134-593: The cave bear ( Ursus spelaeus ) is a prehistoric species of bear that lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago during the Last Glacial Maximum . Both the word cave and the scientific name spelaeus are used because fossils of this species were mostly found in caves . This reflects the views of experts that cave bears may have spent more time in caves than
268-718: A molecular clock technique. Medical technicians may sequence genes (or, theoretically, full genomes) from patients to determine if there is risk of genetic diseases. This is a form of genetic testing , though some genetic tests may not involve DNA sequencing. As of 2013 DNA sequencing was increasingly used to diagnose and treat rare diseases. As more and more genes are identified that cause rare genetic diseases, molecular diagnoses for patients become more mainstream. DNA sequencing allows clinicians to identify genetic diseases, improve disease management, provide reproductive counseling, and more effective therapies. Gene sequencing panels are used to identify multiple potential genetic causes of
402-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
536-542: A two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
670-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
804-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
938-468: A bear humerus , a scraper, a core, and some flakes, which were interpreted as grave offerings. An unusual discovery in a deep chamber of Basura Cave in Savona , Italy, is thought to be related to cave bear worship, because there is a vaguely zoomorphic stalagmite surrounded by clay pellets. It is thought to have been used by Neanderthals for a ceremony; bear bones scattered on the floor further suggests it
1072-407: A body of water, sewage , dirt, debris filtered from the air, or swab samples from organisms. Knowing which organisms are present in a particular environment is critical to research in ecology , epidemiology , microbiology , and other fields. Sequencing enables researchers to determine which types of microbes may be present in a microbiome , for example. As most viruses are too small to be seen by
1206-811: A cDNA molecule, which can be time-consuming and labor-intensive. They are prone to errors and biases, which can affect the accuracy of the sequencing results. They are limited in their ability to detect rare or low-abundance transcripts. Advances in RNA Sequencing Technology In recent years, advances in RNA sequencing technology have addressed some of these limitations. New methods such as next-generation sequencing (NGS) and single-molecule real-timeref >(SMRT) sequencing have enabled faster, more accurate, and more cost-effective sequencing of RNA molecules. These advances have opened up new possibilities for studying gene expression, identifying new genes, and understanding
1340-462: A cave bear that lived between 42,000 and 44,000 years ago. The procedure used genomic DNA extracted from one of the animal's teeth . Sequencing the DNA directly (rather than first replicating it with the polymerase chain reaction ), the scientists recovered 21 cave bear genes from remains that did not yield significant amounts of DNA with traditional techniques. This study confirmed and built on results from
1474-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
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#17328591337681608-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
1742-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
1876-415: A high winter mortality rate for cave bears that failed to find available caves. Therefore, as human populations slowly increased, the cave bear faced a shrinking pool of suitable caves, and slowly faded away to extinction, as both Neanderthals and anatomically modern humans sought out caves as living quarters, depriving the cave bear of vital habitat. This hypothesis is being researched as of 2010. According to
2010-528: A lecturer discovered two complete cave bear skulls, with molars, canines, humerus, three vertebrae and other bones, in a previously unexplored cave. Both the cave bear and the brown bear are thought to be descended from the Plio-Pleistocene Etruscan bear ( Ursus etruscus ) that lived about 5.3 Mya to 100,000 years ago. The last common ancestor of cave bears and brown bears lived between 1.2–1.4 Mya. The immediate precursor of
2144-673: A light microscope, sequencing is one of the main tools in virology to identify and study the virus. Viral genomes can be based in DNA or RNA. RNA viruses are more time-sensitive for genome sequencing, as they degrade faster in clinical samples. Traditional Sanger sequencing and next-generation sequencing are used to sequence viruses in basic and clinical research, as well as for the diagnosis of emerging viral infections, molecular epidemiology of viral pathogens, and drug-resistance testing. There are more than 2.3 million unique viral sequences in GenBank . Recently, NGS has surpassed traditional Sanger as
2278-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
