Adaptive Hypothesis Research Articles

Differences in subjective age by filial caregiving status among US adults in mid and later life

COVID-19 has adversely impacted the well-being of informal caregivers (CG) due to infection risk, changes to the home environment, and changes to resource availability. CG of persons living with dementia (PLWD) may be especially vulnerable due to the intensity of care provided. We compared CG activities and well-being among CG who did and did not care for PLWD during COVID-19. We conducted an anonymous online survey from April 2020-present. Respondents self-identified as 18+ years and CG to a child or adult with mental health or medical conditions. CG answered questions regarding hours of care provision and caregiving activities, and completed measures of CG burden (Zarit Burden Inventory-4), loneliness (UCLA Loneliness Scale), depressive symptoms (Patient Health Questionnaire), and anxiety (Generalized Anxiety Disorder-2). Of the 258 respondents within the United States, 86 cared for PLWD (33%; 88% female; 56±12 years) while 172 did not (66%; 87% female; 49±14 years). Compared to non-dementia CGs, more CGs of PLWD provided 40+ hours of caregiving/week (36% vs. 49%, p<.05), performed more caregiving activities (8.5 vs. 10.5, p<.01), and assisted with more activities of daily living (55% vs. 73%, p<.01). Compared to non-dementia CG, more dementia CG reported CG burden (53% vs. 67%; p<.05) and loneliness (7.3 vs. 9.1, p<.05). No differences in depressive symptoms or anxiety were found. Results suggest that existing needs of CG of PLWD may be exacerbated by the stressors and concerns of the pandemic, necessitating higher levels of support.

On reappearance and complexity in musical calling.

Music is especially valued in human societies, but music-like behavior in the form of song also occurs in a variety of other animal groups including primates. The calling of our primate ancestors may well have evolved into the music of modern humans via multiple selective scenarios. But efforts to uncover these influences have been hindered by the challenge of precisely defining musical behavior in a way that could be more generally applied across species. We propose an acoustic focused reconsideration of “musicality” that could help enable independent inquiry into potential ecological pressures on the evolutionary emergence of such behavior. Using published spectrographic images (n = 832 vocalizations) from the primate vocalization literature, we developed a quantitative formulation that could be used to help recognize signatures of human-like musicality in the acoustic displays of other species. We visually scored each spectrogram along six structural features from human music—tone, interval, transposition, repetition, rhythm, and syllabic variation—and reduced this multivariate assessment into a concise measure of musical patterning, as informed by principal components analysis. The resulting acoustic reappearance diversity index (ARDI) estimates the number of different reappearing syllables within a call type. ARDI is in concordance with traditional measures of bird song complexity yet more readily identifies shorter, more subtly melodic primate vocalizations. We demonstrate the potential utility of this index by using it to corroborate several origins scenarios. When comparing ARDI scores with ecological features, our data suggest that vocalizations with diversely reappearing elements have a pronounced association with both social and environmental factors. Musical calls were moderately associated with wooded habitats and arboreal foraging, providing partial support for the acoustic adaptation hypothesis. But musical calling was most strongly associated with social monogamy, suggestive of selection for constituents of small family-sized groups by neighboring conspecifics. In sum, ARDI helps construe musical behavior along a continuum, accommodates non-human musicality, and enables gradualistic co-evolutionary paths between primate taxa—ranging from the more inhibited locational calls of archaic primates to the more exhibitional displays of modern apes.

Robust adaptive multi‐target tracking with unknown measurement and process noise covariance matrices

A robust adaptive probability hypothesis density (PHD) filter is proposed to address the degradation of PHD performance due to an unknown process noise and measurement noise covariance matrix. Therefore, the inverse Wishart distribution is introduced to model the prior distribution of process noise and measurement noise. Meanwhile, the multi-target posterior intensity is approximated as a mixture of the inverse Wishart distribution and Gaussian distribution. The closed solution of the robust PHD filter is derived by the variational Bayes approach. Simulation results show that the proposed algorithm outperforms the Gaussian-mixed PHD filter and the variational Bayesian PHD filter in terms of target number estimation accuracy and optimal sub-pattern assignment distance.

