We Are Not Our Ancestors: Evidence for Discontinuity between Prehistoric and Modern Europeans
The model of European genetic ancestry has recently shifted away from
the Neolithic diffusion model towards an emphasis on autochthonous Paleolithic
origins. However, this new paradigm
utilizes genetic reconstructions based primarily on contemporary populations
and, furthermore, is often promoted without regard to the findings of ancient
DNA studies. These ancient DNA studies
indicate that contemporary European ancestry is not a living fossil of the
Paleolithic maternal deme; rather, demographic events during the Neolithic and
post-Neolithic periods appear to have had substantial impact on the European
genetic record. In addition, evolutionary
processes, including genetic drift, adaptive selection and disease
susceptibility, may have altered the patterns of maternal lineage frequency and
distribution in existing populations. As
a result, the genetic history of
Address for correspondence: Ellen Coffman, Ellenlevy66 (at) yahoo.com
The genetic model currently
presented by many population geneticists emphasizes the autochthonous
Paleolithic ancestry of contemporary Europeans.
This paradigm is based on the perspective that contemporary Europeans
descend primarily from their hunter-gatherer forbearers who lived in the same
region until approximately 10,000 years ago, when the beginning of settled
agriculture began. This Paleolithic
ancestry is seen as remaining relatively unaffected by later gene flow,
including any large-scale movements of
farmers out of the
In an effort to lend support to
this genetic model, the distribution and frequency of both mitochondrial DNA
(mtDNA) and Y chromosome haplogroups among modern European populations are
utilized in reconstructing ancient population histories. The Basque, lone speakers in of a non-I
Thus, the picture presented by this model is one of substantial genetic continuity between modern groups and the Paleolithic hunter-gatherers who inhabited the same region thousands of years ago.
Yet the DNA evidence suggests a
more complex picture than a direct and undisturbed genetic link between
contemporary Europeans and their Paleolithic forbearers. A significant and as of yet unexplained
genetic discontinuity exists between present and past populations. Since the recent advent of techniques
allowing the extraction of DNA from ancient remains (“aDNA”), in particular
mtDNA, the actual genetic background of the ancient maternal inhabitants of
In contrast to the Paleolithic paradigm, these studies indicate an unexpected and significant genetic discontinuity exists between contemporary Europeans and their Paleolithic predecessors. They also suggest that the exclusive use of contemporary DNA samples in the reconstruction of earlier population histories has created a misleading picture of the European genetic legacy.
Various demographic and
evolutionary mechanisms may have led to this genetic break with the past,
including the strong likelihood of genetic contributions from migratory peoples
that occurred during the Neolithic, and into the Bronze and Iron Ages. This gene flow may have been so significant
that genetic signals from the earlier inhabitants of
As a result, contemporary
Europeans should not be viewed as descending entirely or even significantly
from either Neolithic farmers or the indigenous Paleolithic inhabitants of
The Popular Paradigm of Paleolithic Ancestry: Evidence from
One recent and highly publicized DNA study illustrates not only how the idea of autochthonous Paleolithic origins of modern-day Europeans has been readily adopted by many population geneticists, but also how the researchers fail to address contradictory evidence that appears to conflict with that Paleolithic paradigm.
Anthropologist Joachim Burger and
graduate student Wolfgang Haak of
Out of twenty-four samples, seven
were in mtDNA haplogroup H or V, five were T, four K, one J and one U3. These haplogroups, widespread in
Those six samples were found to be
within haplogroup N1a, a distinctive branch of haplogroup N that is rare among
Europeans today. Among the ancient
samples, however, N1a was found at a high frequency ranging from 8% to 42%, or
150 times more frequent than among modern-day Europeans. It was also widespread, appearing in sites in
Based on this evidence alone, the authors of the study concluded that the early Neolithic agriculturalists had “limited success in leaving a genetic mark on the female lineages of modern Europeans.” They further concluded that because modern Europeans do not appear to be descended from the first farmers, they must therefore be direct descendants of indigenous Paleolithic hunter-gatherers.