2412-462: A major part of cave bears' diets on the basis of dental microwear analysis. Seed fruits are documented to have been consumed by cave bears. The morphological features of the cave bear chewing apparatus, including loss of premolars, have long been suggested to indicate their diets displayed a higher degree of herbivory than the Eurasian brown bear . Indeed, a solely vegetarian diet has been inferred on
2546-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
2680-637: A parallelized, adapter/ligation-mediated, bead-based sequencing technology and served as the first commercially available "next-generation" sequencing method, though no DNA sequencers were sold to independent laboratories. Allan Maxam and Walter Gilbert published a DNA sequencing method in 1977 based on chemical modification of DNA and subsequent cleavage at specific bases. Also known as chemical sequencing, this method allowed purified samples of double-stranded DNA to be used without further cloning. This method's use of radioactive labeling and its technical complexity discouraged extensive use after refinements in
2814-472: A particular modification, e.g., the 5mC ( 5 methyl cytosine ) common in humans, may or may not be detected. In almost all organisms, DNA is synthesized in vivo using only the 4 canonical bases; modification that occurs post replication creates other bases like 5 methyl C. However, some bacteriophage can incorporate a non standard base directly. In addition to modifications, DNA is under constant assault by environmental agents such as UV and Oxygen radicals. At
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#17328591337682948-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
3082-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
3216-529: A previous study using mitochondrial DNA extracted from cave bear remains ranging from 20,000 to 130,000 years old. Both show that the cave bear was more closely related to the brown bear and polar bear than it was to the American black bear , but had split from the brown bear lineage before the distinct eastern and western brown bear lineages diversified, and before the split of brown bears and polar bears. The divergence date estimate of cave bears and brown bears
3350-508: A quick way to sequence DNA allows for faster and more individualized medical care to be administered, and for more organisms to be identified and cataloged. The rapid speed of sequencing attained with modern DNA sequencing technology has been instrumental in the sequencing of complete DNA sequences, or genomes , of numerous types and species of life, including the human genome and other complete DNA sequences of many animal, plant, and microbial species. The first DNA sequences were obtained in
3484-480: A random mixture of material suspended in fluid. Sanger's success in sequencing insulin spurred on x-ray crystallographers, including Watson and Crick, who by now were trying to understand how DNA directed the formation of proteins within a cell. Soon after attending a series of lectures given by Frederick Sanger in October 1954, Crick began developing a theory which argued that the arrangement of nucleotides in DNA determined
3618-431: A relatively restricted geographical range. This was suggested as an explanation as to why it died out so much earlier than the rest. Some experts have disputed this claim, as the cave bear had survived multiple climate changes prior to extinction. Additionally, mitochondrial DNA research indicated that the genetic decline of the cave bear began long before it became extinct, demonstrating habitat loss due to climate change
3752-494: A result of some experiments by Oswald Avery , Colin MacLeod , and Maclyn McCarty demonstrating that purified DNA could change one strain of bacteria into another. This was the first time that DNA was shown capable of transforming the properties of cells. In 1953, James Watson and Francis Crick put forward their double-helix model of DNA, based on crystallized X-ray structures being studied by Rosalind Franklin . According to
3886-409: A series of labeled fragments is generated, from the radiolabeled end to the first "cut" site in each molecule. The fragments in the four reactions are electrophoresed side by side in denaturing acrylamide gels for size separation. To visualize the fragments, the gel is exposed to X-ray film for autoradiography, yielding a series of dark bands each corresponding to a radiolabeled DNA fragment, from which
4020-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
4154-470: A significant turning point in DNA sequencing because it was achieved with no prior genetic profile knowledge of the virus. A non-radioactive method for transferring the DNA molecules of sequencing reaction mixtures onto an immobilizing matrix during electrophoresis was developed by Herbert Pohl and co-workers in the early 1980s. Followed by the commercialization of the DNA sequencer "Direct-Blotting-Electrophoresis-System GATC 1500" by GATC Biotech , which
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4288-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
4422-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
4556-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
