European origin of domesticated dogs

It seems like yesterday that a paper suggested a Southeast Asian origin of domestic dogs. It always seems that ancient DNA upsets inferences from modern populations alone.

Science 15 November 2013: Vol. 342 no. 6160 pp. 871-874

Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs

O. Thalmann et al.

The geographic and temporal origins of the domestic dog remain controversial, as genetic data suggest a domestication process in East Asia beginning 15,000 years ago, whereas the oldest doglike fossils are found in Europe and Siberia and date to >30,000 years ago. We analyzed the mitochondrial genomes of 18 prehistoric canids from Eurasia and the New World, along with a comprehensive panel of modern dogs and wolves. The mitochondrial genomes of all modern dogs are phylogenetically most closely related to either ancient or modern canids of Europe. Molecular dating suggests an onset of domestication there 18,800 to 32,100 years ago. These findings imply that domestic dogs are the culmination of a process that initiated with European hunter-gatherers and the canids with whom they interacted.

Link

Native Native American dogs

Proc. R. Soc. B doi: 10.1098/rspb.2013.1142

Pre-Columbian origins of Native American dog breeds, with only limited replacement by European dogs, confirmed by mtDNA analysis

Barbara van Asch et al.

Dogs were present in pre-Columbian America, presumably brought by early human migrants from Asia. Studies of free-ranging village/street dogs have indicated almost total replacement of these original dogs by European dogs, but the extent to which Arctic, North and South American breeds are descendants of the original population remains to be assessed. Using a comprehensive phylogeographic analysis, we traced the origin of the mitochondrial DNA lineages for Inuit, Eskimo and Greenland dogs, Alaskan Malamute, Chihuahua, xoloitzcuintli and perro sín pelo del Peru, by comparing to extensive samples of East Asian (n = 984) and European dogs (n = 639), and previously published pre-Columbian sequences. Evidence for a pre-Columbian origin was found for all these breeds, except Alaskan Malamute for which results were ambigous. No European influence was indicated for the Arctic breeds Inuit, Eskimo and Greenland dog, and North/South American breeds had at most 30% European female lineages, suggesting marginal replacement by European dogs. Genetic continuity through time was shown by the sharing of a unique haplotype between the Mexican breed Chihuahua and ancient Mexican samples. We also analysed free-ranging dogs, confirming limited pre-Columbian ancestry overall, but also identifying pockets of remaining populations with high proportion of indigenous ancestry, and we provide the first DNA-based evidence that the Carolina dog, a free-ranging population in the USA, may have an ancient Asian origin.

Link

Dog domestication parameters from full genome sequencing

This paper casts doubt on the dominant scenario about the Southeast Asian geographical origin of dogs, while at the same time affirming their monophyletic origin and late pre-Neolithic domestication. The authors also document traits that were under selection during domestication.

It would be interesting to know what kinds of roles early dogs. Presumably early pre-Neolithic dogs functioned more as hunting companions, while those of Neolithic societies also had an increasing role as guards -since there was then property that needed guarding. How do modern dog breeds differ genetically to accommodate these roles, and might we one day figure out the original tasks of "multi-purpose" animals such as dogs?

arXiv:1305.7390 [q-bio.GN]

Genome Sequencing Highlights Genes Under Selection and the Dynamic Early History of Dogs

Adam H. Freedman et al.

To identify genetic changes underlying dog domestication and reconstruct their early evolutionary history, we analyzed novel high-quality genome sequences of three gray wolves, one from each of three putative centers of dog domestication, two ancient dog lineages (Basenji and Dingo) and a golden jackal as an outgroup. We find dogs and wolves diverged through a dynamic process involving population bottlenecks in both lineages and post-divergence gene flow, which confounds previous inferences of dog origins. In dogs, the domestication bottleneck was severe involving a 17 to 49-fold reduction in population size, a much stronger bottleneck than estimated previously from less intensive sequencing efforts. A sharp bottleneck in wolves occurred soon after their divergence from dogs, implying that the pool of diversity from which dogs arose was far larger than represented by modern wolf populations. Conditional on mutation rate, we narrow the plausible range for the date of initial dog domestication to an interval from 11 to 16 thousand years ago. This period predates the rise of agriculture, implying that the earliest dogs arose alongside hunter-gathers rather than agriculturists. Regarding the geographic origin of dogs, we find that surprisingly, none of the extant wolf lineages from putative domestication centers are more closely related to dogs, and the sampled wolves instead form a sister monophyletic clade. This result, in combination with our finding of dog-wolf admixture during the process of domestication, suggests a re-evaluation of past hypotheses of dog origin is necessary. Finally, we also detect signatures of selection, including evidence for selection on genes implicated in morphology, metabolism, and neural development. Uniquely, we find support for selective sweeps at regulatory sites suggesting gene regulatory changes played a critical role in dog domestication.

Link

33,000-year old dog from the Altai

From the paper:

In conclusion, our analyses support the hypothesis that the Altai specimen is more closely related to domestic dogs than to extant wolves, but we stress the point that these analyses were limited to a single, maternally inherited locus and more sequence data would be needed to obtain a statistically well supported phylogeny and unambiguously resolve the genetic relationship of the Altai specimen. However, this preliminary analysis affirms the conclusion that the Altai specimen is likely an ancient dog with a shallow divergence from ancient wolves. These results suggest a more ancient history of the dog outside the Middle East or East Asia, previously suggested as centres of dog origin. Additional discoveries of ancient dog-like remains are essential for further narrowing the time and region of origin for the domestic dog [5].

An ancient dog with shallow divergence from ancient wolves is probably what we might expect if dogs had been domesticated by some of the first Upper Paleolithic Eurasians a few thousand years prior to the date of this particular specimen.

PLoS ONE 8(3): e57754. doi:10.1371/journal.pone.0057754

Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog

Anna S. Druzhkova et al.

The origin of domestic dogs remains controversial, with genetic data indicating a separation between modern dogs and wolves in the Late Pleistocene. However, only a few dog-like fossils are found prior to the Last Glacial Maximum, and it is widely accepted that the dog domestication predates the beginning of agriculture about 10,000 years ago. In order to evaluate the genetic relationship of one of the oldest dogs, we have isolated ancient DNA from the recently described putative 33,000-year old Pleistocene dog from Altai and analysed 413 nucleotides of the mitochondrial control region. Our analyses reveal that the unique haplotype of the Altai dog is more closely related to modern dogs and prehistoric New World canids than it is to contemporary wolves. Further genetic analyses of ancient canids may reveal a more exact date and centre of domestication.

Link

Southeast Asian Neolithic dogs

From the paper:

Nevertheless, the close phylogenetic clustering of haplotypes from Thailand, Brunei, Bali, and the Philippines suggests these populations originated from the same source, consistent with a single migration event, whereas the dingoes, NGSDs, and dogs from Taiwan appear sufficiently distinct from these to reflect a distinct migration event (Fig. 2b-c). The clustering of the three Island Southeast Asian populations with Thailand also was more consistent with origination from Mainland Southeast Asia than Taiwan (in agreement with mtDNA findings of Oskarsson et al. 2011).

and:

In light of findings from the present study, it seems clear that both post-Victorian and Neolithic exchanges link eastern and western Eurasian dogs. However, the cause of post-Victorian haplotype sharing between Western breed dogs and Southeast Asian village dogs apparently reflects very recent introduction of Western dogs to the East rather than extraction of Eastern dogs to create Western breeds during the Victorian Era.

and:

Specifically, our aging of this European haplogroup to 5,800 (±SE = 1750) or 8,400 (±SE = 2500) years (depending on the dingo calibration to 3,500 or 5,000 years, respectively) suggests that the connection between pre-Victorian European and Southeast Asian dogs traces only to the Neolithic period and is not of sufficient antiquity to support the hypothesis of a single origin of dogs from Southeast Asia. Thus, although future studies are needed to combine the Y SNPs and STR markers in a geographically broader sampling of dogs than was considered here, our findings support the hypothesis for a massive Neolithic expansion of dogs from Southeast Asia rather than a Paleolithic origin of dogs from this region.