However, the possibility that either genetic drift or post-Neolithic migrations caused N1a to disappear from modern European lineages requires adequate examination. Haak and Burger dismissed the first possibility and failed to address the second. Using computer simulations intended to reconstruct the impact of genetic drift over the past 7500 years, the researchers found that drift alone could not account for the disappearance of N1a lineages among contemporary Europeans. This scenario, however, did not address other factors such as susceptibility to disease which may have had an impact on mtDNA groups over time and could have affected the longevity of the N1a lineage, particularly when coupled with the effects of genetic drift.
Nor did the authors address the
possibility of a post-Neolithic replacement scenario, noting only that
“[a]rchaeological evidence for such an event is as of yet scant.” Yet large-scale movement of peoples
Haak mentions only a single
additional ancient DNA study in a footnote, addressing such evidence only in
the most cursory fashion. That study
involved the DNA testing of a 2500 year-old skeleton belonging to the
Scytho-Siberian population of the
This conclusion was supported by
the finding that in
Yet this explanation, while
reasonable, did not explain the disappearance of N1a entirely from a region
believed to be the homeland of the Scythian peoples, and when linked with
Haak’s older N1a findings from
Haak also failed to examine other
available aDNA research on ancient Paleolithic remains from
Nor did Haak address the extensive Strontium isotope data derived from the same sites presented in his study. Strontium isotopes from human teeth and bones provide a geochemical signature of the place of birth and the place of death of the individual. Thus, it can be used as a direct measurement of migration, tracking the movement of groups between different geological zones. Three archaeological studies containing Strontium isotope data on the LBK sites generated similar results. (Bentley 2003; Bentley 2002; Price 2001). They suggested that while many of the LBK inhabitants moved to these sites from some distance away, it was also evident that some of the individuals were of local origin. This raised the question, however, of whether the local individuals represent sedentary farmers or local foragers/herders. One study suggested that the non-locals were hunter-gatherers (Bentley 2003) while the other study suggested they were immigrant farmers (Price 2001).
Archaeologists were also able to
differentiate between the locals and immigrants by examining burial goods. In particular, many locals were buried with
shoe-last adzes, particularly at sites like Flomborn in
Intermixture between Paleolithic and Neolithic peoples is further supported by the fact that burial orientation also correlated with place of origin. (Price 2001) This intermixture becomes especially apparent at Schwetzingen, at site also tested by Haak and representing the later phase of the LBK, when the process of contact between the farmers and hunter-gatherers appears to become more complex. At Schwetzingen, all but two of the immigrant burials are oriented in directions from north to east. At Flomborn, 4 of the 5 west-facing burials were of immigrants. Yet in Haak’s samples, the Flomborn and Derenburg individuals were buried in an East-West direction, while in Halberstadt, the burial orientation was West-East. One study suggested that immigrant brides may have been incorporated into the community and given a local identity, including burial in a northeastern direction. (Bentley 2003)
The failure of Haak’s genetic
study to incorporate important archaeological data along with other ancient DNA
results leaves the question of N1a’s ultimate origins unanswered. Nor is the mystery of N1a’s disappearance
among Europeans today adequately addressed.
The idea that N1a represents a Neolithic farming lineage that failed to
impart a genetic legacy is not supported by the evidence. Based on the limited N1a findings, Haak made
a sweeping generalization that the Neolithic farmers overall failed to have a
significant genetic impact on
The Basque: Reflections of a Paleolithic Past?
The group most often presented as
the best representatives of the genetic descendants of
Because of this uniqueness, the Basque have been the subject of numerous genetic studies, allowing researchers to investigate whether the perception of the Basque as representatives of the indigenous Paleolithic gene pool is in fact a valid one. Furthermore, numerous aDNA studies have also been performed on both Neolithic and historic Basque remains, providing the opportunity for researchers to compare modern-day Basque with their Neolithic counterparts. Thus far, however, only a few researchers have performed such a comparison. Those few have reached conclusions that conflict with the idea that the Basque population represents a “living fossil” of the first European settlers of the Paleolithic. (Alonso 2005)
One such study compared the mtDNA variability of a historical Basque population (VI-VII c. AD) recovered from the necropolis of Aldaieta (Nanclares de Gamboa, Araba, Basque Country) with remains tested from three prehistoric sites in Basque Country dating to 4000-5000 Years Before Present (“YBP”). (Alzualde 2005) These populations were then compared with modern-day Basque. The results were stunning.