Decision-making under Market Indeterminacy

The Efficient Markets Hypothesis (EMH) is the focusing topic in the past 50 years of financial market researches. Many empirical studies are then provided that want to test EMH but have no consensus. The perception of EMH determines the attitude and strategy of participants and regulators in financial market. One perception of EMH argues that investors’ behavior of seeking abnormal profits and arbitrage drives prices to their ‘‘correct’’ value. Investigating the “correct” value derives the concept of “market indeterminacy”. It means the inability to determine whether stock prices are efficient or inefficient. Market indeterminacy pervades stock markets because “correct” prices are unknown because of imperfect information and model sensitivity. Market indeterminacy makes arbitrage risky and makes event studies unreliable in some policy and litigation applications. The concept of market efficiency is needed to be re-recognized considering the mechanism of price formation. In order to further research and practice in law and financial market, there needs a view from the “jumping together” of disparate disciplines. Adaptive Markets Hypothesis(AMH) that using the evolutionary principles in financial market is a new viewpoint oncognitive decision and deserves to be paid more attention to.

Behavior of calendar anomalies and the adaptive market hypothesis: evidence from the Baltic stock markets

ABSTRACT This research tests the Adaptive Market Hypothesis (AMH) regarding calendar anomalies in the Baltic stock markets. Analysis of known calendar anomalies over time is carried out by using sub-sample GARCH (1,1) regression with Kruskal–Wallis statistics and rolling windows. Three calendar anomalies were confirmed in these markets: Friday, MoY (July and January), and ToM (turn-of-the-month). The Baltic stock markets demonstrated behavior supporting the AMH. It was found that the opportunity to earn abnormal returns on investment strategies based on Friday, July, and ToM effects disappeared during the financial crisis of 2007–9. The Friday and the ToM effects follow a more time-varying pattern, while the July effect is less so.

Arboreality drives heat tolerance while elevation drives cold tolerance in tropical rainforest ants.

Determining how species thermal limits correlate with climate is important for understanding biogeographic patterns and assessing vulnerability to climate change. Such analyses need to consider thermal gradients at multiple spatial scales. Here we relate thermal traits of rainforest ants to microclimate conditions from ground to canopy (microgeographic scale) along an elevation gradient (mesogeographic scale) and calculate warming tolerance to assess climate change vulnerability in the Australian Wet Tropics Bioregion. We test the thermal adaptation and thermal niche asymmetry hypotheses to explain interspecific patterns of thermal tolerance at these two spatial scales. We tested cold tolerance (CTmin ), heat tolerance (CTmax ), and calculated thermal tolerance range (CTrange ), using ramping assays for 74 colonies of 40 ant species collected from terrestrial and arboreal habitats at lowland and upland elevation sites and recorded microclimatic conditions for one year. Within sites, arboreal ants were exposed to hotter microclimates and on average had a 4.2°C (95% CI: 2.7-5.6°C) higher CTmax and 5.3°C (95% CI: 3.5-7°C) broader CTrange than ground-dwelling ants. This pattern was consistent across the elevation gradient, whether it be the hotter lowlands or the cooler uplands. Across elevation, upland ants could tolerate significantly colder temperatures than lowland ants, whereas the change in CTmax was less pronounced, and CTrange did not change over elevation. Differential exposure to microclimates, due to localized niche preferences, drives divergence in CTmax , while environmental temperatures along the elevation gradient drive divergence in CTmin . Our results suggest that both processes of thermal adaptation and thermal niche asymmetry are at play, depending on the spatial scale of observation, and we discuss potential mechanisms underlying these patterns. Despite the broad thermal tolerance range of arboreal rainforest ants, lowland arboreal ants had the lowest warming tolerance and may be most vulnerable to climate change.

