Niche picking

Niche picking is the tendency for children and adults to choose environments that complement their heredity. For example, people who are extroverted by nature may deliberately engage socially, particularly with other extroverts like themselves. Niche picking fits into the larger discussion of gene-environment correlations. The three-types of genotype-environment correlation are passive, evocative (or reactive), and active (or selective).

Scarr and McCartney's model

In 1983, Sandra Scarr and Kathleen McCartney proposed their theory of genotype→environment effects. The model expresses how an individual’s genes influence the environments they interact with—and likewise, how variable phenotypes influence the nature of an individual’s exchanges with people, places, and situations. Genotype elicits varying levels and forms of responses (if any) an individual has to environments, and together, the genotype-environmental pairs facilitate human development, they explain. Influenced by Robert Plomin's previous findings, Scarr and McCartney recognize 3 types of gene→environment interactional processes that take place over the course of human development:

Passive: During infancy, parents provide the environment for the individual to partake in. This rearing environment reflects the desires of the paternal genes, and is therefore genetically suitable for the biological child.

Evocative: Environment responds to the individual due to the influence of the genes they express (phenotype). Infants and adolescents evoke social and physical responses from the environment through this genotype→environment interaction. Experiences, and therefore development, are more greatly influenced by this effect than the previous one, but the influence of evocation declines over time.

Active: Individuals selectively attend to aspects of their environment that correlate with specific genotypes and choose environments to interact with. Selections correlate with motivational, personality, and intellectual aspects of [the individual’s] genotype. For that reason, environmental interactions are person-specific and can vary greatly or scarcely. Experience and development are influenced to a greater extent under this effect since environments are chosen rather than encountered.

As humans develop, they adopt each subsequent type of genotype-environment stage, the latter being more influential and resulting in a greater impact on development than the former. At this last genotype→environment state—active—the individual is autonomous in how they encounter and respond to elements around them. Scarr and McCartney suggest that the functioning of this type of interaction and the autonomous tendencies themselves rely on niche-picking for the specific selection of environments.

Role of Niche-Picking

Scarr and McCartney identify niche-picking as a tool used in the selecting of environments one finds suitable for their genotype. As a result, an individual’s temperament often impacts the type of niche selected since environment is reflective of one’s general disposition. The niche-picking process is different from selective attention as it is more than discriminating in responses; it is a selection of a desired environment itself, guaranteeing a response.

An individual’s niche can change over time, as explained in Emilie Snell-Rood‘s theory on behavioral plasticity and evolution. Snell-Rood elucidates that one element of developmental behavioral plasticity is the change in a gene’s expressed phenotype as a result of a change in environment. In other words, expressed behaviors are reflective of the environment one welcomes and are subject to change as a result of that environment. Should the environment be one the individual previously encountered, their behavioral change can be attributed to learning—experience leads to development which encourages learning and in turn, allows for the production of different responses. In relation to niche-picking, this suggests that throughout an individual’s continuous process of development, the selected environments evolve, as does their method and level of responsiveness.

Examples of Niche-Picking

The genotype→environment model states that as siblings and fraternal twins age, their phenotypes grow apart due to their respective mastery of the passive, evocative, and active interactions, which then play a role in differentiating their niches. As infants, the environments the siblings’ parents provide are similar, since parental rearing reflects their genes. However, as the siblings age and begin to evoke responses from their environments, the social and physical elements encountered vary between them.

Personal characteristics that encourage environmental responses, such as appearance, personality, and intellect, are not the same between siblings and fraternal twins because of gene variations; therefore, by this stage, environmental preferences emerge which are reflective of the similarities as well as the differences between them. Once siblings can actively interact with their environment and select environments they like, distinctions between their niches are clear. This process is evident in families where one child is outgoing and lively and the other is more timid and cautious.

Social researcher Frank Sulloway explains niche variations between siblings by outlaying the causes and results of sibling differences. Variance in personality and the non-shared environment comprise the majority of characteristic differences between them, both of which are influenced by parental investment, the tendency for siblings to differentiate themselves from each other—often by assuming opposite dispositions, and birth order, personality, and gender roles. In conjunction, these elements afford siblings with different evocative and active environmental experiences which reflect their individual niches.

In identical twins, this process is different. At the same age and with the same appearance—though personality differences may be present—people respond to them identically. Social and physical evocations are the same from their environments—whether reared separately or together—which often causes them to develop similar niches. Nevertheless, the fate of identical twins is not determined to be similar. Rather, this shared genotype→environment interaction suggests a tendency for them to adopt the same niche, but is not absolute.

Contemporary Applications

Scarr and McCartney’s model provides a framework for examining the relationship that children’s genotype might play in determining later environmental interactions. Two major categories that this research has played a role in include: creation of public policies to promote children’s education, and the heritability of political beliefs.

Implications for Policy Makers

In a 1996 study, Sandra Scarr followed up on her own model by examining the implications that the genotype-environment interaction could have on the creation of public policy, specifically within education. Here, Scarr advises policy-makers to use caution when using programs such as Head Start to encourage intellectual development in children. She cites the genotype-environment interactions as explaining why all children (save for those raised in particularly abusive or neglectful homes) have “good-enough opportunities” to develop without the aid of these types of programs.

