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Results for “historical contingency”

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At least 19 recordsLinked to original sources
PubMed2000

Historical contingency and ecological determinism interact to prime speciation in sticklebacks, Gasterosteus.

Historical contingency and determinism are often cast as opposing paradigms under which evolutionary diversification operates. It may be, however, that both factors act together to promote evolutionary divergence, although there are few examples of such interaction in nature. We tested phylogenetic predictions of an explicit historical model of divergence (double invasions of freshwater by marine ancestors) in sympatric species of three-spined sticklebacks (Gasterosteus aculeatus) where determinism has been implicated as an important factor driving evolutionary novelty. Microsatellite DNA variation at six loci revealed relatively low genetic variation in freshwater populations, supporting the hypothesis that they were derived by colonization of freshwater by more diverse marine ancestors. Phylogenetic and genetic distance analyses suggested that pairs of sympatric species have evolved multiple times, further implicating determinism as a factor in speciation. Our data also supported predictions based on the hypothesis that the evolution of sympatric species was contingent upon 'double invasions' of postglacial lakes by ancestral marine sticklebacks. Sympatric sticklebacks, therefore, provide an example of adaptive radiation by determinism contingent upon historical conditions promoting unique ecological interactions, and illustrate how contingency and determinism may interact to generate geographical variation in species diversity

Alleles↗
PubMed2000

The historical contingency of bioethics.

The principles of bioethics have been historically contingent, a product of social values, circumstances, and experience. During the early twentieth century, they rested on a doctor-knows-best autonomy that permitted physicians to perform research on human subjects with a minimum degree, if any, of informed consent. The eugenics movement of the period embraced an implicit bioethics by presuming to sterilize individuals for the sake of a larger social benefit, a practice and doctrine that helped lead to the Nazi medical experiments and death camps. After World War II, the promulgation of the Nuremberg Code failed to halt eugenic sterilization and risky human experimentation without informed consent either in civilian or military venues. However, beginning in the 1960s, these practices came under mounting critical scrutiny, partly because of the increasing attention given to individual rights. By now, it is widely understood that concern for individual rights rather than an appeal to some national good belongs at the heart of bioethics.

Bioethical Issues↗
PubMed2003

Historical contingency in the evolution of primate color vision.

Primates are unique among eutherian mammals for possessing three types of retinal cone. Curiously, catarrhines, platyrrhines, and strepsirhines share this anatomy to different extents, and no hypothesis has hitherto accounted for this variability. Here we propose that the historical biogeography of figs and arborescent palms accounts for the global variation in primate color vision. Specifically, we suggest that primates invaded Paleogene forests characterized by figs and palms, the fruits of which played a keystone function. Primates not only relied on such resources, but also provided high-quality seed dispersal. In turn, figs and palms lost or simply did not evolve conspicuous coloration, as this conferred little advantage for attracting mammals. We suggest that the abundance and coloration of figs and palms offered a selective advantage to foraging groups with mixed capabilities for chromatic distinction. Climatic cooling at the end of the Eocene and into the Neogene resulted in widespread regional extinction or decimation of palms and (probably) figs. In regions where figs and palms became scarce, we suggest primates evolved routine trichromatic vision in order to exploit proteinaceous young leaves as a replacement resource. A survey of the hue and biogeography of extant figs and palms provides some empirical support. Where these resources are infrequent, primates are routinely trichromatic and consume young leaves during seasonal periods of fruit dearth. These results imply a link between the differential evolution of primate color vision and climatic changes during the Eocene-Oligocene transition.

Animals↗
PubMed1991

Historical contingencies in the evolution of human behavior and psychopathology.

Psychopathology may be understood as a product of evolution. Uniquely human capacities, such as human language and creative thinking, evolved out of a matrix of other capacities, including ancestral forms of learning. Applying evolutionary theory to the human nervous system, one might expect to find preexisting forms of learning in some form of coexistence with the recent evolutionary development of human symbolic functioning. A theory is presented in this paper which lays the groundwork for the claim that psychopathology may be understood as the product of interactions between adaptive schemes of different evolutionary origins. While earlier notions about evolution have been used to explain psychopathology (Freud 1913), this paper constitutes a reapplication of evolutionary theory to the problem of psychopathology from a modern perspective.

