Structural, Functional, & Metabolic Brain Differences as a Function of Identity or Orientation: It is possible that more differences too subtle to measure with available tools yet contributing to identity & orientation could be found

Structural, Functional, and Metabolic Brain Differences as a Function of Gender Identity or Sexual Orientation: A Systematic Review of the Human Neuroimaging Literature. Alberto Frigerio, Lucia Ballerini & Maria Valdés Hernández. Archives of Sexual Behavior, May 6 2021. https://rd.springer.com/article/10.1007/s10508-021-02005-9

Abstract: This review systematically explored structural, functional, and metabolic features of the cisgender brain compared with the transgender brain before hormonal treatment and the heterosexual brain compared to the homosexual brain from the analysis of the neuroimaging literature up to 2018, and identified and discussed subsequent studies published up to March 2021. Our main aim was to help identifying neuroradiological brain features that have been related to human sexuality to contribute to the understanding of the biological elements involved in gender identity and sexual orientation. We analyzed 39 studies on gender identity and 24 on sexual orientation. Our results suggest that some neuroanatomical, neurophysiological, and neurometabolic features in transgender individuals resemble those of their experienced gender despite the majority resembling those from their natal sex. In homosexual individuals the majority resemble those of their same-sex heterosexual population rather than their opposite-sex heterosexual population. However, it is always difficult to interpret findings with noninvasive neuroimaging. Given the gross nature of these measures, it is possible that more differences too subtle to measure with available tools yet contributing to gender identity and sexual orientation could be found. Conflicting results contributed to the difficulty of identifying specific brain features which consistently differ between cisgender and transgender or between heterosexual and homosexual groups. The small number of studies, the small-to-moderate sample size of each study, and the heterogeneity of the investigations made it impossible to meta-analyze all the data extracted. Further studies are necessary to increase the understanding of the neurological substrates of human sexuality.

Discussion

Main Findings

The results from our systematic review and meta-analyses do not allow us to conclude on the specific brain phenotypes differential for each of the groups covered by this review. Although functional MRI studies (i.e., involving either fMRI or rs-MRI) on gender identity seem to indicate that fronto-parietal and cingulo-opercular brain regions are differentially relevant in transgenderism, a clear pattern accompanied by consistent structural changes is still to be found. Studies on gender identity with moderate-to-larger samples which included individuals with different sexual orientation in their control groups (Baldinger-Melich et al., 2020; Manzouri & Savic, 2019), exposed the complexities underlying both gender identity and sexual orientation. The data extracted may suggest that before hormonal treatment the majority of transgenders’ brain features covered by the studies reviewed could be similar to those of their natal sex, but certainly some brain parameters differ resembling those of their experienced gender. Also, although homosexual’s neuroanatomy, neurophysiology, and neurometabolism may tend to resemble those of heterosexual individuals of their same sex, some brain features differ and are similar to those of heterosexual individuals of the opposite sex in some of the studies analyzed.

The compilation of the data from the studies included shows neural differences between the groups studied. However, brain functions are mediated by different brain areas and their interactions, rather than by single structures. The correlation or association between a certain brain function, volumetric change or activation, with a certain activity and/or behavior does not establish whether (or not) that structure/function is causally important for that activity/behavior (Koob et al., 2013; Maney, 2016). It merely shows a possible involvement or apparent trend. Complex human behaviors (and few simple behaviors) cannot be entirely explained by phenomena occurring only in a single brain region. Therefore, the idea that brain sexual differences cause behavioral sexual differences, rather than being an assumption, still constitutes a hypothesis to verify.

Studies on cisgender and heterosexual samples have reported sex differences in brain anatomy on a global scale, regarding absolute volumes (Kurth et al., 2016). Studies have also reported sexual dimorphism in the relative sizes and shapes of regional brain structures, with the direction of the sex effect varying between regions, including the Broca’s region (Kurth et al., 2016), corpus callosum (Prendergast et al., 2015), amygdala and hippocampus (Giedd et al., 1996). These findings reflect on the selectivity of the brain regions analyzed by the studies included in this review. However, research investigating differences at the level of regional tissue volumes is highly contradictory. A large study that analyzed MRI data of 1400 cisgender heterosexual individuals from four different datasets (Joel et al., 2015) found substantial overlap in the distribution of anatomical traits between males and females in all brain regions and connections examined, undermining attempts to clearly distinguish between “male” and “female” forms of specific brain features. They arrived at the idea that human brains cannot in fact, be distinctly categorized into two distinct classes but rather, that male and female brains are comprised of “unique mosaics” of features, some of which are more common in one sex than the other and some that are common in both.

Some authors refer to an early programming of gender and sexual inclination driven by sexual differentiation in the brain, proposing that the latter influences the development of the brain areas modulating body perception (i.e., related to gender identity) or sexual arousal (i.e., related to sexual orientation) (Burke et al., 2017; Manzouri & Savic, 2019). Others underline the interaction between brain, culture and behavior, arguing that structural and functional brain changes in transgender individuals may be consequence of culture and behavior (Mohammadi & Khalegi, 2018). The etiology and drivers of differences in gender identity and sexual orientation is out of the scope of this review, and caution must be exercised to drive conclusions from the neuroscience literature alone, as human behavior, ultimately, is not reducible to biological nor to cultural factors, but is a consequence of their interaction. As such, human sexuality is a multilevel complex, and the challenge is to investigate how biological, historical and cultural elements interact with each other.

Regions of Interest Analysis

The lack of data did not allow us to meta-analyze the information obtained from the studies that conducted ROI analyses. From extracting and summarizing all the information available, differences were found between cisgender and transgender people in white matter microstructure, volumetric analyses, cortical thickness, and corpus callosum shape. Differences between heterosexual and homosexual people were found in cortical thickness, subcortical volumes, and cerebral hemisphere, but not in white matter tracts. The studies included, in the rest of the ROIs analyzed, either did not find significant differences between cisgender and transgender brains nor between heterosexual and homosexual; or found significant differences just between transgenders and opposite sex cisgenders, and between homosexuals and opposite sex heterosexuals (see Tables 3 and 4). Our findings on gender identity are consistent with previous studies that also attempted to summarize the literature findings on this topic, according to which gross morphology in transgenders is more similar to cisgender people of their natal sex than to cisgender people of their experienced gender (Guillamon et al., 2016; Kreukels & Guillamon, 2016; Mueller et al., 2017; Smith et al., 2015), even though white matter microstructure (Kreukels & Guillamon, 2016; Mueller et al., 2017; Smith et al., 2015), cortical thickness (Guillamon et al., 2016; Smith et al., 2015), and subcortical volumes (Mueller et al., 2017) may deviate from the biological sex towards values of experienced gender.

Stereotaxic Coordinates Analysis

Occipital brain regions, involved in visual processing, are the ones that most frequently were found to have a different activation in cisgenders compared to transgenders, followed by some fronto-temporal foci. This is not surprising given that, in general, most fMRI studies involved in both analyses involved visual stimulation. In addition, specifically the BA 23 had different activations for heterosexuals with respect to homosexuals. Our meta-analysis found different brain activations between different groups scattered across the whole brain, but overall with low frequency (see Tables 5 and 6). Our results on gender identity are consistent with some of the previous studies mentioned above, according to which in certain brain areas transgenders’ activation is closer to those of their experienced gender (Guillamon et al., 2016; Smith et al., 2015). While there is still concensus that a clear picture has yet to emerge (Mueller et al., 2017), recent advances in artificial intelligence confirm the observations above, by indicating that some fronto-parietal and cingulo-opercular areas may be of relevance for predicting hormonal therapy outcomes (Moody et al., 2021).

