Chapter 3 Summary-Evolution and Species Heredity-Nursing Paper Examples

Evolution and Species Heredity-Nursing Paper Examples

Chapter three examines evolution and species heredity, the aspects of individual heredity, and genetic and environmental influences and analyzes selected behavioral genetics findings. The chapter begins by underlining that even though every human being exhibits subtle differences from their counterparts, some similarities can be observed during development and aging due to species heredity, a genetic endowment that members of a species have in common (Evolution and Species Heredity-Nursing Paper Examples).

Evolution and Species Heredity-Nursing Paper Examples
Evolution and Species Heredity-Nursing Paper Examples

This is founded on Charles Darwin’s theory of evolution, where human evolution is described by how species characteristics change over time and how new species evolve from earlier ones (Sigelman & Rider, 2014). Biological evolution is associated with how the genetic code translates into physical and psychological characteristics through genotypes and phenotypes.

The chapter underlines that parents influence their children’s genotypes and phenotypes through different mechanisms of inheritance. Single gene-pair inheritance is where one pair of genes, each from the mother and father, influences thousands of other human characteristics (Sigelman & Rider, 2014) (Evolution and Species Heredity-Nursing Paper Examples).

Sex-linked inheritance describes a situation where a characteristic is influenced by single genes located on the sex chromosomes rather than on the other 22 pairs of chromosomes, hence the case for X-linked and not sex-linked. Lastly, in polygenic inheritance, human characteristics are influenced by multiple pairs of genes interacting with multiple environmental factors rather than by a single pair of genes and could include one’s personality, weight, height, or susceptibility to health conditions (Evolution and Species Heredity-Nursing Paper Examples).

Furthermore, the chapter elaborates on how human development can be adversely affected by polygene disorders, mutations, diseases and disorders associated with a single gene or pair of genes, copy number variations, and chromosome abnormalities. Common genetic diseases such as sickle-cell disease, Phenylketonuria (PKU), and Huntington’s disease can be diagnosed using prenatal detection systems. The systems include ultrasound, amniocentesis, chorionic villus sampling, maternal blood sampling, and preimplantation genetic diagnosis (Evolution and Species Heredity-Nursing Paper Examples).

In an analysis of behavioral genetics, the chapter shows that it is the scientific study of the extent to which genetic and environmental differences among people or animals are responsible for differences in their physical and psychological traits. In the application of behavioral genetics, researchers can estimate the heritability of measured IQ and of other traits or behaviors (Evolution and Species Heredity-Nursing Paper Examples).

Heritability is the proportion of all the variability in the trait within a large sample of people that can be linked to genetic differences among those individuals (Sigelman & Rider, 2014). The study of twins has been the primary source of evidence on the effects of heredity. A major study is to determine whether identical twins brought up together are more similar to each other in traits of interests than fraternal twins reared together, and another study of adoption where twins are reared in different environments (Evolution and Species Heredity-Nursing Paper Examples).

Moreover, behavioral genetics utilize statistical calculations to calculate concordance rates; and delineate the extent to which heredity, shared environmental influences, and non-shared environmental influence account for individual differences in traits of interest (Sigelman & Rider, 2014) (Evolution and Species Heredity-Nursing Paper Examples).

Since behavioral genetics do not tell us which genes are responsible when they find that a trait is hereditable, molecular genetics provides an analysis of particular genes and their effects. This explains why genes contribute to variations in virtually all human traits, even though some traits are more hereditable than others (Evolution and Species Heredity-Nursing Paper Examples).

The concept of gene-environment interaction is based on the fact that our genes’ effects depend on what kind of environment we experience, and how we respond to the environment depends on what genes we have. Conversely, gene-environment correlations demystify how a person’s genes and their environment or experiences interrelate: passive, evocative, and active. It states that people with different genes have different experiences.

From the chapter, it is clear that genes do not dictate development, but instead, genes and the environment interact with and influence each other to the point that their influences cannot be separated. Epigenetic effects present ways in which environmental factors influence the expression of particular genes in particular cells. They may help to clarify why, despite their identical genes, identical twins often differ (Evolution and Species Heredity-Nursing Paper Examples).

However, behavioral genetics research is controversial. On the one hand, it has provided important insights into human development, but at the same time, some people question the rationale of trying to separate the influences of genes and the environment. They contend that behavioral genetics will never expound epigenesis, the process through which the interplay of genes and environment brings about development (Evolution and Species Heredity-Nursing Paper Examples).


Sigelman, C. K., & Rider, E. A. (2014). Life-span human development. Nelson Education.

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