiens idaltu subspecies which was date to 160 thousands years ago. Unlike the idaltu fossils which were primitive, and were postulated to have belonged to an earlier form of the lineage leading to modern humans, the Omo skulls are fully modern anatomically, and this places them as the oldest members of our species.

Nature 433, 733 - 736 (17 February 2005); doi:10.1038/nature03258

Stratigraphic placement and age of modern humans from Kibish, Ethiopia

IAN MCDOUGALL et al.

In 1967 the Kibish Formation in southern Ethiopia yielded hominid cranial remains identified as early anatomically modern humans, assigned to Homo sapiens. However, the provenance and age of the fossils have been much debated. Here we confirm that the Omo I and Omo II hominid fossils are from similar stratigraphic levels in Member I of the Kibish Formation, despite the view that Omo I is more modern in appearance than Omo II. 40Ar/39Ar ages on feldspar crystals from pumice clasts within a tuff in Member I below the hominid levels place an older limit of 198 plusminus 14 kyr (weighted mean age 196 plusminus 2 kyr) on the hominids. A younger age limit of 104 plusminus 7 kyr is provided by feldspars from pumice clasts in a Member III tuff. Geological evidence indicates rapid deposition of each member of the Kibish Formation. Isotopic ages on the Kibish Formation correspond to ages of Mediterranean sapropels, which reflect increased flow of the Nile River, and necessarily increased flow of the Omo River. Thus the 40Ar/39Ar age measurements, together with the sapropel correlations, indicate that the hominid fossils have an age close to the older limit. Our preferred estimate of the age of the Kibish hominids is 195 plusminus 5 kyr, making them the earliest well-dated anatomically modern humans yet described.

Link

Intelligence (Article in Press)

Big-brained people are smarter: A meta-analysis of the relationship between in vivo brain volume and intelligence


Michael A. McDaniel

Abstract

The relationship between brain volume and intelligence has been a topic of a scientific debate since at least the 1830s. To address the debate, a meta-analysis of the relationship between in vivo brain volume and intelligence was conducted. Based on 37 samples across 1530 people, the population correlation was estimated at 0.33. The correlation is higher for females than males. It is also higher for adults than children. For all age and sex groups, it is clear that brain volume is positively correlated with intelligence.

Link

The Anatolians are the ethnic descendants of both the indigenous populations of Asia Minor who converted to Islam (and were thus spared from the genocidal campaign of the Ottomans and Kemalists during the early 20th century), and also of non-indigenous populations from the Balkans, the Middle East, and Central Asia. From Central Asia came the Turks, who were the main agent for the Islamization and during the last century Turkification of Asia Minor.

To what extent are the Anatolians descended from Central Asian Turks? The study of Cinnioglu et al. (2004) discovered an occurrence of 3.4% of Mongoloid Y-chromosomal haplogroups in Anatolia (haplogroups Q, O, and C).

According to Tambets et al. (2004) the occurrence of Mongoloid haplogroups in present-day Central Asian Turkic Altaic speakers (Altaians) is at least 40%, with an additional 10% which might belong to haplogroup O which was not tested in this study. According to Zerjal et al. (2002) this percentage is for various Turkic speakers: Kyrgyz (22%), Dungans (32%), Uyghurs (33%), Kazaks (86%), Uzbeks (18%).

It is clear that the percentage of Mongoloid ancestry among the Turkic speakers is very variable, yet it is clear that the Proto-Turks must have been partially Mongoloid in lieu of the fact that all current Turkic speakers possess some Mongoloid admixture. The average of the six Central Asian population samples listed above is 38.5% and may serve as a first-order estimate of the paternal contribution of early Turks, who (judging by their modern descendants in Central Asia) were more Caucasoid paternally and more Mongoloid maternally.

Using the figure of 38.5%, the paternal contribution of Turks to the Anatolian population is estimated to about 11%. In lieu of the approximation, allowing for 33% relative error in either direction for both the true frequency of Mongoloid lineages in Anatolia and in early Turks, we obtain a range of 6-22%. It would thus appear that the Turkish element is a minority one in the composition of the Anatolians, but it is by no means negligible.

By Erin Texeira
Associated Press
January 31, 2005

Luke Do was a lively 18-month-old awaiting the birth of his first sibling when he was diagnosed with a rare form of leukemia.

The hopes of his parents, both doctors in San Jose, Calif., immediately turned to a bone marrow transplant, but they soon learned some distressing news -- Luke's ethnic heritage made him a tough match.

Sarah Gaskins, Luke's mother, has Japanese and European ancestors and his father, Lam Do, is Vietnamese-American. Because bone marrow matches usually are made with a relative or someone with the same racial or ethnic background as the patient, multiracial people rarely have success.

"It's tragic," said Lam Do, who specializes in internal medicine. "Your chance of finding a donor is so low, it's like winning the lottery."

For years, the medical community has pushed for increased donor registry among racial minorities to improve survival rates for leukemia, lymphoma and other blood diseases. But to the general public, the situation is not well-known.