Metabolic Analysis

In transgenders and homosexuals, some metabolic features seem to differ slightly from cisgenders of their natal sex and from heterosexuals of their natal sex respectively. However, given the reduced number of studies included that conducted these analyses, these findings cannot be generalized. This is in line with what the scientific literature on gender identity up to date has concluded in this respect (Smith et al., 2015).

Strengths and Limitations

To the best of our knowledge, this is the first systematic review and meta-analysis of the neuroimaging literature on structural, functional, and metabolic differences as a function of both gender identity (before the hormonal treatment) and sexual orientation. In addition, we carefully extracted and processed all data from all studies considered for meta-analyses and made them publicly available to facilitate further research in this important area.

Several limitations regarding the small sample size of the meta-analysis and the heterogeneity of the investigations must be acknowledged. The analyses of our systematic search up to 2018 included 51 studies (i.e., 30 on gender identity and 21 on sexual orientation) all with relatively small samples, conducted with different neuroimaging techniques (1 SPECT, 3 PET, 6 fMRI, 8 rs-fMRI, and 13 MRI on gender identity; 4 PET, 5 MRI, 3 rs-fMRI, and 11 fMRI on sexual orientation). Different studies conducted with MRI investigated different brain structures (cortex, subcortical volumes, white matter, CSF, and ventricles in gender identity; cortex, subcortical volumes, and white matter in sexual orientation). fMRI was conducted under different stimulations (1 smelling, 1 vocal stimulation, 1 mental rotation task, 1 verbal fluency test, and 2 visual in gender identity; 10 visual stimulation and 1 emotional judgment task in sexual orientation). Metabolic analysis investigated different brain areas (hypothalamic network, serotonin transport distribution in different ROI, and rCBF in gender identity studies; hypothalamic activation and functional connectivity in sexual orientation studies) using different neuroimaging techniques (PET and SPECT in gender identity research; PET in sexual orientation research). As a result, it was not possible to meta-analyze the results from all studies that fit our inclusion/exclusion criteria, and the main contribution of our work, therefore, is limited to the scientific compilation and synthesis of the data available. An update on the primary search conducted in one database, added 12 papers to the analyses which, although enriched the data presented, was rather confirmatory of our main findings and added heterogeneity to the results.

Moreover, some studies had some limitations regarding the presentation of their data. First, some studies did not report statistical parameters and just reported whether or not there were significant differences between cisgenders and transgenders and between heterosexuals and homosexuals. Second, other studies reported statistical parameters only in case of significant differences between groups, and omitted reporting negative results (i.e., when no differences were found) (gender identity investigation: Burke et al., 2014; Kranz et al., 2014b, 2015; Ku et al., 2013; Lin et al., 2014; Luders et al., 2009; Nota et al., 2017; Pol et al., 2006; Santarnecchi et al., 2012; Soleman et al., 2013; Spies et al., 2016; Yokota et al., 2005; Zubiaurre-Elorza et al., 2013; sexual orientation investigation: Hu et al., 2008; Ponseti et al., 2007; Savic and Lindström, 2008; Sylva, 2013; Zeki & Romaya, 2010; for more detailed information, please see analysis of bias in Appendix 5 and 6). A complete presentation of scientific data, including negative results, is important to precisely evaluate scientific investigations on a certain topic (Matosin et al., 2014).

Information on the biological sex of the studies’ participants is part of the scientific data we collected and made available. The data presented show MtF and FtM transgender individuals do not have mirror images of brain differences. However, the heterogeneity of the design of the studies involved, despite enriching the scope of this review, due to the limited number of studies included and their sample sizes, made it impossible to draw conclusions on specific biological sex differences for the groups covered in this review. For example, some papers compared MtF with MC, others MtF with FC, others FtM with MC, and others FtM with FC. The studies included in this review on transgenderism did not provide information on early-onset or late-onset transgenderism. Therefore, analysis and information of this important point is lacking.

Finally, as Guillamon et al. (2016) noted, some studies conducted on gender identity did not report the sexual orientation of the individuals that constituted their sample. Gender identity and sexual orientation are conceptually different, i.e., both cisgender and transgender people are either heterosexual or homosexual (Burke et al., 2017; Moser, 2010), and there are more gender identities other than cis-/transgender(ism) (such as genderqueer or non-binary) and other sexual orientations other than hetero-/homosexual(ism) (such as bi-, pan-, and asexual). Sexual orientation could be associated with brain structural specific features regardless and independently from gender identity as some recent studies suggest (Baldinger-Melich et al., 2020; Manzouri & Savic, 2019). Thus, meaning that the structural, functional, and metabolic variations found in homosexual transgenders with respect to heterosexual cisgenders may be related to their sexual orientation rather than to their gender identity (Blanchard et al., 1987). A recent study identified brain regions where both sexual orientation and gender identity seemingly interact (Wang, Han, et al., 2020).

The self-reported quality of the father-son relationship did not predict hegemonic masculinity; adverse childhood experiences, mother-son relationship quality, & family support also failed to predict hegemonic masculinity

Daddy issues: Friends rather than fathers influence adult men's hegemonic masculinity. George Van Doorn, Jacob Dye, Ma Regina de Gracia. Personality and Individual Differences, Volume 171, March 2021, 110467. https://doi.org/10.1016/j.paid.2020.110467

Abstract: Hegemonic masculinity often refers to negative and socially aversive traits and behaviours associated with idealised masculine norms. Extant literature suggests that several social determinants might influence men's conformity to negative and socially-averse masculine norms, but studies are limited. The present study examined whether the quality of the father-son relationship in childhood impacts hegemonic masculinity in adulthood. In addition, we also determined whether adverse childhood experiences, mother-son relationship quality, as well as familial and peer support explained any additional variance in hegemonic masculinity after controlling for the quality of a man's relationship with his father. A sample of 188 men (aged 18 to 62 years) completed an online survey that included the K-Short Form-42, the Adverse Childhood Experiences scale, and the Conformity to Masculine Norms Inventory-29. Results from a hierarchical regression analysis showed that the self-reported quality of the father-son relationship did not predict hegemonic masculinity. Adverse childhood experiences, mother-son relationship quality, and family support also failed to predict hegemonic masculinity. However, a decrease in support from friends was associated with an increase in hegemonic masculinity, even after controlling for all other variables. The importance of peer relationships in developing and maintaining a man's adherence to traditional masculine norms is underscored.

Austria, England, Ireland and Sweden: Voters from all sides are more satisfied if there are more parties to choose from; the positive effect is stronger among the higher educated

Do voters prefer more parties on the ballot? John Högström, André Blais & Carolina Plescia. Acta Politica, May 6 2021. https://rd.springer.com/article/10.1057/s41269-021-00203-w

Abstract: Citizens’ evaluation of how well the system works is central to the legitimacy of a democratic system. Elections and voting are crucial parts of the democratic system, and therefore, it is very important to evaluate voter satisfaction with the electoral process. In this study, we evaluate one aspect of the electoral process: the supply of parties on the ballot paper, and we use a direct measure of satisfaction with the party choices available on the ballot. We performed a survey experiment with a representative sample of citizens in four Western European democracies: Austria, England, Ireland and Sweden. The results point to a clear answer: voters are more satisfied if there are more parties to choose from. The findings also show that the positive effect is stronger among the higher educated. We also examined if it is the presence of an ideologically close option that really matters. The results show that respondents in every ideological position prefer more parties. This strongly suggests that it is the number of parties, as such that matters.

