Suchergebnisse

Epigenetics remains an exciting subdiscipline of biology, generating discoveries and insights about development. Because epigenetic phenomena can draw attention to the dynamic, interactional, and probabilistic nature of phenotype development, epigenetics research could hasten the demise of both nature-nurture debates and reductionist, genetically determinist perspectives on phenotype development. However, new data alone will not inevitably transform conceptualizations of phenotype origins, because it remains possible to assimilate epigenetic phenomena into traditional conceptual frameworks; epigenetic discoveries could even strengthen biologically determinist conclusions if traditional conceptualizations are retained. Although epigenetics will not <i>force</i> conceptual transformation, epigenetics research encourages the dismissal of the nature-nurture dichotomy by emphasizing <i>mechanisms</i> underlying phenotype development, thereby fostering clearer conceptions of how phenotypes emerge from interactions between biological and nonbiological components of developing systems. The developmental systems perspective, which acknowledges the vital roles of contexts in development, offers benefits not provided by reductionist perspectives, making it an appropriate conceptual framework for developmental science.

Currently, a central problem for theoretical biology is the integration of development with genetics and evolutionary theory. Through the late 20th century, biologists held that animals resemble their ancestors strictly because of the transgenerational transmission of DNA. This view effectively wrote development out of evolutionary biology. However, many molecular and developmental biologists now understand that phenotypes – anatomical, physiological, and behavioral traits – are not determined by genes (i.e., DNA segments) alone; instead, they emerge epigenetically from developmental processes involving co-acting genetic factors, environmental factors, molecular epigenetic factors, <i>and</i> other non-genetic factors within organisms' bodies. This insight forces a rethinking of biological inheritance. Perspectives focusing on the dynamics of developmental systems offer a compelling alternative way to think about inheritance, providing a powerful substitute to the reductionistic framework that attributes phenotypic outcomes to genetic instructions set <i>in advance</i> of developmental processes. Rethinking genetics, epigenetics, and inheritance by focusing on the dynamics of developmental systems helps highlight the bidirectional effects of evolutionary and developmental processes on one another, yielding a more integrated understanding of development, inheritance, and evolution. Simultaneously, this approach encourages rejection of genetic determinism, a simplistic perspective that continues to appear in psychological writing, despite its biological implausibility.

Proponents of the Extended Evolutionary Synthesis (EES) emphasize the critical role that organisms and their development play in the process of evolution. This framework explicitly rejects the genocentric focus that once dominated interpretations of the Modern Synthesis in evolutionary theory. In place of genocentrism, EES highlights processes like niche construction, developmental constraint, and extragenetic inheritance as central to any understanding of the evolutionary process. However, much more is at stake in adopting the EES than simply moving beyond the gene-dominant viewpoint of the Modern Synthesis. The EES, in fact, represents a fundamental challenge to the core of classic Darwinism itself by actively repudiating Darwin's key idea that natural selection acts as a creative force in the construction of phenotypes and phenotypic change. In this paper, we more fully explore the assumptive base of Darwinism's population-oriented, selectional focus. We demonstrate how taking development seriously in evolutionary theory mandates a systematic overhaul of Darwinism's assumptive base in favor of grounding all understanding of phenotypic construction in the developmental processes of self-organization endemic to organisms' active engagement with their worlds.

AbstractSome cognitive abilities exhibit reliable gender differences, with females outperforming males in specific aspects of verbal ability, and males showing an advantage on certain spatial tasks. Among these cognitive gender differences, differences in mental rotation are the most robust, and appear to be present even in infants. A large body of animal research suggests that gonadal hormones, particularly testosterone, during early development could contribute to this gender difference in mental rotation. Also, substantial evidence supports an influence of socialization on mental rotation performance. The present study investigated the relationship of two types of factors, early postnatal testosterone exposure and parental attitudes about gender, to mental rotation performance in 61 healthy infants (29 males, 32 females). We measured salivary testosterone at two time points: 1–2.5 months of age and 5–6 months of age. Infants' mental rotation performance and parents' attitudes about gender were assessed at 5–6 months of age. As predicted, testosterone concentrations were significantly higher in boys than girls in early infancy (d = 0.54), and boys performed significantly better than girls on mental rotation (d = 0.64). A significant positive correlation between testosterone at age 1–2.5 months and mental rotation was found only in boys (r = 0.50, p = .01). A significant negative correlation between parents' gender‐stereotypical attitudes and mental rotation performance was found only in girls (r = −.57, p = .002). These findings suggest that the early postnatal testosterone surge (also known as "mini‐puberty") may have organizational influences on mental rotation performance in boys, and that parents may influence their daughters' mental rotation abilities beginning very early in life.