This massive Neolithic expansion of Southeast Asian dogs is testable by looking at early European dogs; these ought not to belong to haplogroup H1. It would also be interesting to speculate about the trade routes and/or population movements that facilitated the spread of dogs from SE Asia to Europe during the Neolithic.

Mol Biol Evol (2013) doi: 10.1093/molbev/mst027

Y chromosome analysis of dingoes and Southeast Asian village dogs suggests a Neolithic continental expansion from Southeast Asia followed by multiple Austronesian dispersals

Benjamin N. Sacks et al.

Dogs originated >14,000 BP, but the location(s) where they first arose is uncertain. The earliest archaeological evidence of ancient dogs was discovered in Europe and the Middle East, some 5–7 millennia before that from Southeast Asia. However, mitochondrial DNA analyses suggest that most modern dogs derive from Southeast Asia, which has fueled the controversial hypothesis that dog domestication originated in this region despite the lack of supporting archaeological evidence. We propose and investigate with Y chromosomes an alternative hypothesis for the proximate origins of dogs from Southeast Asia--a massive Neolithic expansion of dogs from this region that largely replaced more primitive dogs to the west and north. Previous attempts to test matrilineal findings with independent patrilineal markers have lacked the necessary genealogical resolution and mutation rate estimates. Here, we used Y chromosome genotypes, composed of 29 SNPs and 5 STRs, from 338 Australian dingoes, New Guinea singing dogs, and village dogs from Island Southeast Asia, along with modern European breed dogs, to estimate the evolutionary mutation rates of Y chromosome STRs based on calibration to the independently known age of the dingo population. Dingoes exhibited a unique haplogroup characterized by a single distinguishing SNP mutation and 14 STR haplotypes. The age of the European haplogroup was estimated to be only 1.7 times older than that of the dingo population, suggesting an origin during the Neolithic rather than the Paleolithic (as predicted by the Southeast Asian origins hypothesis). We hypothesize that isolation of Neolithic dogs from wolves in Southeast Asia was a key step accelerating their phenotypic transformation, enhancing their value in trade and as cargo, and enabling them to rapidly expand and replace more primitive dogs to the West. Our findings also suggest that dingoes could have arrived in Australia directly from Taiwan, independently of later dispersals of dogs through Thailand to Island Southeast Asia.

Link

Dog food

Diet Shaped Dog Domestication

The analysis turned up 36 regions, with 122 genes in all, that may have contributed to dog evolution, the team reports online today in Nature. Nineteen of these regions contain genes important for the brain, eight of which are involved with nervous system development, which makes sense given the importance of behavioral changes in the transition to becoming man's best friend, Axelsson notes.

More surprising were genes for digesting starch. Dogs had four to 30 copies of the gene for amylase, a protein that starts the breakdown of starch in the intestine. Wolves have only two copies, one on each chromosome. As a result, that gene was 28-fold more active in dogs, the researchers found. More copies means more protein, and test-tube studies indicate that dogs should be fivefold better than wolves at digesting starch, the chief nutrient in agricultural grains such as wheat and rice. The number of copies of this gene also varies in people: Those eating high carbohydrate diets -- such as the Japanese and European Americans -- have more copies than people with starch-poor diets, such as the Mbuti in Africa. "We have adapted in a very similar way to the dramatic changes that happened when agriculture was developed," Axelsson says.

Nature (2013) doi:10.1038/nature11837

The genomic signature of dog domestication reveals adaptation to a starch-rich diet

Erik Axelsson et al.

The domestication of dogs was an important episode in the development of human civilization. The precise timing and location of this event is debated1, 2, 3, 4, 5 and little is known about the genetic changes that accompanied the transformation of ancient wolves into domestic dogs. Here we conduct whole-genome resequencing of dogs and wolves to identify 3.8 million genetic variants used to identify 36 genomic regions that probably represent targets for selection during dog domestication. Nineteen of these regions contain genes important in brain function, eight of which belong to nervous system development pathways and potentially underlie behavioural changes central to dog domestication6. Ten genes with key roles in starch digestion and fat metabolism also show signals of selection. We identify candidate mutations in key genes and provide functional support for an increased starch digestion in dogs relative to wolves. Our results indicate that novel adaptations allowing the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in the early domestication of dogs.

Link

SMBE 2012 abstracts (part I)

Some abstracts of interest from SMBE 2012. Part II will follow.

Reconstructing demographic histories from long tracts of DNA sequence identity 

Kelley Harris 1 , Rasmus Nielsen 1,2 1 UC Berkeley, Berkeley, CA, USA,  2 University of Copenhagen, Copenhagen, Denmark 
There has been recent excitement and debate about the details of human demographic history, involving gene flow that  has occurred between populations as well as the extent and timing of bottlenecks and periods of population growth.  Much of the debate concerns the timing of past admixture events; for example, whether Neanderthals exchanged  genetic material with the ancestors of non-Africans before before or after they left Africa. Here, we present a method for  using sequence data to jointly estimate the timing and magnitude of past genetic exchanges, along with population  divergence times and changes in effective population size. To achieve this, we look at the length distribution of regions  that are shared identical by state (IBS) and maximize an analytic composite likelihood that we derive from the  sequentially Markov coalescent (SMC). Recent gene flow between populations leaves behind long tracts of identity by  descent (IBD), and these tracts give our method its power by influencing the distribution of shared IBS tracts. However,  since IBS tracts are directly observable, we do not need to infer the precise locations of IBD tracts. In this way, we can  accurately estimate admixture times for relatively ancient events where admixture mapping is not possible, and in  simulated data we show excellent power to characterize admixture pulses that occurred 100 to several hundred  generations ago. When we study the IBS tracts shared between and within the populations sequenced by the 1000  Genomes consortium, we find evidence that there was no significant gene flow between Europeans and Asians within  the past few hundred generations. It also looks unlikely that the Yorubans of Nigeria interbred with Europeans or Asians  in a population-specific way, though there may have been admixture between Africans and an ancestral non-African  population. 

Which way did they go? Detecting directional migration from genetic data

Benjamin Peter, Montgomery Slatkin University of California, Berkeley, Berkeley, USA  

Range expansions and colonizations are ubiquitous in many species and are studied from many different perspectives in e.g. anthropology, biogeography and invasion biology. It has been well established that these colonization events lead to a loss of genetic diversity and that in many cases it is possible to infer the history of a species' range from present-day genetic data. Previous approaches were mainly based on within-population measures of diversity such as heterozygosity, which then have been compared between populations. However, it is also well established that these statistics are susceptible to confounding demographic factors such as unequal subpopulation sizes or population size changes. In this study, we propose a novel method using data from multiple populations to infer a population's history. Our approach is based on a statistic that detects asymmetries in the 2D-allele frequency spectrum that occur when one population consists mostly of offspring of another population, as we expect in an expanding population. We show that our statistic is able to detect the direction of an expansion using data from multiple populations. Using simulations, we further show that our statistic is generally more powerful than previous approaches and that it is robust to a wide array of confounding demographic factors. We further illustrate the use of our statistic on several data sets for humans, Drosophila and Neurospora and show that we are both able to detect global patterns of colonization and fine-scale population structure.