Adaptation, Psychological↗
PubMed1995

Importance of historical contingency in the stereochemistry of hydratase-dehydratase enzymes.

There are two stereochemical classes of hydratase-dehydratase enzymes. Those that catalyze the addition of water to alpha, beta-unsaturated thioesters give syn addition-elimination stereochemistry, whereas those that catalyze the addition of water to conjugated carboxylate substrates give anti stereochemistry. This dichotomy could reflect different adaptive advantages or contingencies of separate evolutionary histories. Determination of the nonenzymatic stereochemistry of deuterium oxide addition to fumarate and to S-crotonyl N-acetylcysteamine has provided direct evidence for the importance of the contingencies of evolutionary history, rather than chemical efficiency, in the pathways of these hydratase-dehydratase enzymes.

Biological Evolution↗
PubMed2026

Historical metabolic adaptation potentiates the rapid evolution of flonicamid resistance in Myzus persicae.

Rapid adaptation to novel environments is often shaped not only by newly acquired mutations but also by historical genetic backgrounds established through prior evolutionary events. However, the extent to which such historical contingency contributes to the rapid evolution of insecticide resistance remains poorly understood. Here, we investigated the emergence of resistance to flonicamid, a recently deployed insecticide, in the green peach aphid, Myzus persicae. We show that constitutive overexpression of the P450 enzymes CYP6CY3 and CYP6CY4, already widespread in populations of M. persicae before flonicamid deployment, confers a previously cryptic tolerance phenotype to flonicamid. However, biochemical and transgenic analyses demonstrated that these metabolic adaptations provide only weak protection against flonicamid. Following flonicamid deployment, however, a novel target-site mutation, NaamV251I, in the recently identified molecular target of 4-trifluoromethylnicotinamide (TFNA-AM), emerged in M. persicae on a genetic background of CYP6CY3 or CYP6CY4 overexpression. Structural modeling, enzymatic assays, and CRISPR-Cas9 genome editing demonstrated that this mutation reduces target sensitivity and independently confers moderate resistance. Strikingly, combining the nicotinamidase (Naam) mutation with pre-existing CYP6CY3 or CYP6CY4 overexpression produced substantially elevated resistance phenotypes that far exceeded the effects of either mechanism alone. Our results demonstrate that the pre-existing metabolic background did not itself evolve further following flonicamid deployment but fundamentally altered the phenotypic consequences of a subsequently acquired target-site mutation. These findings provide direct evidence that historical adaptive variation can potentiate rapid resistance evolution to newly introduced insecticides and reveal how interactions between past and contemporary adaptations shape evolutionary responses to novel environmental challenges.

Animals↗
PubMed1996

Anthropology, clinical pathology and the electronic fetal monitor: lessons from the heart.

Clinical pathology, the social process of applying disease categories and managing disease processes, is defined and its anthropological study described using examples from a study of Electronic Fetal Monitor (EFM) use during hospital obstetrical care in a rural Canadian village. Anthropological work on clinical pathology is shown to have helped doctors and nurses in this village to better understand both the cultural contingencies of their basic science knowledge and the historical contingencies of its application to the care of women during pregnancy and birth. It is argued that cultural anthropologists should study diagnostic and treatment activities, especially those involving sophisticated technology; their methods and theories make them ideally suited to this task.

Anthropology, Cultural↗
PubMed1995

Complexity, contingency, and criticality.

Complexity originates from the tendency of large dynamical systems to organize themselves into a critical state, with avalanches or "punctuations" of all sizes. In the critical state, events which would otherwise be uncoupled become correlated. The apparent, historical contingency in many sciences, including geology, biology, and economics, finds a natural interpretation as a self-organized critical phenomenon. These ideas are discussed in the context of simple mathematical models of sandpiles and biological evolution. Insights are gained not only from numerical simulations but also from rigorous mathematical analysis.

