scholarly journals A synthesis of the theories and concepts of early human evolution

2015 ◽  
Vol 370 (1663) ◽  
pp. 20140064 ◽  
Author(s):  
Mark A. Maslin ◽  
Susanne Shultz ◽  
Martin H. Trauth
Keyword(s):  
Climate Variability ◽  
East Africa ◽  
Human Evolution ◽  
Brain Size ◽  
Homo Erectus ◽  
Current Evidence ◽  
Red Queen Hypothesis ◽  
Long Distance ◽  
The Past ◽  
Macro Scale

Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium ; second, at a more focused level of human evolution comparing allopatric speciation , aridity hypothesis , turnover pulse hypothesis , variability selection hypothesis , Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus ( sensu lato ), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation.

Climate Change in Eastern Africa

2021 ◽  
Author(s):  
Rob Marchant
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
East Africa ◽  
Future Climate ◽  
Eastern Africa ◽  
Future Climate Change ◽  
Human Populations ◽  
The Past ◽  
Tropical Conditions ◽  
Convergence Zones

The climatology of East Africa results from the complex interaction between major global convergence zones with more localized regional feedbacks to the climate system; these in turn are moderated by a diverse land surface characterized by coastal to land transitions, high mountains, and large lakes. The main climatic character of East Africa, and how this varies across the region, takes the form of seasonal variations in rainfall that can fall as one, two, or three rainy seasons, the times and duration of which will be determined by the interplay between major convergence zones with more localized regional feedbacks. One of the key characteristics of East Africa are climatic variations with altitude as climates change along an altitudinal gradient that can extend from hot, dry, “tropical” conditions to cool, wet, temperate conditions and on the highest mountains “polar” climates with permanent ice caps. With this complex and variable climate landscape of the present, as scientists move through time to explore past climatic variability, it is apparent there have been a series of relatively rapid and high-magnitude environmental shifts throughout East Africa, particularly characterized by changing hydrological budgets. How climate change has impacted on ecosystems, and how those ecosystems have responded and interacted with human populations, can be unearthed by drawing on evidence from the sedimentary and archaeological record of the past six thousand years. As East African economies, and the livelihoods of millions of people in the region, have been clearly heavily affected by climate variability in the past, so it is expected that future climate variability will impact on ecosystem functioning and the preparedness of communities for future climate change.

Decadal record of climate variability spanning the past 700 yr in the Southern Tropics of East Africa

Geology ◽  
2001 ◽  
Vol 29 (1) ◽  
pp. 83 ◽  
Author(s):  
Thomas C. Johnson ◽  
Sylvia L. Barry ◽  
Yvonne Chan ◽  
Paul Wilkinson
Keyword(s):  
Climate Variability ◽  
East Africa ◽  
The Past

scholarly journals Mindfulness Promotes Control of Brain Network Dynamics for Self-Regulation and Discontinues the Past from the Present

2021 ◽  
Author(s):  
Dale Zhou ◽  
Yoona Kang ◽  
Danielle Cosme ◽  
Mia Jovanova ◽  
Xiaosong He ◽  
...  
Keyword(s):  
Alcohol Consumption ◽  
Resting State ◽  
Brain Network ◽  
Neural Dynamics ◽  
Current Evidence ◽  
External Control ◽  
The Past ◽  
Alcohol Cues ◽  
Present Experience ◽  
Macro Scale

Mindfulness is characterized by attentiveness to the present experience with nonjudgmental awareness and acceptance. Practicing mindfulness alters brain function to support the executive regulation of thoughts, feelings, and behavior. While early stages of practice are thought to require greater "neural effort" for later efficiency, current evidence relies on circular definitions of effort based on functional activity magnitude. Here we used network control theory as a model of how external control inputs, which operationalize effort, can distribute changes in neural activity across the macro-scale structural brain network. Further, we inferred the intrinsic timescale of activity to operationalize present-centered activity as shorter momentary timescales that discontinue the past and update the present. To explain effects of mindful regulation on alcohol consumption, we applied these methods to a randomized controlled intervention study with resting-state and task fMRI data. The task primed participants to either mindfully respond or naturally react to alcohol cues. Mobile text interventions and measurements of alcohol consumption were administered using ecological momentary assessments during the subsequent 4 weeks. We hypothesized that neural states of mindfulness require greater effort to enact and sustain. This effort may support deautomatized habitual natural reactions, discontinued processing, and updated present-centered neural dynamics. We found that mindful regulation of alcohol cues, compared to the natural reactions of the benchmark group, involved more effortful control of neural dynamics across cognitive control and attention networks. This effort persisted in the natural reactions of the mindful group compared to the benchmark group. Using resting-state fMRI, we found that more effortful neural states tended to occur over shorter timescales than less effortful states. Our findings provide an explanation for how neural dynamics with altered effort and stability, such as mindful states, tend to center the present experience.

Cardiovascular Risk in Rheumatoid Arthritis and Mechanistic Links: From Pathophysiology to Treatment

2020 ◽  
Vol 18 (5) ◽  
pp. 431-446 ◽  
Author(s):  
George E. Fragoulis ◽  
Ismini Panayotidis ◽  
Elena Nikiphorou
Keyword(s):  
Rheumatoid Arthritis ◽  
Risk Factors ◽  
Current Evidence ◽  
Pharmacological Intervention ◽  
Cvd Risk ◽  
The Past ◽  
Increased Risk ◽  
Cv Disease ◽  
Obesity Hypertension ◽  
Inflammatory Burden

