Relationship Between Childhood (Un)predictability and Life Milestones in Young Brazilians

Like other human processes, development involves the integration of phylogenetic, ontogenetic, and cultural components. The relationship between these elements distinguishes human maturation from the maturation of other species, with intra-species variations (Ellis, Figueredo, Brumbach, & Schlomer, 2009). Throughout this development, choices are made based on decision making. Some very important choices, referred to as life milestones, occur as adulthood emerges, when the body has reached sexual maturity and the individual is professionally active (Rickard, Frankenhuis, & Nettle, 2014).

The term “milestone” was used by Wilson and Daly (2006) to refer to special events in the lives of young people, such as the first sexual intercourse, first childbirth, first formal employment, and starting a family. According to the authors, the option of accomplishing or not accomplishing each milestone and the age at which each milestone occurs reflect the adjustment of strategies between individual and environmental components of decision making. According to evolutionary life history theory, such adjustments occur while facing life’s dilemmas between the reproductive and somatic domains, which are constantly present in the life history of individuals. The somatic domain is related to investments that earn reproductive potential, contributing to maintenance of the body, physical and mental development, and growth. The reproductive domain is related to find, to attract and to hold partners, to produce offspring (e.g. sexual activity, gametes production, gestation and childbirth), and to invest in the quality of the offspring (e.g. lactation, parental care, protection, teaching, and socialization). Within the reproductive domain, there is still another dilemma: current versus future reproduction. Make choices for the current reproduction has greater reproductive value, since it produces offspring that matures sooner than the future offspring (still uncertain). Consequently, investment in an allocation domain restricts investment in another domain (Ellis et al., 2009; Geary, 2003).

Evolutionary dilemmas appear to be solved according to a species-specific pattern as human development progresses. Primarily, somatic investment increases from birth until puberty, eventually showing nepotistic investment with the presence of younger siblings. Reproductive effort begins to be more expressive once sexual maturation occurs, reaching its peak in the middle of adulthood and decreasing over time. Advancing age gives way to investments in nepotism, including alloparental care that is offered by grandparents (Geary, 2003). Furthermore, these dilemmas are adjusted by individuals throughout their development based on the stability and availability of environmental resources: environments with stable and predictable resources favor strategies focused on somatic investment and long-term outcomes. Otherwise, environments with unstable and unpredictable resources favor strategies focused on immediate reproductive domains and short-term outcomes (Ellis et al., 2009; Wilson & Daly, 1997). In this way, early investment in reproductive domains, and consequently the postponement of the investment in somatic domains, can be considered as a strategy of “fast” life cycle. Likewise, the inverse relationship between reproductive and somatic domain, can be considered as a strategy of “short” life cycle (Ellis et al., 2009).

Some previous researches showed evidence for the life history propose. Wilson and Daly (1997) analyzed demographic data from Chicago neighborhoods in the United States. They concluded that residents in low-income and more violent neighborhoods had higher risk-taking behaviors, faster life history strategies, lower life expectancy, shorter time horizons, and an advance of life history stages (e.g., getting married, having children, etc.). In another research, Wilson and Daly (2006) compared expectations between 91 young offenders and 284 high school students and hypothesized that young offenders were excessively oriented in the present because of their difficult developmental history and compressed life courses (e.g., expectations of early reproduction, early deaths of relatives, and so on). These researchers presented pairs of future milestones to the subjects and asked them to indicate which of them they expected to happen first. The groups of individuals who had not yet achieved the milestone were significantly different. The offenders expected to marry earlier and have children sooner and saw themselves as less likely to graduate from high school compared with the other group. Although the offenders were more likely to have reached the milestone of first sexual intercourse, the participants in the two groups were very similar for the other milestones.

Empirical neuroimaging evidence for the life history proposes is growing. Gonzalez, Allen, and Coan (2016) made a longitudinal study with functional magnetic resonance imaging of 83 participants. The parents of the participants answered scales about the neighborhood quality and parental practices when they were 13 years old. After 12 years, participants completed a monetary incentive delay task. The authors concluded that findings suggest that neighborhood ecology in adolescence is associated with greater neural reward sensitivity in adulthood above the influence of parental practices or current income.

