PS330 Unit 4 Biological Perspectives Paper Example

A Temper He Shares With His Father: A PS330 Unit 4 Paper on Biological and Evolutionary Perspectives

[Student Name]

Purdue University Global

PS330: Personality Development

Unit 4 Biological and Evolutionary Perspectives Paper

[Instructor Name]

[Date]

The coach and his family are composite; the research cited is real.

The Question

Darnell's mother says he was a fierce, intense toddler who screamed when other children took his toys and who would practice catching a ball until dark. His father had the same temper. It is tempting to say Darnell inherited it. Biological perspectives on personality ask how much of such a pattern reflects genes and biology, and how biology and environment interact.

Genes and Twin Studies

Researchers compare how alike identical twins are with how alike fraternal twins are, since only the first share virtually every gene. If identical twins are more alike on a trait, genes are implicated. Polderman et al. (2015) combined fifty years of twin studies across thousands of traits and found that, averaged across traits, genetic differences accounted for close to half of the differences between people. Personality traits typically show heritability estimates in the range of 40 to 50 percent (Bouchard, 2004).

Heritability describes differences in a population, not how much of one man's temper came from his father.

Heritability does not mean that half of Darnell's temper is genetic. It is a statement about a group: what share of the differences between its members tracks differences in their genes. It also says nothing about whether a trait can change. Darnell shares genes with his father, but he also shared a household with him and watched him argue with umpires, so genes and learning are tangled together in his case.

Temperament

Temperament refers to biologically based differences in reactivity and self-regulation that appear early in life. Darnell's intensity as a toddler suggests a reactive temperament, which tends to be moderately stable and forms a foundation for adult traits such as negative emotionality. Temperament is not destiny; the same reactive child, raised with patient guidance, may learn strong self-control.

Evolutionary Perspectives

Evolutionary psychology asks why certain tendencies might have helped ancestors survive and reproduce. Anger at being treated unfairly may have helped people defend resources and status in small groups, and competitiveness may have helped individuals rise in status hierarchies. These accounts can explain why such tendencies are common. They are harder to test than twin studies, and they explain species-wide tendencies better than one person's intensity.

Epigenetics

Epigenetic research shows experience switching genes up or down while the DNA code stays the same. Weaver et al. (2004) found that rat pups who received more licking and grooming from their mothers showed lasting changes in the expression of a stress hormone receptor gene in the brain and calmer stress responses as adults. Whether similar processes shape human personality is an active research question, but the finding illustrates that biology responds to experience.

Conclusion

Biology offers part of the explanation for Darnell's temper and drive: a reactive temperament, traits with substantial heritability and tendencies that may have deep evolutionary roots. But the same research shows that genes and environment are intertwined and that heritable traits are not fixed, which leaves room for the learning and change examined in other units.

References

Bouchard, T. J., Jr. (2004). Genetic influence on human psychological traits: A survey. Current Directions in Psychological Science, 13(4), 148-151. https://doi.org/10.1111/j.0963-7214.2004.00295.x

Polderman, T. J. C., Benyamin, B., de Leeuw, C. A., Sullivan, P. F., van Bochoven, A., Visscher, P. M., & Posthuma, D. (2015). Meta-analysis of the heritability of human traits based on fifty years of twin studies. Nature Genetics, 47(7), 702-709. https://doi.org/10.1038/ng.3285

Weaver, I. C. G., Cervoni, N., Champagne, F. A., D'Alessio, A. C., Sharma, S., Seckl, J. R., Dymov, S., Szyf, M., & Meaney, M. J. (2004). Epigenetic programming by maternal behavior. Nature Neuroscience, 7(8), 847-854. https://doi.org/10.1038/nn1276