 

Beauty perceptions causally influenced moral standing attributions across a wide range of animal species independently from perceived patiency, agency, and harmfulness

Beauty of the Beast: Beauty as an important dimension in the moral standing of animals. Christoph Klebl et al. Journal of Environmental Psychology, May 7 2021, 101624. https://doi.org/10.1016/j.jenvp.2021.101624

Highlights

• Beauty perceptions predicted moral standing attributions across a wide range of animal species independently from perceived patiency, agency, and harmfulness.

• Beauty causally influenced moral standing attributions to animals independently from other factors likely to influence moral standing.

• The findings may help conservationists to identify the most effective ways to attract funds for the conservation of endangered species.

Abstract: Conservationists have sought to identify avenues through which to gain public support for efforts to halt the accelerating decline in animal diversity. Previous research has identified perceived internal qualities of animals that lead people to view them as deserving of protection for their own sake; that is, increase their moral standing. In two studies, we found that perceived beauty is an external aesthetic quality that leads people to attribute moral standing to animals independently from animals’ perceived mental capacities associated with patiency or agency, and dispositional harmfulness, as well as other factors likely to influence moral standing. In Study 1, we found that beauty perceptions predicted moral standing across a wide range of animal species from 12 biological categories independently from perceived patiency, agency, and harmfulness. In Study 2 (pre-registered), we found that beauty causally influenced moral standing attributions to animals independently from animals’ perceived internal qualities, as well as their perceived similarity to humans, familiarity, and edibility. Our findings provide insight into another factor which contributes to the perceived moral status of animals, and therefore may help conservationists to identify the most effective ways to attract funds for conservation efforts.

Keywords: beautyattractivenessmoral standinganimal conservation

Greater likelihood of substance use when a worker receives performance pay: Result supports conjectures that stress & effort increase with performance pay & that alcohol & drug use is a coping mechanism for workers

From 2020... Does performance pay increase alcohol and drug use? Benjamin Artz, Colin P. Green & John S. Heywood. Journal of Population Economics volume 34, pages969–1002. Jun 2020. https://link.springer.com/article/10.1007/s00148-020-00776-4

Abstract: Using US panel data on young workers, we demonstrate that those who receive performance pay are more likely to consume alcohol and illicit drugs. Recognizing that this likely reflects worker sorting, we first control for risk, ability, and personality proxies. We further mitigate sorting concerns by introducing worker fixed effects, worker-employer match fixed effects, and worker-employer-occupation match fixed effects. Finally, we present fixed effect IV estimates. All of these estimates continue to indicate a greater likelihood of substance use when a worker receives performance pay. The results support conjectures that stress and effort increase with performance pay and that alcohol and drug use is a coping mechanism for workers.

We not only favor our genes (altruism for those with similar genetics), greater memetic similarity (similarity in important attitudes & values) was associated with greater altruism

Baucal, Aleksandar, and Aleksandra Lazić. 2021. “Selfish Genes or Selfish Memes?.” PsyArXiv. May 5. doi:10.31234/osf.io/c4j92

Abstract: When “selfish genes” and “selfish memes” compete, who would one rather help – an ideologically similar acquaintance or a relative with a different worldview? Two preregistered experiments disentangled the effects of selfish genes and selfish memes (operationalized as similarity in important attitudes and values) on participants’ self-reported willingness to help in hypothetical everyday-favor and life-or-death situations. In Study 1 (N = 364), altruism was highest for siblings, and the same for cousins and nonkin; greater memetic similarity was associated with greater altruism, and the interaction term was not significant. Study 2 (N = 252) replicated this during the COVID-19 pandemic, suggesting the effects are not altered in life-threatening situations. Studies suggest that meme selfishness shapes altruism independently of gene selfishness. This becomes especially important in times of rising social polarization.

Violating the male breadwinning norm results in a 35 per cent increase in the likelihood of partner violence and a 20 per cent increase in emotional abuse against women

Gender norms and domestic abuse: Evidence from Australia. Zhang, Y; Breunig, R. Tax and Transfer Policy Institute, Working paper 5/2021. May 2021. https://taxpolicy.crawford.anu.edu.au/publication/ttpi-working-papers/18650/gender-norms-and-domestic-abuse-evidence-australia

Abstract: Australia conforms to the gender norm that women should earn less than their male partners. We investigate the impact of violating this cultural norm on the incidence of domestic violence and emotional abuse against women and men in Australia. Violating the male breadwinning norm results in a 35 per cent increase in the likelihood of partner violence and a 20 per cent increase in emotional abuse against women. We find no effect on abuse against men. The strong effect of violating the gender norm on abuse against women is present across age ranges, income groups and cultural and educational backgrounds.

Damselflies: Latitudinal clines in sexual selection, sexual size dimorphism and sex-specific genetic dispersal during a poleward range expansion

Latitudinal clines in sexual selection, sexual size dimorphism and sex-specific genetic dispersal during a poleward range expansion. Rachael Y Dudaniec et al. In Journal of Animal Ecology, May 2021. https://lup.lub.lu.se/search/publication/9833d2c4-cb48-44b4-a762-f66e253670ab

Abstract: Range expansions can be shaped by sex differences in behaviours and other phenotypic traits affecting dispersal and reproduction. Here, we investigate sex differences in morphology, behaviour and genomic population differentiation along a climate-mediated range expansion in the common bluetail damselfly (Ischnura elegans) in northern Europe. We sampled 65 sites along a 583-km gradient spanning the I. elegans range in Sweden and quantified latitudinal gradients in site relative abundance, sex ratio and sex-specific shifts in body size and mating status (a measure of sexual selection). Using single nucleotide polymorphism (SNP) data for 426 individuals from 25 sites, we further investigated sex-specific landscape and climatic effects on neutral genetic connectivity and migration patterns. We found evidence for sex differences associated with the I. elegans range expansion, namely (a) increased male body size with latitude, but no latitudinal effect on female body size, resulting in reduced sexual dimorphism towards the range limit, (b) a steeper decline in male genetic similarity with increasing geographic distance than in females, (c) male-biased genetic migration propensity and (d) a latitudinal cline in migration distance (increasing migratory distances towards the range margin), which was stronger in males. Cooler mean annual temperatures towards the range limit were associated with increased resistance to gene flow in both sexes. Sex ratios became increasingly male biased towards the range limit, and there was evidence for a changed sexual selection regime shifting from favouring larger males in the south to favouring smaller males in the north. Our findings suggest sex-specific spatial phenotype sorting at the range limit, where larger males disperse more under higher landscape resistance associated with cooler climates. The combination of latitudinal gradients in sex-biased dispersal, increasing male body size and (reduced) sexual size dimorphism should have emergent consequences for sexual selection dynamics and the mating system at the expanding range front. Our study illustrates the importance of considering sex differences in the study of range expansions driven by ongoing climate change.