While policy makers might expect to see a jump in children’s intellectual abilities following programs such as Head Start—which introduces children to a school setting and work to create a stable environment and further their cognitive talents. Scarr instead postures that they merely provide the appearance of giving children more opportunities.

These programs attempt to provide more intellectually challenging environments to less able children, but cannot fully recreate the experience that intelligent parents and a nurturing environment allow them, thus creating unrealistic expectations concerning their success. Instead, Scarr advocates for a varied and stimulating program environment that lets children access multiple modes of niche expression for optimal development.

To support her claim, Scarr conducted an experiment in 1997 that examined the impact out-of-home daycare has on children. From this study, as well as evidence gathered from previous studies, she concluded that daycare quality only had small, temporary impacts on children’s intellectual development. She noted that children from good homes usually have the genotype-environment interaction that provides the greater portion of the intellectual development they need. Parental and environmental support among these children affords them the opportunity to explore the niche most suited to their intellectual desires and abilities.

These findings suggest that children from low-income families who may not have these opportunities at home can benefit from early start programs that offer the same kind of support. Thus, the true goal of childcare improvement should be to provide a wide-ranging, stimulating, and interesting learning environment for children who don’t necessarily have access to one elsewhere. An environment such as this, rather than a narrower one that focuses on specific techniques in assimilating children into educational institutions, provides the most benefit to children who do not get adequate levels of genotype-environment interaction in their homes.

Heritability of Political Beliefs?

More recently, a 2010 study completed by a panel of political scientists, psychologists, and geneticists used the design of individuals’ extended families to examine the impact that genetic influence might have on political beliefs. One facet of this study examined the impact of Scarr and McCartney’s genotype-environment effect to determine if future political beliefs could be predicted. Using this model, researchers concluded that an individual’s genes and environment interacting both actively and passively, as well as positively or negatively, indicate their specific niches and, in turn, the types of beliefs they support because of them.

A passive genotype-environment political interaction occurs through exposure to subconscious actions of the child’s adult role models. A child exposed to a TV diet of left-wing or right wing broadcasting might be more inclined to liberalism or conservatism later in life. Active interactions, meanwhile, require the input of the child himself, such as choosing to attend a conservative institution such as Brigham Young University which is a display of niche picking tinged with political implications. Positive and negative interactions, researchers found, were even more telling of future beliefs.

The strongest support to their claim occurred in negative interactions, in which a child was constantly exposed to social environments opposite those they would select based on their niche. After prolonged exposure throughout their childhood to political social settings in opposition to their genetically assumed beliefs, most adults reported choosing environments that supported their initial genetic values, political positions, and niches. In both cases, the interaction between genotype and environment plays a significant role in socializing individuals into their later political positions.

References

1. Jaffee, S. R., Jaffee, S. R., & Price, T. S. (2008). Genotype-environment correlations: Implications for determining the relationship between environmental exposures and psychiatric illness. Psychiatry (Abingdon, England), 7(12), 496-499.

2. Scarr, S., McCartney, K. (1983). How People Make Their Own Environments: A Theory of Genotype → Environment Effects. Child Development, 54 (2). Retrieved from http://www.jstor.org/stable/1129703.

3. Plomin, R., DeFries, J. C., & Fulker, D. W. (1988). Nature and nurture during infancy and early childhood. Cambridge: Cambridge University Press.

4. Lemery, K. (2005). Temperament. In N. Salkind (Ed.), Encyclopedia of human development. (pp. 1256–1258). Thousand Oaks, CA: SAGE Publications, Inc. doi: http://dx.doi.org/10.4135/9781412952484.n606

5. Snell-Rood, E. (2013). An overview of the evolutionary causes and consequences of behavioural plasticity. Animal Behaviour, 85. Retrieved from http://dx.doi.org/10.1016/j.anbehav.2012.12.031

6. Sulloway, F. (2010). Why Siblings Are Like Darwin's Finches: Birth Order, Sibling Competition, and Adaptive Divergence within the Family. The evolution of personality and individual differences. New York: Oxford University Press.

7. Plomin R, DeFries JC, and Loehlin JC. (1977). "Genotype-environment interaction and correlation in the analysis of human behavior". Psychological Bulletin 84 (2): 309–322.

8. Scarr, S. (1996). How people make their own environments: Implications for parents and policy makers. Psychology, Public Policy, and Law, 2(2), 204-228.

9. Scarr, S. (1997). Why child care has little impact on most children's development. Current Directions in Psychological Science, 6(5), 143-148. Retrieved from http://www.jstor.org/stable/20182472

10. Hatemi, P. K., Hibbing, J. R., Medland, S. E., Keller, M. C., Alford, J. R., Smith, K. B., . . . Lindon J. Eaves. (2010). Not by twins alone: Using the extended family design to investigate genetic influence on political beliefs. American Journal of Political Science, 54(3), 798-814. Retrieved from http://www.jstor.org/stable/27821953