Effects of early life adversity on maternal effort and glucocorticoids in wild olive baboons

Adverse experiences during early life exert important effects on development, health, reproduction, and social bonds, with consequences often persisting across generations. A mother's early life experiences can impact her offspring's development through a number of pathways, such as maternal care, physiological signaling through glucocorticoids, or even intergenerational effects like epigenetic inheritance. Early life adversity in female yellow baboons (Papio cynocephalus) predicts elevated glucocorticoids, reduced sociality, shortened lifespan, and higher offspring mortality. If baboon mothers with more early life adversity, experience poorer condition and struggle to provide for their offspring, this could contribute to the persisting transgenerational effects of adversity. Here, we examined the effects of mothers' early life adversity on their maternal effort, physiology, and offspring survivability in a population of olive baboons, Papio anubis. Mothers who experienced more adversity in their own early development exerted greater maternal effort (i.e., spent more time nursing and carrying) and had higher glucocorticoid metabolites than mothers with less early life adversity. Offspring of mothers with more early life adversity had reduced survivability compared to offspring of mothers with less early life adversity. There was no evidence that high maternal social rank buffered against the effects of early life adversity. Our data suggest early life experiences can have lasting consequences on maternal effort and physiology, which may function as proximate mechanisms for intergenerational effects of maternal experience.

Redefining Second Stage of Labor: Number of Pushing Contractions

Introduction Despite time standards for second stage labor, “delayed pushing,” uterine contraction frequency, and alternate contraction pushing may alter the effective maternal effort. We sought to quantify the number of pushing contractions needed for a spontaneous vaginal delivery (SVD) among primipara and multipara patients. Methods Deliveries at Harbor-UCLA Medical Center in 2017 were selected for SVD of singleton, term newborns. The first 100 primipara and 100 multipara deliveries were analyzed and monitor tracings quantified for pushing contractions. Results Significantly more pushing contractions were required by primiparas versus multiparas (17.3 ± 1.7 vs. 5.5 ± 0.7; p < 0.001) in accord with a longer second stage (86.7 ± 7.8 vs. 27.2 ± 4.9 min; p < 0.001) and epidural was associated with greater number of pushing contractions among both primipara (18.5 ± 1.8 vs. 10.8 ± 0.8) and multipara women (6.1 ± 0.8 vs. 4.1 ± 0.3). Newborn weight (<3000, 3000–3500, >3500 g) demonstrated a trend for increased pushing contractions among primipara (16.9, 16.5, 19.8 pushes, respectively) though not multiparas. Conclusion Although correlated with the absolute duration of the second stage, the number of pushing contractions eliminates ambiguities of “delayed pushing,” pushing every-other, and frequency of contractions. Examination of larger databases and patients with second stage “arrest disorders” may provide pushing contraction criteria predictive of SVD and prevention of morbidity.

Life-history trade-offs: are they linked to personality in a precocial mammal ( Cavia aperea )?

Life-history trade-offs are predicted to contribute to the maintenance of personality variation. Individuals with ‘fast’ lifestyles should develop faster, reproduce earlier and exhibit more risky behaviours. Evidence for such predicted links, however, remains equivocal. Here, I test how growth rate, timing of maturation, litter size and maternal effort correlate with exploration, boldness, fearlessness, docility and escape latency. I found several links that were predicted by recent theory while others were against theoretical predictions, e.g. fast-growing individuals were more fearful. Thus, while I found personality to be integrated with life history, I cannot fully support recent hypotheses aiming to explain such behaviour–life-history associations.

Selective Instability: Maternal Effort and the Evolution of Gene Activation and Deactivation Rates

We previously used simulations of gene expression to demonstrate that rapid activation and deactivation rates stabilized outcomes in stochastic systems. We hypothesized that transient single allele inactivation of an autosomal gene during gametogenesis or very early embryogenesis could have a selective advantage if it permits the functional sampling of each allele and precludes committing maternal effort to an embryo with a deleterious mutation. To test this hypothesis, we simulated the evolution of gene expression activation and deactivation rates and imposed two different selective pressures on the populations: (a) late selection against individuals that cannot maintain a threshold level of gene product that occurs after the investment of maternal effort (i.e., after birth); or (b) early selection: in addition to late selection, maintenance of the gene product above a threshold level was necessary for early development prior to commitment of maternal effort. We found that the opportunity to save reproductive effort from early selection caused the evolution of higher deactivation rates and lower activation rates than in the late selection condition. Thus, we predict that in the special case where early selection can save maternal investment in non-viable offspring, gene expression activation rates and deactivation rates might be selected to permit sampling of the product from each allele.