Populations genetics of the Neolithic transition

Joachim Burger 1 , Mark Thomas 2,3 1  

Johannes Gutenberg University, Institute of Anthropology, D-55128 Mainz, Germany,  2 Research Department of  Genetics, Evolution and Environment, University College London, Wolfson House, 4 Stephenson Way, London NW1  2HE, UK,  3 Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvagen 18D, SE- 752 36 Uppsala, Sweden     

About 11,000 years ago, a change in human lifestyle took place in the territories of present-day western Iran, the Levant  region and south-east Anatolia, which is characterised particularly by four factors: the people founded permanent  settlements with buildings for various functions; plants such as Einkorn and beans were cultivated; goats, sheep, pigs  and cattle were domesticated; a new kind of culture evolved, that became conspicuous with the appearance of a new  material culture including ground stone tools and later, pottery products. The transition from the partly nomadic huntergatherer subsistence strategy to a settled lifestyle based on food production is also known as the “Neolithic Revolution”.  About 8,500 years ago, the Neolithic culture spread to the southeast of Europe and later expanded episodically across  central and northern Europe. The extent to which this movement of a farming culture was accompanied by a movement  of people, as opposed to just a spread of ideas and skills, has been a subject of considerable debate and dispute  over  the last 100 years. Population genetic computer simulations of genetic data from ancient human remains, based on  coalescent theory have shown that the early Neolithic farmers could not have been descended just from the later  hunter-gatherers of central Europe (Bramanti et al. 2009). As the hunter-gatherers had already been settled in Central  Europe since the retreat of the glaciers 20 kya, Neolithic famers must have migrated into this area.   

There is good evidence of cultural contact between hunter-gatherers and early farmers in central Europe. Whether the  exchange of hunting tools also led also to the exchange of men is still not clear, as Y-chromosomal DNA has not yet  been studied systematically in ancient human remains. Moreover, ancient DNA evidence is now emerging that other  regions don/t follow the patterns of population discontinuity observed in Central Europe. While the overall results  support a model of demic diffusion of farmers from southeastern Europe, or even further East, in to Central Europe, it is  very likely that modern populations in most parts of Europe were formed by varying degrees of admixture between  incoming farmers and indigenous hunter-gatherers. Analyses of the appropriate neutral and phenotypically informative  markers using next generation sequencing technologies will provide more information on this in the near future. 

Population genetic properties of time serial data with examples from ancient population-genomic data 

Mattias Jakobsson Uppsala University, Uppsala, Sweden  

Extracting genetic information from ancient material has for long been hampered by numerous difficulties since its first  steps some two decades ago, but in the last few years, many of these problems have been solved and the use of  ancient DNA (aDNA) is now beginning to show its full potential. We will likely see a wealth of genomic data from ancient  populations, but the statistical properties of time-structured genetic samples are considerably less explored than  population genetic patterns arising from spatial structure. Using simulations, we explore and highlight features of  temporal structure and spatial structure, such as an 'isolation-by-time' effect that is similar to isolation-by-distance.  Using model- and simulation-based approaches, we can now make novel inferences about demographic and  evolutionary questions from time serial data. We will discuss examples from the long standing debate about the  introduction of farming in Europe and question about archaic ancestry in East Asia using paleogenomic data.  

Inferences on dog domestication - genetic analysis of the most ancient dogs utilizing DNA capture arrays

Olaf Thalmann 1,2 , Daniel Greenfield 2 , Matthias Meyer 3 , Susanna Sawyer 3 , Pin Cui 3 , Mietje Germonpre 4 , Mikhail V.  Sablin 5 , Francesc Lopez-Giraldez 9 , Daniel LePont 1 , Brian Worthington 10 , Jeff P. Blick 6 , Jeniffer A. Leonard 7 , Richard E.  Green 8 , Robert K. Wayne 2 1 University of Turku, Turku, Finland,  2 University of California, Los Angeles, USA,  3 Max Planck Institute for Evolutionary  Anthropology, Leipzig, Germany,  4 Royal Belgian Institute of Natural Sciences, Brussels, Belgium,  5 Zoological Institute  RAS, Saint-Petersburg, Russia,  6 Georgia College & State University, Milledgeville, USA,  7 Estacion Biologica de  Donana- CSIC, Seville, Spain,  8 University of California, Santa Cruz, USA,  9 Yale University, New Haven, USA, 10 Southeastern Archaeological Research, Inc., Newberry, USA 

The geographical and temporal origin of the dog is controversial. Genetic data suggest a domestication event in Asia or  the Middle East about 15,000 - 30,000 years ago, whereas the oldest dog-like fossils are found in Europe dating to over  30 thousand years ago. We genetically analyzed the remains of 14 prehistoric wolves and dogs including some of the  oldest dog remains described from the New and Old World. Utilizing array based DNA capture techniques coupled with  Illumina double indexed sequencing, we targeted a total of ~750,000 nucleotides in each of the ancient canids and  additional 20 contemporary wolves from North America and Eurasia. The sequence information comprised the complete  mitochondrial genome, 3,000 SNPs previously identified as highly informative for differentiating dogs from wolves,  exonic sequences from 62 potential domestication genes and ~150,000 nucleotides of non-coding regions spread  throughout the genome.   Initial analyses reveal that we have successfully captured and sequenced the complete mitochondrial genome with high  coverage as wells as a substantial number of autosomal fragments from ten prehistoric canids and all contemporary  wolves. Phylogenetic analysis combining the complete mitochondrial genomes of the prehistoric canids with those of a  large collection of modern dogs and wolves result in a statistically well supported tree. While some haplotypes cluster  within modern dogs or wolves, others show a basal placement in the phylogeny. The latter finding might support a  previous notion that an aberrant lineage of dog-like canids might have existed throughout the northern hemisphere  during the late Pleistocene and became globally extinct during the last 20,000 years. We will test this hypothesis by  investigating the autosomal loci and employ sophisticated phylogenetic analyses, demographic modeling and selection  scans to better understand the influence of early human society and artificial selection on the canine genome.

Admixed human genomes reveal complex demographic patterns from early modern humans to the  contemporary era 

Simon Gravel 1 , Jeffrey M Kidd 2 , Jake K Byrnes 1 , Andres Moreno Estrada 1 , Fouad Zakharia 1 , Shaila Musharoff 1 ,  Francisco M De La Vega 1 , Carlos D Bustamante 1 1 Stanford University, Stanford, CA, USA,  2 University of Michigan, Ann Arbor, MI, USA     

A substantial proportion of humans are "admixed", in the sense that their recent ancestors belong to statistically distinct  groups. This needs to be accounted for if unbiased inference and associations are to be performed. We present a  diversity of methods for the analysis of whole-genome sequence data from admixed individuals, and apply them to 50  genomes sequenced by Complete Genomics, including 4 Mexican-Americans, 4 African-Americans and 2 individuals  from Puerto Rico, together with SNP genotype data from hundreds of additional samples.     

Many methods have been presented recently to infer the population of origin of specific loci along the genomes of  admixed individuals, leading to inferred mosaics of ancestry.  We first propose a simple Markov model that relates the  time-dependent migration history to the inferred patterns of local ancestry. We use this framework to infer the timing of  admixture and to differentiate between punctual and continuous models of migration: using demographic models that  are consistent with both historical records and genetic data, we find evidence for continuous migration patterns in both  Mexican and African-American populations.     

We also propose models to study the longer-term evolution of the ancestral populations, by considering the allele  frequency distribution, pairwise TMRCA's, and a simple extension of the recently introduced Pairwise Sequentially  Markovian Coalescent approach for demographic inference. The inferred source population demographic histories are  in broad agreement with previous results for European and West-African populations, and the inferred demography for  the Native source population closely follows the European one until about 20,000 years ago. Taken together, whole  genome sequencing and local ancestry assignment therefore permit inferences about long-term histories of unsampled  ancestral populations and highlights recent historical demographic processes that altered patterns of variation observed  in admixed populations. 

