Environment Institute Leaders publications

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Browsing Environment Institute Leaders publications by Author "Adler, C."

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    Ancient DNA from European early Neolithic farmers reveals their near eastern affinities
    (Public Library of Science, 2010) Haak, W.; Balanovsky, O.; Sanchez, J.; Koshel, S.; Zaporozhchenko, V.; Adler, C.; Dersarkissian, C.; Brandt, G.; Schwarz, C.; Nicklisch, N.; Dresely, V.; Fritsch, B.; Balanovska, E.; Villems, R.; Meller, H.; Alt, K.; Cooper, A.; Penny, D.; Genographic Consortium
    In Europe, the Neolithic transition (8,000–4,000 B.C.) from hunting and gathering to agricultural communities was one of the most important demographic events since the initial peopling of Europe by anatomically modern humans in the Upper Paleolithic (40,000 B.C.). However, the nature and speed of this transition is a matter of continuing scientific debate in archaeology, anthropology, and human population genetics. To date, inferences about the genetic make up of past populations have mostly been drawn from studies of modern-day Eurasian populations, but increasingly ancient DNA studies offer a direct view of the genetic past. We genetically characterized a population of the earliest farming culture in Central Europe, the Linear Pottery Culture (LBK; 5,500–4,900 calibrated B.C.) and used comprehensive phylogeographic and population genetic analyses to locate its origins within the broader Eurasian region, and to trace potential dispersal routes into Europe. We cloned and sequenced the mitochondrial hypervariable segment I and designed two powerful SNP multiplex PCR systems to generate new mitochondrial and Y-chromosomal data from 21 individuals from a complete LBK graveyard at Derenburg Meerenstieg II in Germany. These results considerably extend the available genetic dataset for the LBK (n = 42) and permit the first detailed genetic analysis of the earliest Neolithic culture in Central Europe (5,500–4,900 calibrated B.C.). We characterized the Neolithic mitochondrial DNA sequence diversity and geographical affinities of the early farmers using a large database of extant Western Eurasian populations (n = 23,394) and a wide range of population genetic analyses including shared haplotype analyses, principal component analyses, multidimensional scaling, geographic mapping of genetic distances, and Bayesian Serial Simcoal analyses. The results reveal that the LBK population shared an affinity with the modern-day Near East and Anatolia, supporting a major genetic input from this area during the advent of farming in Europe. However, the LBK population also showed unique genetic features including a clearly distinct distribution of mitochondrial haplogroup frequencies, confirming that major demographic events continued to take place in Europe after the early Neolithic.
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    Ancient DNA identifies post-glacial recolonisation, not recent bottlenecks, as the primary driver of contemporary mtDNA phylogeography and diversity in Scandinavian brown bears
    (Blackwell Publishing Ltd., 2013) Bray, S.; Austin, J.; Metcalf, J.; Ostbye, K.; Ostbye, E.; Lauritzen, S.; Aaris-Sorensen, K.; Valdiosera, C.; Adler, C.; Cooper, A.
    AbstractAimBrown bear populations in Scandinavia show a strong mitochondrial DNA (mtDNA) phylogeographic structure and low diversity relative to other parts of Europe. Identifying the timing and origins of this mtDNA structure is important for conservation programs aimed at restoring populations to a natural state. Therefore, it is essential to identify whether contemporary genetic structure is linked to post‐glacial recolonisation from divergent source populations or an artefact of demographic impacts during recent population bottlenecks. We employed ancient DNA techniques to investigate the timing and potential causes of these patterns.LocationScandinavia and Europe.MethodsAncient mtDNA sequences from 20 post‐glacial Scandinavian bears were used to investigate phylogeographic structure and genetic diversity over the last 6000 years. MtDNA from 19 Holocene Norwegian bears was compared with 499 sequences from proximate extant populations in Sweden, Finland, Estonia and western Russia. A single mtDNA sequence from a Holocene Denmark sample was compared with 149 ancient and modern bears from Western Europe.ResultsAll nineteen Holocene Norwegian samples are identical to or closely related to the most common mtDNA haplotype found in northern Europe today. MtDNA diversity was low and not significantly different from extant populations in northern Europe. In Denmark, we identified a single mtDNA haplotype that is previously unrecorded from Scandinavia.Main conclusionsThe current discrete phylogeographic structure and lack of mtDNA diversity in Scandinavia is attributed to serial founder effects during post‐glacial recolonisation from divergent source populations rather than an artefact of recent anthropogenic impacts. In contrast to previous interpretations, the recolonisation of southern Scandinavia may not have been limited to bears from a single glacial refugium. Results highlight the importance of conserving the long‐term evolutionary separation between northern and southern populations and identify southern Scandinavia as an important reservoir of mtDNA diversity that is under threat in other parts of Europe.