4690-488: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
4824-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
4958-403: A suspected disorder. Also, DNA sequencing may be useful for determining a specific bacteria, to allow for more precise antibiotics treatments , hereby reducing the risk of creating antimicrobial resistance in bacteria populations. DNA sequencing may be used along with DNA profiling methods for forensic identification and paternity testing . DNA testing has evolved tremendously in
5092-519: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
5226-506: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
5360-469: A unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given
5494-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
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5628-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
5762-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
5896-471: Is "far from convincing". Insoll also states that comparisons with the religious practices involving bears that are known from historic times are invalid. A similar phenomenon was encountered in Regourdou, southern France. A rectangular pit contained the remains of at least twenty bears, covered by a massive stone slab. The remains of a Neanderthal lay nearby in another stone pit, with various objects, including
6030-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
6164-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
6298-471: Is about 1.2–1.4 Mya. However, a recent study showed that both species had some hybridization between them. The cave bear had a very broad, domed skull with a steep forehead; its stout body had long thighs, massive shins and in-turning feet, making it similar in skeletal structure to the brown bear. Cave bears were comparable in size to, or larger than, the largest modern-day bears, measuring up to 2 m (6.6 ft) in length. The average weight for males
6432-576: Is also the most efficient way to indirectly sequence RNA or proteins (via their open reading frames ). In fact, DNA sequencing has become a key technology in many areas of biology and other sciences such as medicine, forensics , and anthropology . Sequencing is used in molecular biology to study genomes and the proteins they encode. Information obtained using sequencing allows researchers to identify changes in genes and noncoding DNA (including regulatory sequences), associations with diseases and phenotypes, and identify potential drug targets. Since DNA
6566-480: Is an informative macromolecule in terms of transmission from one generation to another, DNA sequencing is used in evolutionary biology to study how different organisms are related and how they evolved. In February 2021, scientists reported, for the first time, the sequencing of DNA from animal remains , a mammoth in this instance, over a million years old, the oldest DNA sequenced to date. The field of metagenomics involves identification of organisms present in
6700-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
6834-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
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#17328591337686968-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
7102-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
7236-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
7370-468: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
7504-587: Is now implemented in Illumina 's Hi-Seq genome sequencers. In 1998, Phil Green and Brent Ewing of the University of Washington described their phred quality score for sequencer data analysis, a landmark analysis technique that gained widespread adoption, and which is still the most common metric for assessing the accuracy of a sequencing platform. Lynx Therapeutics published and marketed massively parallel signature sequencing (MPSS), in 2000. This method incorporated
7638-436: Is possible because multiple fragments are sequenced at once (giving it the name "massively parallel" sequencing) in an automated process. NGS technology has tremendously empowered researchers to look for insights into health, anthropologists to investigate human origins, and is catalyzing the " Personalized Medicine " movement. However, it has also opened the door to more room for error. There are many software tools to carry out
7772-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
7906-424: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. DNA sequencing DNA sequencing is the process of determining
8040-405: Is the determination of the physical order of these bases in a molecule of DNA. However, there are many other bases that may be present in a molecule. In some viruses (specifically, bacteriophage ), cytosine may be replaced by hydroxy methyl or hydroxy methyl glucose cytosine. In mammalian DNA, variant bases with methyl groups or phosphosulfate may be found. Depending on the sequencing technique,
8174-455: Is then synthesized through a process called PCR ( Polymerase Chain Reaction ), which amplifies the cDNA to produce multiple copies. 3) Sequencing : The amplified cDNA is then sequenced using a technique such as Sanger sequencing or Maxam-Gilbert sequencing . Challenges and Limitations Traditional RNA sequencing methods have several limitations. For example: They require the creation of