We find support for coalition formation between individuals who share food & labour, & especially kinship; physically formidable men & men higher in informal status were more likely to provide coalitional support over time

Coalitions and conflict: A longitudinal analysis of men's politics. Daniel Redhead, Christopher R. von Rueden. Evolutionary Human Sciences, May 5 2021. https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/coalitions-and-conflict-a-longitudinal-analysis-of-mens-politics/06D187167A6F3B1C7D2379D13D89BFA0

Abstract: To negotiate conflict and navigate status hierarchy, individuals in many species form coalitions. We describe inter-personal conflicts and assess theories of coalitionformation in a small-scale human society. Based on longitudinal and cross-sectional social network analysis of men in two communities of Tsimane forager-horticulturalists, we find evidence of reciprocity in coalitional support, as well as evidence of transitivity: an ally of my ally is likely to become my ally. We find mixed support for coalition formation between individuals who share a common adversary. Coalition formation was also predicted by food- and labour-sharing and especially by kinship. Physically formidable men and men higher in informal status were more likely to provide coalitional support over time; evidence was mixed that they receive more coalitional support. The highest status men are hubs of a dense coalitional support network that indirectly link all men in the community. These findings suggest male coalition formation is multiply motivated, and in general reveals the political dynamics that structure men’s lives in small, relatively egalitarian communities.

Media Summary: Among the Tsimane, the emergence of coalitions over time is primarily motivated by social status and existing social relationships between individuals.

Popular version https://www.eurekalert.org/pub_releases/2021-05/mpif-cac050521.php

From 2020... Sex and gender: modifiers of health, disease, and medicine

From 2020... Sex and gender: modifiers of health, disease, and medicine. Franck Mauvais-Jarvis et al. The Lancet, Volume 396, Issue 10250, August 22-28, 2020, Pages 565-582. https://doi.org/10.1016/S0140-6736(20)31561-0

Summary: Clinicians can encounter sex and gender disparities in diagnostic and therapeutic responses. These disparities are noted in epidemiology, pathophysiology, clinical manifestations, disease progression, and response to treatment. This Review discusses the fundamental influences of sex and gender as modifiers of the major causes of death and morbidity. We articulate how the genetic, epigenetic, and hormonal influences of biological sex influence physiology and disease, and how the social constructs of gender affect the behaviour of the community, clinicians, and patients in the health-care system and interact with pathobiology. We aim to guide clinicians and researchers to consider sex and gender in their approach to diagnosis, prevention, and treatment of diseases as a necessary and fundamental step towards precision medicine, which will benefit men's and women's health.

Personality might at least partly be expressed in people’s voice pitch: Results suggest substantial negative relationships between voice pitch and self-reported sociosexuality, dominance & extraversion in men & women

Stern, Julia, Christoph Schild, Benedict C. Jones, Lisa M. DeBruine, Amanda Hahn, David Puts, Ingo Zettler, et al. 2019. “Do Voices Carry Valid Information About a Speaker's Personality?.” PsyArXiv. April 11. doi:10.31234/osf.io/9a68c

Abstract: Research on links between peoples’ personality traits and their voices has primarily focused on other peoples’ personality judgments about a target person based on a target person’s vocal characteristics, particularly voice pitch. However, it remains unclear whether individual differences in voices are linked to actual individual differences in personality traits, and thus whether vocal characteristics are indeed valid cues to personality. Here, we investigate how the personality traits of the Five Factor Model of Personality, sociosexuality, and dominance are related to measured fundamental frequency (voice pitch) and formant frequencies (formant position). For this purpose, we conducted a secondary data analysis of a large sample (2,217 participants) from eleven different, independent datasets with a Bayesian approach. Results suggest substantial negative relationships between voice pitch and self-reported sociosexuality, dominance and extraversion in men and women. Thus, personality might at least partly be expressed in people’s voice pitch. Evidence for an association between formant frequencies and self-reported personality traits is not compelling but remains uncertain. We discuss potential underlying biological mechanisms of our effects and suggest a number of implications for future research.

Rolf Degen summarizing... Win–win denial: People have a strong tendency to misperceive trade as a zero sum game in which buyers get the short end of the stick

Win–win denial : the psychological underpinnings of zero-sum thinking. Johnson, Samuel G B, Zhang, Jiewen and Keil, Frank C. Journal of Experimental Psychology: General (In Press). May 2021. http://wrap.warwick.ac.uk/151065

Rolf Degen's take: https://twitter.com/DegenRolf/status/1389868809796866048

Abstract: A core proposition in economics is that voluntary exchanges benefit both parties. We show that people often deny the mutually beneficial nature of exchange, instead espousing the belief that one or both parties fail to benefit from the exchange. Across 4 studies (and 8 further studies in the Supplementary Materials), participants read about simple exchanges of goods and services, judging whether each party to the transaction was better off or worse off afterwards. These studies revealed that win–win denial is pervasive, with buyers consistently seen as less likely to benefit from transactions than sellers. Several potential psychological mechanisms underlying win–win denial are considered, with the most important influences being mercantilist theories of value (confusing wealth for money) and theory of mind limits (failing to observe that people do not arbitrarily enter exchanges). We argue that these results have widespread implications for politics and society.

Gender differences in climate change views are statistically significant only in relatively affluent countries, the differences are larger at higher levels of affluence, & greater climate risk amplifies the difference in concern

Gender and climate change views in context: a cross-national multilevel analysis. Kyle W. Knight & Jennifer E. Givens. The Social Science Journal, Apr 27 2021. https://doi.org/10.1080/03623319.2021.1913041

Abstract: Women express statistically significantly greater climate change concern than men in a number of countries, but this gender gap is not universal around the world. We use multilevel models with cross-level interactions to analyze how the individual-level effects of gender on climate change concern and perceived seriousness are influenced by three macro-level contextual factors: national affluence, climate risk, and gender equality. We find that gender differences in climate change views are statistically significant only in relatively affluent countries, the differences are larger at higher levels of affluence, and greater climate risk amplifies the difference in concern but not perceived seriousness. The effect of gender on climate change views does not statistically significantly vary by level of gender equality.

KEYWORDS: Climate changegender gapconcernperceived seriousnessmultilevelcross-national

Is Divisive Politics Making Americans Sick? Associations of Perceived Partisan Polarization with Physical and Mental Health Outcomes Among Adults in the US

Is Divisive Politics Making Americans Sick? Associations of Perceived Partisan Polarization with Physical and Mental Health Outcomes Among Adults in the United States. Sameera S. Nayak et al. Social Science & Medicine, May 4 2021, 113976, https://doi.org/10.1016/j.socscimed.2021.113976

Highlights

• Perceived partisan polarization has plausible effects on physical and mental health

• Increased perceived polarization was associated with incident anxiety and depression

• No significant associations were found with hypertension or high cholesterol

• Perceived partisan polarization may be a key determinant of mental health outcomes

Abstract:

Objectives: To investigate whether changes in perceived partisan polarization since the 2016 US presidential election and current perceptions of polarization are associated with the onset of physical and mental health conditions in adults.

Methods: We surveyed a nationally-representative sample (n=2,752) of US adults between December 2019 and January 2020. We used multivariable logistic regression to estimate associations between perceived polarization and the incidence of hypertension, high cholesterol, obesity, diabetes, and anxiety, depressive, and sleep disorders in or after 2016 and current self-rated health. Our secondary exposure variables measured perceptions of mass and elite polarization at the state and national level. Perceived mass polarization measured perceptions of the partisan gap between Democrat and Republican voters; perceived elite polarization measured perceptions of the partisan gap between Democrat and Republican elected officials.

Results: Participants reporting an increase in polarization had 52-57% higher odds of developing depressive disorders (OR=1.52, 95% CI: 1.01, 2.29, P=0.047) and anxiety disorders (OR=1.57, 95% CI: 1.07, 2.29, P=0.02) compared to participants who perceived no change in polarization. Those reporting high (vs. low) levels of perceived state-level mass polarization had a 49% higher odds of incident depressive disorders (P=0.03). Participants who perceived high levels of state-level elite polarization reported a 71% higher odds of incident depressive disorders (P=0.004) and a 49% higher odds of incident sleep disorders (P=0.03).