It should be emphasized that the researches presented above did not work specifically with the construct of the environment unpredictability. Nevertheless, the construct is directly related with the data showed such as quality of the place of residence and income. Unpredictability does not refer to a lack of resources but rather the variability of availability (Ellis et al., 2009; Ross & Hill, 2002). However, according to Rickard, Frankenhuis, and Nettle (2014), financial deprivation exposes the individual to a harsh environment that results in perceiving the future in the short term. Ramirez-Valles, Zimmerman, and Newcomb (1998) stated that financial deprivation is commonly accompanied by indications of unpredictable care/support, such as weak supervision by caregivers, which results in unpredictable discipline (e.g., maintenance and application of agreed rules) and difficulty maintaining routines.

With regard to the perception of the (un)predictability of the environment, Ross and Hill (2002) proposed a model in which an individual’s perception of unpredictability is formed during childhood and develops during maturation. This model of the perception of unpredictability consists of an individual understanding of the availability of resources in the environment during development and especially in childhood, and it is a precursor of the expectations of the individual regarding what is available in the long and short term (Rickard, Frankenhuis, & Nettle, 2014).

Other studies have documented the relationship between unpredictability environment, and the acceleration of life history stages, especially with regard to the reproductive domain. The Oregon Social Learning Center (Kerr, Leve, & Chamberlain, 2009; Leve & Chamberlain, 2004; Leve, Van Ryzin, & Chamberlain, 2015) works with female juvenile offenders and has found a relationship between high unpredictability and earlier ages of sexual behavior investment (i.e., fast life history strategies). Researchers are working with a group of 13-to 17-year-old girls in the Multidimensional Treatment Foster Care (MTFC) program for delinquent girls, a family-based alternative to residential, institutional, and group care for children and adolescents who have behavioral, emotional, and mental health problems. Data have shown a high frequency of risky sexual behavior and teenage pregnancy, accompanied by high environmental unpredictability in childhood, including changes in caregiver structure (e.g., the lack of a parent, new parental relationships, and housing with relatives or other adults) that require constant changes in rules and routines. Such unpredictability is associated with an increase in exposure to childhood sexual abuse and parental neglect. On the other hand, Kerr, Leve, and Chamberlain (2009) evaluated a sample of 166 girls who were enrolled in the MTFC program and found a delay in reproduction activity. The MTFC program involves individual placement in foster homes with parents who are highly trained, supervised, and certified by the state to create maximally structured and predictable environments for girls.

The present study sought to investigate whether perceived family unpredictability affects the development of life history strategies in both the reproductive and somatic domains by evaluating the ages at which life milestones occurred. Importantly, unlike other studies that dealt with life milestones, the participants in our sample did not necessarily already achieve the milestones. We expected that individuals who had higher perceptions of family unpredictability during life would present a shorter timeframe of achieving the milestones and short-term expectations of the occurrence of each milestone (short life cycle strategy) (Belsky, Schlomer, & Ellis, 2012; Ellis et al., 2009; Gonzalez, Allen, & Coan, 2016; Wilson & Daly, 2006). This hypothesis regarding the relationship between the occurrence and expected occurrence of milestones was based on Ross and Hill (2002), who proposed a model in which the individual perception of unpredictability has more of an influence on human behavior than actual resources that are available.

Researches showed above explored items related to current reproduction (e.g. first sexual intercourse, first childbirth, start a family, marry), presenting the relationship between unpredictability and early ages in life milestones to reproductive domain. We also expected a relationship between predictability and early ages in life milestones to somatic domain items that depend on long-term resources such as buy own house, leave parents’ house/live alone, buy own car, go to college, and graduate from college. Furthermore, we used one somatic item, first formal employment, which is necessary to maintain the individual subsistence; because of its singularity, we expected the inverse result. In Brazil, family socioeconomic status is directly related to beginning work at an earlier age. According to Romanelli (1997), in Brazilian lower-class families, children begin labor assignments at 6 or 7 years of age. This includes both performing housework and being included in an informal labor market. As family financial conditions improve, years of education increase, and entry into the labor market is postponed.