A genomewide map of Neandertal ancestry in modern humans

Sriram Sankararaman 1,2 , Nick Patterson 2 , Swapan Mallick 1,2 , Svante Paabo 3 , David Reich 1,2 1 Harvard Medical School, Boston, USA, 2 Broad Institute of Harvard and MIT, Cambridge, USA, 3 Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany 

Analysis of the genomes of archaic hominins, such as Neandertals and Denisovans, has revealed that these groups have contributed to the genetic variation of modern human populations. Yet, we know little about how these ancient mixtures have shaped the genetic structure of human populations and even less about their impact on human evolution. To answer these questions systematically, we need a map of archaic ancestry i.e., a map that labels whether each region of an individual genome is descended from these archaics.

Building such a map is technically challenging because of the antiquity of these gene flow events. We have identified signatures based on patterns of variation at single SNPs as well as haplotypes that are informative of ancient gene flow.

We propose a principled method based on the statistical framework of Conditional Random Fields (CRFs) that integrates these patterns leading to highly accurate predictions. We applied our method to polymorphism data in European and East Asian individuals from the 1000 genomes project, in conjunction with the draft sequence of the Neandertal genome, to obtain the first genomewide map of Neandertal ancestry. Analysis of this map reveals several findings:

1. We identify around 35,000 Neandertal-derived alleles in Europeans and 21,000 in East Asians.

2. The map allows us to identify Neandertal alleles that have been the target of selection since introgression. We identified over 100 regions in which the frequency of Neandertal ancestry is extremely unlikely under a model of neutral evolution. The highest frequency region on chromosome 4 has a frequency of Neandertal ancestry of about 85% in Europe and overlaps CLOCK, a key gene in Circadian function in mammals. The high frequency, Neandertal-derived variant is specific to Europeans; it is not very common in East Asians. This gene has been found in other selection scans in Eurasian populations, but has never before been linked to Neandertal gene flow.

3. Several of the Neandertal-derived alleles identified in 1) above are found in the >6,000 SNPs associated with common diseases listed in the NHGRI catalog. These Neandertal derived variants are found to be risk variants associated with obesity and protective variants against breast cancer.

4. We also investigate the possibility of using this map to reconstruct the genome of the introgressing Neandertal. Using the ancestries in Europe and East Asia, we can reconstruct about 600 Mb which we expect to increase with larger samples and additional populations.

Origins and evolution of the Etruscans’ DNA

Silvia Ghirotto 1 , Francesca Tassi 1 , Erica Fumagalli 2,1 , Vincenza Colonna 3,1 , Anna Sandionigi 4 , Martina Lari 4 , Stefania Vai 4 , Emmanuele Petiti 4 , Giorgio Corti 5 , Ermanno Rizzi 5 , Gianluca De Bellis 5 , David Caramelli 4 , Guido Barbujani 1 1 Department of Biology and Evolution, University of Ferrara, Ferrara, Italy, 2 Department of Biotechnologies and BiosciencesUniversity of Milano-Bicocca, Milano, Italy, 3 Institute of Genetics e Biophysics "Adriano Buzzati-Traverso", National Research Council, Napoli, Italy, 4 Department of Evolutionary Biology, University of Firenze, Firenze, Italy, 5 Institute for Biomedical Technologies (ITB), National Research Council (CNR), Milano, Italy

The Etruscan culture is documented in Etruria, Central Italy, from the 7 th to the 1 st century BC. For more than 2,000 years there has been disagreement on the Etruscans’ biological origins, whether local or in Anatolia. Genetic affinities with both Tuscan and Anatolian populations have been reported, but so far all attempts have failed to fit the Etruscans’ and modern populations in the same genealogy. We extracted and typed mitochondrial DNA of 14 individuals buried in two Etruscan necropoleis, analyzing them along with other Etruscan and Medieval samples, and 4,910 contemporary individuals. Comparing ancient and modern diversity with the results of millions of computer simulations, we show that the Etruscans can be considered ancestral, with a high degree of confidence, to the modern inhabitants of two communities, Casentino and Volterra, but not to most contemporary populations dwelling in the former Etruscan homeland. We also estimate that the genetic links between Tuscany and Anatolia date back to at least 5,000 years ago, strongly suggesting that the Etruscan culture developed locally, without a significant contribution of recent Anatolian immigrants.

Human population genomics in time and space: paleogenomics of populations in Bulgaria

Meredith L. Carpenter 1 , Hannes Schroeder 2 , Nikola Theodossiev 3 , M. Thomas P. Gilbert 2 , Carlos D. Bustamante 1 1 Department of Genetics, Stanford University, Stanford, CA, USA, 2 Centre for Geogenetics, University of Copenhagen, Copenhagen, Denmark, 3 Department of Archaeology, Sofia University, Sofia, Bulgaria

With a few exceptions, most ancient human DNA studies to date have restricted their analysis to the mitochondrial DNA (mtDNA) and Y chromosome. These approaches have led to some interesting theories regarding the spread of human populations; however, they are inherently limited by their use of these two non-recombining markers, which are subject to forces such as genetic drift and natural selection and also represent only the histories of the female and male lines, respectively, from which they descend. Recently, the whole genomes of several ancient individuals have been sequenced. These genomes yielded much more information about the individuals’ ancestry than their mtDNA alone; nevertheless, a single ancient individual is not sufficient for population genetic analyses. Thus, the goal of our study is to sequence the genomes of multiple ancient individuals from the same population. This type of study has the potential to dramatically improve our ability to address demographic questions about ancient human populations. We have begun the low-coverage sequencing of genomic DNA from the teeth of 16 individuals from different time periods (1500 BC-400 BC) in Bulgaria, and we plan to ultimately extend the study to at least 50 ancient Bulgarian individuals from the Neolithic to the Iron Age (6300 BC-400 BC). The results of these initial experiments will be presented, including the identification of mtDNA haplogroups and initial population genetic analyses. Ultimately, we plan to analyze whole-genome sequence variation in these individuals and to compare it to variation present in modern populations. This will be the first systematic population-level study of ancient human genomes and therefore will allow us address demographic questions that have previously been restricted to the realm of theoretical modeling using extant populations.

Horse domestication: a computer simulation approach

Michela Leonardi 1 , Christine Weber 1 , Norbert Benecke 2 , Mark G. Thomas 3,4 , Joachim Burger 1 1 AG Palaeogenetik, Institute of Anthropology, SBII, Johannes Gutenberg University, Colonel Kleinmann-Weg 2, 55128, Mainz, Germany, 2 German Archaeological Institute, Im Dol 4-6, 14165, Berlin, Germany, 3 Research Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, WC1E 6BT, London, UK, 4 Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvagen 18D, SE-752 36, Uppsala, Sweden

The domestication of horse played a key role in human history. It seems to have happened far both in time and space from the domestication of other ungulates such as cattle, pig, sheep and goat. Archaeological studies, nevertheless, failed in determining exactly the region and modality for horse domestication: several centers have been proposed (at least one in Europe and one in Central Asia) and the relationship between wild and early domestic populations are not clear. From a genetic point of view a phylogenetic approach on modern mitochondrial diversity could not find any structure related with geography or breeds. In the last decade ancient DNA became an important tool to reconstruct past demography. We obtained more than 100 HVR I sequences from pre domestic and domestic specimens found in Europe and Central Asia. After collecting all the previously published ancient and modern comparable sequences from the sub mentioned regions, computer simulations with a Bayesian approach were performed in order to test demographic models related with single or multiple domestications with or without gene flow. A single domestication appears to be unrealistic on the basis of mitochondrial data, while possible model of multiple domestications will be discussed.

