We challenge the view that our species, Homo sapiens, evolved within a single population and/or region of Africa. The chronology and physical diversity of Pleistocene human fossils suggest that ...morphologically varied populations pertaining to the H. sapiens clade lived throughout Africa. Similarly, the African archaeological record demonstrates the polycentric origin and persistence of regionally distinct Pleistocene material culture in a variety of paleoecological settings. Genetic studies also indicate that present-day population structure within Africa extends to deep times, paralleling a paleoenvironmental record of shifting and fractured habitable zones. We argue that these fields support an emerging view of a highly structured African prehistory that should be considered in human evolutionary inferences, prompting new interpretations, questions, and interdisciplinary research directions.
The view that Homo sapiens evolved from a single region/population within Africa has been given primacy in studies of human evolution.
However, developments across multiple fields show that relevant data are no longer consistent with this view.
We argue instead that Homo sapiens evolved within a set of interlinked groups living across Africa, whose connectivity changed through time.
Genetic models therefore need to incorporate a more complex view of ancient migration and divergence in Africa.
We summarize this new framework emphasizing population structure, outline how this changes our understanding of human evolution, and identify new research directions.
Dopamine is involved in physiological processes like learning and memory, motor control and reward, and pathological conditions such as Parkinson’s disease and addiction. In contrast to the extensive ...studies on neurons, astrocyte involvement in dopaminergic signaling remains largely unknown. Using transgenic mice, optogenetics, and pharmacogenetics, we studied the role of astrocytes on the dopaminergic system. We show that in freely behaving mice, astrocytes in the nucleus accumbens (NAc), a key reward center in the brain, respond with Ca2+ elevations to synaptically released dopamine, a phenomenon enhanced by amphetamine. In brain slices, synaptically released dopamine increases astrocyte Ca2+, stimulates ATP/adenosine release, and depresses excitatory synaptic transmission through activation of presynaptic A1 receptors. Amphetamine depresses neurotransmission through stimulation of astrocytes and the consequent A1 receptor activation. Furthermore, astrocytes modulate the acute behavioral psychomotor effects of amphetamine. Therefore, astrocytes mediate the dopamine- and amphetamine-induced synaptic regulation, revealing a novel cellular pathway in the brain reward system.
•Astrocytes in the Nucleus Accumbens respond to synaptic dopamine in vivo•Astrocytes mediate the synaptic regulation induced by dopamine and amphetamine•Amphetamine-induced enhancement in locomotion activity is modulated by astrocytes
Corkrum et al. report that astrocyte activity is required for dopamine- and amphetamine-evoked synaptic regulation and amphetamine-induced locomotor effects. Their study reveals astrocytes as active components of dopaminergic signaling and the brain reward system.
An adaptive variant of the human Ectodysplasin receptor, EDARV370A, is one of the strongest candidates of recent positive selection from genome-wide scans. We have modeled EDAR370A in mice and ...characterized its phenotype and evolutionary origins in humans. Our computational analysis suggests the allele arose in central China approximately 30,000 years ago. Although EDAR370A has been associated with increased scalp hair thickness and changed tooth morphology in humans, its direct biological significance and potential adaptive role remain unclear. We generated a knockin mouse model and find that, as in humans, hair thickness is increased in EDAR370A mice. We identify new biological targets affected by the mutation, including mammary and eccrine glands. Building on these results, we find that EDAR370A is associated with an increased number of active eccrine glands in the Han Chinese. This interdisciplinary approach yields unique insight into the generation of adaptive variation among modern humans.
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► Selected East Asian EDAR allele, 370A, emerged in central China ∼30,000 years ago ► Hair, sweat, and mammary glands are altered in a 370A knockin mouse model ► The novel effect of 370A on mouse sweat gland density is recapitulated in humans
Engineering mice to express an allele of the human Ectodysplasin receptor, which originated in China approximately 30,000 years ago, alters hair thickness and mammary and sweat gland morphology, modeling effects that are also observed in human populations.
