Modern families

Kevin Lewis

January 12, 2020

When is the breast best? Infant feeding as a domain of intrasexual competition
Anthony Volk & Prarthana Franklin
Evolutionary Behavioral Sciences, January 2020, Pages 6–18


Medical science is unanimous in stating the numerous and significant benefits (to child and mother) of breastfeeding. Breastfeeding is free and is biologically plausible for most mothers. Yet a significant percentage of mothers do not breastfeed their infants. Feminist theorists have aligned themselves on both sides of this issue (as well as the fence in between). Some view breastfeeding as an inherently natural and empowering aspect of femininity. Others view it as a means of suppressing women’s choices and belittling their contributions. We suggest that one reason for this controversy is that breastfeeding may be about more than just providing nutrition to one’s infant. Breastfeeding may also represent a domain of female intrasexual competition. We review evidence from modern developed and developing countries, historical countries, and hunter–gatherer cultures and find it consistent with our hypothesis. Specifically, wealthy women in developed countries tend to have fewer children yet flaunt their breastfeeding as a display of their resources whereas wealthy women in developing/historical countries tend to demonstrate their resources by focusing on having more children and avoiding breastfeeding. We therefore find support for breastfeeding as an intrasexual domain for signaling one’s social status and resources. Given this variation in breastfeeding practices, we argue that breastfeeding is an agentic expression of women’s proximate and evolved psychological decisions and advocate for providing supports that allow women to freely make the best decisions for themselves.

Early childhood deprivation is associated with alterations in adult brain structure despite subsequent environmental enrichment
Nuria Mackes et al.
Proceedings of the National Academy of Sciences, 7 January 2020, Pages 641-649


Early childhood deprivation is associated with higher rates of neurodevelopmental and mental disorders in adulthood. The impact of childhood deprivation on the adult brain and the extent to which structural changes underpin these effects are currently unknown. To investigate these questions, we utilized MRI data collected from young adults who were exposed to severe deprivation in early childhood in the Romanian orphanages of the Ceaușescu era and then, subsequently adopted by UK families; 67 Romanian adoptees (with between 3 and 41 mo of deprivation) were compared with 21 nondeprived UK adoptees. Romanian adoptees had substantially smaller total brain volumes (TBVs) than nondeprived adoptees (8.6% reduction), and TBV was strongly negatively associated with deprivation duration. This effect persisted after covarying for potential environmental and genetic confounds. In whole-brain analyses, deprived adoptees showed lower right inferior frontal surface area and volume but greater right inferior temporal lobe thickness, surface area, and volume than the nondeprived adoptees. Right medial prefrontal volume and surface area were positively associated with deprivation duration. No deprivation-related effects were observed in limbic regions. Global reductions in TBV statistically mediated the observed relationship between institutionalization and both lower intelligence quotient (IQ) and higher levels of attention deficit/hyperactivity disorder symptoms. The deprivation-related increase in right inferior temporal volume seemed to be compensatory, as it was associated with lower levels of attention deficit/hyperactivity disorder symptoms. We provide compelling evidence that time-limited severe deprivation in the first years of life is related to alterations in adult brain structure, despite extended enrichment in adoptive homes in the intervening years.

Why Firms Offer Paid Parental Leave: An Exploratory Study
Claudia Goldin, Sari Pekkala Kerr & Claudia Olivetti
NBER Working Paper, January 2020


Why do competitive firms in the US provide paid parental leave (PPL)? Which firms do and to what extent? We use several firm- and individual-level data sets to answer these questions. These include the BLS-Employee Benefit Survey (EBS) for 2010 to 2018 and an extensive firm-level data collection that we compiled. Our work is undergirded by a two-period model with competitive firms whose workers vary by their optimal firm-specific training and the probability that each will remain on the job after PPL is taken. We find that firm-provided PPL has greatly increased in the last two decades and generally covers new fathers. The levels of provision differ greatly by the industry, firm size, and the degree of firm-specific training. But even the top-of-the-line firm in the US provides fewer fully paid parental weeks than does the median OECD nation.


Sibling Warmth Moderates the Intergenerational Transmission of Romantic Relationship Hostility
April Masarik & Christina Rogers
Journal of Marriage and Family, forthcoming

Method: Using prospective longitudinal data from a community sample, 351 participants completed home assessments during adolescence (7th, 8th, 9th, and 10th grades) and adulthood (Mage = 31 years old). Romantic relationship hostility was coded from videotaped observations of participant interparental relations in adolescence and participant behavior toward a romantic partner in adulthood. In addition, the participants reported on the support they received from a sibling in adolescence, which was modeled as a moderator between romantic hostility in adolescence and adulthood using structural equation modeling.

Results: Across sibling dyads, sibling support did not moderate the intergenerational transmission of romantic relationship hostility; however, sex differences revealed that sibling support buffered this effect in sister pairs, whereas sibling support exacerbated this effect in brother pairs. Sibling support moderated this association above and beyond parental support, socioeconomic status, and sibling age spacing.

The long-term indirect effect of the early Family Check-Up intervention on adolescent internalizing and externalizing symptoms via inhibitory control
Rochelle Hentges et al.
Development and Psychopathology, forthcoming


This study examined the long-term effects of a randomized controlled trial of the Family Check-Up (FCU) intervention initiated at age 2 on inhibitory control in middle childhood and adolescent internalizing and externalizing problems. We hypothesized that the FCU would promote higher inhibitory control in middle childhood relative to the control group, which in turn would be associated with lower internalizing and externalizing symptomology at age 14. Participants were 731 families, with half (n = 367) of the families assigned to the FCU intervention. Using an intent-to-treat design, results indicate that the FCU intervention was indirectly associated with both lower internalizing and externalizing symptoms at age 14 via its effect on increased inhibitory control in middle childhood (i.e., ages 8.5–10.5). Findings highlight the potential for interventions initiated in toddlerhood to have long-term impacts on self-regulation processes, which can further reduce the risk for behavioral and emotional difficulties in adolescence.


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