The complete mitochondrial genome of a third individual from Denisova Cave

Susanna Sawyer 1 , Bence Viola 1 , Marie-Theres Gansauge 1 , Michael Shunkov 2 , Anatoly Derevianko 2 , Svante Paabo 1 1 Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, 2 Paleolithic Department, Institute of Archaeology and Ethnography, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia

A draft genome sequence was determined in 2010 from a small finger bone found in Denisova Cave in southern Siberia and was recently completed to 30-fold coverage. Its analysis reveals that it derived from an individual that belonged to a population related to, but distinct from, Neandertals. A large molar has also been described from Denisova Cave and shown to carry an mtDNA genome closely related to that of the finger bone. A second molar was found in Denisova Cave in 2010. We have captured and sequenced the complete mitochondrial genome of this tooth. While the mtDNAs of the finger bone and the first molar differ at only two nucleotide positions, they carry 86 and 84 differences, respectively, to the second molar. Thus, the maximum amount of mtDNA differences observed among these three Denisovans found within one cave is almost twice as large as the maximum differences seen among six Neandertals for which complete mtDNAs are available. Interestingly, the mtDNA of the second molar has a shorter branch than the other two Denisovan mtDNAs, suggesting that it may be older than the others.

TreeMix: fitting trees in the presence of admixture

Pickrell and Pritchard have made available a preprint of a new paper that shows how to fit a graph model to a set of populations. Tree models are commonly used to infer the relationship between populations, but these are often inappropriate for populations within the same species where lateral gene flow may (and often does) play a role.

I have wished for something like this for a long time, so it's great that it has finally been attempted. Moreover, the TreeMix software is available for anyone who wants to play with it.

If my CPUs were not already on fire between several new projects, I would love to try this right away, but I'm sure that I will get around to it before too long.

Inference of population splits and mixtures from genome-wide allele frequency data

Joseph K. Pickrell1 and Jonathan K. Pritchard

Many aspects of the historical relationships between populations in a species are reflected in genetic data. Inferring these relationships from genetic data, however, remains a challenging task. In this paper, we present a statistical model for inferring the patterns of population splits and mixtures in multiple populations. In this model, the sampled populations in a species are related to their common ancestor through a graph of ancestral populations. Using genome-wide allele frequency data and a Gaussian approximation to genetic drift, we infer the structure of this graph. We applied this method to a set of 55 human populations and a set of 82 dog breeds and wild canids. In both species, we show that a simple bifurcating tree does not fully describe the data; in contrast, we infer many migration events. While some of the migration events that we find have been detected previously, many have not. For example, in the human data we infer that Cambodians trace approximately 16% of their ancestry to a population ancestral to other extant East Asian populations. In the dog data, we infer that both the boxer and basenji trace a considerable fraction of their ancestry (9% and 25%, respectively) to wolves subsequent to domestication, and that East Asian toy breeds (the Shih Tzu and the Pekingese) result from admixture between modern toy breeds and ``ancient” Asian breeds. Software implementing the model described here, called TreeMix, is available at http://treemix.googlecode.com.

Link

Paleolithic Siberian domestic dog

From the press release:

A 33,000-year-old dog skull unearthed in a Siberian mountain cave presents some of the oldest known evidence of dog domestication and, together with an equally ancient find in a cave in Belgium, indicates that modern dogs may be descended from multiple ancestors.

I've been following the dog domestication saga for a few years now; it seems that geneticists are in general agreement that domestic dogs share a fairly recent ancestry from East Asia, although there are some lingering controversies about the role of other dogs in the formation of modern breeds. On the contrary, there are now two cases of Upper Paleolithic domesticated dogs, from both Belgium and Siberia. I can't wrap my head around the idea that dogs that were domesticated more than 30 thousand years ago, and would -presumably- have plenty of time to adapt would be totally replaced.

It would be great if we could get some Paleolithic dog DNA for comparison, as this would show whether some modern dog breeds are differentially affiliated to Paleolithic dogs, which would support a "multiregional evolution of domestic dogs".

PLoS ONE 6(7): e22821. doi:10.1371/journal.pone.0022821

A 33,000-Year-Old Incipient Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum

Nikolai D. Ovodov et al.


Abstract
Background
Virtually all well-documented remains of early domestic dog (Canis familiaris) come from the late Glacial and early Holocene periods (ca. 14,000–9000 calendar years ago, cal BP), with few putative dogs found prior to the Last Glacial Maximum (LGM, ca. 26,500–19,000 cal BP). The dearth of pre-LGM dog-like canids and incomplete state of their preservation has until now prevented an understanding of the morphological features of transitional forms between wild wolves and domesticated dogs in temporal perspective.

Methodology/Principal Finding
We describe the well-preserved remains of a dog-like canid from the Razboinichya Cave (Altai Mountains of southern Siberia). Because of the extraordinary preservation of the material, including skull, mandibles (both sides) and teeth, it was possible to conduct a complete morphological description and comparison with representative examples of pre-LGM wild wolves, modern wolves, prehistoric domesticated dogs, and early dog-like canids, using morphological criteria to distinguish between wolves and dogs. It was found that the Razboinichya Cave individual is most similar to fully domesticated dogs from Greenland (about 1000 years old), and unlike ancient and modern wolves, and putative dogs from Eliseevichi I site in central Russia. Direct AMS radiocarbon dating of the skull and mandible of the Razboinichya canid conducted in three independent laboratories resulted in highly compatible ages, with average value of ca. 33,000 cal BP.

Conclusions/Significance
The Razboinichya Cave specimen appears to be an incipient dog that did not give rise to late Glacial – early Holocene lineages and probably represents wolf domestication disrupted by the climatic and cultural changes associated with the LGM. The two earliest incipient dogs from Western Europe (Goyet, Belguim) and Siberia (Razboinichya), separated by thousands of kilometers, show that dog domestication was multiregional, and thus had no single place of origin (as some DNA data have suggested) and subsequent spread.

Link

Southeast Asian origin of dogs (again)

PLoS ONE 6(12): e28496. doi:10.1371/journal.pone.0028496

Phylogenetic Distinctiveness of Middle Eastern and Southeast Asian Village Dog Y Chromosomes Illuminates Dog Origins

Sarah K. Brown et al.

Modern genetic samples are commonly used to trace dog origins, which entails untested assumptions that village dogs reflect indigenous ancestry or that breed origins can be reliably traced to particular regions. We used high-resolution Y chromosome markers (SNP and STR) and mitochondrial DNA to analyze 495 village dogs/dingoes from the Middle East and Southeast Asia, along with 138 dogs from >35 modern breeds to 1) assess genetic divergence between Middle Eastern and Southeast Asian village dogs and their phylogenetic affinities to Australian dingoes and gray wolves (Canis lupus) and 2) compare the genetic affinities of modern breeds to regional indigenous village dog populations. The Y chromosome markers indicated that village dogs in the two regions corresponded to reciprocally monophyletic clades, reflecting several to many thousand years divergence, predating the Neolithic ages, and indicating long-indigenous roots to those regions. As expected, breeds of the Middle East and East Asia clustered within the respective regional village dog clade. Australian dingoes also clustered in the Southeast Asian clade. However, the European and American breeds clustered almost entirely within the Southeast Asian clade, even sharing many haplotypes, suggesting a substantial and recent influence of East Asian dogs in the creation of European breeds. Comparison to 818 published breed dog Y STR haplotypes confirmed this conclusion and indicated that some African breeds reflect another distinct patrilineal origin. The lower-resolution mtDNA marker consistently supported Y-chromosome results. Both marker types confirmed previous findings of higher genetic diversity in dogs from Southeast Asia than the Middle East. Our findings demonstrate the importance of village dogs as windows into the past and provide a reference against which ancient DNA can be used to further elucidate origins and spread of the domestic dog.