Methods

This paper is part of a large research Project that analyzes the human behavior from a evolutionary approach. This study has a descriptive design that adopts quantitative procedures.

Results

The data were tabulated and statistically analyzed using SPSS 16 software. Descriptive statistics were employed to investigate the distribution of sociodemographic variables. Pearson correlation analysis was employed to verify relationships between perceived family unpredictability and the age at which milestones occurred. Each age of milestones was correlated to participants who had already accomplished those milestones (yes category in Table 1), and to participants who had not achieved the milestone (no category in Table 1). Answers from participants who reported that would never accomplish a specific milestone were excluded from the analysis of that milestone. In the final model, variables were considered statistically significant at p < 0.05.

Discussion

Our initial hypothesis was that unpredictability would be negatively correlated with the ages at which the reproductive milestones occurred, and the ages of a specific somatic item (first formal employment), including participants who had previously achieved the milestones and participants who had not yet achieved the milestones but reported a date when they would meet them (Belsky, Schlomer, & Ellis, 2012; Ellis et al., 2009; Gonzalez, Allen, & Coan, 2016; Wilson & Daly, 2006). Our hypothesis was confirmed for four of the 10 milestones. For participants who had already achieved the milestone, age at first sexual intercourse was negatively correlated with care/support and meals, and age at first formal employment was negatively correlated with care/support, meals, and financial resources. Although only five participants had married and started a family, the unpredictability of support/care was significantly correlated with both of these milestones. This kind of behavior can be considered as a strategy of “short” life cycle (Ellis et al., 2009).

Consistent with previous studies (Kerr, Leve, & Chamberlain, 2009; Leve & Chamberlain, 2004; Leve, Van Ryzin, & Chamberlain, 2015; Wilson & Daly, 1997), the reproductive domain (i.e., age at first intercourse, marrying, and starting a family) presented a clear relationship with some unpredictability factors, especially care/support. Higher unpredictable care/support scores were associated with a younger age of having a first child, marrying, and starting a family, indicating fast life history strategies. Neglect, little support, and low parental monitoring provide cues to the child about levels of environmental stress. These environmental cues cause the individual to adjust life history strategies accordingly and adopt fast life cycle traits, such as early puberty, early onset of sexual activity, teenage pregnancy, and lower life expectancy (Belsky, Schlomer, & Ellis, 2012; Ellis et al., 2009).

Age at first formal employment also presented the expected relationship with unpredictability (Romanelli, 1997). Our data showed that higher perceived unpredictability for all unpredictability factors was correlated to a lower age at first formal employment. In Brazilian lower-class families, children begin labor in early ages. Otherwise, as Brazilian higher-class families present an increase in years of education, entry into the labor market is postponed (Romanelli, 1997). This result supports the positive correlation between age at going to college and financial resources. When considering that investment in the labor market limits investment in education, and vice versa, this positive relationship makes sense.

Wilson and Daly (2006) previous data showed important differences between groups of individuals who had achieved the milestone and those who had not yet achieved the milestone. They compared high school students and young offenders. Differently, in the present study, significant correlations were found more frequently for the participants who had already met the milestones. For the participants who had not yet achieved the milestones, only age at college graduation was significantly correlated with unpredictable financial resources. However, although the participants had not yet graduated from college, most of them were in college at the time of the study and could predict their age at graduation with good accuracy. We can assume that being our most homogeneous sample in terms of unpredictability, these differences may not have appeared. Environmental unpredictability is closely related to shorter time horizons (Wilson & Daly, 2006) and a decreased life expectancy (Wilson & Daly, 1997). However, when dealing with plans for the future, the estimate of when a plan will be carried out does not appear to be based on homogeneous environmental cues.