Code-Switching patterns differentially shape cognitive control: Testing the predictions of the adaptive control hypothesis

AbstractBilinguals engage in qualitatively different code-switching patterns (alternation, insertion, and congruent lexicalization) to different degrees, according to their engagement in different types of interactional contexts (single-language context, dual-language context, and dense code-switching context). Drawing on the adaptive control hypothesis, we examined whether bilinguals’ code-switching patterns would differentially shape multiple aspects of cognitive control (interference control, salient cue detection, and opportunistic planning). We found that a dense code-switching context, which predominantly involves insertion and congruent lexicalization, was positively associated with verbal opportunistic planning but negatively associated with interference control and salient cue detection. In contrast, a dual-language context, which predominantly involves alternation, was not associated with interference control or salient cue detection, but with significantly reduced response times for opportunistic planning. Our findings partially corroborate the theoretical predictions of the adaptive control hypothesis. Altogether, our study illustrates the importance of bilinguals’ disparate code-switching practices in shaping cognitive control outcomes.

Adaptive market hypothesis: An empirical analysis of the Wine Market

We test the nature of weak form informational efficiency present in the wine market using daily return of LIV-EX 50 index from 1/1/2010 to 12/6/2020. First, we employ a number of statistical tests including variance ratio tests, tests for linear and non-linear dependence and Hurst coefficient. The tests are applied on the full dataset and on four non overlapping sub-samples of equal length. The variance ratio tests provide a mixed regarding informational efficiency. Evidence of non-linear dependence in the return series was found. The Hurst coefficient values confirm the presence of long run persistence in the wine market. Based on the mixed evidence, we test the possibility of adaptive nature of the wine market. We employ the newly proposed Adaptive Index (AI) to quantify the degree of information inefficiency in the wine market at any instance. Our results confirm that wine market is adaptive and periodically shifts between states of efficiency and inefficiency. The wine market is found to be relatively free from the Covid-19 induced shock and the safe haven property of wine is thus confirmed. Finally, impact of various macroeconomic and financial events on wine market efficiency is identified by using AI.

An agent-based model of financial market efficiency dynamics

We build a parsimonious agent-based model under the adaptive market hypothesis (AMH), which can explain the formation of equilibrium prices and market efficiency dynamics. Our model combines heterogeneous interacting agents, switching behavior, and investor feedback on past realized returns, with realistic assumptions on the market microstructure. Numerical simulations show that our model is empirically robust to the facts observed in returns of developed and emerging financial markets (leptokurtic distribution, excess volatility, time-varying linear and nonlinear autocorrelations in returns, and time-varying degree of market efficiency). These results reveal that the elements in the model are necessary for generating these empirical facts. They also confirm the AMH. The model can be used as an artificial laboratory to assess the effectiveness of regulatory policies and the profitability of trading strategies.

Regime-Switching Determinants of Mutual Fund Performance in South Africa

This study assesses the effect of fund-level and systemic factors on the performance of mutual funds in the context of changing market conditions. A Markov regime-switching model is used to analyze the performance of 33 South African equity mutual funds from 2006 to 2019. From the results, fund flow and fund size exert more predictive influences on performance in the bearish state of the market than in the bullish state. Fund age, fund risk, and market risk were found to be the most significant factors driving the performance of active portfolios under time-varying conditions of the market. These variables exert more influence on fund performance under bearish conditions than under bullish conditions, emphasizing the flight-to-liquidity assets phenomenon and risk-aversion behavior of fund contributors during unstable conditions of the market. Consequently, fund managers need to maintain adequate asset bases while implementing policies that minimize dispersions in fund returns to engender persistence in performance. This study provides novel perspectives on how the determinants of fund performance change with market conditions as portrayed by the adaptive market hypothesis (AMH).

Entropy Method for Decision-Making: Uncertainty Cycles in Tourism Demand.