Link

Dogs domesticated in East Asia after all?

I'm not holding my breath that this will be the final chapter of the dog domestication saga. Previous installments:

• Dogs were probably domesticated in the Near East rather than East Asia
• Dog domestication history reconsidered
• Dog domestication in the Aurignacian (c. 32kyBP)

Press release of current study:

Data on genetics, morphology and behaviour show clearly that dogs are descended from wolves, but there's never been scientific consensus on where in the world the domestication process began. "Our analysis of Y-chromosomal DNA now confirms that wolves were first domesticated in Asia south of Yangtze River -- we call it the ASY region -- in southern China or Southeast Asia", Savolainen says.

The Y data supports previous evidence from mitochondrial DNA. "Taken together, the two studies provide very strong evidence that dogs originated in the ASY region", Savolainen says.

Archaeological data and a genetic study recently published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view. "Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked," he says.

Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study was published in the scientific journal Heredity.

The paper is open access, so you can make up your own mind on whether or not this seals the case.

Heredity advance online publication 23 November 2011; doi: 10.1038/hdy.2011.114

Origins of domestic dog in Southern East Asia is supported by analysis of Y-chromosome DNA

Z-L Ding et al.

Global mitochondrial DNA (mtDNA) data indicates that the dog originates from domestication of wolf in Asia South of Yangtze River (ASY), with minor genetic contributions from dog–wolf hybridisation elsewhere. Archaeological data and autosomal single nucleotide polymorphism data have instead suggested that dogs originate from Europe and/or South West Asia but, because these datasets lack data from ASY, evidence pointing to ASY may have been overlooked. Analyses of additional markers for global datasets, including ASY, are therefore necessary to test if mtDNA phylogeography reflects the actual dog history and not merely stochastic events or selection. Here, we analyse 14 437 bp of Y-chromosome DNA sequence in 151 dogs sampled worldwide. We found 28 haplotypes distributed in five haplogroups. Two haplogroups were universally shared and included three haplotypes carried by 46% of all dogs, but two other haplogroups were primarily restricted to East Asia. Highest genetic diversity and virtually complete phylogenetic coverage was found within ASY. The 151 dogs were estimated to originate from 13–24 wolf founders, but there was no indication of post-domestication dog–wolf hybridisations. Thus, Y-chromosome and mtDNA data give strikingly similar pictures of dog phylogeography, most importantly that roughly 50% of the gene pools are shared universally but only ASY has nearly the full range of genetic diversity, such that the gene pools in all other regions may derive from ASY. This corroborates that ASY was the principal, and possibly sole region of wolf domestication, that a large number of wolves were domesticated, and that subsequent dog–wolf hybridisation contributed modestly to the dog gene pool.

Link

Dogs were probably domesticated in the Near East rather than East Asia

Nicholas Wade writes in the NY Times:

Borrowing methods developed to probe the genetics of human disease, researchers have concluded that dogs were probably first domesticated from wolves somewhere in the Middle East, in contrast to an earlier survey suggesting dogs originated in East Asia.

This finding puts the first known domestication — that of dogs — in the same place as the domestication of plants and other animals, and strengthens the link between the first animal to enter human society and the subsequent invention of agriculture about 10,000 years ago.

From a methodological standpoint, this study shows how we shouldn't infer population history and dispersals from the study of uniparental markers. It is quite possible that the most recent common ancestor (MRCA) at a locus may have lived at a different location than the ancestral population, prior to its dispersal.

With dogs, mtDNA seemingly coalesces to an East Asian ancestor, a finding that has recently been both challenged and re-affirmed. However, this new Nature paper shows that in terms of overall genomic diversity the Middle East rather than East Asia is the region where grey wolves were first domesticated, becoming the earliest dog populations.

Any locus (in this case mtDNA) may have its MRCA in a location somewhere across its geographical range. In fact it is expected that due to either luck or advantage, successful mutations at every locus may arise throughout a species' range, and indeed should be more likely to arise in more populous areas (more bodies = more new mutations).

It is by looking at multiple genetic loci that the true history of a species may be inferred. But this, too, requires caution, as great genetic diversity may arise from either great antiquity or substantial admixture (being at the crossroads).

Indeed, "central" regions of a species have the tendency to accumulate a greater level of variation, since genetic mutations must travel a shorter distance to get there, from their point of origin.

All in all, I am a priori skeptical of attempts to reconstruct population history (in either dogs or humans) from modern population data. Nonetheless, this study casts serious doubt on the East Asian origin of dogs, and adds support for the Near Eastern hypothesis.

From the press release:

"That research made extrapolations about how the domestic dog has evolved from examination of one region in the mitochondrial genome," Wayne said. "This new Nature paper is a much more comprehensive analysis because we have analyzed 48,000 markers distributed throughout the nuclear genome to try to conclude where the most likely ancestral population is.

"What we found is much more consistent with the archaeological record," he said. "We found strong kinship to Middle Eastern gray wolves and, to some extent, European gray wolves — but much less so to any wolves from East Asia. Our findings strongly contradict the conclusions based on earlier mitochondrial DNA sequence data."

Eighty percent of dog breeds are modern breeds that evolved in the last few hundred years, Wayne said. But some dog breeds have ancient histories that go back thousands of years.

"We sampled both groups, the modern explosion of dog breeds and some of the ancient lineages," he said. "Our data were aimed at resolving questions about the origin of domestic dogs, the evolution of dog breeds, and the history of dog breeds and relationships to their closest wild progenitor, the gray wolf."

The first dogs that appeared in the Middle Eastern archaeological record date back some 12,000 to 13,000 years, Wayne said. Wolves have been in the Old World for hundreds of thousands of years. The oldest dogs from the archaeological record come from Europe and Western Russia. A dog from Belgium dates back 31,000 years, and a group of dogs from Western Russia is approximately 15,000 years old, Wayne said.

"We know that dogs from the Middle East were closely associated with humans because they were found in ancient human burial sites," Wayne said. "In one case, a puppy is curled up in the arms of a buried human."

Some very old strains of dogs, with a history dating back more than several thousand years, may be mixed with modern breeds, enhancing their diversity in certain areas such as East Asia, Wayne said, interpreting the higher mitochondrial DNA diversity in that area of the globe.

There is one small set of East Asian breeds that does not indicate a strong Middle East origin, showing instead a high level of genetic sharing with Chinese wolves. This finding suggests there was some intermixing between East Asian dog breeds and East Asian wolves; the data do not make clear how long ago this occurred.

"However, the vast majority of dogs that we studied show significant levels of sharing with Middle Eastern wolves," said Novembre, a population geneticist who studies genetic diversity and the lessons that can be learned from it.

Nature doi:10.1038/nature08837

Genome-wide SNP and haplotype analyses reveal a rich history underlying dog domestication

Bridgett M. vonHoldt et al.

