Thursday, March 17, 2022

Multiple pathways to paternal care in primates: The case studies we have presented here challenge the assumption that male parental care & extended breeding bonds are strictly limited to species that live in pairs or form cooperatively breeding groups

Pathways to paternal care in primates. Stacy Rosenbaum, Joan B. Silk. Evolutionary Anthropology: Issues, News, and Reviews, March 15 2022.

Abstract: Natural selection will favor male care when males have limited alternative mating opportunities, can invest in their own offspring, and when care enhances males' fitness. These conditions are easiest to fulfill in pair-bonded species, but neither male care nor stable “breeding bonds” that facilitate it are limited to pair-bonded species. We review evidence of paternal care and extended breeding bonds in owl monkeys, baboons, Assamese macaques, mountain gorillas, and chimpanzees. The data, which span social/mating systems and ecologies, suggest that there are multiple pathways by which conditions conducive to male care can arise. This diversity highlights the difficulty of making inferences about the emergence of male care in early hominins based on single traits visible in the fossil record. We discuss what types of data are most needed and the questions yet to be answered about the evolution of male care and extended breeding bonds in the primate order.

Genetic variation in a bitter taste receptor gene alter early smoking behaviors in adolescents and young adults

Does genetic variation in a bitter taste receptor gene alter early smoking behaviors in adolescents and young adults? Alaa Alsaafin et al. Addiction, March 16 2022.


Background and aims: Variation in the TAS2R38 taste receptor gene alters the ability to taste bitter compounds. We tested whether TAS2R38 variation influences early smoking behaviors in adolescence, a critical period of acquisition when taste may influence the natural course of tobacco use.

Design and participants: Observational study (Nicotine Dependence in Teens (NDIT)). Cox proportional hazards models were conducted using data from European ancestry adolescent participants who initiated smoking during follow-up (n=219, i.e., incident smokers). In young adulthood, cross-sectional analyses were restricted to self-reported European ancestry current smokers at age 24 (n=148).

Setting: Montreal, Canada.

Measurements: In adolescents, the rates of attaining early smoking milestones were estimated for tasters {PAV diplotypes (i.e., PAV/PAV or PAV/AVI)} versus non-tasters {AVI diplotype (i.e., AVI/AVI)}. In young adults, associations between tasting status and a nicotine intake biomarker (cotinine + 3’hydroxycotinine) and past-week cigarette consumption were assessed.

Findings: Among incident smokers, similar rates to first whole cigarette were found between the diplotype groups (hazard ratio (HR)=1.05; 95% confidence interval (CI) 0.75-1.48, p=0.765). However, smokers with the PAV (versus AVI) diplotypes attained monthly smoking more rapidly (HR=1.55, 95% CI 1.04-2.32, p=0.033) and had faster conversion to three different measures of tobacco dependence (International Classification of Diseases: HR=2.29, 95% CI 0.99-5.28, p=0.052; modified Fagerström Tolerance Questionnaire: HR=3.02, 95% CI 1.04-8.79, p=0.043; Hooked on Nicotine Checklist: HR=1.87, 95% CI 0.98-3.60, p=0.059). At age 24, those with PAV (versus AVI) diplotypes had higher mean cotinine + 3’hydroxycotinine (197 versus 143 ng/mL; p=0.053).

Conclusions: Adolescents with a genetic variation increasing their ability to taste bitter compounds appear to escalate more quickly to monthly smoking and tobacco dependence during adolescence and have higher nicotine intake in young adulthood versus those without that genetic variation.

Conservatives are less likely than liberals to accept welfare handouts for themselves unless the welfare program has a work requirement policy

Goenka, Shreyans and Thomas, Manoj, Are Conservatives Less Likely Than Liberals to Accept Welfare? The Psychology of Welfare Politics (April 1, 2022). Journal of the Association for Consumer Research 7(3),

Abstract: Research has shown that conservatives tend to oppose the distribution of welfare to other people. However, are conservatives less likely than liberals to accept welfare for themselves? We find that the difference in liberals' and conservatives' welfare enrollment depends on whether the welfare program has a work requirement policy. A natural field experiment shows that when the supplemental nutritional program (SNAP) had a work requirement, liberals and conservatives were equally likely to enroll in this program. In the absence of a work requirement, conservatives were less likely than liberals to enroll in it. Follow-up experiments replicate this result and demonstrate the underlying mechanism: conservatives' adherence to binding moral values (loyalty, authority, and purity; Graham, Haidt and Nosek 2009) makes them hesitant to accept welfare without a work requirement. Policymakers can deploy marketing messages to mitigate this effect and boost conservatives' enrollment in such welfare programs.

Contrary to the social brain hypothesis, new work suggests that ecological factors, rather than social complexity, best predict bigger brain size in primates

Understanding the human brain: insights from comparative biology. Alex R. DeCasien, Robert A. Barton, James P. Higham. Trends in Cognitive Sciences, March 16 2022.


.  New research has questioned or contradicted multiple long-standing claims about human brain evolution.

.  Contrary to the social brain hypothesis, new work suggests that ecological factors, rather than social complexity, best predict relative brain size across primate species.

.  Brain size does not have similar effects or cognitive implications in different phylogenetic lineages since it is associated with different mosaic structural changes.

.  Although the human prefrontal cortex is proportionally large, this may not represent an adaptive specialization and research emphasis on this region has distracted attention from the importance of wider neural networks.

.  Functional and anatomical integration, rather than developmental constraints, may primarily explain patterns of brain region size covariation across species.

Abstract: Human brains are exceptionally large, support distinctive cognitive processes, and evolved by natural selection to mediate adaptive behavior. Comparative biology situates the human brain within an evolutionary context to illuminate how it has been shaped by selection and how its structure relates to evolutionary function, while identifying the developmental and molecular changes that were involved. Recent applications of powerful phylogenetic methods have uncovered new findings, some of which overturn conventional wisdom about how and why brains evolve. Here, we focus on four long-standing claims about brain evolution and discuss how new work has either contradicted these claims or shown the relevant phenomena to be more complicated than previously appreciated. Throughout, we emphasize studies of non-human primates and hominins, our close relatives and recent ancestors.

Keywords: evolutionselectionneurodevelopmentneuroanatomygenomicstranscriptomics