Rheumatoid arthritis (RA) is an autoimmune inflammatory arthritis. Inflammation, however, can spread beyond the joints to involve other organs. During the past few years, it has been well recognized that RA associates with increased risk for cardiovascular (CV) disease (CVD) compared with the general population. This seems to be due not only to the increased occurrence in RA of classical CVD risk factors and comorbidities like smoking, obesity, hypertension, diabetes, metabolic syndrome, and others but also to the inflammatory burden that RA itself carries. This is not unexpected given the strong links between inflammation and atherosclerosis and CVD. It has been shown that inflammatory cytokines which are present in abundance in RA play a significant role in every step of plaque formation and rupture. Most of the therapeutic regimes used in RA treatment seem to offer significant benefits to that end. However, more studies are needed to clarify the effect of these drugs on various parameters, including the lipid profile. Of note, although pharmacological intervention significantly helps reduce the inflammatory burden and therefore the CVD risk, control of the so-called classical risk factors is equally important. Herein, we review the current evidence for the underlying pathogenic mechanisms linking inflammation with CVD in the context of RA and reflect on the possible impact of treatments used in RA.

scholarly journals What Has Clinical Research in Suicide Prevention Done for You Lately?

CNS Spectrums ◽  
2006 ◽  
Vol 11 (6) ◽  
pp. 440-441 ◽  
Author(s):  
Jan Fawcett
Keyword(s):  
Suicidal Ideation ◽  
Suicide Risk ◽  
Clinical Status ◽  
Panic Attacks ◽  
Current Evidence ◽  
Suicide Risk Assessment ◽  
Short Term ◽  
The Past ◽  
Standard Risk ◽  
Suicide Plan

What have you heard or read over the past 10 years that has improved you ability to assess and manage suicide risk in your patients?There has been a paucity of data. What little data there is reviewed in this month's articles.They highlight findings that you should know about. Clinicians seem to cling to the familiar, unless some intense marketing is done.For instance, are you aware that the current evidence shows that a denial of suicide thoughts, plans, or intent—even a contract for safety—means absolutely nothing in the absence of a full suicide risk assessment?Yet clinicians seem to rely on these ’reassurances“ from their patients and are shocked when the patient later commits suicide. Why should a patient who is deciding that life is too painful to live tell you the truth? Robert I. Simon, MD, and Daniel W. Shuman, JD, review these facts.Are you aware that severe psychic anxiety, panic attacks, agitation, and severe insomnia often precede suicide within hours, days, or weeks and can be rapidly modified with treatment?On the other hand, standard risk factors for suicide such as suicidal ideation, hopelessness, and past suicidal attempts are not good predictors of suicide in the short term. A suicide plan, recent high intent attempt, or refusal to contract for safety may well indicate immediate risk, but a denial of suicidal ideation or intent and a contract for no harm mean absolutely nothing without a full suicide assessment that takes current clinical status, past suicidal tendencies, social support, and willingness to accept help into account.

scholarly journals Conceptualizing histories of multispecies entanglements: Ancient pathogen genomics and the case of Borrelia recurrentis

2021 ◽  
pp. 146960532199394
Author(s):  
Venla Oikkonen
Keyword(s):  
East Africa ◽  
Ancient Dna ◽  
Relapsing Fever ◽  
Borrelia Recurrentis ◽  
The Past ◽  
Cultural Implications ◽  
Past Millennium

This article explores the conceptual and cultural implications of using pathogen ancient DNA (aDNA) collected in archaeological contexts to understand the past. More specifically, it examines ancient pathogen genomics as a way of conceptualizing multispecies entanglements. The analysis focuses on the 2018 sequencing of Borrelia recurrentis bacteria retrieved from a medieval graveyard in Oslo, Norway. B. recurrentis is associated with louse-borne relapsing fever (LBRF), known to have killed several million people in Europe during the past millennium, and it is still encountered in parts of East Africa. The article demonstrates that while aDNA research often foregrounds multispecies entanglements, its epistemic tools cannot easily address the ontological blurriness of pathogens and their embeddedness in vibrant material processes. The article draws on feminist posthumanities work on microbes and materiality to highlight conceptual openings that a theorization of ancient pathogens could engender.

COMBINING ORAL TRADITIONS AND BAYESIAN CHRONOLOGICAL MODELING TO UNDERSTAND VILLAGE DEVELOPMENT IN THE GULF OF PAPUA (PAPUA NEW GUINEA)

Radiocarbon ◽  
2021 ◽  
pp. 1-21
Author(s):  
Chris Urwin ◽  
Quan Hua ◽  
Henry Arifeae
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Oral Traditions ◽  
Long Distance ◽  
Spatial History ◽  
The Past ◽  
History Of ◽  
Gulf Of Papua ◽  
The Village

ABSTRACT When European colonists arrived in the late 19th century, large villages dotted the coastline of the Gulf of Papua (southern Papua New Guinea). These central places sustained long-distance exchange and decade-spanning ceremonial cycles. Besides ethnohistoric records, little is known of the villages’ antiquity, spatiality, or development. Here we combine oral traditional and 14C chronological evidence to investigate the spatial history of two ancestral village sites in Orokolo Bay: Popo and Mirimua Mapoe. A Bayesian model composed of 35 14C assays from seven excavations, alongside the oral traditional accounts, demonstrates that people lived at Popo from 765–575 cal BP until 220–40 cal BP, at which time they moved southwards to Mirimua Mapoe. The village of Popo spanned ca. 34 ha and was composed of various estates, each occupied by a different tribe. Through time, the inhabitants of Popo transformed (e.g., expanded, contracted, and shifted) the village to manage social and ceremonial priorities, long-distance exchange opportunities and changing marine environments. Ours is a crucial case study of how oral traditional ways of understanding the past interrelate with the information generated by Bayesian 14C analyses. We conclude by reflecting on the limitations, strengths, and uncertainties inherent to these forms of chronological knowledge.

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