A new methodology is presented for measuring, classifying and predicting the cycles of uncertainty that occur in temporary decision-making in the tourist accommodation market (apartments and hotels). Special attention is paid to the role of entropy and cycles in the process under the Adaptive Markets Hypothesis. The work scheme analyses random cycles from time to time, and in the frequency domain, the linear and nonlinear causality relationships between variables are studied. The period analysed is from January 2005 to December 2018; the following empirical results stand out: (1) On longer scales, the periodicity of the uncertainty of decision-making is between 6 and 12 months, respectively, for all the nationalities described. (2) The elasticity of demand for tourist apartments is approximately 1% due to changes in demand for tourist hotels. (3) The elasticity of the uncertainty factor is highly correlated with the country of origin of tourists visiting Spain. For example, it has been empirically shown that increases of 1% in uncertainty cause increases in the demand for apartments of 2.12% (worldwide), 3.05% (UK), 1.91% (Germany), 1.78% (France), 7.21% (Ireland), 3.61% (The Netherlands) respectively. This modelling has an explanatory capacity of 99% in all the models analysed.

Evidence of the adaptive market hypothesis in shares traded by B3 listed banking companies

PurposeThe authors aim to verify the indicators that influence the efficiency reported by Brazilian listed financial companies.Design/methodology/approachThe sample consists of companies in the financial segment that have shares traded in B3, comprising nine institutions from 2000 to 2018 were selected. The authors adopted the regression model with unbalanced panel data to analyze the data. The dependent is the efficiency, which the authors calculated using Hurst Exponent. As independent variables, we used the sector-specific indicators: earnings management, banking resilience, management efficiency, and profitability. The authors controlled the models by size and type of control.FindingsThe findings indicate that the efficiency of financial companies' securities is affected by aspects related to management, resilience, and efficiency in administration. The lower the earnings management, the greater the banking resilience, the efficiency in the management of resources, and the efficiency of stock prices of these companies. These results show that efficiency is affected by intrinsic factors of the entities, corroborating the hypothesis that markets adapt, among others, to institutional factors.Originality/valueMany users of financial institutions understand whether their stock prices reflect the information provided by accounting. The findings are original because they provide evidence that institutional factors affect the efficiency of companies in the Brazilian financial segment.

Predictions about the Cognitive Consequences of Language Switching on Executive Functioning Inspired by the Adaptive Control Hypothesis Fail More Often than Not.

The adaptive control hypothesis developed by Green and Abutalebi is the most influential theory of bilingual language control. The focus of this article is on the predictions that other researchers have derived based on the three different modes of interactional context described by the hypothesis. Foremost, that dual-language contexts should enhance domain-general executive functions more than single-language contexts. Several recent and ambitious behavioral tests of these predictions are reviewed. Although there was some evidence that dual-language contexts are associated with smaller switch costs, the evidence is inconsistent and there were no similar advantages for inhibitory control. The hypothesis also predicts neuroanatomical adaptations to the three types of interactional context. A careful evaluation of the relevant fMRI and ERP studies that take into account whether behavioral differences align with neuroscience differences and resolves valence ambiguities led to the conclusion that the neuroscience evidence for the hypothesis is, at best, inconsistent. The study also includes new analyses of two large-sample studies that enable the identification of relatively pure cases of single-language bilinguals, dual-language bilinguals, and dense-code switchers. Across nine different measures of executive functioning, the predicted advantage of the dual-language context never materialized. The hypotheses derived from the adaptive control hypothesis do not accurately predict behavioral performance on tests of executive functioning and do not advance our understanding as to what dimensions of bilingualism may lead to enhancements in specific components of executive functioning.

