Chimpanzees are highly motivated to copy the behaviour of subordinate demonstrators and innovators; but behaviours seeded by dominant individuals were not transmitted as faithfully

Factors shaping social learning in chimpanzees. Stuart K. Watson. A Thesis Submitted for the Degree of PhD at the University of St Andrews, 2018. http://hdl.handle.net/10023/12781

Abstract: Culture is an important means by which both human and non-human animals transmit useful behaviours between individuals and generations. Amongst animals, chimpanzees live particularly varied cultural lives. However, the processes and factors that influence whether chimpanzees will be motivated to copy an observed behaviour are poorly understood. In this thesis, I explore various factors and their influence on social learning decisions in chimpanzees. In turn, the chapters examine the influence of (i) rank-bias towards copying dominant individuals, (ii) majority and contextual influences and finally (iii) individual differences in proclivity for social learning. In my first experiment, I found evidence that chimpanzees are highly motivated to copy the behaviour of subordinate demonstrators and innovators in an open - diffusion puzzle - box paradigm. In contrast, behaviours seeded by dominant individuals were not transmitted as faithfully. This finding has important implications for our understanding of the emergence of novel traditions. In my second experiment, I found that some chimpanzees are highly motivated to relinquish an existing behaviour to adopt an equally rewarding alternative if it is consistently demonstrated by just one or two individuals within a group context, but not in a dyadic context. This contrasts with prior studies which argue that chimpanzees are highly conservativ e and may hint at a hitherto unrecognised process by which conformity-like behaviour might occur. Finally, I performed a novel type of ‘meta’ analysis on 16 social learning studies carried out at our research site to determine whether individuals demonstra ted consistency in their social learning behaviour across experimental contexts. Strong evidence for individual differences in social information use was found, with females more likely to use social information than males. No effect of age, research exper ience or rearing history was found. This presents a promising new method of studying individual differences in behaviour using the accumulated findings of previous work at a study site.

No evidence that mate choice in humans is dependent on the major histocompatibility complex (MHC)

No evidence that mate choice in humans is dependent on the MHC. Mircea Cretu Stancu, Wigard Kloosterman, Sara L Pulit. bioRxiv, doi: https://doi.org/10.1101/339028

Abstract: A long-standing hypothesis in biology proposes that various species select mates with a major histocompatibility complex (MHC) composition divergent from their own, so as to improve immune response in offspring. However, human and animal studies investigating this mate selection hypothesis have returned inconsistent results. Here, we analyze 239 mate-pairs of Dutch ancestry, all with whole-genome sequence data collected by the Genome of the Netherlands project, to investigate whether mate selection in humans is MHC dependent. We find no evidence for MHC-mediated mate selection in this sample (with an average MHC genetic similarity in mate pairs (Qc) = 0.829; permutation-based p = 0.703). Limiting the analysis to only common variation or considering the extended MHC region does not change our findings (Qc = 0.671, p = 0.513; and Qc = 0.844, p = 0.696, respectively). We demonstrate that the MHC in mate-pairs is no more genetically dissimilar (on average) than a pair of two randomly selected individuals, and conclude that there is no evidence to suggest that mate choice is influenced by genetic variation in the MHC.

Depleted feelings were correlated with being young, female, politically non-extreme, less well educated, having pain/illness, & with finding life less meaningful, & with multitasking and hurrying. They increased across the day & droppped after meal times, attesting to the value of food & sleep

Self-Control “In the Wild”: Experience Sampling Study of Trait and State Self-Regulation. Roy F. Baumeister, Bradley R.E. Wright, David Carreon. Self & Identity, https://www.researchgate.net/publication/325405317_Self-Control_in_the_Wild_in_press

