Only Human
Sick Body, Vigilant Mind: The Biological Immune System Activates the Behavioral Immune System
Saul Miller & Jon Maner
Psychological Science, forthcoming
Abstract:
Activation of the behavioral immune system has been shown to promote activation of the biological immune system. The current research tested the hypothesis that activation of the biological immune system (as a result of recent illness) promotes activation of the behavioral immune system. Participants who had recently been ill, and had therefore recently experienced activation of their biological immune system, displayed heightened attention to (Study 1) and avoidance of (Study 2) disfigured individuals - cognitive and behavioral processes reflecting activation of the behavioral immune system. These findings shed light on the interactive nature of biological and psychological mechanisms designed to help people overcome the threat of disease.
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Caveman Politics: Evolutionary Leadership Preferences and Physical Stature
Gregg Murray & David Schmitz
Social Science Quarterly, December 2011, Pages 1215-1235
Objective: Following evolutionary psychology, we argue that physical stature matters in preferences regarding political leadership. Particularly, a preference for physically formidable leaders evolved to promote survivability in the violent human ancestral history.
Methods: We present two studies of original data to assess individual attitudes regarding the association between physical stature and political leadership. Analytical methods include ordered probit regression.
Results: The findings are consistent with the evolutionary theory presented here. Study 1 indicates that individuals tend to prefer leaders with greater physical stature, while Study 2 indicates that males with greater physical stature are more likely to think of themselves as qualified to be a leader and, through this increased sense of efficacy, they are more likely to demonstrate interest in pursuing a leadership position.
Conclusion: Consistent with emerging evidence from other research perspectives, political behavior, in this case preferences regarding political leadership, is shaped by both environmental and evolutionary forces.
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The earliest evidence for anatomically modern humans in northwestern Europe
Tom Higham et al.
Nature, forthcoming
Abstract:
The earliest anatomically modern humans in Europe are thought to have appeared around 43,000-42,000 calendar years before present (43-42 kyr cal bp), by association with Aurignacian sites and lithic assemblages assumed to have been made by modern humans rather than by Neanderthals. However, the actual physical evidence for modern humans is extremely rare, and direct dates reach no farther back than about 41-39 kyr cal bp, leaving a gap. Here we show, using stratigraphic, chronological and archaeological data, that a fragment of human maxilla from the Kent's Cavern site, UK, dates to the earlier period. The maxilla (KC4), which was excavated in 1927, was initially diagnosed as Upper Palaeolithic modern human. In 1989, it was directly radiocarbon dated by accelerator mass spectrometry to 36.4-34.7 kyr cal bp. Using a Bayesian analysis of new ultrafiltered bone collagen dates in an ordered stratigraphic sequence at the site, we show that this date is a considerable underestimate. Instead, KC4 dates to 44.2-41.5 kyr cal bp. This makes it older than any other equivalently dated modern human specimen and directly contemporary with the latest European Neanderthals, thus making its taxonomic attribution crucial. We also show that in 13 dental traits KC4 possesses modern human rather than Neanderthal characteristics; three other traits show Neanderthal affinities and a further seven are ambiguous. KC4 therefore represents the oldest known anatomically modern human fossil in northwestern Europe, fills a key gap between the earliest dated Aurignacian remains and the earliest human skeletal remains, and demonstrates the wide and rapid dispersal of early modern humans across Europe more than 40 kyr ago.
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Yexin Jessica Li et al.
Journal of Personality and Social Psychology, forthcoming
Abstract:
Much research shows that people are loss averse, meaning that they weigh losses more heavily than gains. Drawing on an evolutionary perspective, we propose that although loss aversion might have been adaptive for solving challenges in the domain of self-protection, this may not be true for men in the domain of mating. Three experiments examine how loss aversion is influenced by mating and self-protection motives. Findings reveal that mating motives selectively erased loss aversion in men. In contrast, self-protective motives led both men and women to become more loss averse. Overall, loss aversion appears to be sensitive to evolutionarily important motives, suggesting that it may be a domain-specific bias operating according to an adaptive logic of recurring threats and opportunities in different evolutionary domains.
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Adaptive memory: Young children show enhanced retention of fitness-related information
Alp Aslan & Karl-Heinz T. Bäuml
Cognition, January 2012, Pages 118-122
Abstract:
Evolutionary psychologists propose that human cognition evolved through natural selection to solve adaptive problems related to survival and reproduction, with its ultimate function being the enhancement of reproductive fitness. Following this proposal and the evolutionary-developmental view that ancestral selection pressures operated not only on reproductive adults, but also on pre-reproductive children, the present study examined whether young children show superior memory for information that is processed in terms of its survival value. In two experiments, we found such survival processing to enhance retention in 4- to 10-year-old children, relative to various control conditions that also required deep, meaningful processing but were not related to survival. These results suggest that, already in very young children, survival processing is a special and extraordinarily effective form of memory encoding. The results support the functional-evolutionary proposal that young children's memory is "tuned" to process and retain fitness-related information.