Ecogeography of Plumage Pigmentation in Great Horned Owls

ABSTRACT Plumage pigmentation is fundamental to a bird's phenotype, with pigment deposition causing relative crypsis or conspicuousness, depending on the environmental context. Geographic variation in plumage melanin tends to be predictable, suggesting that aspects of climate cause local matching of plumage to environment via genetic adaptation. Ecogeographic rules describe this predictability: Gloger's rule predicts that populations in wetter and warmer environments will be more pigmented; Bogert's Rule predicts more pigmentation in cold environments. The Great Horned Owl (Bubo virginianus) exhibits extensive geographic variation in the degree of melanin-based pigmentation. We examined fine-scale spatial variation in owl plumage melanism along environmental gradients in southwestern North America. We tested whether variation is explained by either of two non-mutually exclusive hypotheses: (1) a history of allopatric divergence between subspecies or (2) in situ local adaptation consistent with ecogeographic rules. The allopatric divergence hypothesis predicts a bimodal distribution of plumage melanism, with a geographic cline across a zone of secondary contact, whereas the local adaptation hypothesis predicts that climate explains variation independently of geography. Using a colorimeter, we measured coloration in 101 museum specimens of breeding-season Great Horned Owls that had been obtained from variable environments and elevations. Specimens previously identified as separate subspecies were distinguishable by colorimetry. Plumage lightness, however, was continuously distributed, rather than bimodal. While accounting for males having reduced pigmentation relative to females, linear models revealed that lighter plumage was associated with low latitude, low elevation, high temperature, and low precipitation. These findings suggest that variation in Great Horned Owl plumage pigmentation is best understood as continuous ecogeographic variation, consistent with ecogeographic predictions, and currently maintained in situ along multiple environmental gradients that characterize the “sky island” topography of the southwestern USA.

Are the least successful traders those most likely to exit the market? A survival analysis contribution to the efficient market debate

Concerns regarding the assumptions of the Efficient Market Hypothesis have led to a greater emphasis on how the behaviour of different groups of traders might impact the evolution of financial markets; ideas encapsulated in the Adaptive Markets Hypothesis (AMH). A key assumption of the AMH is that the dynamics of competition and natural selection will drive ‘noise traders’, those least likely to push prices to efficient levels because they follow sub-optimal trading strategies, to exit the market. To test the key assumptions of the AMH, survival analysis is employed to examine the behaviour of retail spread-traders, a group who are widely reported to include many noise traders. Analysis of the trades executed by 5,164 individuals in the period 24th March 2006 to 7th February 2012 found that the least profitable and those who adopted ill-disciplined trading strategies tended to cease trading sooner than others. These findings are consistent with the AMH. However, profitable traders were also found to be more likely to cease trading than the average trader and a V-shaped relationship was found between a trader's Sharpe ratio and their likelihood of ceasing to trade (cf. the average trader). Furthermore, during the financial crisis of 2008–09, the disposition effect of traders and the proportion of noise traders increased and throughout the period of the study, the ill-discipline of new generations of traders increased. The results suggest that the forces underpinning the AMH are complex and the move towards market efficiency may not be as straightforward as some expect.

Flocking in birds increases annual adult survival in a global analysis.

Adaptive hypotheses for the evolution of group foraging in animals typically invoke enhanced foraging efficiency and reduced predation risk. Net benefits of group foraging in different species should translate into a survival advantage for group members. Despite numerous interspecific studies in birds and mammals, few have documented a survival advantage for group foraging species. Using a large dataset in birds (> 1100 species worldwide), I investigated whether annual adult apparent survival was higher in species that forage in flocks than in solitary species. Using a phylogenetic framework to account for relatedness among species and controlling for known correlates of adult survival in birds such as body size, clutch size, latitude, and diet, I documented a positive effect of flocking on annual adult apparent survival. The increase in survival was less pronounced in occasionally flocking species suggesting that the benefits of group foraging can depend on the frequency of its use. The results highlight how group foraging can increase fitness in animals.

Bilinguals are better than monolinguals in detecting manipulative discourse.

One of the most contentious topics in cognitive science concerns the impact of bilingualism on cognitive functions and neural resources. Research on executive functions has shown that bilinguals often perform better than monolinguals in tasks that require monitoring and inhibiting automatic responses. The robustness of this effect is a matter of an ongoing debate, with both sides approaching bilingual cognition mainly through measuring abilities that fall outside the core domain of language processing. However, the mental juggling that bilinguals perform daily involves language. This study takes a novel path to bilingual cognition by comparing the performance of monolinguals and bilinguals in a timed task that features a special category of stimulus, which has the peculiar ability to manipulate the cognitive parser into treating it as well-formed while it is not: grammatical illusions. The results reveal that bilinguals outperform monolinguals in detecting illusions, but they are also slower across the board in judging the stimuli, illusory or not. We capture this trade-off by proposing the Plurilingual Adaptive Trade-off Hypothesis (PATH), according to which the adaptation of bilinguals' cognitive abilities may (i) decrease fallibility to illusions by means of recruiting sharpened top-down control processes, but (ii) this is part of a larger bundle of effects, not all of which are necessarily advantageous.