Only 2 percent of those who list their ancestry with the National Marrow Donor Program are multiracial, though the NMDP will -- for the first time -- study multiracial patients' medical records this year to better understand what kind of marrow tissue they tend to inherit from their parents. The group also will try to recruit potential donors more effectively, said Helen Ng, an NMDP spokeswoman.

Matt Kelley, president of Mavin Foundation, a Seattle-based advocacy group for multiracial people, says the inattention to the problem reflects society's reluctance to accept today's increasingly complex racial landscape.

"It's a headache," said Kelley, whose group has an ongoing bone marrow program. "The reality is that many organizations are afraid of addressing race . . . and when it comes to addressing mixed-heritage issues, they don't want to go there."

Today, whites in need of a bone marrow transplant have about a 90 percent chance of finding a match, said Dr. Patrick Beatty, an oncologist with the Montana Cancer Specialists in Missoula, Mont. For those who aren't white, "your chances of getting a match are pretty remote," he said.

The biological reason has to do with the body's response to infections, Beatty said. Because the world's ancient peoples were exposed to different diseases over millennia, each group developed different tissue antigens, substances that help fight illness.

Descendants retain those highly varied tissue antigens, he said, making it tough to match the bone marrow of individuals from different ancestries.

Luke Do's family was elated when, about six months after his diagnosis, they learned a match had been found in a Japanese-American police officer in Seattle.

Now the Dos are making plans for Luke to start kindergarten -- and to celebrate the third anniversary of his transplant on March 18.

Nationwide, census data counted about 7 million people of multiracial heritage -- the first time an option was available to check more than one racial category. Mavin organizers estimate the true number is closer to 10 million.

Within that group, there are millions of possible ethnic mixes, and therefore millions of potential challenges for someone seeking a bone marrow match. Complicating the situation further, research shows that minorities have greater tissue variation than whites. Africans and their descendants globally have the most variation of any population in the world, "many, many more tissue types than Caucasians," Beatty said, adding that current research is focusing on finding matches with umbilical cord blood and developing matching tissues.

"Many (multiracial) people have very little contact with entities that recognize them correctly," said Kelley of Mavin, adding that this typically results in hurt feelings and a sense of social isolation. "We don't have that luxury when it comes to people's health."

Link (Indianapolis Star)

A recent study found that elite Ethiopian athletes differed from controls in their frequency of Y-chromosome haplogroups. A new study based on mtDNA did not find any significant differences based on this genetic system.

Comp Biochem PB Biochem Mol Biol. 140(3):497-503.

Mitochondrial DNA lineages of elite Ethiopian athletes.

Scott RA et al.

Previous studies have hypothesised that mitochondrial DNA (mtDNA) polymorphisms may influence aerobic performance. The matrilineal inheritance and accumulation of polymorphisms in mtDNA means that mtDNA haplogroups, characterised by key polymorphisms, are often represented at different frequencies in different populations. The present study aimed to compare the mtDNA haplogroup distribution of elite Ethiopian athletes relative to the general Ethiopian population. The haplogroup distribution of 76 endurance athletes (E), members of the Ethiopian national athletics team, was compared to 108 members of the general Ethiopian population (C). DNA was extracted from buccal swabs and haplogroups assigned by sequencing part of the hypervariable sequence (HVS-I), followed by analysis of key coding-region polymorphisms. A high proportion of African 'L' haplogroups was found in athletes and controls (C=53%; E=55%). Haplogroup distribution of endurance runners did not differ from that of C (P=0.63). Elite Ethiopian athletes are not a mitochondrially distinct group relative to the Ethiopian population. It appears that environment and, perhaps, polymorphisms in the nuclear genome are more important determinants of Ethiopian running success than mtDNA polymorphisms.

Link

Am J Phys Anthropol. 2005 Feb 3; (Early View)

Reconstructing the population history of Puerto Rico by means of mtDNA phylogeographic analysis.

Martinez-Cruzado JC et al.

The haplogroup identities of 800 mtDNAs randomly and systematically selected to be representative of the population of Puerto Rico were determined by restriction fragment length polymorphism (RFLP), revealing maternal ancestries in this highly mixed population of 61.3% Amerindian, 27.2% sub-Saharan African, and 11.5% West Eurasian. West Eurasian frequencies were low in all 28 municipalities sampled, and displayed no geographic patterns. Thus, a statistically significant negative correlation was observed between the Amerindian and African frequencies of the municipalities. In addition, a statistically highly significant geographic pattern was observed for Amerindian and African mtDNAs. In a scenario in which Amerindian mtDNAs prevailed on either side of longitude 66 degrees 16' West, Amerindian mtDNAs were more frequent west of longitude 66 degrees 16' West than east of it, and the opposite was true for African mtDNAs. Haplogroup A had the highest frequency among Amerindian samples (52.4%), suggesting its predominance among the native Tainos. Principal component analysis showed that the sub-Saharan African fraction had a strong affinity to West Africans. In addition, the magnitudes of the Senegambian and Gulf of Guinea components in Puerto Rico were between those of Cape Verde and Sao Tome. Furthermore, the West Eurasian component did not conform to European haplogroup frequencies. HVR-I sequences of haplogroup U samples revealed a strong North African influence among West Eurasian mtDNAs and a new sub-Saharan African clade.

