Sexually antagonistic selection on educational attainment and body size in Estonian children

Abstract

Natural selection is a key mechanism of evolution, which results from the differential reproduction of phenotypes. We describe fecundity selection at different parity transitions on 15 anthropometric traits and educational attainment in Estonian children sampled in the middle of 20th century. The direction of selection on educational attainment and bodily traits was sexually antagonistic, and it occurred via different parity transitions in boys and girls. Compared to boys with primary education, obtaining tertiary education was associated with 3.5 times and secondary education two times higher odds of becoming a father. Transition to motherhood was not related to educational attainment, while education above primary was associated with lower odds (OR = 0.5-0.7) to progression to parities above one and two. Selection on anthropometric traits occurred almost exclusively via childlessness in boys, while among the girls, most of the traits that were associated with becoming a mother were additionally associated with a transition from one child to higher parities. Male (but not female) fitness was thus primarily determined by traits related to mating success.Selection favored stronger and larger boys and smaller girls. Selection on girls favored some traits that associate with perceived femininity, while other feminine traits were selected against.

Mothers of small-bodied children and fathers of vigorous sons live longer

“…Among these, handgrip strength and lung capacity are indices of physical ability and robustness, predicting short-and longterm morbidity and mortality in adult populations (44). In our study population, childhood handgrip strength predicted the reproductive success of men (but not women) (45), while cranial volume predicted educational attainment in both sexes (46).…”

“…The full dataset for calculation of residuals of morphometric traits consisted of 9,586–15,253 girls (depending on the trait) and 7,170–11,842 boys [age range 6.4–20.0 years, mean = 12.7 ± 6.4 (SD) years, born between 1937 and 1962]. Given the correlations between traits, we also performed principal component (PC) analysis as described in ( 45 ). All linear measures and handgrip strength loaded positively to PC1 (termed hereafter as size) and explained altogether 81% of its variance.…”

Survival costs and benefits of reproduction: A register‐based study in 20th century Estonia

“…Such selection pressures can be sexually antagonistic and lead to intralocus sexual conflict when there is differential selection on a trait for males and females, but the genetic expression of a trait is determined similarly in each sex. For instance, a study of Estonian schoolchildren born in 1937−1962 found that selection favored stronger, larger, and better‐educated boys and smaller, less‐educated girls 35 …”

“…For instance, deaths attributable to external causes such as accidents are lower among parents than among the childless 11 . The pressure of natural (and sexual) selection via childlessness is stronger in men than in women, as shown by Valge et al 35 …”

Juhan Aul – 125 years from the birth of the founder of Estonian anthropology

“…Markus Valge, together with his supervisor Professor Peeter Hõrak, has also published several articles [23][24][25][26][27][28]. In these, Juhan Aul data have been juxtaposed with the data of the Estonian Biobank and have been used for checking several essential evolutionary hypotheses of human development.…”