Conclusions: Perceptions of partisan polarization may represent important factors that are linked to the onset of mental health and sleep disorders.

Keywords: Partisan polarizationsocial determinants of healthdepressionanxietypresidential election

National development—and particularly economic growth—is under severe challenge as an important and legitimate objective of action within the development industry

National Development Delivers: And How! And How? Lant Pritchett. April 26, 2021. https://lantpritchett.org/wp-content/uploads/2021/05/Development-Delivers_firstdraft.pdf

Abstract: Core dual ideas of early development, economics and practice, were that (a) national  development was a four-fold transformation of countries towards: (i) a more productive  economy, (ii) a more responsive state, (iii) more capable administration, and (iv) a shared  identity and equal treatment of citizens and that (b) this four-fold transformation of national  development would lead to higher levels of human wellbeing. The second is strikingly correct:  development delivers. National development is empirically necessary for high wellbeing (no  country with low levels of national development has high human wellbeing) and also empirically sufficient (no country with high national development has low levels of human wellbeing).  Three measures of national development: productive economy, capable administration, and  responsive state, explain (essentially) all of the observed variation in an omnibus indicator of  wellbeing based on over 58 distinct indicators, the Social Progress Index. How national  development delivers on wellbeing varies, in three ways. One, economic growth is much more  important for achieving wellbeing at low versus high levels of income. Two, economic growth  matters more for “basic needs” than for other dimensions of wellbeing (like social inclusiveness or environmental quality). Three, state capability matters more for wellbeing outcomes that  depend on public production than on private goods (and for some wellbeing indicators, like  physical safety, for which growth doesn’t matter at all). While these findings may seem too  common sense to be worth a paper, national development—and particularly economic growth—is, strangely, under severe challenge as an important and legitimate objective of action within the  development industry. 

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I argue that this de-emphasis on national development is wrong. National development (including economic growth) does powerfully deliver on human wellbeing for low-income countries—but much less so for richer countries. The development debate is largely a confusion of preference and priority and the powerful human tendency to project our immediate concerns onto others: to look in a mirror and describe what we see out a window. Suppose one ignores the “cold” economic numbers and takes the Social Progress Index (and its three major components Basic Human Needs, Foundations of Wellbeing, and Opportunity) as the “true” normative goal to be pursued. National development, measured by GDP per capita, State Capability, and Democracy is a strongly necessary and sufficient condition for achieving high levels of human wellbeing measured on these indicators. There are no countries with high levels of the SPI with low national development and there are no countries with high levels of national development with low levels of SPI.

In addition, a flexible examination of the connections between the different physical indicators of wellbeing and three components of national development (GDPPC, State Capability, and Democracy) reveals three interesting, and ultimately sensible, findings.

First, if one allows the impact of GDPPC on wellbeing indicators to vary flexibly across the level of GDPC the data shows that growth is tremendously more important for improving well being in developing than in developed economies.

Second, for developing countries GDPPC is much more important for elements the SPI regards as “Basic Needs” (like nutrition and basic health, access to water and sanitation, improved shelter) than it is for those classified as “Opportunity.”

Third, if one separates the components of national development into “economic” (GDPPC) and “governance” (state capability and democracy) the data suggests that growth has a larger impact on elements of wellbeing that are “private” goods (like nutrition) whereas “governance” is more important for “public” goods—like the environment.

The empirical data suggest that Prime Minister Arden and the OECD might be right, at their high levels of national development, to emphasize as their priorities direct measures of wellbeing over GDP (or national development). But developing country politicians—even with the exact same preferences—cannot reach the levels of human wellbeing enjoyed by those living New Zealand without much higher levels of GDP per capita and state capability.

Both men and women stereotype women (but not men) who engage in casual sex as having low self-esteem, mediated by inferences that women who have casual sex are unsatisfied with their mating strategy

Lay Beliefs About Gender and Sexual Behavior: First Evidence for a Pervasive, Robust (but Seemingly Unfounded) Stereotype. Jaimie Arona Krems et al. Psychological Science, May 4, 2021. https://doi.org/10.1177/0956797620983829

Abstract: Although casual sex is increasingly socially acceptable, negative stereotypes toward women who pursue casual sex remain pervasive. For example, a common trope in television, film, and other media is that women who engage in casual sex have low self-esteem. Despite robust work on prejudice against women who engage in casual sex, little empirical work has focused on the lay theories individuals hold about them. Across six experiments with U.S. adults (N = 1,469), we found that both men and women stereotype women (but not men) who engage in casual sex as having low self-esteem. This stereotype is held explicitly and semi-implicitly; is not driven by individual differences in religiosity, conservatism, or sexism; and is mediated by inferences that women who have casual sex are unsatisfied with their mating strategy—yet the stereotype persists when women are explicitly described as choosing to have casual sex. Finally, the stereotype appears to be unfounded; across experiments, the same participants’ sexual behavior was not significantly correlated with their self-esteem.

Keywords: social perception, social cognition, self-esteem, sex differences, sex/gender, stereotypes, sexual behavior, open data

Single dose testosterone administration enhances novelty responsiveness and short-term habituation in healthy males

Single dose testosterone administration enhances novelty responsiveness and short-term habituation in healthy males. Huihua Fang et al. Hormones and Behavior, Volume 131, May 2021, 104963. https://doi.org/10.1016/j.yhbeh.2021.104963

Highlights

• Testosterone increased P2 habituation in response to repeated standard tones.

• Testosterone attenuated involuntary attention toward repeated sensory events.

• Testosterone increased P3a responses to infrequent deviant tones.

• Testosterone decreased Mismatch Negativity responses to infrequent deviant tones.

• Testosterone facilitated involuntary attentional orienting toward sensory changes.

Abstract: The role of testosterone in sensory perception suggests that testosterone likely regulates adaptive responses to sensory changes, including habituation to repeated events and responsiveness to novel events. To test this hypothesis, we investigated how testosterone modulates brain responses to rapid changes in sensory inputs. Using a double-blind, placebo-controlled, within-participant design, each participant received a single dose of either testosterone or placebo, and then completed a passive auditory oddball task in which infrequent deviant tones were embedded in a series of frequent standard tones. Analysis of novelty-evoked potentials revealed smaller Mismatch Negativity (MMN) responses, but larger P3a responses in the testosterone session than in the placebo session. This suggests testosterone attenuates MMN responses that are associated with pre-attentive novelty detection and enhances P3a responses that are associated with involuntary attentional orientation toward novelty. Along with the repetition of standard tones, P2 responses on the auditory evoked potentials became significantly attenuated in the testosterone session, but not in the placebo session. This suggests testosterone enhances short-term habituation of P2 responses to recurring sensory events, which has been associated with bottom-up attention allocation. Mediation analysis further revealed that the role of testosterone in promoting attentional orientation toward novelty could be explained by the influence it exerts on short-term habituation and pre-attentive novelty detection. Overall, testosterone facilitated involuntary attention switching—withdrawal of attention from repeated sensory events and orientation toward novel sensory events—at the cost of attenuated pre-attentive novelty detection. This finding provides insight into the interplay between endocrinology and involuntary attentional processes.

