Marriage and Parental Investment

Figure 8.8 on page 160 shows a shockingly steep trend line for white nonmarital births within the 50 years under study. Also among the more startling data points presented in Coming Apart is the numeric inversion from 84 to 48 % of prime-aged adults being married within the new lower class. With nearly one third of this subpopulation never having been married, disinvestment in marriage as a cultural institution accounts for as much of the decline as divorce. This contrasts with the new upper class whose marriage rates have hardly deviated from the general norms as measured in 1960. The result is that 22% of Fishtown children, as compared to 3 % of Belmont children, now live in single parent homes. There are correspondingly more unattached males, many of whom are not employed and who do not channel resources to offspring. Also, high rates of teenaged pregnancies and unplanned pregnancies are reported. Murray’s interest in these variables stems from their associations with childhood outcomes. In contrast with the intact family composed of a married couple and their biological children, the outcomes for alternative arrangements, such as cohabitation and single motherhood, are correlated with everything from delinquency, criminality, illness, and injury, to externalizing behaviors, mortality, scholastic problems, and sexual precocity.⁵

All such variables are of central importance to life history evolution. Consequently, The K Factor, a global index of life history variation, aggregates reproductively relevant variables under the Sexual Restrictedness Factor, which measures sexually relevant values, decisions, and norms assessing restraint, abstinence, and attitudes (Figueredo et al. 2006). Across these traits, population variation is evident. Supporting Murray’s position on intact homes, the life history literature found that “youth from two-parent homes were more likely to be sexual[ly] restricted than those from one-parent homes” (Figueredo et al. 2006). As compared with the r selected, the K selected better approximate monogamous mating, forming stable pair bonds with minimal promiscuity (Figueredo et al. 2006; Olderbak and Figueredo 2010). The opposite pattern of promiscuity and marital instability cause the r selected to have a young age at first reproduction, making teenaged pregnancy an artifact of a fast life history (Chisholm 1999; Belsky et al. 2012). Early pregnancy, particularly in the teen years, is not only frowned upon socially, but is risky biologically. Yet, the behavior of unmarried pregnant teens will be discouraged but not understood, except from a life history perspective. As with life history as a whole, the timing of a female’s first birth is based on a calculus, with every position imposing some matter of risk, as best summarized by Ellis et al. (2009):

Trade-offs between growth and current reproduction are well-documented in research on adolescent childbearing. Adolescent mothers have a smaller pool of energetic resources to devote to production of offspring. Such mothers tend to be smaller and convert less of their weight gain during pregnancy to fetal weight gain than do adult mothers (Garn et al. 1986), experience higher rates of antenatal complications and mortality than do adult mothers, and their offspring are at increased risk of stillbirths, congenital abnormalities, prematurity, low birthweight, and retardation (Black and DeBlassie 1985; Furstenberg et al. 1989; Luster and Mittelstaedt 1993). At the same time, however, adolescent childbearing reduces the probability of death prior to first reproduction (shorter exposure to all sources of mortality), increases the total reproductive output of lineages through shorter generation times, and results in longer reproductive lifespans (Ellis 2004).

Conception and care are subject to the same calculus. Again, as compared with the r selected, the K selected have lower levels of infant mortality and higher levels of parental investment (Thornhill and Palmer 2004; Figueredo et al. 2006; Belsky et al. 2012). Long deferred conception and high paternal investment have their own risks, as Crews and Ice (2008, p. 653) state: “investing in the embodied capital or future reproduction of another organism [a son or daughter] requires an evolutionary gamble on an outcome with diminishing probabilities.” In this way, the K selected strategy of high investment in a small number of offspring presupposes the efficacy of that investment (Figueredo et al. 2006). Parental effort, embodied capital, somatic effort, encephalization... they all follow the same slow life history calculus. To develop, they must yield returns on investment (Kaplan et al. 2000) which can only be expected if the lifecourse is sufficiently slowed and secured. Not incidentally then, for instance, parental care scales with intelligence across species and among humans (MacDonald 1997). The teenaged pregnancies and out of wedlock births of Fishtown are nothing but the expression of a fast life history strategy that takes any available resources and quickly converts them into offspring (Chisholm 1999; p. 217; Hertler 2016). This is r selected rapid baton passing.