Abstract: An experience sampling study with a large community sample (N=3,327) furnished data on trait and state self-control in everyday life. State measures were self-reports of ego-depleting events (restraining self, effortful decisions, and pushing self to do unwanted tasks) and feelings of depletion (emotional overreactions, difficulty making up mind, less mental energy). People with high trait self-control reported fewer such feelings and events than others. Poor sleep quality and interpersonal conflict were strong predictors of depleted feelings, and indeed the combination of very poor sleep and high interpersonal conflict led to a dramatic spike in reports of extremely depleted feelings. Depleted feelings were positively correlated with being young, female, politically non-extreme, and less well educated, and with finding life less meaningful, as well as with multitasking and hurrying. They increased across the day despite drops after meal times, thus attesting to the value of food and sleep. Pain and illness also raised them. Among other implications, the data suggest a composite picture of the daily life of someone with low trait self-control: frequently rushing and hurrying, not thinking about what they are doing, and just responding automatically to the current situation, as well as suffering aftereffects of interpersonal conflict and poor quality sleep.

KEYWORDS: self-control, self-regulation, ego depletion, interpersonal conflict, sleep

We present multiple lines of direct and indirect evidence showing that both an increased prenatal androgen load and increased adult androgen activity are involved in suicide completion

The androgen model of suicide completion. Bernd Lenz et al. Progress in Neurobiology, https://doi.org/10.1016/j.pneurobio.2018.06.003

Highlights
•    Hitherto, no objective markers, either alone or in combination, can reliably predict who will complete a suicide.
•    Organizational and activational androgen effects are implicated in the transition from suicidal ideation to suicide completion.
•    Prenatal androgen-induced neurodevelopmental aspects contribute to the risk for suicide completion later in life.
•    Modifiable maternal behavioral traits during pregnancy influence the offspring’s prenatal androgen load and may increase the risk for suicide completion later in life.
•    The novel ideation-to-completion framework in suicide research and the androgen model of suicide completion provide the basis for the development of predictive and preventive strategies in the future.

Abstract

Suicide is a devastating public health issue that imposes severe psychological, social, and economic burdens not only for the individuals but also for their relatives, friends, clinicians, and the general public. Among the different suicidal behaviors, suicide completion is the worst and the most relevant outcome. The knowledge of biological etiopathological mechanisms involved in suicide completion is limited. Hitherto, no objective markers, either alone or in combination, can reliably predict who will complete a suicide. However, such parameters are strongly needed to establish and optimize prediction and prevention.

We introduce here a novel ideation-to-completion framework in suicide research and discuss the problems of studies aiming at identifying and validating clinically useful markers. The male gender is a specific risk factor for suicide, which suggests that androgen effects are implicated in the transition from suicidal ideation to suicide completion. We present multiple lines of direct and indirect evidence showing that both an increased prenatal androgen load (with subsequent permanent neuroadaptations) and increased adult androgen activity are involved in suicide completion. We also review data arguing that modifiable maternal behavioral traits during pregnancy contribute to the offspring’s prenatal androgen load and increase the risk for suicide completion later in life.

We conclude that in utero androgen exposure and adult androgen levels facilitate suicide completion in an additive manner. The androgen model of suicide completion provides the basis for the development of novel predictive and preventive strategies in the future.

Abbreviations: AAS, anabolic-androgenic steroids; BDNF, brain derived neurotrophic factor; BMI, body mass index; CSF, cerebrospinal fluid; DHEA, dehydroepiandrosterone; DSM, Diagnostic and Statistical Manual of Mental Disorders; HPA, hypothalamic-pituitary-adrenal; HPG, hypothalamic-pituitary-gonadal; HR, hazard ratio; ICD, International Classification of Diseases; NGFI-A, nerve growth factor-induced protein A; OR, odds ratio; PMDD, premenstrual dysphoric disorder; PMS, premenstrual syndrome; PTSD, posttraumatic stress disorder; SD, standard deviation; WHO, World Health Organization; YMRS, Young Mania Rating Scale; 2D:4D ratio, second-to-fourth-finger length ratio; 5HTTPR, 5-hydroxytryptamine transporter

Keywords: Prenatal androgen exposure; 2D:4D; suicide; suicidal ideation; suicide attempt; suicide completion; sex hormones; testosterone; androgens; brain organization; ideation-to-completion framework in suicide research