This article will debate the usefulness of POCT measurements and the contribution microdialysis can make to generating valuable information. A particular theme will be the rarely considered ...difference between ex vivo sampling, which typically generates only a static measure of concentration, and in vivo measurements that are subject to dynamic changes due to mass transfer. Those dynamic changes provide information about the patients’ physiological state.
It is difficult to overstate the cultural and biological impacts that the domestication of plants and animals has had on our species. Fundamental questions regarding where, when, and how many times ...domestication took place have been of primary interest within a wide range of academic disciplines. Within the last two decades, the advent of new archaeological and genetic techniques has revolutionized our understanding of the pattern and process of domestication and agricultural origins that led to our modern way of life. In the spring of 2011, 25 scholars with a central interest in domestication representing the fields of genetics, archaeobotany, zooarchaeology, geoarchaeology, and archaeology met at the National Evolutionary Synthesis Center to discuss recent domestication research progress and identify challenges for the future. In this introduction to the resulting Special Feature, we present the state of the art in the field by discussing what is known about the spatial and temporal patterns of domestication, and controversies surrounding the speed, intentionality, and evolutionary aspects of the domestication process. We then highlight three key challenges for future research. We conclude by arguing that although recent progress has been impressive, the next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not.
Following its initial arrival in SE Europe 8,500 years ago agriculture spread throughout the continent, changing food production and consumption patterns and increasing population densities. Here we ...show that, in contrast to the steady population growth usually assumed, the introduction of agriculture into Europe was followed by a boom-and-bust pattern in the density of regional populations. We demonstrate that summed calibrated radiocarbon date distributions and simulation can be used to test the significance of these demographic booms and busts in the context of uncertainty in the radiocarbon date calibration curve and archaeological sampling. We report these results for Central and Northwest Europe between 8,000 and 4,000 cal. BP and investigate the relationship between these patterns and climate. However, we find no evidence to support a relationship. Our results thus suggest that the demographic patterns may have arisen from endogenous causes, although this remains speculative.
The driving force behind the transition from a foraging to a farming lifestyle in prehistoric Europe (Neolithization) has been debated for more than a century 1–3. Of particular interest is whether ...population replacement or cultural exchange was responsible 3–5. Scandinavia holds a unique place in this debate, for it maintained one of the last major hunter-gatherer complexes in Neolithic Europe, the Pitted Ware culture 6. Intriguingly, these late hunter-gatherers existed in parallel to early farmers for more than a millennium before they vanished some 4,000 years ago 7, 8. The prolonged coexistence of the two cultures in Scandinavia has been cited as an argument against population replacement between the Mesolithic and the present 7, 8. Through analysis of DNA extracted from ancient Scandinavian human remains, we show that people of the Pitted Ware culture were not the direct ancestors of modern Scandinavians (including the Saami people of northern Scandinavia) but are more closely related to contemporary populations of the eastern Baltic region. Our findings support hypotheses arising from archaeological analyses that propose a Neolithic or post-Neolithic population replacement in Scandinavia 7. Furthermore, our data are consistent with the view that the eastern Baltic represents a genetic refugia for some of the European hunter-gatherer populations.
Meningitis in adults: diagnosis and management Young, Nicholas; Thomas, Mark
Internal medicine journal,
November 2018, 2018-Nov, 2018-11-00, 20181101, Letnik:
48, Številka:
11
Journal Article
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Bacterial meningitis is a medical emergency. All clinicians who provide acute medical care require a sound understanding of the priorities of managing a patient with suspected meningitis during the ...first hour. These include obtaining blood cultures, performing lumbar puncture and initiating appropriate therapy, while avoiding harmful delays such as those that result from not administering treatment until neuroimaging has been performed. Despite the increasing availability of newer diagnostic techniques, the interpretation of cerebrospinal fluid parameters remains a vital skill for clinicians. International and local guidelines differ with regard to initial empirical therapy of bacterial meningitis in adults; the North American guideline recommends ceftriaxone and vancomycin for all patients, while the Australian, UK and European guidelines recommend that vancomycin only be added for patients who are more likely to have pneumococcal meningitis or who have a higher likelihood of being infected with a strain of Streptococcus pneumoniae with reduced susceptibility to ceftriaxone. Patients with risk factors for Listeria meningitis also require an anti‐Listeria agent, such as benzylpenicillin, to be added to this treatment regimen. Dexamethasone should be a routine component of empirical therapy due to its proven role in reducing morbidity and mortality from pneumococcal meningitis.