The researchers discovered that
the mtDNA of the historical Basque population falls within the range of
present-day populations along
Haplogroup H, hypothesized to have been present in Europe since at least the late Paleolithic and the most common haplogroup among present-day Europeans (approximately 50%) and Basque (62%), was also found at a high frequency of 48% among the historical remains at Aldaieta, but at lower frequencies at the prehistoric sites (37% at SJAPL and Rico Ramos, 44% at Longar). This variation suggests that there was heterogeneity between the various prehistoric communities themselves, with some communities having a higher frequency of certain haplogroups than others. (Alzualde 2005)
Haplogroup V, on the other hand,
is believed to have originated in the vicinity of
Further aDNA evidence supports the
view that V either did not originate in this region or does not represent the
vestiges of an autochthonous Paleolithic lineage. It has been theorized that the Spanish and
the Basque may share genetic affinities as relics of indigenous Paleolithic
Europeans. The ancient Iberians, a group
Similar conclusions were reached
when analyzing the mtDNA haplogroup J results among the Basque. Haplogroup J is considered a main lineage of
Neolithic expansion out of the
Frequency differences among the mtDNA results between modern and prehistoric Basque populations led researchers to conclude that a “discontinuity” exists between prehistoric and modern-day groups (Alzualde 2005). The results also suggest that the reconstruction of the biological history of European populations based only on current DNA results is often misleading and incorrect. Using haplogroup J as an example, Alzualde explains that because “the Basque population is considered an outlier regarding the Neolithic component, it has been proposed that this region experienced a smaller genetic impact from Neolithic farmers. But if we accept that lineage J is a marker of migrations of Neolithic populations from the Near East, then the Basque Country also experienced the impact of these people, as shown by the high frequency of haplogroup J in certain ancient populations” (Alzualde 2005).
Additional aDNA evidence from Basque archaeological sites lends support to this conclusion. Alzualde more closely investigated the frequency and presence of various haplogroups, including a number of uncommon haplotypes, among the Basque of the 6th-7th centuries from the historic site of Aldaieta. (Alzualde 2006) He had also examined the mtDNA from Aldaieta in his previous study, though not with the depth of coverage present in this subsequent investigation.
The study emphasized the uncertain background of the Aldaieta population. While the remains suggested that the site was settled by “autochthonous individuals” with stable familial ties, the high percentage of weaponry and similarity of mortuary objects with Frankish cemeteries were also noted, indicating possible trade links or even temporary Frankish control of Basque territory.
Of the fifteen haplotypes from
Aldaieta, nine are uncommon or unique haplotypes. The unique haplotypes are found within
haplogroups T, U5, U2 and J. One of
these haplotypes bore close affinities with modern-day populations in
The researchers also discovered
the presence of haplogroup M1 at Aldaieta, a rare haplogroup among present-day
Europeans and peoples of the
The researchers issued a warning to other geneticists, suggesting that hypotheses formulated solely on the basis of DNA results from modern-day populations, without accompanying aDNA evidence, can lead to inaccurate reconstructions of population histories. Geneticists who propose an undiluted Paleolithic ancestry for the Basque often do so without reference to numerous aDNA studies. As a result, they incorrectly attribute the unique and unusual genetic results of contemporary Basque as indicators of undiluted Paleolithic ancestry.
The Aldaieta study concluded with the controversial suggestion that the Basque were not only impacted by cumulative gene flow from Neolithic Near East ancestors and as well as later invaders, but may have been affected by significant post-Neolithic biological events, including genetic drift and natural selection. Given the genetic discontinuity between present and prehistoric populations, the researchers urged their colleagues to consider the idea that “the genetic patterns of present-day populations reflect the evolutionary processes experienced by their predecessors,” suggesting that these post-Neolithic processes have altered the genetic composition of the Basque and European populations as a whole.