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Sociality, Pathogen Avoidance, and the Neuropeptides Oxytocin and Arginine Vasopressin
Martin Kavaliers & Elena Choleris
Psychological Science, November 2011, Pages 1367-1374
Abstract:
Both humans and nonhumans have evolved a variety of mechanisms to recognize pathogen threat and a variety of adaptive behavioral responses to minimize exposure to it. Because social interactions facilitate the spread of infection among individuals, the ability to recognize and avoid infected and potentially infected individuals is crucial. The neuropeptides oxytocin (OT) and arginine vasopressin (AVP) are involved in mediating various facets of social behavior, including social recognition and responses to salient social threats. Results of studies with rodents have revealed that OT and AVP are also associated with the olfactory-mediated recognition and avoidance of actually or potentially infected individuals. The evidence reviewed here suggests that OT and AVP likely play parallel roles in modulating the recognition and avoidance of socially relevant pathogen threat in both humans and rodents.
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Stepwise evolution of stable sociality in primates
Susanne Shultz, Christopher Opie & Quentin Atkinson
Nature, 10 November 2011, Pages 219-222
Abstract:
Although much attention has been focused on explaining and describing the diversity of social grouping patterns among primates, less effort has been devoted to understanding the evolutionary history of social living. This is partly because social behaviours do not fossilize, making it difficult to infer changes over evolutionary time. However, primate social behaviour shows strong evidence for phylogenetic inertia, permitting the use of Bayesian comparative methods to infer changes in social behaviour through time, thereby allowing us to evaluate alternative models of social evolution. Here we present a model of primate social evolution, whereby sociality progresses from solitary foraging individuals directly to large multi-male/multi-female aggregations (approximately 52 million years (Myr) ago), with pair-living (approximately 16 Myr ago) or single-male harem systems (approximately 16 Myr ago) derivative from this second stage. This model fits the data significantly better than the two widely accepted alternatives (an unstructured model implied by the socioecological hypothesis or a model that allows linear stepwise changes in social complexity through time). We also find strong support for the co-evolution of social living with a change from nocturnal to diurnal activity patterns, but not with sex-biased dispersal. This supports suggestions that social living may arise because of increased predation risk associated with diurnal activity. Sociality based on loose aggregation is followed by a second shift to stable or bonded groups. This structuring facilitates the evolution of cooperative behaviours and may provide the scaffold for other distinctive anthropoid traits including coalition formation, cooperative resource defence and large brains.
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The return of the anal character
Nick Haslam
Review of General Psychology, forthcoming
Abstract:
The anal character is a central concept in the psychoanalytic theory of personality. It was originally described in the first decade of the 20th century, and quickly applied to the analysis of clinical cases, psychobiographies, and cultural phenomena. In midcentury a generation of psychoanalytically oriented psychologists found some evidence that anal traits cohere and that they are related to attitudes toward excreta. Subsequently, the concept of the anal character lost currency as studies failed to support the psychoanalytic explanation of its origins and enthusiasm for psychoanalysis dwindled. However, although the concept might seem to have met its demise, it has resurfaced under different names as a diverse assortment of characteristics that have inspired active research programs. These characteristics - authoritarianism, conscientiousness, detail focus, disgust sensitivity, hoarding, obsessive-compulsive personality disorder, perfectionism, and Type A - have a rarely remarked family resemblance that the anal character illuminates. I argue that the anal character has not so much been consigned to the scrap heap of bad ideas, but has been recycled into several smaller but better ones.
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Human values: Genetic and environmental effects on five lexically derived domains and their facets
Walter Renner et al.
Personality and Individual Differences, January 2012, Pages 89-93
Abstract:
Whereas a substantial genetic component of Conservatism and Religiosity is well documented, there is little evidence with respect to the behavior genetics of other aspects of human values. A sample of 157 monozygotic and 74 dizygotic twins reared together received the Austrian Value Questionnaire (AVQ), which measures a broad variety of value domains and their facets, found by the lexical approach in the German language. Family resemblance of Intellectualism, Harmony, Materialism, and Conservatism was best explained by additive or dominance genetic and non-shared environmental effects, whereas the influence of the environment shared by twins was negligible. In contrast, Religiosity was transmitted by additive genetic, shared and non-shared environmental influences. At the level of facets, the Intellectualism and Harmony showed a homogenous etiology while Religiosity, Materialism, and Conservatism were etiologically heterogeneous.
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Experiments with humans indicate that decision accuracy drives the evolution of niche width
Colin Tosh et al.