Keywords: TestosteroneHabituationNovelty responsivenessInvoluntary attention orientationAuditory evoked potentials

While children felt about 3 years or 34% older than their chronological age, older adults (60+ years) felt, on average, between 10.74 and 21.07 years or 13%–18% younger

Pinquart, M., & Wahl, H.-W. (2021). Subjective age from childhood to advanced old age: A meta-analysis. Psychology and Aging, 36(3), 394–406, May 2021. https://doi.org/10.1037/pag0000600

Abstract: The present meta-analysis analyzed how the gap between subjective age and chronological age changes across the life-span and whether the size of this gap varies across regions of the globe. In addition, we tested for sources of the national differences. A systematic search in electronic databases (PsycInfo, Medline, Google Scholar, PSYNDEX) and cross-referencing identified 294 studies (with mean age ranging from 8 to 105 years) that were included in random-effects meta-analyses. While children felt about 3 years or 34% older than their chronological age, older adults (60+ years) felt, on average, between 10.74 and 21.07 years or 13%–18% younger. Associations between chronological age and the size of proportional differences between subjective and chronological were best described as a quadratic relationship, while associations with the size of absolute differences could also be described as a linear relationship. The widening of the gap between subjective age and chronological age across adulthood was found in all continents. Although adults reported a relatively younger subjective age across the globe, these differences were strongest in North America, Western Europe, and Australia/Oceania, and weakest in Africa. The regional differences disappeared after statistically controlling for national levels of individualism-collectivism, power distance, preference for young people rather than older adults, and quality of life of older people.

Dramatic Changes to Well-known Places Go Unnoticed

Rosenbaum, R. Shayna, Julia G. Halilova, Sabrina Agnihotri, Maria C. D'Angelo, Gordon Winocur, Jennifer Ryan, and Morris Moscovitch. 2020. “Dramatic Changes to Well-known Places Go Unnoticed.” PsyArXiv. October 30. doi:10.31234/osf.io/ypg96

Abstract: How well do we know our city? It turns out, much more poorly than we might imagine. We used declarative memory and eye-tracking techniques to examine people’s ability to detect modifications of landmarks in Toronto locales with which they have had extensive experience. Participants were poor at identifying which scenes contained altered landmarks, whether the modification was to the landmarks’ relative size, internal features, or surrounding context. To determine whether an indirect measure would prove more sensitive, we tracked eye movements during viewing. Changes in overall visual exploration, but not to specific regions of change, were related to participants’ explicit endorsement of scenes as modified. These results support the contention that very familiar landmarks are strongly integrated within the spatial context in which they were first experienced, so that any changes that are consciously detected are at a global or coarse, but not local or fine-grained, level.

When people exercised with their romantic partner, they experienced higher positive affect during exercise, higher daily positive affect, and were more satisfied with their relationship

Better together: The impact of exercising with a romantic partner. Kyrsten Sackett-Fox, Judith Gere, John Updegraff. Journal of Social and Personal Relationships, April 27, 2021. https://doi.org/10.1177/02654075211012086

Abstract: Many people have goals to increase their physical activity levels through engaging in exercise, but have difficulty establishing and maintaining an exercise routine. Research shows that people are more successful at exercising if they do so together with their romantic partner. In this study, we examined how exercising with a romantic partner may influence the experience of exercise itself, as well as people’s daily experiences. Specifically, we examined how joint exercise influences daily and exercise affect, daily relationship satisfaction, and amount of daily exercise. Young adults who were currently involved in a romantic relationship (N = 95) completed intake questionnaires and 14 daily reports of their exercise behavior, exercise and daily affect, and daily relationship satisfaction. Multilevel models showed that on days when people exercised with their romantic partner, they experienced higher positive affect during exercise, higher daily positive affect, and were more satisfied with their relationship compared to days when they exercised without their partner. No effects were found on daily and exercise negative affect, or amount of exercise. This study illustrates how exercising with a romantic partner may improve people’s experience of both exercising and their daily experiences, and may help provide a reason why people might be more successful at maintaining their exercise routine when they exercise together with their romantic partner.

Keywords: Affect, daily diary, exercise, goal pursuit, physical activity, relationship satisfaction, romantic relationships, young adults

Heterosexual, lesbian, and gay participants all perceived bisexual men as more attracted to men than to women

Bisexual erasure: Perceived attraction patterns of bisexual women and men. Thekla Morgenroth  Teri Kirby. European Journal of Social Psychology, May 3 2021. https://doi.org/10.1002/ejsp.2773

Abstract: Bisexual individuals face identity denial and erasure and qualitative analyses suggest that it may be gendered, such that people stereotype bisexual women as truly heterosexual and bisexual men as truly gay. Across three studies (total N = 787), we examined perceptions of bisexual targets’ attraction patterns. Participants rated the attraction of either a female or male bisexual target to both the same gender/sex and opposite gender/sex. An internal meta‐analysis revealed that heterosexual, lesbian, and gay participants all perceived bisexual men as more attracted to men than to women. No such pattern emerged for bisexual women. These differences between the perception of bisexual women and bisexual men were also reflected in the endorsement of an explicit measure of bisexual erasure. Our findings add to the understanding of the unique bias bisexual people face by showing that perceived attraction patterns may underlie the labelling of bisexual men as “actually gay”.

The assisted reproduction families generally showed high levels of family functioning and children's adjustment from early childhood through to adolescence

Love and Truth: What Really Matters for Children Born Through Third‐Party Assisted Reproduction. Susan Golombok. Child Development Perspectives, May 4 2021. https://doi.org/10.1111/cdep.12406

Abstract: Ever since the birth of the first baby born through in vitro fertilization in 1978, advances in reproductive technologies have raised new concerns about the outcomes for children. In this article, I summarize research on children born through assisted reproduction involving a third party, that is, children born through egg donation, sperm donation, and surrogacy, with particular attention to the findings of a longitudinal study of children born to heterosexual couples in the United Kingdom. The assisted reproduction families generally showed high levels of family functioning and children's adjustment from early childhood through to adolescence, suggesting that biological relatedness is less important than positive parent–child relationships for the well‐being of children conceived by third‐party assisted reproduction. Similarly, studies of families created by third‐party reproduction with two mothers, single mothers, two fathers, and single fathers have shown that these families function well.

Conclusions

Despite concerns to the contrary, in the U.K. Longitudinal Study of Assisted Reproduction Families, the assisted reproduction families generally showed high levels of family functioning and children's adjustment from early childhood through to adolescence. The differences identified did not point to dysfunctional family relationships but instead reflected variation within the expected range. The idea that third‐party assisted reproduction adversely affects parenting and children's adjustment comes, in part, from research showing an increased likelihood of childhood psychological problems in adoptive families (Palacios & Brodzinsky, 2010) and stepfamilies (Dunn, Deater‐Deckard, Pickering, O'Connor, & Golding, 1998), in which children similarly lack a biological link to one or both parents. However, the problems experienced by adopted children and stepchildren often arise from difficult family situations before being adopted, or before or after moving into a stepfamily. Adopted children often have suffered maltreatment before being placed with their adoptive parents, sometimes for years, and many have been moved from one foster family to another before being adopted (Palacios & Brodzinsky, 2010). Children in stepfamilies often have been separated from a parent to whom they were attached and are required to form relationships with new family members. Moreover, stepparents generally do not see stepchildren as their own children (Dunn, Davies, O'Connor, & Sturgess, 2000). In contrast, children born through assisted reproduction are raised from birth by parents who wanted to have them and who consider them to be their own children. Biological relatedness seems to be less important for the well‐being of children conceived by third‐party assisted reproduction than are warm and responsive relationships between parents and their children.