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    ItemOpen Access
    Population differentiation of Southern Indian male lineages correlates with agricultural expansions predating the caste system
    (Public Library of Science, 2012) ArunKumar, G.; Soria-Hernanz, D.; Kavitha, V.; Arun, V.; Syama, A.; Ashokan, K.; Gandhirajan, K.; Vijayakumar, K.; Narayanan, M.; Jayalakshmi, M.; Ziegle, J.; Royyuru, A.; Parida, L.; Wells, R.; Renfrew, C.; Schurr, T.; Smith, C.; Platt, D.; Pitchappan, R.; Adler, C.; et al.; Kayser, M.; Adler, Christina Jane; Cooper, Alan; Der Sarkissian, Clio Simone Irmgard; Haak, Wolfgang
    Previous studies that pooled Indian populations from a wide variety of geographical locations, have obtained contradictory conclusions about the processes of the establishment of the Varna caste system and its genetic impact on the origins and demographic histories of Indian populations. To further investigate these questions we took advantage that both Y chromosome and caste designation are paternally inherited, and genotyped 1,680 Y chromosomes representing 12 tribal and 19 non-tribal (caste) endogamous populations from the predominantly Dravidian-speaking Tamil Nadu state in the southernmost part of India. Tribes and castes were both characterized by an overwhelming proportion of putatively Indian autochthonous Y-chromosomal haplogroups (H-M69, F-M89, R1a1-M17, L1-M27, R2-M124, and C5-M356; 81% combined) with a shared genetic heritage dating back to the late Pleistocene (10–30 Kya), suggesting that more recent Holocene migrations from western Eurasia contributed, <20% of the male lineages. We found strong evidence for genetic structure, associated primarily with the current mode of subsistence. Coalescence analysis suggested that the social stratification was established 4–6 Kya and there was little admixture during the last 3 Kya, implying a minimal genetic impact of the Varna(caste) system from the historically-documented Brahmin migrations into the area. In contrast, the overall Y-chromosomal patterns, the time depth of population diversifications and the period of differentiation were best explained by the emergence of agricultural technology in South Asia. These results highlight the utility of detailed local genetic studies within India, without prior assumptions about the importance of Varna rank status for population grouping, to obtain new insights into the relative influences of past demographic events for the population structure of the whole of modern India.
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    Survival and recovery of DNA from ancient teeth and bones
    (Academic Press Ltd, 2011) Adler, C.; Haak, W.; Donlon, D.; Cooper, A.; Dersarkissian, C.; Australian Centre for Ancient DNA
    The recovery of genetic material from preserved hard skeletal remains is an essential part of ancient DNA, archaeological and forensic research. However, there is little understanding about the relative concentrations of DNA within different tissues, the impact of sampling methods on extracted DNA, or the role of environmentally-determined degradation rates on DNA survival in specimens. We examine these issues by characterizing the mitochondrial DNA (mtDNA) content of different hard and soft tissues in 42 ancient human and bovid specimens at a range of fragment lengths (77-235 bp) using real-time PCR. Remarkably, the standard drill speeds used to sample skeletal material (c. 1000 RPM) were found to decrease mtDNA yields up to 30 times (by 3.1 × 105 mtDNA copies on average) compared to pulverization in a bone mill. This dramatic negative impact appears to relate to heat damage, and disappeared at very low drill speeds (e.g. 100 RPM). Consequently, many ancient DNA and forensic studies may have obtained false negative results, especially from important specimens which are commonly sampled with drills to minimize signs of damage. The mtDNA content of tooth cementum was found to be five times higher than the commonly used dentine (141 bp, p = 0.01), making the cementum-rich root tip the best sample for ancient human material. Lastly, mtDNA was found to display a consistent pattern of exponential fragmentation across many depositional environments, with different rates for geographic areas and tissue types, improving the ability to predict and understand DNA survival in preserved specimens. © 2010.
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    The Basque paradigm: genetic evidence of a maternal continuity in the Franco-Cantabrian region since pre-neolithic times
    (Univ Chicago Press, 2012) Behar, D.; Haak, W.; Adler, C.; Cooper, A.; Dersarkissian, C.
    Different lines of evidence point to the resettlement of much of western and central Europe by populations from the Franco-Cantabrian region during the Late Glacial and Postglacial periods. In this context, the study of the genetic diversity of contemporary Basques, a population located at the epicenter of the Franco-Cantabrian region, is particularly useful because they speak a non-Indo-European language that is considered to be a linguistic isolate. In contrast with genome-wide analysis and Y chromosome data, where the problem of poor time estimates remains, a new timescale has been established for the human mtDNA and makes this genome the most informative marker for studying European prehistory. Here, we aim to increase knowledge of the origins of the Basque people and, more generally, of the role of the Franco-Cantabrian refuge in the postglacial repopulation of Europe.We thus characterize the maternal ancestry of 908 Basque and non-Basque individuals from the Basque Country and immediate adjacent regions and, by sequencing 420 complete mtDNA genomes, we focused on haplogroup H.We identified six mtDNA haplogroups, H1j1, H1t1, H2a5a1, H1av1, H3c2a, and H1e1a1, which are autochthonous to the Franco-Cantabrian region and, more specifically, to Basque-speaking populations. We detected signals of the expansion of these haplogroups at ~4,000 years before present (YBP) and estimated their separation from the pan-European gene pool at ~8,000 YBP, antedating the Indo-European arrival to the region. Our results clearly support the hypothesis of a partial genetic continuity of contemporary Basques with the preceding Paleolithic/Mesolithic settlers of their homeland.