Abstract

Advances in genome technology have facilitated a new understanding of the historical and genetic processes crucial to rapid phenotypic evolution under domestication1, 2. To understand the process of dog diversification better, we conducted an extensive genome-wide survey of more than 48,000 single nucleotide polymorphisms in dogs and their wild progenitor, the grey wolf. Here we show that dog breeds share a higher proportion of multi-locus haplotypes unique to grey wolves from the Middle East, indicating that they are a dominant source of genetic diversity for dogs rather than wolves from east Asia, as suggested by mitochondrial DNA sequence data3. Furthermore, we find a surprising correspondence between genetic and phenotypic/functional breed groupings but there are exceptions that suggest phenotypic diversification depended in part on the repeated crossing of individuals with novel phenotypes. Our results show that Middle Eastern wolves were a critical source of genome diversity, although interbreeding with local wolf populations clearly occurred elsewhere in the early history of specific lineages. More recently, the evolution of modern dog breeds seems to have been an iterative process that drew on a limited genetic toolkit to create remarkable phenotypic diversity.

Link

A Single Origin for Dogs South of Yangtze River, less than 16,300 Years Ago (Pang et al. 2009)

Another recent study by Boyko et al. raised some doubts about the strength of the evidence for dog domestication in Asia, by pointing out that including semi-feral village dogs may increase the observed Asian diversity. The advance access manuscript for this paper is free, so anyone interested in the sampling details. The authors do cite the other recent paper:

Notably, in a recent study of African village dogs (Boyko et al. 2009) it was claimed that the reported high diversity for mtDNA in East Asia compared to other parts of the world (Savolainen et al. 2002), was the result of sampling bias. However, in the present study (see “Results”) we show this assertion to be incorrect.

...

Thus, a direct comparison shows that the smaller South Chinese sample has 73% more haplotypes than the African one; the assertion by Boyko et al. (2009) is the result of not adequately compensating for differences in sample size between the relatively small East Asian samples in Savolainen et al. (2002) and the larger African samples. The African sample has also all the other characteristics of the “western” dog populations: The haplotypes fall in the same parts of the MS networks as for other western populations, leaving large parts unique to East Asia (data not shown); and values are high for UT (66.7%) and UTd (90.9%), and number of unique haplotypes low (12) (compare with e.g. South China: UT (42.0%), UTd (53.4%), and number of unique haplotypes (40; i.e. only one less than the total number of haplotypes in the African sample!)). To conclude, the sample of African village dogs in Boyko et al. (2009), like all “western” samples, has considerably lower genetic variation than the populations in ASY.

Molecular Biology and Evolution, doi:10.1093/molbev/msp195

mtDNA Data Indicates a Single Origin for Dogs South of Yangtze River, less than 16,300 Years Ago, from Numerous Wolves

Jun-Feng Pang et al.

Abstract

There is no generally accepted picture of where, when, and how the domestic dog originated. Previous studies of mitochondrial DNA (mtDNA) have failed to establish the time and precise place of origin because of lack of phylogenetic resolution in the so far studied control region (CR), and inadequate sampling. We therefore analysed entire mitochondrial genomes for 169 dogs to obtain maximal phylogenetic resolution, and the CR for 1,543 dogs across the Old World for a comprehensive picture of geographical diversity. Hereby, a detailed picture of the origins of the dog can for the first time be suggested. We obtained evidence that the dog has a single origin in time and space, and an estimation of the time of origin, number of founders and approximate region, which also gives potential clues about the human culture involved. The analyses showed that dogs universally share a common homogenous gene pool containing 10 major haplogroups. However, the full range of genetic diversity, all 10 haplogroups, was found only in south-eastern Asia south of Yangtze River, and diversity decreased following a gradient across Eurasia, through 7 haplogroups in Central China, and 5 in North China and Southwest Asia, down to only 4 haplogroups in Europe. The mean sequence distance to ancestral haplotypes indicates an origin 5,400-16,300 years ago from at least 51 female wolf founders. These results indicate that the domestic dog originated in southern China less than 16,300 years ago, from several hundred wolves. The place and time coincide approximately with the origin of rice agriculture, suggesting that the dogs may have originated among sedentary hunter-gatherers or early farmers, and the numerous founders indicate that wolf taming was an important culture trait.

Link

Dog domestication history reconsidered

There are several important lessons from this new study:

1. We are back to square one when it comes to the origin of domestic dogs, as the discovery of similar genetic diversity in African and Asian dogs casts doubt on the Asian origin theory
2. In general, making inferences of gene flow based on diversity measures is very sensitive to sampling.
3. Greater genetic diversity may be the result of either greater antiquity or admixture; if an extra-terrestrial scientist, knowing nothing about human history, studied the genetic diversity of humans, he would probably conclude that they originated in the Americas, if he overlooked the possibility that the highly diverse population of the New World is the result of very recent admixture and settlement.
4. Domestication resulting from artificial selection leads to loss of genetic diversity. Thus, differences in genetic diversity may be due to differences in the intensity of domestication-related changes, rather than due to differences in antiquity.
   

One generally does not speak of humans as "domesticated" or "wild", but, nonetheless, humans vary greatly in the way they reproduce. In some cases, choice of marriage partner is a complex long-term process of selection from alternatives, while in others it is a shorter more "natural" one. It would be a great idea to study the social correlates of human genetic diversity, rather than assume that all humans are at a similar level of self-domestication and thus differences between them are simply the product of their respective antiquity.

PNAS doi:10.1073/pnas.0902129106

Complex population structure in African village dogs and its implications for inferring dog domestication history

Adam R. Boyko et al.

Abstract

High genetic diversity of East Asian village dogs has recently been used to argue for an East Asian origin of the domestic dog. However, global village dog genetic diversity and the extent to which semiferal village dogs represent distinct, indigenous populations instead of admixtures of various dog breeds has not been quantified. Understanding these issues is critical to properly reconstructing the timing, number, and locations of dog domestication. To address these questions, we sampled 318 village dogs from 7 regions in Egypt, Uganda, and Namibia, measuring genetic diversity >680 bp of the mitochondrial D-loop, 300 SNPs, and 89 microsatellite markers. We also analyzed breed dogs, including putatively African breeds (Afghan hounds, Basenjis, Pharaoh hounds, Rhodesian ridgebacks, and Salukis), Puerto Rican street dogs, and mixed breed dogs from the United States. Village dogs from most African regions appear genetically distinct from non-native breed and mixed-breed dogs, although some individuals cluster genetically with Puerto Rican dogs or United States breed mixes instead of with neighboring village dogs. Thus, African village dogs are a mosaic of indigenous dogs descended from early migrants to Africa, and non-native, breed-admixed individuals. Among putatively African breeds, Pharaoh hounds, and Rhodesian ridgebacks clustered with non-native rather than indigenous African dogs, suggesting they have predominantly non-African origins. Surprisingly, we find similar mtDNA haplotype diversity in African and East Asian village dogs, potentially calling into question the hypothesis of an East Asian origin for dog domestication.

Link

The shape of dogs' heads and their performance

A nice study establishing a relationship between dogs' abilities and (i) their modus operandi (independent/co-operating in proximity with humans), or (ii) their head shape (brachycephalic vs. dolichocephalic).

It would be interesting to do similar studies in humans. I seriously doubt that a proposal for the study of the human cephalic index, or cranial shape, with any type of human ability would have a high chance of getting funded.

It is true that a lot of nonsense on the topic was published by statistically naive anthropologists of past decades, but this is no reason to refrain from it forever.

We can now do 3D scans of human heads, we have the fast computers and sophisticated statistical methods to analyze large quantities of anthropometric data. It's a shame that timidity is keeping anthropologists from exploring the plethora of opportunities for exciting research in the area of anthropometry-psychology interactions.

Behav Brain Funct. 2009 Jul 24;5(1):31.

Effects of selection for cooperation and attention in dogs.

Gacsi M, McGreevy P, Kara E, Miklosi A.