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#17328591337688308-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
8442-649: The Balkans , Romania , Georgia , and parts of Russia , including the Caucasus ; and northern Iran . No traces of cave bears have been found in the northern British Isles, Scandinavia or the Baltic countries , which were all covered in extensive glaciers at the time. The largest numbers of cave bear remains have been found in Austria , Switzerland , northern Italy, northern Spain, southern France, and Romania, roughly corresponding with
8576-693: The Heinrichshöhle in Hemer and the Dechenhöhle in Iserlohn , Germany . A complete skeleton, five complete skulls, and 18 other bones were found inside Kletno Bear Cave , in 1966 in Poland . In Romania , in a cave called Bears' Cave , 140 cave bear skeletons were discovered in 1983. Cave bear bones are found in several caves in the country of Georgia . In 2021, Akaki Tsereteli State University 's students and
8710-523: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
8844-474: The MRC Centre , Cambridge , UK and published a method for "DNA sequencing with chain-terminating inhibitors" in 1977. Walter Gilbert and Allan Maxam at Harvard also developed sequencing methods, including one for "DNA sequencing by chemical degradation". In 1973, Gilbert and Maxam reported the sequence of 24 basepairs using a method known as wandering-spot analysis. Advancements in sequencing were aided by
8978-531: The University of Ghent ( Ghent , Belgium ), in 1972 and 1976. Traditional RNA sequencing methods require the creation of a cDNA molecule which must be sequenced. Traditional RNA Sequencing Methods Traditional RNA sequencing methods involve several steps: 1) Reverse Transcription : The first step is to convert the RNA molecule into a complementary DNA (cDNA) molecule using an enzyme called reverse transcriptase . 2) cDNA Synthesis : The cDNA molecule
9112-552: The brown bear , which uses caves only for hibernation . It is thought to have been largely herbivorous. Cave bear skeletons were first described in 1774 by Johann Friedrich Esper, in his book Newly Discovered Zoolites of Unknown Four Footed Animals . While scientists at the time considered that the skeletons could belong to apes , canids , felids , or even dragons or unicorns , Esper postulated that they actually belonged to polar bears . Twenty years later, Johann Christian Rosenmüller , an anatomist at Leipzig University , gave
9246-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
9380-498: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
9514-811: The nucleic acid sequence – the order of nucleotides in DNA . It includes any method or technology that is used to determine the order of the four bases: adenine , guanine , cytosine , and thymine . The advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. Knowledge of DNA sequences has become indispensable for basic biological research, DNA Genographic Projects and in numerous applied fields such as medical diagnosis , biotechnology , forensic biology , virology and biological systematics . Comparing healthy and mutated DNA sequences can diagnose different diseases including various cancers, characterize antibody repertoire, and can be used to guide patient treatment. Having
9648-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
9782-646: The ABI 370, in 1987 and by Dupont's Genesis 2000 which used a novel fluorescent labeling technique enabling all four dideoxynucleotides to be identified in a single lane. By 1990, the U.S. National Institutes of Health (NIH) had begun large-scale sequencing trials on Mycoplasma capricolum , Escherichia coli , Caenorhabditis elegans , and Saccharomyces cerevisiae at a cost of US$ 0.75 per base. Meanwhile, sequencing of human cDNA sequences called expressed sequence tags began in Craig Venter 's lab, an attempt to capture
9916-618: The NGS field have been attempted to address these challenges, most of which have been small-scale efforts arising from individual labs. Most recently, a large, organized, FDA-funded effort has culminated in the BioCompute standard. On 26 October 1990, Roger Tsien , Pepi Ross, Margaret Fahnestock and Allan J Johnston filed a patent describing stepwise ("base-by-base") sequencing with removable 3' blockers on DNA arrays (blots and single DNA molecules). In 1996, Pål Nyrén and his student Mostafa Ronaghi at
10050-622: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
10184-652: The Pyrenees, Alps, and Carpathians. The huge number of bones found in southern, central and eastern Europe has led some scientists to think Europe may have once had herds of cave bears. Others, however, point out that, though some caves have thousands of bones, they were accumulated over a period of 100,000 years or more, thus requiring only two deaths in a cave per year to account for the large numbers. The cave bear inhabited low mountainous areas, especially in regions rich in limestone caves. They seem to have avoided open plains, preferring forested or forest-edged terrains. Between