Journal Article↗
PubMed1998

The changing moral landscape of human reproduction: two moments in the history of in vitro fertilization.

Ethical attitudes toward in vitro fertilization (IVF) have varied historically. This paper discusses the changes in views about the morality of human IVF by exploring the response to a pair of critical moments in the history of this reproductive technology: the announcement of the first successful IVF experiment by John Rock and Miriam Menkin in 1944 and the first successful IVF live birth of Louise Brown in 1978. By exploring public and private reactions to these two events in the context of wider social and political developments, this paper demonstrates the degree to which our notions of the morality of medical experimentation and of reproductive technologies are socially constructed and historically contingent.

England↗
PubMed2003

The development of the intramural research program at the National Institutes of Health after World War II.

This paper explores the rise of the National Institutes of Health after World War II from the perspective of intramural scientists working at the NIH's main campus in Bethesda. Several postwar social circumstances-the local research tradition, the wartime experience of civilian scientists, the doctor draft, and anti-nepotism rules in academia-affected the recruitment of research-oriented scientists into the NIH. These historically contingent factors were no less important than the larger political, legislative context for the development of the NIH intramural program as a prominent research institution.

Biomedical Research↗
PubMed1998

Contingency and determinism in replicated adaptive radiations of island lizards

The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.

Journal Article↗
PubMed1995

Who wrote the book of life? Information and the transformation of molecular biology, 1945-55.

This paper focuses on the opening of a discursive space: the emergence of informational and scriptural representations of life and hereditiy and their self-negating consequences for the construction of biological meaning. It probes the notion of writing and the book of life and shows how molecular biology's claims to a status of language and texuality undermines its own objective of control. These textual significations were historically contingent. The informational representations of heredity and life were not an outcome of the internal cognitive momentum of molecular biology; they were not a logical necessity of the unravelling of the base-pairing of the DNA double-helix. They were transported into molecular biology still within the protein paradigm of the gene in the 1940s and permeated nearly every discipline in the life and social sciences. These information-based models, metaphors, linguistic, and semiotic tools which were central to the formulation of the genetic code were transported into molecular biology from cybernetics, information theory, electronic computing, and control and communication systems--technosciences that were deeply embedded with the military experiences of World War II and the Cold War. The information discourse thus became fixed in molecular biology not because it worked in the narrow epistemic sense (it did not), but because it positioned molecular biology within postwar discourse and culture, perhaps within the transition to a post-modern information-based society.

History, 20th Century↗
PubMed2001

Stem cell grafting for epilepsy: clinical promise and ethical concerns.

The recent explosion of research on stem cells and neural grafting holds great promise for many neurological conditions, including epilepsy. Potential roles for cell grafting in epilepsy include remodeling of dysfunctional neuronal circuits and local delivery of neuromodulatory or neuroprotective factors. While many basic questions remain to be answered, initial human trials are underway in epilepsy as well as Parkinson's disease, Alzheimer's disease, stroke, and other conditions. It is not too early to begin ethical reflection on this dynamic field. Donor cells are often derived from human embryos, raising scarcity concerns as well as opposition from anti-abortion forces. Alternative donor sources are being actively developed. Safety concerns, adequate consent, and equitable access to care will also become important issues. Ethical issues most unique to neural grafting will revolve around redefining self-identity when personality and cognition may be altered by therapy. Views of selfhood and of being human have evolved in a historically contingent process, so that neural grafting and other consequences of the genetic revolution fall within a series of reductionist scientific developments that lead to an increasing instrumentation of our self-image. Neuroscientists and clinicians must interact with other cultural, religious, and academic groups to promote mutual understanding and richer, but scientifically accurate, views of what it means to be human. A good starting point may come by telling patients' stories, connecting scientific knowledge with the density of lived experience.