Expectations and Stock Market in Nepal

This study examines the presence of both rational and adaptive expectations hypotheses in the Nepalese stock market by employing panel data analysis under the Fama–French three-factor model. Under the adaptive expectation hypothesis, the book to market equity is an essential determinant in the Nepalese stock market, and only the past 2-year information can explain investment decisions. Likewise, under the rational expectation hypothesis, the value factor, size factor and excess market return are important determinants during the investment decision. The past 3 years of information and the next 3 years of future information are necessary to estimate stock market return under rational expectation. Thus, this study reveals that the investment decision in the Nepalese stock market depends on the investor’s choice and preference upon the factors that are incorporated in the Fama–French three-factor model and the types of expectations in which the investors mostly believe.

Evaluating adaptive hypotheses for female-led infanticide in wild chimpanzees

Although rare among group-living primates, infanticide by females has been reported in several chimpanzee, Pan troglodytes, populations. We examined 13 infanticidal attacks over 47 years at Gombe National Park, Tanzania to evaluate three adaptive hypotheses. (1) Exploitation of the infant as a food resource – by eating a vulnerable neonate, attackers gain calories that may be important during periods of food scarcity or energetic stress. (2) Resource competition – Gombe females concentrate their foraging in overlapping core areas and dominance rank influences foraging success. By killing the infant of a female with high core area overlap, the perpetrator removes a current and future competitor, improving her access to food. (3) Low cost – female chimpanzees mature and reproduce slowly, and longevity increases reproductive success. Physical aggression causes risk of severe injury or death, so females will only mount attacks when risks to the perpetrator are low. In support of hypothesis 1, females usually consumed the carcass. However, attacks were not more likely in times of resource or energy scarcity. In support of hypothesis 2, females attacked others with whom they shared core areas, but attacks did not cause shifts in ranging patterns. In support of hypothesis 3, one or more attackers always outranked the victim, the attacks often involved coalitions and victims usually lacked kin support. Attacks were more likely to be successful when attackers were not hindered by clinging infants and victims could not retreat. Our results provide further evidence for female competition and the adaptive value of female-led infanticide in this species.

Evidence for genetic isolation and local adaptation in the field cricket Gryllus campestris.

Understanding how species can thrive in a range of environments is a central challenge for evolutionary ecology. There is strong evidence for local adaptation along large-scale ecological clines in insects. However, potential adaptation among neighbouring populations differing in their environment has been studied much less. We used RAD sequencing to quantify genetic divergence and clustering of ten populations of the field cricket Gryllus campestris in the Cantabrian Mountains of northern Spain, and an outgroup on the inland plain. Our populations were chosen to represent replicate high and low altitude habitats. We identified genetic clusters that include both high and low altitude populations indicating that the two habitat types do not hold ancestrally distinct lineages. Using common-garden rearing experiments to remove environmental effects, we found evidence for differences between high and low altitude populations in physiological and life-history traits. As predicted by the local adaptation hypothesis, crickets with parents from cooler (high altitude) populations recovered from periods of extreme cooling more rapidly than those with parents from warmer (low altitude) populations. Growth rates also differed between offspring from high and low altitude populations. However, contrary to our prediction that crickets from high altitudes would grow faster, the most striking difference was that at high temperatures, growth was fastest in individuals from low altitudes. Our findings reveal that populations a few tens of kilometres apart have independently evolved adaptations to their environment. This suggests that local adaptation in a range of traits may be commonplace even in mobile invertebrates at scales of a small fraction of species' distributions.