ABSTRACT: BACKGROUND: It has been suggested that the functional similarities in the socio-cognitive behaviour of dogs and humans emerged as a consequence of comparable environmental selection pressures. Here we use a novel approach to account for the facilitating effect of domestication in dogs and reveal that selection for two factors under genetic influence (visual cooperation and focused attention) may have led independently to increased comprehension of human communicational cues. METHOD: In Study 1, we observed the performance of three groups of dogs in utilizing the human pointing gesture in a two-way object choice test. We compared breeds selected to work while visually separated from human partners (N=30, 21 breeds, clustered as independent worker group), with those selected to work in close cooperation and continuous visual contact with human partners (N=30, 22 breeds, clustered as cooperative worker group), and with a group of mongrels (N=30). Secondly, it has been reported that, in dogs, selective breeding to produce an abnormal shortening of the skull is associated with a more pronounced area centralis (location of greatest visual acuity). In Study 2, breeds with high cephalic index and more frontally placed eyes (brachycephalic breeds, N=25, 14 breeds) were compared with breeds with low cephalic index and laterally placed eyes (dolichocephalic breeds, N=25, 14 breeds). RESULTS: In Study 1, cooperative workers were significantly more successful in utilizing the human pointing gesture than both the independent workers and the mongrels. In study 2, we found that brachycephalic dogs performed significantly better than dolichocephalic breeds. DISCUSSION: After controlling for environmental factors, we have provided evidence that at least two independent phenotypic traits with certain genetic variability affect the ability of dogs to rely on human visual cues. This finding should caution researchers against making simple generalizations about the effects of domestication and on dog-wolf differences in the utilization of human visual signals.

Link

mtDNA from Neolithic European dogs

It is interesting that one out of three mtDNA haplotypes is not observed in modern dogs, just as all seven Paleolithic ones are not so observed. This, together with the apparently dramatic change in frequency of clade C since the Neolithic, is perfectly consistent with selection I hypothesized about earlier, which in the case of dogs may have been human-induced.

Journal of Archaeological Science doi:10.1016/j.jas.2008.10.011

Ancient DNA supports lineage replacement in European dog gene pool: insight into Neolithic South-East France

M.F. Deguilloux et al.

Abstract

We report palaeogenetic analysis of domesticated dog (Canis familiaris) remains excavated from three archaeological sites from South-East France and dating from Middle Neolithic. Ancient DNA analysis was attempted on teeth and bone samples taken from 11 dogs. Three 266-base-pair fragments of the mitochondrial genome hypervariable region I (HVR-I) could be retrieved and revealed two haplotypes belonging to HVR-I lineage C. These three sequences were compared to the sequences of Swedish and Italian Neolithic dogs and permitted to confirm that clade C was largely represented all over Western Europe during this period. One haplotype defined in Neolithic French dog was observed for the first time in Canis mtDNA, underlining the loss of mitochondrial diversity in Europe since the Neolithic. Finally, these results point out mitochondrial lineage replacement in Europe, since lineage C represents only 5% of extant European dogs. Altogether, these results support the proposition that palaeogenetic studies are essential for the reconstruction of the past demographic history and the domestication process of dogs.

Link

Dog domestication in the Aurignacian (c. 32kyBP)

From the paper:

Interestingly, when compared to extant wolf and dog sequences available from GenBank, all seven haplotypes found in the Pleistocene samples were found to be unique and not described to date. This result is remarkable when considering the large number of wolf (~160) and particularly dog sequences (> 1,000 from almost all breeds known today) available in Genbank.

This may be consistent with selection affecting mtDNA since the Paleolithic, with recent dogs and wolves being descended from a small subset of the Paleolithic mtDNA diversity. Also from the paper:

Compared to wolves, ancient dogs exhibit a shorter and broader snout (Lawrence, 1967; Olsen, 1985; Sablin and Khlopachev, 2002). All Palaeolithic dogs in our study conform to this pattern.

...

As demonstrated above, the Palaeolithic dogs in our data set are very uniform in their skull shape. Even the Goyet dog, with an age of c. 31,700 BP, is not intermediate in form between the fossil wolves and the prehistoric dogs, but conforms to the configuration of the other Palaeolithic dogs, which are approximately 18,000 years younger. The abrupt appearance of a dog, much older than the Eliseevich I dogs, the oldest recognized dogs so far, suggest that the domestication process must have been quite rapid (cf. Crockford, 2000a).

Was the dog the very first animal to be domesticated by man, truly his "oldest friend"? I would not be surprised if our relationship with dogs stretches even further to the past. Dogs are such useful helpers in a hunting culture, that their value must have been recognized from early on.

Journal of Archaeological Science doi:10.1016/j.jas.2008.09.033

Fossil dogs and wolves from Palaeolithic sites in Belgium, the Ukraine and Russia: osteometry, ancient DNA and stable isotopes

Mietje Germonpré et al.

Abstract

Using multivariate techniques, several skulls of fossil large canids from sites in Belgium, Ukraine and Russia were examined to look for possible evidence of the presence of Palaeolithic dogs. Reference groups constituted of prehistoric dogs, and recent wolves and dogs. The fossil large canid from Goyet (Belgium), dated at c. 31,700 BP is clearly different from the recent wolves, resembling most closely the prehistoric dogs. Thus it is identified as a Palaeolithic dog, suggesting that dog domestication had already started during the Aurignacian. The Epigravettian Mezin 5490 (Russia) and Mezhirich (Ukraine) skulls are also identified as being Palaeolithic dogs. Select Belgian specimens were analysed for mtDNA and stable isotopes. All fossil samples yielded unique DNA sequences, indicating that the ancient Belgian large canids carried a substantial amount of genetic diversity. Furthermore, there is little evidence for phylogeographic structure in the Pleistocene large canids, as they do not form a homogenous genetic group. Although considerable variation occurs in the fossil canid isotope signatures between sites, the Belgian fossil large canids preyed in general on horse and large bovids.

Link

Northern dogs, ancient and modern

This is an interesting study because it highlights once again a very important point: conclusions about prehistoric events based on modern populations should always be taken with a grain of salt. In this case, modern Scandinavian dogs harbor an mtDNA haplogroup at high frequency (HgD) not found in other dog breeds. This led previous research into the erroneous conclusion that there was an ancient dog domestication event in prehistoric Scandinavia. However, when one looks at actual ancient Scandinavian dogs, one fails to find HgD. Thus the suggestion that modern northern European dogs are similar to ancient northern European dogs is not supported.

BMC Evol Biol. 2008 Feb 28;8(1):71 [Epub ahead of print]

Barking up the wrong tree: Modern northern European dogs fail to explain their origin.

Malmstrom H, Vila C, Gilbert MT, Stora J, Willerslev E, Holmlund G, Gotherstrom A.

ABSTRACT: BACKGROUND: Geographic distribution of the genetic diversity in domestic animals, particularly mitochondrial DNA, has often been used to infer centers of domestication. The underlying presumption is that phylogeographic patterns among domesticates were established during, or shortly after the domestication. Human activities are assumed not to have altered the haplogroup frequencies to any great extent. We studied this hypothesis by analyzing 24 mtDNA sequences in ancient Scandinavian dogs. Breeds originating in northern Europe are characterized by having a high frequency of mtDNA sequences belonging to a haplogroup rare in other populations (HgD). This has been suggested to indicate a possible origin of the haplogroup (perhaps even a separate domestication) in central or northern Europe. RESULTS: The sequences observed in the ancient samples do not include the haplogroup indicative for northern European breeds (HgD). Instead, several of them correspond to haplogroups that are uncommon in the region today and that are supposed to have an Asian origin. CONCLUSION: Thus, we find no evidence for local domestication. We conclude that interpretation of the processes responsible for current domestic haplogroup frequencies should be carried out with caution if based only on contemporary data. They do not only tell their own story, but also that of humans.

Link