10318-631: The Royal Institute of Technology in Stockholm published their method of pyrosequencing . On 1 April 1997, Pascal Mayer and Laurent Farinelli submitted patents to the World Intellectual Property Organization describing DNA colony sequencing. The DNA sample preparation and random surface- polymerase chain reaction (PCR) arraying methods described in this patent, coupled to Roger Tsien et al.'s "base-by-base" sequencing method,
10452-491: The Sanger methods had been made. Maxam-Gilbert sequencing requires radioactive labeling at one 5' end of the DNA and purification of the DNA fragment to be sequenced. Chemical treatment then generates breaks at a small proportion of one or two of the four nucleotide bases in each of four reactions (G, A+G, C, C+T). The concentration of the modifying chemicals is controlled to introduce on average one modification per DNA molecule. Thus
10586-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
10720-473: The advent of the glaciers. Populations living south of the Alps possibly survived significantly longer. Species A species ( pl. : species) is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as
10854-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
10988-440: The basis of tooth morphology. Results obtained on the stable isotopes of cave bear bones also point to a largely vegetarian diet in having low levels of nitrogen-15 and carbon-13 , which are accumulated at a faster rate by carnivores as opposed to herbivores. However, some evidence points toward the occasional inclusion of animal protein in cave bear diets. For example, toothmarks on cave bear remains in areas where cave bears are
11122-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
11256-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
11390-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
11524-475: The breeding season. Cave bear longevity is unknown, though it has been estimated that they seldom exceeded twenty years of age. Paleontologists doubt adult cave bears had any natural predators, save for pack-hunting wolves and cave hyenas , which would probably have attacked sick or infirm individuals. Cave hyenas are thought to be responsible for the disarticulation and destruction of some cave bear skeletons. Such large carcasses were an optimal food resource for
11658-486: The cave bear population drastically declined starting around 40,000 years ago at the onset of the Aurignacian , coinciding with the arrival of anatomically modern humans. It was concluded that human hunting and/or competition played a major role in their decline and ultimate disappearance, and that climate change was not likely to have been the dominant factor. In a study of Spanish cave bear mtDNA, each cave used by cave bears
11792-476: The cave bear was probably Ursus deningeri (Deninger's bear), a species restricted to Pleistocene Europe about 1.8 Mya to 100,000 years ago. The transition between Deninger's bear and the cave bear is given as the last interglacial, although the boundary between these forms is arbitrary, and intermediate or transitional taxa have been proposed, e.g. Ursus spelaeus deningeroides , while other authorities consider both taxa to be chronological variants of
11926-507: The cave bear's survival. However, the two species may have competed for living space in caves. The Chauvet Cave contains around 300 "bear hollows" created by cave bear hibernation. Unlike brown bears, cave bears are seldom represented in cave paintings, leading some experts to believe the cave bear may have been avoided by human hunters or their habitat preferences may not have overlapped. Paleontologist Björn Kurtén hypothesized cave bear populations were fragmented and under stress even before
12060-418: The coding fraction of the human genome . In 1995, Venter, Hamilton Smith , and colleagues at The Institute for Genomic Research (TIGR) published the first complete genome of a free-living organism, the bacterium Haemophilus influenzae . The circular chromosome contains 1,830,137 bases and its publication in the journal Science marked the first published use of whole-genome shotgun sequencing, eliminating
12194-406: The computational analysis of NGS data, often compiled at online platforms such as CSI NGS Portal, each with its own algorithm. Even the parameters within one software package can change the outcome of the analysis. In addition, the large quantities of data produced by DNA sequencing have also required development of new methods and programs for sequence analysis. Several efforts to develop standards in
12328-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
12462-458: The concurrent development of recombinant DNA technology, allowing DNA samples to be isolated from sources other than viruses. The first full DNA genome to be sequenced was that of bacteriophage φX174 in 1977. Medical Research Council scientists deciphered the complete DNA sequence of the Epstein-Barr virus in 1984, finding it contained 172,282 nucleotides. Completion of the sequence marked