Although the absence of a biological connection between children and their parents does not appear to cause difficulties for children, not telling children about their origins or delaying disclosure beyond the preschool years is associated with less positive outcomes for adolescents' well‐being and family relationships. Moreover, just because adolescents born through donor conception and surrogacy are functioning well does not mean that their donor or surrogate is of no significance to them. Some donor‐conceived adolescents have little interest in finding out about their donor. But others search for information on the Internet. In investigations of motivations, adolescents and young adults who searched for their sperm donor and donor siblings were curious about resemblances in physical and personality characteristics, wanted to learn about their ancestry, and wished for a more complete story of how they were born (Canzi, Accordini, & Facchin, 2019; Jadva, Freeman, Kramer, & Golombok, 2010; Scheib, McCormick, Benward, & Ruby, 2020; Scheib, Ruby, & Benward, 2017). In many cases, these youth were more interested in their donor siblings than in their donors; they wanted information about their donor, and some wanted to meet him, but they usually did not see him as their father, and they were more likely to develop enduring connections with their donor siblings. In a study that explored why some adolescents are more interested in their donor relations than others, secure attachment relationships with mothers were associated with greater acceptance of and curiosity about donor conception (Slutsky et al., 2016).

The U.K. Longitudinal Study of Assisted Reproduction Families collected data from mothers, fathers, children, and teachers using standardized interviews, observational assessments, and standardized questionnaires. Nevertheless, it is the only prospective, comparative study of parent–child relationships and children's psychological adjustment in families formed through sperm donation, egg donation, surrogacy, and unassisted conception and the only in‐depth study of children born through surrogacy. Therefore, replication should be a priority, especially given the increasing numbers of children being born through assisted reproduction worldwide. Because the parents in the study were predominantly White and of medium to high socioeconomic status, the findings may not be relevant to more diverse families, who may struggle financially to afford fertility treatment, or who are from religious or ethnic backgrounds that do not accept third‐party assisted reproduction, requiring parents to keep their children's biological origins secret.

The study also focused on children born to heterosexual couples. More research is being done on lesbian‐mother families formed by sperm donation (Bos & Gartrell, 2020), single heterosexual‐mother families formed by sperm donation (Golombok, Zadeh, Freeman, Lysons, & Foley, 2020; Golombok, Zadeh, Imrie, Smith, & Freeman, 2016), families with gay fathers created through surrogacy and egg donation (Golombok, Blake, et al., 2017; Rubio et al., 2020), and single‐father families with children born through surrogacy and egg donation (Carone, Baiocco, Lingiardi, & Barone, 2020), all with similarly positive outcomes. These findings show that families created by third‐party reproduction with two mothers, single mothers, two fathers, or single fathers function well, irrespective of the number, gender, and sexual orientation of the parents. As with traditional families formed by assisted reproduction, in nontraditional families, the quality of parent–child relationships appears to be more important for children than the way in which the family is constructed.

The overall findings of research on children born through third‐party assisted reproduction are consistent with a relational developmental systems framework (Osher, Cantor, Berg, Steyer, & Rose, 2020; Overton, 2015): Relationships, such as those between parents and children, and context, such as the disclosure or nondisclosure of children's biological origins, interact reciprocally with characteristics of the child to influence development. Newly emerging family forms raise new questions about the psychological consequences for children. Transgender parents who have had children through fertility preservation and lesbian couples that use one partner's egg to create the other partner's pregnancy are just two examples of 21st‐century families made possible through advances in assisted reproduction. Researchers need to study the outcomes of parents and children in these families. However, based on what we know from current studies, warm and supportive relationships between parents and their children, and openness about the children's origins, seem to be what matter most for children born through third‐party assisted reproduction.

Polycarpa mytiligera, a chordate incapable of asexual development, achieves bidirectional regeneration & fully regenerates all body structures & organs after being cut in three pieces; each fragment got to be an independent, functional individual

And Then There Were Three…: Extreme Regeneration Ability of the Solitary Chordate Polycarpa mytiligera. Tal Gordon et al. Front. Cell Dev. Biol., April 15 2021. https://doi.org/10.3389/fcell.2021.652466

Abstract: Extensive regenerative ability is a common trait of animals capable of asexual development. The current study reveals the extraordinary regeneration abilities of the solitary ascidian Polycarpa mytiligera. Dissection of a single individual into separate fragments along two body axes resulted in the complete regeneration of each fragment into an independent, functional individual. The ability of a solitary ascidian, incapable of asexual development, to achieve bidirectional regeneration and fully regenerate all body structures and organs is described here for the first time. Amputation initiated cell proliferation in proximity to the amputation line. Phylogenetic analysis demonstrated the close affinity of P. mytiligera to colonial species. This evolutionary proximity suggests the ability for regeneration as an exaptation feature for colonial lifestyle. P. mytiligera’s exceptional regenerative abilities and phylogenetic position highlight its potential to serve as a new comparative system for studies seeking to uncover the evolution of regeneration and coloniality among the chordates.

Discussion

Ascidians are unique among the chordates as they present robust regeneration abilities, including whole body regeneration, following an injury (Voskoboynik et al., 2007; Blanchoud et al., 2018; Kassmer et al., 2020). The current study has uncovered exceptional regeneration abilities in a solitary ascidian, a group of animals considered to be regeneratively deficient compared to their colonial relatives (Kassmer et al., 2019). P. mytiligera’s provides a valuable opportunity to elucidate the evolution of coloniality and reveal conserved pathways that regulate chordate regeneration.

P. mytiligera Regeneration Involves Extensive Cell Proliferation and Reorganization Processes

P. mytiligera presented an extraordinary regeneration plasticity, being able to reconstruct an entire animal from each small body fragment. Histological sections confirmed that despite no residue of essential organs, such as the heart and neural complex, remaining in the body fragment, the animal was nonetheless able to regenerate and regain its complete morphology and functionality.

P. mytiligera’s regeneration process can be divided into three phases: (1) wound-healing; (2) increased cell proliferation in the injured area; and (3) morphogenesis and formation of tissues and organs. These basic stages, underlying tissue regeneration, are highly conserved, being found in a wide variety of animals capable of regeneration (Alvarado and Tsonis, 2006; Ricci and Srivastava, 2018). In planarians, regeneration involves the assembly of a blastema composed of pluripotent somatic stem cells. Limb regeneration in salamanders and fin regeneration in zebrafish also require the formation of a blastema; however, there the blastema is composed of a mixture of cells with different and restricted potentials (Alvarado and Tsonis, 2006; Sánchez Alvarado, 2006; Tanaka and Reddien, 2011; Tanaka, 2016; Marques et al., 2019). In P. mytiligera, amputation initiated extensive cell division in proximity to the amputation line, resembling a blastema formation. Proliferating cell were also found in regenerating structures at later stages of regeneration, suggesting their direct involvement in the formation of the new tissue (see Figure 7 for summary). Undifferentiated circulatory cells were shown to be involved in tissue regeneration in solitary and colonial ascidians (Rinkevich et al., 2006; Auger et al., 2010; Jeffery, 2014, 2015, 2019). In colonial Styelidae species, a population of pluripotent or multipotent undifferentiated circulatory cells contributes to the formation of somatic tissues during budding and whole body regeneration (Laird et al., 2005; Voskoboynik et al., 2007; Brown and Swalla, 2012; Kassmer et al., 2020). In the solitary ascidian C. intestinalis, injury-induced regeneration resulted in the proliferation of circulatory cells located in the branchial basket. These cells were also labeled with alkaline phosphatase and anti-piwi antibody, indicating their undifferentiated state (Auger et al., 2010; Jeffery, 2014). In P. mytiligera, the branchial basket showed high level of EdU+ cells along the regeneration process. In addition, all dissected body fragments contained part of the branchial basket and the circulatory cells enclosed within it. While it is remained to be determined if these cells originated in the branchial basket or merely use it as a means of transport to the regenerating area, the high numbers of proliferating cells found in the branchial basket following amputation indicate a possible role in anterior regeneration.

