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PubMed2005

Geologically ancient DNA: fact or artefact?

Studies continue to report ancient DNA sequences and viable microbial cells that are many millions of years old. In this paper we evaluate some of the most extravagant claims of geologically ancient DNA. We conclude that although exciting, the reports suffer from inadequate experimental setup and insufficient authentication of results. Consequently, it remains doubtful whether amplifiable DNA sequences and viable bacteria can survive over geological timescales. To enhance the credibility of future studies and assist in discarding false-positive results, we propose a rigorous set of authentication criteria for work with geologically ancient DNA.

Amber↗

PubMed2026

Ancient DNA as a temporal lens: reconstructing evolution, migration, and disease dynamics.

Ancient DNA (aDNA) has transformed evolutionary biology and anthropology by providing direct, chronologically validated genetic evidence over millennia. This review synthesizes significant findings from the paleogenomic era (2010-2025), demonstrating how ancient DNA has resolved persistent debates across four interconnected themes: (i) human migration and admixture, revealing complex population transitions from archaic hominins to Holocene expansions; (ii) adaptation, tracking allele frequency changes during domestication and selection; (iii) pathogen history, clarifying the origins of pandemics and the evolution of microbiomes; and (iv) ecosystem dynamics, identifying extinction causes through sedimentary DNA and conservation genomics. We contend that scientific rigor and ethical stewardship are crucial for accurate conclusions, given ancient DNA study requires the destructive collection of culturally significant remains. This review argues that continued advancement will depend on the integration of genomic data with archaeological, isotopic, and proteomic evidence, and highlights the necessity for equitable involvement with descendant communities. By conceptualizing the past as a continuum of dynamic processes rather than static events, ancient DNA provides a revised historical narrative and insights relevant to contemporary concerns in conservation, health, and social justice.

Evolution↗

PubMed1994

Ancient DNA: methodological challenges.

The study of ancient DNA offers the possibility of following genetic change over time. However, the field is plagued by a problem which is unique in molecular biology--the difficulty of verifying results by reproduction. Some of the reasons for this are technical and derive from the low copy number and damaged state of ancient DNA molecules. Other reasons are the unique nature of many of the objects from which DNA is extracted. We describe methodological approaches with which these problems can be alleviated in order to ensure that results are scientific in the sense that they can be reproduced by others.

Base Sequence↗

PubMed1994

The biochemistry of ancient DNA in bone.

The amount of DNA in ancient bone was determined by ethidium bromide staining after the removal of the potent Taq inhibitor, fulvic acid. A complete decalcification and a perfusion protocol were used to recover DNA from bone. A variety of purification techniques including molecular sieve, hydroxyapatite binding and 'Magic' preparations yielded DNA that spanned from 3.4 micrograms/g of bone to below detectable limits. Fulvic acid was shown to interfere with the quantification of DNA derived from ancient human skeletal material one hundred to over seven thousand years old. Scanning UV in the 300 to 230 nm range is a simple and sensitive technique for documenting fulvic acid contamination in ancient bone extracts.

Benzopyrans↗

PubMed2006

[Ancient DNA].

The review is devoted to molecular genetic studies of ancient DNA. The problems of DNA preservation and modification after cell death, as well as techniques of working with ancient DNA, including its retrieval, removal of inhibitors, PCR amplification, and phylogenetic analysis, are discussed in detail. The possibilities are considered of using ancient DNA in resolving issues of systematics and evolution of various animal taxa, population genetics of humans and rare species, taxonomic identification and paleontological reconstructions, geographic origin of populations, microbiological analysis of paleontological and archeological finds, as well as some humanitarian aspects of its use.

Animals↗

PubMed2006

Patterns of nucleotide misincorporations during enzymatic amplification and direct large-scale sequencing of ancient DNA.

Whereas evolutionary inferences derived from present-day DNA sequences are by necessity indirect, ancient DNA sequences provide a direct view of past genetic variants. However, base lesions that accumulate in DNA over time may cause nucleotide misincorporations when ancient DNA sequences are replicated. By repeated amplifications of mitochondrial DNA sequences from a large number of ancient wolf remains, we show that C/G-to-T/A transitions are the predominant type of such misincorporations. Using a massively parallel sequencing method that allows large numbers of single DNA strands to be sequenced, we show that modifications of C, as well as to a lesser extent of G, residues cause such misincorporations. Experiments where oligonucleotides containing modified bases are used as templates in amplification reactions suggest that both of these types of misincorporations can be caused by deamination of the template bases. New DNA sequencing methods in conjunction with knowledge of misincorporation processes have now, in principle, opened the way for the determination of complete genomes from organisms that became extinct during and after the last glaciation.

Animals↗

PubMed1997

Ancient DNA is thirteen years old.

The first successful recovery of ancient DNA, from quagga and human mummies inspired significant enough interest to open an entire field of research. Efforts from many research groups, often in a hunt for the oldest sequences, showed that ancient DNA was a poor substrate for the enzymes used in molecular biology; it is present in tiny amounts, hard to purify, and frequently damaged. These obstacles have been partially overcome by the use of drastic laboratory precautions and by the introduction of polymerase chain reaction and phylogenetic studies. Ancient DNA analysis now finds applications in many research domains.