Individuals exhibiting exaggerated blood pressure responses to stress are at increased risk for later cardiovascular disease. Engagement in brief bouts of moderate‐to‐vigorous physical activity may ...reduce instances of these exaggerated blood pressure responses. While observational work has shown that periods of light physical activity may also be associated with reduced blood pressure responses to stress in daily life, the few experimental studies involving light physical activity have methodological limitations that temper conclusions. The current investigation sought to understand the effects of brief bouts of light physical activity on blood pressure responses to psychological stress. In a between‐person, single‐session experimental design, 179 healthy, young adults were randomized to 15 min of light physical activity, moderate physical activity, or sitting before engaging in a 10‐min computerized Stroop Color‐Word Interference Task. Blood pressure readings were collected throughout the study session. Surprisingly, the light physical activity participants showed higher systolic blood pressure responses to stress than control participants by 2.9 mmHg (F (2, 174) = 3.49, ηp2 = 0.038, p = .03), whereas no significant differences were shown between moderate physical activity and control groups (F (2, 174) = 2.59, ηp2 = 0.028, p = .078). These findings show that light physical activity may not be related to reduced blood pressure responses to stress in an experimental session involving healthy, college‐aged adults and question the extent to which brief bouts of physical activity may reduce acute blood pressure responses to stress.
In a well‐controlled experimental study to examine the effect of different intensities of brief physical activity on blood pressure responses to stress, we found that engaging in brief bouts of light or moderate physical activity did not significantly reduce blood pressure responses to stress.
Mice learn to avoid regret Sweis, Brian M; Thomas, Mark J; Redish, A David
PLoS biology,
06/2018, Letnik:
16, Številka:
6
Journal Article
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Regret can be defined as the subjective experience of recognizing that one has made a mistake and that a better alternative could have been selected. The experience of regret is thought to carry ...negative utility. This typically takes two distinct forms: augmenting immediate postregret valuations to make up for losses, and augmenting long-term changes in decision-making strategies to avoid future instances of regret altogether. While the short-term changes in valuation have been studied in human psychology, economics, neuroscience, and even recently in nonhuman-primate and rodent neurophysiology, the latter long-term process has received far less attention, with no reports of regret avoidance in nonhuman decision-making paradigms. We trained 31 mice in a novel variant of the Restaurant Row economic decision-making task, in which mice make decisions of whether to spend time from a limited budget to achieve food rewards of varying costs (delays). Importantly, we tested mice longitudinally for 70 consecutive days, during which the task provided their only source of food. Thus, decision strategies were interdependent across both trials and days. We separated principal commitment decisions from secondary reevaluation decisions across space and time and found evidence for regret-like behaviors following change-of-mind decisions that corrected prior economically disadvantageous choices. Immediately following change-of-mind events, subsequent decisions appeared to make up for lost effort by altering willingness to wait, decision speed, and pellet consumption speed, consistent with past reports of regret in rodents. As mice were exposed to an increasingly reward-scarce environment, we found they adapted and refined distinct economic decision-making strategies over the course of weeks to maximize reinforcement rate. However, we also found that even without changes in reinforcement rate, mice transitioned from an early strategy rooted in foraging to a strategy rooted in deliberation and planning that prevented future regret-inducing change-of-mind episodes from occurring. These data suggest that mice are learning to avoid future regret, independent of and separate from reinforcement rate maximization.
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