Sibling analysis of 232 mice: Twins were exposed to either enriched or impoverished environments; enrichment was associated with an increase in the heritability of some personality & cognitive traits

Mouse twins separated when young: A history of exploration doubles the heritability of boldness and differentially affects the heritability of measures of learning. Louis D. Matzel et al. Intelligence, Volume 74, May–June 2019, Pages 34-42. https://doi.org/10.1016/j.intell.2019.01.005

Highlights
• A sibling analysis of 232 mice assessed the sensitivity of heritability to environmental history
• Twins were exposed to either enriched or impoverished environments
• Learning, physical, and personality traits were all heritable
• Environmental enrichment was associated with an increase in the heritability of some personality and cognitive traits
• Estimates of heritability can be sensitive to manipulation of environmental history

Abstract: Most quantifiable traits exhibit some degree of heritability. The heritability of physical traits is often high, but the heritability of some personality traits and intelligence can also be highly heritable. Importantly, estimates of heritability can change dramatically depending on such variables as the age or the environmental history of the sample from which the estimate is obtained. Interpretation of these changing estimates is complicated in studies of humans, where (based on correlational observations) environmental variables are hard to directly control or specify. Using laboratory mice, here we could control specific environmental variables. We assessed 58 groups of four full sibling male CD-1 genetically heterogeneous mice (n = 232). Using a standard full-sibling analysis, physical characteristics (body weight and brain weight) were highly heritable (h of body weight = 0.66 on a 0–1 scale), while behaviors indicative of a personality trait (exploration/boldness) and learning abilities (in a passive avoidance and egocentric maze task) were weakly-to-moderately heritable. Half of the siblings from each set of four were housed in an “enriched” environment, which provided extensive and varied opportunities for exploration. This enrichment treatment promoted improvements in learning and a shift toward a more bold personality type. Relative to animals in control (“impoverished” environments), the history of enrichment had significant impact on estimates of heritability. In particular, the heritability of behaviors related to the personality trait (exploration/boldness) more than doubled, and a similar increase was observed for learning (in the passive avoidance task). Physical traits (brain and body weight), however, were insensitive to environmental history (where in both environments, animals received the same diet). These results indicate that heritable traits can be responsive to variations in the environment, and moreover, that estimates of heritability of learning and personality traits are strongly influenced by environments that modulate those traits.

Keywords: HeritabilityLearningEnvironmental enrichmentBoldnessBody weightBrain weight

Paternal biobehavioral influence on the family: Preliminary data from the D.A.D.I.O. Project

Paternal biobehavioral influence on the family: Preliminary data from the D.A.D.I.O. Project. Nikki J Clauss, Erin Harrington, Jennifer Byrd-Craven. Human Behavior and Evolution Society 31st annual meeting. Boston 2019. http://tiny.cc/aa1w6y

Abstract: While research on maternal influence on the family unit has increased in recent years, assessment of the paternal influence remains sparse. The goal of this research was to increase our understanding of paternal influence on the biobehavioral dynamics of the family unit. Participants consisted of 40 family units recruited between 28- and 36-weeks’ gestation. Participants completed 6 monthly questionnaires and an in-home visit when the infant was 4 months of age, during which parents and infants completed semistructured interaction tasks and provided saliva samples. Saliva was assayed for testosterone, progesterone, and cortisol. Results revealed that fathers’ testosterone was associated with father-infant synchrony (p = .03), mother-infant synchrony (p = .02), and marginally with partner synchrony (p = .08). Maternal progesterone responses were correlated with father-infant synchrony and marginally with couple satisfaction (p = .08) Finally, Infant cortisol was inversely correlated with alloparental support (p = .003). Together, results suggest that a more muted testosterone response is associated with maternal sensitive responding, that maternal progesterone and paternal testosterone may serve similar functions in the familial context, and that alloparental support facilitates infant HPA response selectivity.

The duty to vote is more widespread than the duty to be informed and almost half of those who say that they have a moral obligation to vote indicate that they do not have a duty to keep informed

Is It a Duty to Vote and to be Informed? André Blais, Carol Galais, Danielle Mayer. Political Studies Review, August 1, 2019. https://doi.org/10.1177/1478929919865467

Abstract: We know that many people feel that they have a duty to vote in elections, but we know little about what other civic duties they believe they ought to fulfill. In this study, we address the question of whether people feel that they have both a duty to vote and to be informed. We use an original Canadian survey which includes questions about whether respondents construe voting and keeping informed as duties or a matter of choice. We find that the duty to vote is more widespread than the duty to be informed and that almost half of those who say that they have a moral obligation to vote indicate that they do not have a duty to keep informed. The better educated are more likely to feel that they have a moral obligation to both vote and keep informed while younger respondents are more prone to reject both duties.

Keywords: civic duty, duty to vote, duty to be informed, choice