Other genetic studies on the Basque have focused on examining blood groups, STR loci, and autosomal markers, often in an attempt to support the Paleolithic paradigm. However, in light of the aDNA studies, Basque distinctiveness can be accounted for by the processes of genetic drift, inbreeding over long periods of time and natural selective processes. For instance, a correlation was observed between increased genetic differentiation between Europeans and Basque groups still speaking the Basque language. (Perez-Miranda 2005) It has been postulated that one of the causative agents of Basque isolation over the centuries is the Basque language. Thus, the more conservative the retention of the Basque language, the more likely the particular Basque community suffered the effects of isolation and genetic drift.
Moreover, the researchers noted that the Basque are unique among European populations due to their extremely high rate of consanguinity. Basque social and cultural traditions continue to promote consanguinity. The genetic impact of such inbreeding has yet to fully explored by geneticists, but the high frequency of inherited disorders among the Basque, including Coagulation Deficiences (Factor XI) and Mutation F508 (Cystic Fibrosis Gene), support the suggestion that drift, inbreeding, and a small population size maintained over many generations, as opposed to significant retention of Paleolithic genetic ancestry, best explains the present genetic makeup of the Basque (Alonso 2005; Bauduer 2005).
Finally, even researchers that have found limited genetic evidence of probable Paleolithic ancestry among the Basque also acknowledge that such findings do not support the contention that contemporary Basque retain significant genetic links with indigenous Paleolithic Europeans. (Gonzalez 2006) For instance, although the Basque mtDNA lineage U8a may date to the late Paleolithic, it is rarely found today among modern-day Europeans and, furthermore, constitutes only 1% of contemporary Basque mtDNA results. Thus, U8a has diminished in frequency among populations today in a manner similar to the N1a lineage.
Etruscans: Extinction or Mutation?
Like the ancient Basque, the
origin of the Etruscan people remains obscure.
The Etruscans lived in central
Two separate aDNA studies on the Etruscans reached similar conclusions, finding essentially no genetic relationship between the ancient Etruscans and the modern-day inhabitants of Tuscany (ie, “Tuscans”) (Belle 2006; Vernesi 2004). Specifically, out of twenty-eight mtDNA sequences, only six occur in any modern-day groups. The remaining twenty-one haplotypes, identified as belonging to the JT haplogroup, do not occur in any contemporary European populations, including the common Etruscan haplotypes 16126- 16193 and 16126-16193-16278. These sequences, while occurring among modern-day haplogroups J2 and T, are not accompanied by substitutions at 16069 and 16294, respectively, which are inevitably present among the contemporary motifs (Vernesi 2004).
The researchers attributed this
lack of genetic relationship between Etruscans and Tuscans to two possible
processes – the extinction of Etruscan mtDNA lineages among modern-day
Europeans, or demographic and evolutionary processes occurring in the last
2,500 years. These processes, if they
occurred, were severe enough to disrupt the genetic continuity between the
modern and ancient inhabitants of
Researchers performed a number of simulations to investigate whether certain phenomenon, such as genetic drift, migration or a higher than average mtDNA mutation rates, could have impacted the genetic continuity between Etruscans and Tuscans. (Belle 2006) None of their simulations were compatible with the DNA results. The genetic evidence did not support the conclusion that Tuscans were the modern-day descendants of the Etruscans, although the researchers noted that the skeletal remains used for their aDNA samples may not have been representative of the entire Etruscan population, but of a more elite sub-strata. Even so, they seemed to have contributed very little to the mtDNA background of modern Tuscans.
However, the researchers also found that genetic continuity could be generated if the mtDNA mutation rate was set very high (0.5 mutations per million years as opposed to commonly used lower rate of approx. 0.05 mutations per million years per nucleotide) or if gene flow from other areas was so extensive that Etruscan descendants became underrepresented in the modern Tuscan samples. They concluded, however, that the very high mtDNA mutation rates needed to reproduce genetic continuity were “implausible” and, furthermore, the only way to determine if descendants were underrepresented in the study was to collect more modern samples over time.