12596-499: The current prevailing opinion concludes that cave bears were largely herbivorous, and more so than any modern species of the genus Ursus , increasing evidence points to omnivorous diets, based both on regional variability of isotopic composition of bone remains indicative of dietary plasticity, and on a recent re-evaluation of craniodental morphology that places the cave bear squarely among omnivorous modern bear species with respect to its skull and tooth shapes. Death during hibernation
12730-593: The days and weeks leading up to hibernation. Additionally, cave bear remains from Peștera cu Oase in the southwestern tip of the Romanian part of the Carpathian Mountains had elevated levels of nitrogen-15 in their bones, indicative of omnivorous diets, although the values are within the range of those found for the strictly herbivorous mammoth . One isotopic study concluded that cave bears displayed omnivorous habits similar to those of modern brown bears. Although
12864-569: The development of new forensic techniques, such as DNA phenotyping , which allows investigators to predict an individual's physical characteristics based on their genetic data. In addition to its applications in forensic science, DNA sequencing has also been used in medical research and diagnosis. It has enabled scientists to identify genetic mutations and variations that are associated with certain diseases and disorders, allowing for more accurate diagnoses and targeted treatments. Moreover, DNA sequencing has also been used in conservation biology to study
12998-437: The earlier methods, including Sanger sequencing . In contrast to the first generation of sequencing, NGS technology is typically characterized by being highly scalable, allowing the entire genome to be sequenced at once. Usually, this is accomplished by fragmenting the genome into small pieces, randomly sampling for a fragment, and sequencing it using one of a variety of technologies, such as those described below. An entire genome
13132-478: The early 1970s by academic researchers using laborious methods based on two-dimensional chromatography . Following the development of fluorescence -based sequencing methods with a DNA sequencer , DNA sequencing has become easier and orders of magnitude faster. DNA sequencing may be used to determine the sequence of individual genes , larger genetic regions (i.e. clusters of genes or operons ), full chromosomes, or entire genomes of any organism. DNA sequencing
13266-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
13400-400: The genetic diversity of endangered species and develop strategies for their conservation. Furthermore, the use of DNA sequencing has also raised important ethical and legal considerations. For example, there are concerns about the privacy and security of genetic data, as well as the potential for misuse or discrimination based on genetic information. As a result, there are ongoing debates about
13534-481: The hyenas, especially at the end of the winter, when food was scarce. The presence of fully articulated adult cave lion skeletons, deep in cave bear dens, indicates the lions may have occasionally entered dens to prey on hibernating cave bears, with some dying in the attempt. The cave bear's range stretched across Europe; from Spain and the British Isles in the west, Belgium, Italy , parts of Germany , Poland ,
13668-484: The last few decades to ultimately link a DNA print to what is under investigation. The DNA patterns in fingerprint, saliva, hair follicles, etc. uniquely separate each living organism from another. Testing DNA is a technique which can detect specific genomes in a DNA strand to produce a unique and individualized pattern. DNA sequencing may be used along with DNA profiling methods for forensic identification and paternity testing , as it has evolved significantly over
13802-529: The last molar is very elongated, with supplementary cusps. The humerus of the cave bear was similar in size to that of the polar bear , as were the femora of females. The femora of male cave bears, however, bore more similarities in size to those of Kodiak bears . Cave bear teeth were very large and show greater wear than most modern bear species, suggesting a diet of tough materials. However, tubers and other gritty food, which cause distinctive tooth wear in modern brown bears, do not appear to have constituted
13936-438: The model, DNA is composed of two strands of nucleotides coiled around each other, linked together by hydrogen bonds and running in opposite directions. Each strand is composed of four complementary nucleotides – adenine (A), cytosine (C), guanine (G) and thymine (T) – with an A on one strand always paired with T on the other, and C always paired with G. They proposed that such a structure allowed each strand to be used to reconstruct
14070-461: The most popular approach for generating viral genomes. During the 1997 avian influenza outbreak , viral sequencing determined that the influenza sub-type originated through reassortment between quail and poultry. This led to legislation in Hong Kong that prohibited selling live quail and poultry together at market. Viral sequencing can also be used to estimate when a viral outbreak began by using