Journal Article↗
PubMed2003

Post-diagnostic abortion in Germany: reproduction gone awry, again?

Routine use of prenatal diagnostic technologies (PDTs) such as ultrasound and amniocentesis result in the detection of a small percentage of fetal anomalies. For those women faced with the diagnosis of fetal disability, a decision must be made to continue or terminate the pregnancy. When the diagnosis is merely hypothetical, the discursive specter of post-diagnostic abortion is shaped by social and historical contexts in which interested discourses (regional, political, ethical, and religious) weigh in with varying degrees of authority and influence. However, when the diagnosis is actual, in this sample population of women, an estimated minimum of 90% opt to terminate their pregnancies. Data collected at two German hospitals-one in former East Germany, one in former West Germany-illuminate rates of PDT use and provide data with which to discuss the specter of post-diagnostic abortion in relation to mainstream medical discourses, Germany's divided history, abortion politics, feminism, disability activism, and religion. These data demonstrate how reproductive discourses are shaped by ideological and historical contingencies, even when women's ultimate reproductive decisions are not.

Abortion, Eugenic↗
PubMed2000

Evolution: to seek out new worlds.

A recent study of stickleback 'ecomorphs' generated by independent speciation events in different freshwater lakes suggests that, despite historical contingency, natural selection can run in surprisingly similar ways on multiple occasions.

Animals↗
PubMed2001

How evolutionary history shapes recognition mechanisms.

Evolutionary psychologists have emphasized the importance of natural selection in shaping cognitive functions, but historical contingency has not received direct study. This is crucial because in response to selection, complex traits tend to be fine-tuned or jury-rigged rather than totally reconstructed. We hypothesize that the neural and cognitive strategies an animal employs in signal recognition are influenced by the strategies used by its ancestors. The responses of female túngara frogs to ancestral calls and to calls of other closely related species are influenced by history. By training artificial neural networks with a series of calls that mimic the species' past history of call evolution or various control histories, we have shown that only networks that evolved through the mimetic history predict the response biases of túngara frogs.

Journal Article↗
PubMed2000

Large-scale processes and the Asian bias in species diversity of temperate plants.

An important issue in the study of biodiversity is the extent to which global patterns of species richness reflect large-scale processes and historical contingencies. Ecological interactions in local assemblages may constrain the number of species that can coexist, but differences in diversity in similar habitats within different regions (diversity anomalies) suggest that this limit is not firm. Variation in rate of species production could influence regional and perhaps local diversity independently of the ecological capacity of an area to support coexisting species, thereby creating diversity anomalies. Temperate Zone genera of plants that are disjunct between similar environments in eastern Asia and eastern North America (EAS-ENA) have twice as many species in Asia as in North America. Because lineages of these genera in Asia and North America are mostly sister pairs, they share a common history of adaptation and ecological relationship before disjunction. Thus, the diversity anomaly in EAS-ENA genera is not an artefact of taxon or habitat sampling but reflects differences in the net diversification (speciation-extinction) of the lineages in each of the continents. Here we propose that the most probable cause of the EAS-ENA anomaly in diversity is the extreme physiographical heterogeneity of temperate eastern Asia, especially compared with eastern North America, which in conjunction with climate and sea-level change has provided abundant opportunities for evolutionary radiation through allopatric speciation.

Asia↗
PubMed2002

Genome-wide deleterious mutation favors dispersal and species integrity.

Here I develop the idea that ubiquitous harmful genome-wide mutation with local differentiation favors dispersal, even though migration reduces average fitness. Historical contingency of the mutational process means that demes (sub-populations) differentiate from one another. Deleterious or lethal partially recessive mutations carried by migrants then do not encounter similar mutations in the recipient deme. Migrant offspring have higher fitness than offspring of residents, because migrant offspring are heterozygous rather than homozygous for harmful mutations. The advantage is inversely related to local inbreeding depression. Genome-wide deleterious mutation favors the evolution of dispersal, which in turn enhances the genetic integrity of the species.

Animals↗