Proceedings of the Royal Society: Biological Sciences, 7 December 2011, Pages 3504-3509
Abstract:
One theory to explain the high incidence of niche specialization in many animals is that it reduces attentional load during resource-seeking behaviour and thus leads to more accurate resource selection. A recent neural network model refined the predictions of this theory, indicating that a cognitive advantage in specialists is likely to occur under realistic ecological conditions, namely when ‘mistakes' (i.e. selection of non-host resources) contribute moderately but positively to fitness. Here, we present a formal empirical test of the predictions of this model. Using a human-computer interactive, we demonstrate that the central prediction of the model is supported: specialist humans are more accurate decision-makers than generalists when their mistakes are rewarded, but not when mistakes are punished. The idea that increased decision accuracy drives the evolution of niche width in animals has been supported in almost all empirical systems in which it has been investigated. Theoretical work supports the idea, and now the predictions of a key theoretical model have been demonstrated in a real biological information-processing system. Considering these interlocking pieces of evidence, we argue that specialization through increased decision accuracy may contribute significantly, along with other mechanisms, to promote niche specialization in animals.
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Archaic human ancestry in East Asia
Pontus Skoglund & Mattias Jakobsson
Proceedings of the National Academy of Sciences, 8 November 2011, Pages 18301-18306
Abstract:
Recent studies of ancient genomes have suggested that gene flow from archaic hominin groups to the ancestors of modern humans occurred on two separate occasions during the modern human expansion out of Africa. At the same time, decreasing levels of human genetic diversity have been found at increasing distance from Africa as a consequence of human expansion out of Africa. We analyzed the signal of archaic ancestry in modern human populations, and we investigated how serial founder models of human expansion affect the signal of archaic ancestry using simulations. For descendants of an archaic admixture event, we show that genetic drift coupled with ascertainment bias for common alleles can cause artificial but largely predictable differences in similarity to archaic genomes. In genotype data from non-Africans, this effect results in a biased genetic similarity to Neandertals with increasing distance from Africa. However, in addition to the previously reported gene flow between Neandertals and non-Africans as well as gene flow between an archaic human population from Siberia ("Denisovans") and Oceanians, we found a significant affinity between East Asians, particularly Southeast Asians, and the Denisova genome - a pattern that is not expected under a model of solely Neandertal admixture in the ancestry of East Asians. These results suggest admixture between Denisovans or a Denisova-related population and the ancestors of East Asians, and that the history of anatomically modern and archaic humans might be more complex than previously proposed.
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Early dispersal of modern humans in Europe and implications for Neanderthal behavior
Stefano Benazzi et al.
Nature, forthcoming
Abstract:
The appearance of anatomically modern humans in Europe and the nature of the transition from the Middle to Upper Palaeolithic are matters of intense debate. Most researchers accept that before the arrival of anatomically modern humans, Neanderthals had adopted several ‘transitional' technocomplexes. Two of these, the Uluzzian of southern Europe and the Châtelperronian of western Europe, are key to current interpretations regarding the timing of arrival of anatomically modern humans in the region and their potential interaction with Neanderthal populations. They are also central to current debates regarding the cognitive abilities of Neanderthals and the reasons behind their extinction. However, the actual fossil evidence associated with these assemblages is scant and fragmentary, and recent work has questioned the attribution of the Châtelperronian to Neanderthals on the basis of taphonomic mixing and lithic analysis. Here we reanalyse the deciduous molars from the Grotta del Cavallo (southern Italy), associated with the Uluzzian and originally classified as Neanderthal. Using two independent morphometric methods based on microtomographic data, we show that the Cavallo specimens can be attributed to anatomically modern humans. The secure context of the teeth provides crucial evidence that the makers of the Uluzzian technocomplex were therefore not Neanderthals. In addition, new chronometric data for the Uluzzian layers of Grotta del Cavallo obtained from associated shell beads and included within a Bayesian age model show that the teeth must date to ~45,000-43,000 calendar years before present. The Cavallo human remains are therefore the oldest known European anatomically modern humans, confirming a rapid dispersal of modern humans across the continent before the Aurignacian and the disappearance of Neanderthals.
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Variation in the Oxytocin Receptor Gene Is Associated with Pair-Bonding and Social Behavior
Hasse Walum et al.
Biological Psychiatry, forthcoming
Background: In specific vole and primate species the neuropeptide oxytocin plays a central role in the regulation of pair-bonding behavior. Here we investigate the extent to which genetic variants in the oxytocin receptor gene (OXTR) are associated with pair-bonding and related social behaviors in humans.
Methods: We first genotyped twelve single nucleotide polymorphisms (SNPs) in the TOSS (Twin and Offspring Study in Sweden) (n = 2309) and the TCHAD (Swedish Twin Study of Child and Adolescent Development) (n = 1240), comprising measures of self-reported pair-bonding behavior. In the TOSS sample we further investigated one of the SNPs for measures of marital status and quality. Moreover, in the TCHAD sample we explored the longitudinal relationship between precursors of pair-bonding during childhood and subsequent behavior in romantic relationships. Finally, in the TCHAD study and in the Child and Adolescent Twin Study of Sweden (CATSS) (n = 1771), the association between the same SNP and childhood behaviors was investigated.