Link

Am. J. Phys. Anthropol. (Early View)

Mitochondrial DNA diversity in 17th-18th century remains from Tenerife (Canary Islands)

Nicole Maca-Meyer et al.

Mitochondrial DNA sequences and restriction fragment length polymorphisms were retrieved (with >80% efficiency) from a 17th-18th century sample of 213 teeth from Tenerife. The genetic composition of this population reveals an important ethnic heterogeneity. Although the majority of detected haplotypes are of European origin, the high frequency of sub-Saharan African haplotypes (15.63%), compared to that of the present-day population (6.6%), confirms the importance of the Canary Islands in the black slave trade of that epoch. The aboriginal substrate, inferred from the U6b1 haplotypes (8.59%), has also decreased due to European input. Finally, the presence of Amerindian lineages (1.5%) reveals that the Canary Islands have also received genetic flow from America.

Link

A very interesting post by John Hawks on the (possibly neglected) importance of positive selection during the evolution of the human lineage.

Molecular Biology and Evolution (published online)

Neandertal Evolutionary Genetics; Mitochondrial DNA Data from the Iberian Peninsula

Carles Lalueza-Fox et al.

Abstract

Mitochondrial DNA (mtDNA) was retrieved for the first time from a Neandertal from the Iberian Peninsula, excavated from the El Sidrón Cave (Asturias, North of Spain), and dated to circa 43,000 YA. The sequence suggests that Iberian Neandertals were not genetically distinct from those of other regions. An estimate of effective population size indicates that the genetic history of the Neandertals was not shaped by an extreme population bottleneck associated with the glacial maximum of 130 KYA. A high level of polymorphism at sequence position 16,258 reflects deeply rooted mtDNA lineages, with the time to the most recent common ancestor (TMRCA) at ca. 250 KYA. This coincides with the full emergence of the "classical" Neandertal morphology and fits chronologically with a proposed speciation event of H. neanderthalensis.

Link

The multiregional (MR) model of modern human origins, despite having been largely superseded by the Out-of-Africa model (OOA), just won't die, and why should it, given that much recent evidence seems to cast doubt on at least the pure OOA model which denies any contribution of older hominids in modern humans?

In a new paper in Human Biology, Dr. Relethford, a main proponent of MR shows under which conditions one of the main objections to MR can be overcome. Critics of MR start by the observation that our species is fairly homogeneous, or in genetic terms, has a very low effective population size of just 10,000. But, if we count as ancestors populations of erectus which spread over the earth more than a million years ago, then this number should be quite higher.

In this paper, the authors show that as long as these scattered human populations had (i) low gene flow among themselves, (ii) were subject to relatively frequent extinction events and (iii) migration between them was kin-structured, i.e., genetically related individuals tended to migrate, then the low effective population size could be explained, even though our prehistoric ancestors may have had much larger census sizes.

(i) must hold so as to prevent the formation of one big relatively homogeneous gene pool, (ii) would limit the time during which populations could exist and thus contribute to other neighboring populations, and (iii) would limit the amount of genetic variation exchanged due to migration, as family members are a more homogeneous unit than random samples of a population.

The authors are agnostic as to whether these conditions hold in our ancestral history, but in any case, their theory is worthy of consideration.

Human Biology 76.5 (2004) 689-709

Local Extinction and Recolonization, Species Effective Population Size, and Modern Human Origins


Elise Eller et al.

Abstract

A primary objection from a population genetics perspective to a multiregional model of modern human origins is that the model posits a large census size, whereas genetic data suggest a small effective population size. The relationship between census size and effective size is complex, but arguments based on an island model of migration show that if the effective population size reflects the number of breeding individuals and the effects of population subdivision, then an effective population size of 10,000 is inconsistent with the census size of 500,000 to 1,000,000 that has been suggested by archeological evidence. However, these models have ignored the effects of population extinction and recolonization, which increase the expected variance among demes and reduce the inbreeding effective population size. Using models developed for population extinction and recolonization, we show that a large census size consistent with the multiregional model can be reconciled with an effective population size of 10,000, but genetic variation among demes must be high, reflecting low interdeme migration rates and a colonization process that involves a small number of colonists or kin-structured colonization. Ethnographic and archeological evidence is insufficient to determine whether such demographic conditions existed among Pleistocene human populations, and further work needs to be done. More realistic models that incorporate isolation by distance and heterogeneity in extinction rates and effective deme sizes also need to be developed. However, if true, a process of population extinction and recolonization has interesting implications for human demographic history.

Link