Thus, the study concluded that modern-day Tuscans largely descend from non-Etruscan ancestors. Regarding the fate of the Etruscans, the suspicion voiced by the researchers was that the Etruscan lineages simply went extinct.
Evolutionary Extinction of mtDNA Lineages
If the idea of mtDNA lineage extinction is accepted as the most likely scenario leading to the weak genealogical relationship between ancient and modern-day populations, then the question arises as to what evolutionary, demographic or human processes have caused such extinctions.
For example, in the case of the Etruscans, significant historic gene flow could have diluted the Etruscan lineages to the point where they have become difficult to detect in modern-day Tuscans, particularly if the lineages were already weakened by extensive gene flow from the Romans. DNA studies examining ancient remains from periods much later in time than the Iron Age Etruscans suggest admixture with other populations may indeed be a strong contributing factor to the apparent genetic break between past and present populations. Given the later date of these aDNA remains, more genetic traces of these ancient lineages are often found among their modern-day European descendants. Still, notable differences remain.
One such study examined the
genetic legacy of the ancient Cumanians, believed to have migrated from
In another study examining aDNA
from an early Danish Christian cemetery dating to 1000-1250 AD, two rare
haplotypes were found among the ten samples.
One belonged to haplogroup U7, absent from modern-day Scandinavians, but
found in contemporary groups in the
The researchers speculated that the Scandinavian population had either not yet become stable, or in the alternative, that the close proximity of the site to a nearby port town had brought in significantly more immigrants than might be found in groups residing in the surrounding countryside. This suggests the possibility of increased genetic continuity of ancient lineages among populations living far from ancient urban centers where admixture and cumulative gene flow with other incoming populations may have been more significant. It also indicates that ancient populations were not genetically static or homogenous, but incorporated immigrants from regions far away.
This fact was further emphasized
in a study of Anglo-Saxon remains from a number of archaeological sites in
The idea of dilution of genetic
lineages was also proposed in the ancient Iberian study in which the
researchers noted the likely cumulative genetic impact exerted by the invading
Romans, Visigoths and Vandals on the peoples of the
There are numerous studies suggesting that mtDNA genetic variation may be associated with adaptive selective, as well as linked with complex diseases and disorders. (Ruiz-Pesini 2004; Moilanen 2003) Some researchers have argued that the human genome evolution has been shaped over time primarily by infectious disease and that mtDNA has played a central role in the selection process due to its control of cellular metabolism (Samuels 2006).
Mitochondrial haplogroup J has been associated with Leber’s hereditary optic neuropathy, a rare disease that causes blindness in young people (Man 2004). It has also been associated with possible protection against Parkinson Disease, but increased susceptibility to multiple sclerosis (Ruiz-Pesini 2004; Ross 2003). Furthermore, Haplogroup J has been linked to increased longevity (De Benedictis 1999; Coskun PE 2003). Haplogroups K and T have been associated with protection against Alzheimer’s disease (Ruiz-Pesini 2004). Haplogroup K has also been linked with a lower risk of Parkinson’s Disease (Ghezzi 2005). Haplogroup U has been linked to increased risk of occipital stroke, and sub-clade U5 specifically to migrainous stroke (Finnila 2000). Haplogroup H has been linked to increased survival rates after recovery from sepsis (Baudouin 2006).
However, a number of other studies have failed to substantiate links between various mtDNA haplogroups and selective disease resistance or adaptive advantages (Houshmand 2004; Yao 2002; Rose 2001). Thus, the role that mitochondrial function and variability may play in adaptive selection, particularly disease resistance, remains unclear.
Other researchers have asserted
that specific mtDNA replacement mutations allowed our prehistoric ancestors to
adapt to more northern climates as they migrated out of
In this scenario, lineages that encounter new environments for which their mitochondria were maladapted would be eliminated by selection, as would any lineages that developed deleterious mutations. These extinctions would leave no traces in the phylogeny. Similarly, selection would cause lineages with mutations that were positively adaptive to become more numerous. Those adaptive mutations can still be observed in the internal nodes of the phylogeny where their position indicates that they have been highly conserved.