Animals↗

PubMed2006

[Biological evolution and ancient DNA].

Twenty years after the advent of ancient DNA studies, this discipline seems to have reached the maturity formerly lacking to the fulfilment of its objectives. In its early development paleogenetics, as it is now acknowledged, had to cope with very limited data due to the technical limitations of molecular biology. It led to phylogenetic assumptions often limited in their scope and sometimes non-focused or even spurious results that cast the reluctance of the scientific community. This time seems now over and huge amounts of sequences have become available which overcome the former limitations and bridge the gap between paleogenetics, genomics and population biology. The recent studies over the charismatic woolly mammoth (independent sequencing of the whole mitochondrial genome and of millions of base pairs of the nuclear genome) exemplify the growing accuracy of ancient DNA studies thanks to new molecular approaches. From the earliest publications up to now, the number of mammoth nucleotides was multiplied by 100,000. Likewise, populational approaches of ice-age taxa provide new historical scenarios about the diversification and extinction of the Pleistocene megafauna on the one hand, and about the processes of domestication of animal and vegetal species by Man on the other. They also shed light on the differential structure of molecular diversity between short-term populational research (below 2 My) and long-term (over 2 My) phylogenetic approaches. All those results confirm the growing importance of paleogenetics among the evolutionary biology disciplines.

Animals↗

PubMed1994

Ancient DNA sequences reveal unsuspected phylogenetic relationships within New Zealand wrens (Acanthisittidae).

Ancient DNA sequences from preserved specimens are increasingly being used for the investigation of Pacific Island ecosystems prior to the large scale modification and extinction of endemic biota associated with human colonization. However, many difficulties are associated with the use of ancient DNA sequences in studies of genetically close taxa. In this paper, these difficulties are discussed as they relate to a study involving extinct and extant members of an ancient New Zealand avian family, the New Zealand wrens (Acanthisittidae). Sequences of the mitochondrial small ribosomal subunit RNA gene (12S) were obtained from museum specimens of several wren taxa in order to investigate their phylogenetic relationships and the taxonomic status of a rock wren (Xenicus gilviventris) subspecies. Limitations due to sample size and 12S sequence variability as well as the difficulties in authenticating ancient DNA sequences prevent firm conclusions but the data suggest unsuspected phylogenetic relationships exist and raise the possibility that conservation management of rock wren populations is required.

Animals↗

PubMed1999

How microbial ancient DNA, found in association with human remains, can be interpreted.

The analysis of the DNA of ancient micro-organisms in archaeological and palaeontological human remains can contribute to the understanding of issues as different as the spreading of a new disease, a mummification process or the effect of diets on historical human populations. The quest for this type of DNA, however, can represent a particularly demanding task. This is mainly due to the abundance and diffusion of bacteria, fungi, yeasts, algae and protozoans in the most diverse environments of the present-day biosphere and the resulting difficulty in distinguishing between ancient and modern DNA. Nevertheless, at least under some special circumstances, by using rigorous protocols, which include an archaeometric survey of the specimens and evaluation of the palaeoecological consistency of the results of DNA sequence analysis, glimpses of the composition of the original microbial flora (e.g. colonic flora) can be caught in ancient human remains. Potentials and pitfalls of this research field are illustrated by the results of research works performed on prehistoric, pre-Columbian and Renaissance human mummies.

Animals↗

PubMed2005

Methods for the study of ancient DNA.

Whereas the analysis of ancient DNA (aDNA) has become an increasingly popular mode of investigation in both archaeological and evolutionary studies, this approach is complicated by the degraded nature of ancient nucleic acids, the presence of enzymatic inhibitors in aDNA extracts, as well as the risk of contamination during either excavation or manipulation of samples. Despite these difficulties, numerous methods have been developed to optimize the recovery, study, and authentication of aDNA. In this article, we describe the procedures used in our laboratory to extract and amplify informative DNA segments from prehistoric or protohistoric human samples, as well as the precautions and strategies implemented to avoid or at least detect contaminations.

Archaeology↗

PubMed1993

Ancient DNA from a pre-Columbian Amerindian population.

Ancient DNA was obtained from skeletal remains from the Norris Farms #36 cemetery, a pre-Columbian archeological site in central Illinois that dates to A.D. 1300. Four mitochondrial DNA (mtDNA) markers were analyzed that delineate the four primary mtDNA lineages found in contemporary Amerindian populations. mtDNA types were determined for 50 individuals; 49 belonged to one of these four lineages. One lineage occurred only in males, suggesting an immigration of maternally related males into this community. There was no significant spatial patterning of mtDNA lineages within the cemetery. This survey of ancient DNA variation in a pre-Columbian population supports the view that the initial colonization of the New World comprised just four primary mtDNA lineages.