FIGURE 7

Figure 7. Summary of proliferating cell dynamic in P. mytiligera inferred from EdU experiments. (A,A′) Control. (A) In vivo image, (A′) illustration. During homeostasis, proliferating cells (purple spheres) are evenly dispersal along the branchial basket (BB) and body wall (BW) [Oral siphon (OS), atrial siphon (AS)]. (B,B′) Amputation day. (B) In vivo image, (B′) illustration. The level of proliferating cells remains similar to that of the control. (C,C′) 5 days following anterior amputation. (C) In vivo image, (C′) illustration. Proliferating cells specifically accumulate at the amputation site in the branchial basket and body wall in proximity to the regenerating area. (D,D′) 10 days following amputation. (D) In vivo image, (D′) illustration. As the amputated structures regenerated, the level of proliferating cell decreased in relation to 5 dpa, although remaining higher than those of the control. Scale bar in (A,B): 1 mm, and in: (C,D): 500 μm.

While we focused on the cell division in the body wall and branchial basket in the current study, proliferating cells were also found in other structures as the digestive system and endostyle. The digestive system of the control animals as well as in animals in different stages of regeneration showed EdU positive cells. These cells, however, are probably unrelated to the regeneration signals, as intestinal and stomach tissues are continuously being replaced as part of their normal homeostasis (Ermak, 1981; Jeffery, 2014). The endostyle, which serves as a stem-cell niche in colonial species (Voskoboynik et al., 2008), showed EdU labeling at the early stages of regeneration, implying a local cell proliferation and its possible involvement in regeneration. However, it is important to note that the results of the DV axis amputation experiment indicate that the endostyle is not essential for regeneration to occur, as the dorsal body part was still able to complete the regeneration process following endostyle removal.

Among ascidians, the ability to regenerate amputated body fragments into separate individuals is strongly associated with coloniality and asexual development, as no solitary species has to date been observed to possess such robust abilities (Jeffery, 2015; Kassmer et al., 2019). The model system, C. intestinalis, is capable of regenerating its anterior structures, such as the siphons and neural complex from the posterior parts; whereas the anterior parts failed to regenerate posterior structures such as the heart and digestive system, and eventually decomposed (Jeffery, 2014). P. mytiligera’s bidirectional regeneration and unusual ability to regenerate all tissue types and organ systems distinguishes it from other solitary ascidian species studied so far (see Supplementary Table 4 for summary) and suggests the activation of regeneration programs that might be compromised or inhibited in other solitary species (Liu et al., 2013; Sikes and Newmark, 2013).

P. mytiligera’s High Regeneration Abilities Might Constitute a Pre-adaptation (Exaptation) Trait for a Colonial Life-Style

P. mytiligera’s reproduction and developmental processes resemble those of most solitary ascidians and no indication of asexual development has been found for this species (Gordon et al., 2020). However, its ability to create “clones″ following dissection led us to further question its phylogenetic position.

The Stolidobranchia common ancestor is believed to have been solitary, and coloniality is assumed to be a derived life-style (Mukai et al., 1978; Zeng et al., 2006). The Styelidae is the only stolidobranch family composed of colonial and solitary species, with both presenting a wide range of developmental and regeneration processes (Alié et al., 2020). Phylogenetic analyses have indicated several independent acquisitions of coloniality in this group (Kott, 1985, 2005; Pérez-Portela et al., 2009; Alié et al., 2018, 2020). Further support for multiple transition events from a solitary to a colonial life-style comes from species that have diverged from the classical solitary or colonial characteristics, and which present intermediate morphological and developmental features. For example, solitary species of Polycarpa and Dendrodoa genera present colonial characteristics such as viviparity, a typical colonial feature (Millar, 1954, 1962; Svane and Young, 1989; Pérez-Portela et al., 2009).

Our phylogenetic results agree with Alié et al. (2018) and separate the Polycarpa genus from the exclusively solitary clade, placing it in a single mixed clade composed of colonial and solitary species. This topology suggests that the last common ancestor of the mixed clade was a solitary animal from which coloniality evolved at a later stage (Alié et al., 2018). According to this scenario, high regeneration abilities, as presented by P. mytiligera, might be a pre-adaptation (exaptation) trait for colonial life-style. The position of the colonial Polyandrocarpa zorritensis among members of the genus Polycarpa is especially intriguing, as it further supports the genetic similarity of Polycarpa to highly regenerative colonial species, as well as indicating a recent transition event from solitary to colonial form in this family (Alié et al., 2018; Scelzo et al., 2019).

To date, ascidian whole-body regeneration has been considered a colonial feature, as no solitary species had been shown before to possess such robust abilities. P. mytiligera’s ability to regenerate each individual body fragment into a whole animal has the potential to separate regeneration specific pathways from asexual development programs.

Our present findings present a valuable new model system for comparative developmental studies seeking to elucidate the evolution of regeneration and coloniality among the chordates.

Data Availability Statement

The datasets generated for this study can be found in the online repositories. The names of the repository/repositories and accession number(s) can be found below: Sequence data have been deposited under: https://www.ncbi.nlm.nih.gov/bioproject/660913. The phylogenetic datasets are available at: https://github.com/dorohuchon/Polycarpa_mytiligera_transcriptome. The maximum likelihood trees, the alignments, and the transcriptome assembly have been deposited at https://github.com/dorohuchon/Polycarpa_mytiligera_transcriptome.

CMIP6 models: They considerably overestimate the warming rate observed in 1998–2013, exhibiting an obvious warming acceleration rather than the observed deceleration

Could CMIP6 climate models reproduce the early-2000s global warming slowdown? Meng Wei, Qi Shu, Zhenya Song, Yajuan Song, Xiaodan Yang, Yongqing Guo, Xinfang Li & Fangli Qiao. Science China Earth Sciences, Apr 15 2021. https://link.springer.com/article/10.1007/s11430-020-9740-3

Abstract: The unexpected global warming slowdown during 1998–2013 challenges the existing scientific understanding of global temperature change mechanisms, and thus the simulation and prediction ability of state-of-the-art climate models since most models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) cannot simulate it. Here, we examine whether the new-generation climate models in CMIP6 can reproduce the recent global warming slowdown, and further evaluate their capacities for simulating key-scale natural variabilities which are the most likely causes of the slowdown. The results show that although the CMIP6 models present some encouraging improvements when compared with CMIP5, most of them still fail to reproduce the warming slowdown. They considerably overestimate the warming rate observed in 1998–2013, exhibiting an obvious warming acceleration rather than the observed deceleration. This is probably associated with their deficiencies in simulating the distinct temperature change signals from the human-induced long-term warming trend and or the three crucial natural variabilities at interannual, interdecadal, and multidecadal scales. In contrast, the 4 models that can successfully reproduce the slowdown show relatively high skills in simulating the long-term warming trend and the three key-scale natural variabilities. Our work may provide important insight for the simulation and prediction of near-term climate changes.