The researchers suggested that
mtDNA haplogroup variation was primarily influenced by climatic selective
pressures. Specifically, changes in
mtDNA amino acid variants permitted certain ancient European mtDNA lineages to
adapt to colder climates, particularly among haplogroups H, I + N1b, J, and
X. These haplogroups had higher
replacement mutation values among their internal branches and higher retention
of the altered amino acids when compared to those in mtDNA haplogroup L, the
most common haplogroup in
However, it should be noted that haplogroups I, N1b, and X occur at much lower frequencies among European populations today than haplogroups H and J, in conflict with the idea that these particular lineages have equivalent survival advantages based on climatic adaptation. Additionally, the theory of climatic selective pressure shaping the mtDNA genome continues to remain a matter of debate among geneticists.
In another study, researchers suggested that differences observed between the mtDNA groups utilized in the Ruiz-Pesini study were merely the result of comparing “region-specific haplogroups of different diversity levels: e.g., the “old” paragroup L in Africans vs. “young” Arctic haplogroups” (Kivisild 2006). Although Kivisild’s study did not detect lineage-specific positive selection, evidence of site-specific positive selection was found within mitochondrion-encoded rRNA. This selection appeared to involve the replacement of two specific amino acids, threonine and valine, with two other acids, alanine and isoleucine. This pattern led Kivisild to suggest that diet rather than climate could be one important selective factor impacting mtDNA population histories. According to Kivisild, [t]hreonine and valine, essential amino acids that must be taken in the diet, are abundant in meats, fish, peanuts, lentils, and cottage cheese, but deficient in most grains.”
Given the significant modification in diet that European populations underwent during the Neolithic era as they transitioned from hunter-gatherer subsistence to an agricultural grain-based diet, Kivisild’s theory of potential selective pressure based on dietary factors warrants further investigation.
Ancient mtDNA variants advantageous in one climate or dietary environment may have been maladaptive in a different environment, contributing to the rise of modern bioenergetic disorders such as obesity, hypertension, diabetes and cardiovascular disease. (Mishmar 2002) However, whether due to dietary factors, climate adaptation, disease resistance or a combination of selective pressures, these studies suggest that natural selection may have played a role in determining which mtDNA lineages survived over time.
Conclusion: Why We Are Not Our Ancestors
The ancient DNA studies present a
picture of genetic break or “discontinuity” between ancient and modern-day
European maternal histories. This
evidence indicates that modern-day mtDNA haplogroup frequencies and
distributions should not be considered living fossils of
Currently, the genetic picture
presented by the aDNA studies is based exclusively on mitochondrial DNA
results. This form of DNA, unlike that
of the Y chromosome, is generally preserved in a form that allows for testing
of ancient remains. However, the Y
chromosome genetic picture of
These findings stand in stark contrast to the model presented by many DNA studies of an undisturbed genetic link between contemporary and Paleolithic European groups. Yet evidence of such genetic continuity is sparse, even among populations such as the Basque. More problematically, it contradicts the findings of the ancient DNA studies. These studies indicate that populations have indeed changed dramatically over time, with some ancient lineages suffering reductions and even extinctions from the European gene pool.
Extinction appears to be the fate suffered by the Etruscans maternal lineages. Many other ancient groups appear to have suffered a similar fate, the continuity of their genetic lineages extinguished for future generations. Only the archaeological record remains a testament to their existence. Certain genetic lineages, like mtDNA haplogroup H, came to dominate the genetic landscape over time. The contemporary European genetic picture is thus a reflection of these complex demographic and evolutionary processes, changing and adapting until it is no longer a mere reflection of its genetic past, but a new and constantly evolving population.
Alonso S, Flores C, Cabrera V, Alonso A, Martin P, Albarran C, Izagirre N, de la Rua C, Garcia O (2005) The place of the Basque in the European Y-chromosome diversity landscape. Eur J Hum Genet, 1-10.
Alzualde A, Izagirre N, Alonso S, Alonso A, Albarran C, Azkarate A, de la Rua C (2006) Insights into the “isolation” of the Basques: mtDNA lineages from the historical site of Aldaieta (6th-7th centuries AD). Am J Phys Anthr 130:394-404.