Adult↗

PubMed2006

Early history of European domestic cattle as revealed by ancient DNA.

We present an extensive ancient DNA analysis of mainly Neolithic cattle bones sampled from archaeological sites along the route of Neolithic expansion, from Turkey to North-Central Europe and Britain. We place this first reasonable population sample of Neolithic cattle mitochondrial DNA sequence diversity in context to illustrate the continuity of haplotype variation patterns from the first European domestic cattle to the present. Interestingly, the dominant Central European pattern, a starburst phylogeny around the modal sequence, T3, has a Neolithic origin, and the reduced diversity within this cluster in the ancient samples accords with their shorter history of post-domestic accumulation of mutation.

Animals↗

PubMed2003

Ancient DNA enables timing of the pleistocene origin and holocene expansion of two adélie penguin lineages in antarctica.

The timing of divergent events in history is one of the central goals of contemporary evolutionary biology. Such studies are however dependent on accurate evolutionary rates. Recent developments in ancient DNA analysis enable the estimation of more accurate evolutionary rates and therefore more accurate timing of divergence events. Consequently, this leads to a better understanding of changes in populations through time. We use an evolutionary rate calculated from ancient DNA of Adélie penguins (Pygoscelis adeliae) to time divergent events in their history. We report the presence of two distinct and highly variable mitochondrial DNA lineages and track changes in these lineages through space and time. When the ancient DNA and the phylogenetic rates are used to estimate the time of origin of the lineages, two very different estimates resulted. In addition, these same rates provide very different estimates of the time of expansion of these lineages. We suggest that the rate calculated from ancient DNA is more consistent with the glacial history of Antarctica and requires fewer assumptions than does a narrative based on the phylogenetic rate. Finally, we suggest that our study indicates an important new role for ancient DNA studies in the timing of divergent events in history.

Animals↗

PubMed2002

Detection of bone glue treatment as a major source of contamination in ancient DNA analyses.

Paleogenetic investigations of ancient DNA extracted from fossil material is for many reasons susceptible to falsification by the presence of more recent contamination from several sources. Gelatine-based bone glue that has been used extensively for nearly two centuries by curators to preserve hard tissues contributes nonauthentic DNA to paleontological material. This fact has been frequently neglected and is barely mentioned in the literature. Now paleogeneticists, curators, and conservators are faced with the problem that treatment of samples with adhesives and consolidants for conservatory purposes has seldom been recorded. Here, we show that racemization of amino acids, and in particular serine, is an excellent indicator for the treatment of paleontological samples with glue.

Animals↗

PubMed2004

Mutations induced by ancient DNA extracts?

We have investigated whether some factor in ancient DNA extracts induces site-specific mutations in modern DNA. We find no evidence for higher mutation rates when extracts from three different Pleistocene mammals are added to modern DNA than when water or extraction blanks are added. We also fail to find evidence that any such factor affects ancient DNA sequences determined from the same extracts. This as well as the patterns of nucleotide substitutions seen in DNA sequences determined from hundreds of other specimens leads us to doubt that a previously unknown mutagenic factor can be a general feature of extracts from old tissues.

Animals↗

PubMed1999

Proving the authenticity of ancient DNA by comparative genomic hybridization.

In PCR-supported amplification of ancient, degraded DNA, contamination with contemporary DNA can lead to false-positive results, which frequently give rise to discussions in which the mere existence of ancient DNA is doubted. Our confirmation of ancient DNA using comparative genome hybridization (CGH) eliminates these doubts. Unlike PCR methods, CGH requires no amplification of the DNA to be analyzed if adequate amounts of specimen DNA is used. Thus, false results traceable to contaminations are practically ruled out. The examples provided here prove the authenticity of ancient DNA for a 250-year-old and a 3,000-year-old sample. At the same time, the CGH of ancient DNA offers the chance to gain insight into the pattern of DNA degradation and to monitor the preservation of certain chromosomal segments.

Chromosomes, Human↗

PubMed2001

DNA sequences from multiple amplifications reveal artifacts induced by cytosine deamination in ancient DNA.

We show that DNA molecules amplified by PCR from DNA extracted from animal bones and teeth that vary in age between 25 000 and over 50 000 years carry C-->T and G-->A substitutions. These substitutions can reach high proportions among the molecules amplified and are due to the occurrence of modified deoxycytidine residues in the template DNA. If the template DNA is treated with uracil N-glycosylase, these substitutions are dramatically reduced. They are thus likely to result from deamination of deoxycytidine residues. In addition, 'jumping PCR', i.e. the occurrence of template switching during PCR, may contribute to these substitutions. When DNA sequences are amplified from ancient DNA extracts where few template molecules initiate the PCR, precautions such as DNA sequence determination of multiple clones derived from more than one independent amplification are necessary in order to reduce the risk of determination of incorrect DNA sequences. When such precautionary measures are taken, errors induced by damage to the DNA template are unlikely to be more frequent than approximately 0.1% even under the unlikely scenario where each amplification starts from a single template molecule.

Animals↗