14204-414: The need for initial mapping efforts. By 2001, shotgun sequencing methods had been used to produce a draft sequence of the human genome. Several new methods for DNA sequencing were developed in the mid to late 1990s and were implemented in commercial DNA sequencers by 2000. Together these were called the "next-generation" or "second-generation" sequencing (NGS) methods, in order to distinguish them from
14338-438: The need for regulations and guidelines to ensure the responsible use of DNA sequencing technology. Overall, the development of DNA sequencing technology has revolutionized the field of forensic science and has far-reaching implications for our understanding of genetics, medicine, and conservation biology. The canonical structure of DNA has four bases: thymine (T), adenine (A), cytosine (C), and guanine (G). DNA sequencing
14472-478: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
14606-439: The only recorded potential carnivores suggests occasional cannibalistic scavenging, possibly on individuals that died during hibernation, and dental microwear analysis indicates the cave bear may have fed on a greater quantity of bone than its contemporary, the smaller Eurasian brown bear. The dental microwear patterns of cave bear molars from the northeastern Iberian Peninsula show that cave bears may have consumed more meat in
14740-427: The other, an idea central to the passing on of hereditary information between generations. The foundation for sequencing proteins was first laid by the work of Frederick Sanger who by 1955 had completed the sequence of all the amino acids in insulin , a small protein secreted by the pancreas. This provided the first conclusive evidence that proteins were chemical entities with a specific molecular pattern rather than
14874-585: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
15008-974: The past few decades to ultimately link a DNA print to what is under investigation. The DNA patterns in fingerprint, saliva, hair follicles, and other bodily fluids uniquely separate each living organism from another, making it an invaluable tool in the field of forensic science . The process of DNA testing involves detecting specific genomes in a DNA strand to produce a unique and individualized pattern, which can be used to identify individuals or determine their relationships. The advancements in DNA sequencing technology have made it possible to analyze and compare large amounts of genetic data quickly and accurately, allowing investigators to gather evidence and solve crimes more efficiently. This technology has been used in various applications, including forensic identification, paternity testing, and human identification in cases where traditional identification methods are unavailable or unreliable. The use of DNA sequencing has also led to
15142-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
15276-411: The present time, the presence of such damaged bases is not detected by most DNA sequencing methods, although PacBio has published on this. Deoxyribonucleic acid ( DNA ) was first discovered and isolated by Friedrich Miescher in 1869, but it remained under-studied for many decades because proteins, rather than DNA, were thought to hold the genetic blueprint to life. This situation changed after 1944 as
15410-672: The regulation of gene expression. The first method for determining DNA sequences involved a location-specific primer extension strategy established by Ray Wu at Cornell University in 1970. DNA polymerase catalysis and specific nucleotide labeling, both of which figure prominently in current sequencing schemes, were used to sequence the cohesive ends of lambda phage DNA. Between 1970 and 1973, Wu, R Padmanabhan and colleagues demonstrated that this method can be employed to determine any DNA sequence using synthetic location-specific primers. Frederick Sanger then adopted this primer-extension strategy to develop more rapid DNA sequencing methods at
15544-733: The research study, published in the journal Molecular Biology and Evolution , radiocarbon dating of the fossil remains shows that the cave bear ceased to be abundant in Central Europe around 35,000 years ago. In addition to environmental change, human hunting has also been implicated in the ultimate extinction of the cave bear. In 2019, the results of a large scale study of 81 bone specimens (resulting in 59 new sequences) and 64 previously published complete mitochondrial genomes of cave bear mitochondrial DNA remains found in Switzerland, Poland, France, Spain, Germany, Italy and Serbia, indicated that
15678-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
15812-573: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
15946-489: The same species. Cave bears found anywhere will vary in age, thus facilitating investigations into evolutionary trends. The three anterior premolars were gradually reduced, then disappeared, possibly in response to a largely vegetarian diet. In a fourth of the skulls found in the Conturines , the third premolar is still present, while more derived specimens elsewhere lack it. The last remaining premolar became conjugated with