Alzualde A, Izagirre N, Alonso S, Alonso A, de la Rua C (2005) Temporal mitochondrial DNA variation in Basque Country: influence of Post-Neolithic events. Annal of Hum Genet, 69, 1-16.
Ammerman AJ, Cavalli-Sforza LL
(1984) The Neolithic transition and the genetics of poulations in
Baudouin S.V., Saunders D, Tiangyou W, Elson JL, Poynter J, Pyle A, Keers S, Turnbull DM, Howell N, Chinnery PF (2006) Mitochondrial DNA and survival of sepsis: a prospective study. Lancet, 366:2118-2121.
Bentley RA, Price TD, Luning J, Gronenborn D, Wahl J, Fullagar PD (2002) Prehistoric migration in Europe: strontium isotope analysis of early Neolithic skeletons. (Reports). Curr Anthr 43.5:p799(6).
Bogacsi-Szabo E, Kalmar T, Csany B, Tomory G, Czibula A, Priskin K, Horvath F, Downes CS, Rasko I (2005) Mitochondrial DNA of ancient Cumanians: culturally Asian steppe nomadic immigrants with substantially more Western Eurasian mitochondrial DNA lineages. Hum Biol, 77:639-662.
Caramelli D, Lalueza-Fox C, Vernesi C, Lari M, Casoli A, Mallegni F, Chiarelli B, Dupanloup I, Bertranpetit J, Barbujani G, Bertorelle (2003) Evidence for a genetic discontinuity between Neandertals and 24,000-year-old anatomically modern Europeans. PNAS, 100:6593-6597.
De Benedictis B, Rose G., Carrieri G, De Luca M, Falcone E., Passarino G, Bonafe M, Monti D, Baggio G, Bertolini S, Mari D, Mattace R, Francheschi C (1999) Mitochondrial DNA inherited variants are associated with successful aging and longevity in humans. FASEB Journal 13:1532-1536.
Finnila Saara (2000) Phylogenetic
Analysis of Mitochondrial DNA (Dissertation).
Ghezzi D, Marelli C, Achilli A, Goldwurm S, Pezzoli G, Barone P, Pellecchia T, Stanzione P, Brusa L, Bentivoglio AR, Bonuccelli U, Petrozzi L, Abbruzzese G, Marchese R, Cortelli P, Grimaldi D, Marinelli P, Ferrarese C, Garavaglia B, Sangiorgi S, Carelli V, Torroni A, Albanese A, Zeriani M (2005) Mitochondrial DNA haplogroup K is associated with a lower risk of Parkinson’s Disease in Italians. Eur J Hum Genet, 13:748-752.
Haak W, Forster P, Bramanti B, Matsumura S, Brandt G, Tanzer M, Villems R, Renfrew C, Gronenborn D, Alt KW, Burger J (2005) Ancient DNA from the first European farmers in 7500-year-old Neolithic sites. Science, 310:1016.
Herity M, Eogan G (1977)
Houshmand M, Sharifpanah F, Tabasi A, Sanati M-H, Vakilian M, Lavasani SH, Joughehdoust S (2004) Leber’s Hereditary Optic Neuropathy: The spectrum of mitochondrial DNA mutations and Iranian patients. Ann NY Acad Sci. 1011:345-349.
Izagirre N, de la Rua C (1999) An mtDNA analysis in ancient Basque populations: implications for haplogroup V as a marker for a major Paleolithic expansion from southwestern Europe. Am J Hum Genet, 65:199-207.
Jobling MA, Williams GA, Schiebel GA, Pandya GA, McElreavey GA, Salas GA, Rappold GA, Affara NA, Tyler-Smith C (1998) A selective difference between human Y-chromosome DNA haplotypes. Curr Biol 8(25):1391-4.
Kivisild T, Shen P, Wall DP, Do B, Sung R, David K, Passarino G, Underhill P, Scharfe C, Torroni A, Scozzari R, Modiano D, Coppa A, De Knijff P, Feldman M, Cavalli-Sforza LL, Oefner PJ (2006) The Role of Selection in the Evolution of Human Mitochondrial Genomes. Genetics 172:373-387.