Results: One SNP (rs7632287) in OXTR was associated with traits reflecting pair-bonding in women in the TOSS and TCHAD samples. In girls the rs7632287 SNP was further associated with childhood social problems, which longitudinally predicted pair-bonding behavior in the TCHAD sample. This association was replicated in the CATSS sample in which an association between the same SNP and social interaction deficit symptoms from the autism spectrum was detected.
Conclusion: These results suggest an association between variation in OXTR and human pair-bonding and other social behaviors, possibly indicating that the well-described influence of oxytocin on affiliative behavior in voles could also be of importance for humans.
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Developmental stability and leadership effectiveness
Carl Senior et al.
Leadership Quarterly, forthcoming
Abstract:
Developmental stability is the degree to which we can withstand environmental or genetic stressors during development. Fluctuating asymmetry (FA), concerns the extent to which the right and left side of the body is asymmetrical and is one way to measure developmental stability. Two studies were carried out that examined both the predictive value of leader FA with leadership behaviors and its role in facilitating group performance. The first study examined the hypothesis that a leader's FA is correlated with scores on the Multifactor Leadership Questionnaire (MLQ). The results revealed individuals with a more asymmetrical morphology scored higher on the transformational, but not transactional, dimensions of leadership behavior. A second study examined the hypothesis that asymmetrical morphology and leadership effectiveness would share a positive relationship. In this study participants who led a business game exercise, revealed a positive relationship between FA and self-reported well-being and task satisfaction. Importantly, there was also a positive correlation between the leader's FA score and group performance. The role that developmental stability may play in leadership effectiveness is discussed in the wider context of evolutionary psychology.
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It's My Body and I'll Do What I Like With It: Bodies as Objects and Property
Anne Phillips
Political Theory, December 2011, Pages 724-748
Abstract:
What, if any, is the problem with treating bodies as objects or property? Is there a defensible basis for seeing bodies as different from "other" material resources? Or is thinking the body special a kind of sentimentalism that blocks clear thinking about matters such as prostitution, surrogate motherhood, and the sale of spare kidneys? I argue that the language we use does matter, and that thinking of the body as property encourages a self/body dualism that obscures the power relations involved in all contracts that cedes authority over the body. Recognising the self as embodied, however, also makes it harder to insist on sharp distinctions between activities that involve the body and those that "just" involve the mind, hence harder to justify refusing payment for explicitly body services while condoning it for those to which the body is more incidental. I therefore provide a modest defence of monetary compensation for those who "donate" bodily products or services. Compensation does not, however, mean markets for there is at least one sense in which the body is special. This is that more so, and more intrinsically than other markets, markets in body parts or bodily services depend on inequality. I use this to make a case against such markets.
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The Uncertain Timing of Reaching 8 Billion, Peak World Population, and Other Demographic Milestones
Sergei Scherbov, Wolfgang Lutz & Warren Sanderson
Population and Development Review, September 2011, Pages 571-578
Abstract:
We present new probabilistic forecasts of the timing of the world's population reaching 8 billion, the world's peak population, and the date at which one-third or more of the world's population would be 60+ years old. The timing of these milestones, as well as the timing of the Day of 7 Billion, is uncertain. We compute that the 60 percent prediction interval for the Day of 8 Billion is between 2024 and 2033. Our figures show that there is around a 60 percent chance that one-third of the world's population would be 60+ years old in 2100. In the UN 2010 medium variant, that proportion never reaches one-third. As in our past forecasts (Lutz et al. 2001, 2008), we find the chance that the world's population will peak in this century to be around 84 percent and the timing of that peak to be highly uncertain. Focal days, like the Day of 7 Billion, play a role in raising public awareness of population issues, but they give a false sense of the certainty of our knowledge. The uncertainty of the timing of demographic milestones is not a constant of nature. Understanding the true extent of our demographic uncertainty can help motivate governments and other agencies to make the investments necessary to reduce it.
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Mortality, The Family and The Indian Ocean Tsunami
Elizabeth Frankenberg et al.
Economic Journal, August 2011, Pages F162-F182
Abstract:
Over 130,000 people died in the 2004 Indian Ocean tsunami. The correlates of survival are examined using data from the Study of the Tsunami Aftermath and Recovery (STAR), a population-representative survey collected in Aceh and North Sumatra, Indonesia, before and after the tsunami. Children, older adults and females were the least likely to survive. Whereas socio-economic factors mattered relatively little, the evidence is consistent with physical strength playing a role. Pre-tsunami household composition is predictive of survival and suggests that stronger members sought to help weaker members: men helped their wives, parents and children, while women helped their children.