16080-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
16214-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
16348-400: The sequence of amino acids in proteins, which in turn helped determine the function of a protein. He published this theory in 1958. RNA sequencing was one of the earliest forms of nucleotide sequencing. The major landmark of RNA sequencing is the sequence of the first complete gene and the complete genome of Bacteriophage MS2 , identified and published by Walter Fiers and his coworkers at
16482-502: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
16616-519: The species its binomial name. The bones were so numerous that most researchers had little regard for them. During World War I , with the scarcity of phosphate dung, earth from the caves where cave bear bones occurred was used as a source of phosphates. When the "dragon caves" in Austria ’s Styria region were exploited for this purpose, only the skulls and leg bones were kept. Many caves in Central Europe have skeletons of cave bears inside, such as
16750-399: The true molars , enlarging the crown and granting it more cusps and cutting borders. This phenomenon, called molarization , improved the mastication capacities of the molars, facilitating the processing of tough vegetation. This allowed the cave bear to gain more energy for hibernation, while eating less than its ancestors. In 2005, scientists recovered and sequenced the nuclear DNA of
16884-537: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
17018-474: The years 1917 and 1923, the Drachenloch cave in Switzerland was excavated by Emil Bächler. The excavation uncovered more than 30,000 cave bear skeletons. It also uncovered a stone chest or cist , consisting of a low wall built from limestone slabs near a cave wall with a number of bear skulls inside it. A cave bear skull was also found with a femur bone from another bear stuck inside it. Scholars speculated that it
17152-467: Was 350 to 600 kg (770 to 1,320 lb), while females weighed 225 to 250 kg (495 to 550 lb). Of cave bear skeletons in museums, 90% are classified as male due to a misconception that the female skeletons were merely "dwarfs". Cave bears grew larger during glaciations and smaller during interglacials, probably to adjust heat loss rate. Cave bears of the last Ice Age lacked the usual two or three premolars present in other bears; to compensate,
17286-554: Was a common end for cave bears, mainly befalling specimens that failed ecologically during the summer season through inexperience, sickness or old age. Some cave bear bones show signs of numerous ailments, including spinal fusion , bone tumours , cavities , tooth resorption , necrosis (particularly in younger specimens), osteomyelitis , periostitis , rickets and kidney stones . There is also evidence that cave bears suffered from tuberculosis. Male cave bear skeletons have been found with broken bacula , probably due to fighting during
17420-408: Was found to contain almost exclusively a unique lineage of closely related haplotypes, indicating a homing behaviour for birthing and hibernation. The conclusion of this study is cave bears could not easily colonize new sites when in competition with humans for these resources. Overhunting by humans has been dismissed by some as human populations at the time were too small to pose a serious threat to
17554-510: Was intensively used in the framework of the EU genome-sequencing programme, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II. Leroy E. Hood 's laboratory at the California Institute of Technology announced the first semi-automated DNA sequencing machine in 1986. This was followed by Applied Biosystems ' marketing of the first fully automated sequencing machine,
17688-503: Was likely to have had some sort of ritual purpose. Reassessment of fossils in 2019 indicate that the cave bear probably died out 24,000 years ago. A complex set of factors, rather than a single factor, are suggested to have led to the extinction. Compared with other megafaunal species that also became extinct during the Last Glacial Maximum, the cave bear was believed to have had a more specialized diet of high-quality plants and
17822-421: Was not responsible. Finally, high δN levels were found in cave bear bones from Romania , indicating wider dietary possibilities than previously believed. Some evidence indicates that the cave bear used only caves for hibernation and was not inclined to use other locations, such as thickets , for this purpose, in contrast to the more versatile brown bear . This specialized hibernation behavior would have caused
17956-465: Was proof of prehistoric human religious rites involving the cave bear, or that the Drachenloch cave bears were hunted as part of a hunting ritual, or that the skulls were kept as trophies. In Archaeology, Religion, Ritual (2004), archaeologist Timothy Insoll strongly questions whether the Drachenloch finds in the stone cist were the result of human interaction. Insoll states that the evidence for religious practices involving cave bears in this time period
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