Man PYW, Howell N, Mackey DA, Norby S, Rosenberg T, Turnbull DM, Chinnery PF (2004) Mitochondrial DNA haplogroup distribution within Leber hereditary optic neuropathy pedigrees. Jour Med Gen 41:ed 41.
McEvoy B, Richards M, Forster P, Bradley D (2004) The Longue Duree of genetic ancestry: multiple genetic marker systems and Celtic origins on the Atlantic facade of Europe. Am J Hum Genet, vol. 75(4):693-702.
Mishmar D, Ruiz-Pesini E, Golik P, Macaulay V, Clark AG, Hosseini S, Brandon M, Easley K, Chen E, Brown MD, Sukernik RI, Olckers A, Wallace DC (2002) Natural selection shaped regional mtDNA variation in humans. PNAS, vol. 100, no. 1:171-176.
Perez-Miranda AM, Alfonso-Sanchez MA, Kalantar A, Garcia-Obregon S, de Pancorbo MM, Pena JA, Herrera RJ (2005) Microsatellite data support subpopulation structuring among Basques. J Hum Genet, 50:403-414.
Price TD, Bentley RA, Luning J, Gronenborn D, Wahl J (2001) Prehistoric migration in the Linearbandkeramik of Central Europe. (Statistical Data Included). Antiquity 75.:593.
Quintana-Murci L., Krausz C, McElreavey K (2001) The human Y chromosome: function, evolution and disease. Forensic Sci Int, 118;169-181.
Quintan-Murci L, Chaix R, Spencer Wells R, Behar D, Sayar H, Scozzari R, Rengo C, Al-Zahery N, Semino O, Santachiara-Benerecetti AS, Coppa A, Ayub Q, Mohyuddin A, Tyler-Smith C, Qasim Mehdi S, Torroni A, McElreavey K (2004) Where west meets east: the complex mtDNA landscape of the southwest and Central Asia corridor. Am J Hum Genet 74:827-845.
Ricaut F-X, Keyser-Tracqui C, Bourgeois J, Crubezy E, Ludes B (2004) MtDNA of Scytho-Siberian skeleton and its implications for ancient Central Asian migration. Hum Bio 76:109-125.
Rose G, Passarino G, Carrieri G, Altomare K, Greco V, Bertolini S, Bonafe M, Franceschi C, De Benedictis G (2001) Paradoxes in longevity; sequence analysis of mtDNA haplogroup J in centenarians. Eur J Hum Genet, 9:701-707.
Ross OA, McCormack R, Maxwell LD, Duguid RA, Quinn DJ, Barnett YA, Rea IM, El-Agnaf OM, Gibson JM, Wallace A, Middleton D, Curran MD (2003). Mt4215C variant in linkage with the mtDNA TJ cluster may confer a susceptibility to mitochondrial dysfunction resulting in an increased risk of Parkinson’s disease in the Irish. Exp Gerontol, 38:397-405.
Rudbeck L, Thomas M, Gilberp P, Willerslev E, Hansen AJ, Lynnerup N, Christensen T, Dissing J (2005) MtDNA analysis of Human remains from an early Danish Christian cemetery. Am J Phys Anthr, 128:424-429.
Ruiz-Pesini E, Mishmar D, Bra
Sampietro ML, Caramelli D, Lao O, Calafell F, Comas D, Lari M, Agusti B, Bertranpetit J, Lalueza-Fox C (2005) The genetics of the Pre-Roman Iberian peninsula: a mtDNA study of ancient Iberians. Ann Hum Genet, 69:535-548.
Vernesi C, Caramelli D, Dupanloup I, Bertorelle G, Lari M, Cappellini E, Moggi-Cecchi J, Chiarelli B, Castri L, Casoli A, Mallegni F, Lalueza-Fox C, Barbujani G (2004) The Etruscans: a population-genetic study. Am J Hum Genet 74:694-704.
Yao Y-G, Kong Q-P, Zhang Y-P (2002). Mitochondrial DNA 5178A polymorphism and longevity. Biomed & Life Sciences and Med, 111:462-463.