1 / 15

Heredity and the Environment

Heredity and the Environment. Chapter 2. Biological characteristics interact with the human environment to yield the individual psychological characteristics that emerge from species and individual attributes: Species—Environment Fit: Evolutionary Processes

lazar
Download Presentation

Heredity and the Environment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Heredity and the Environment Chapter 2

  2. Biological characteristics interact with the human environment to yield the individual psychological characteristics that emerge from species and individual attributes: • Species—Environment Fit: Evolutionary Processes • Individual—Environment Fit: Biopsychosocial Processes

  3. Genotype: Genetic code for the individual • Phenotype: Manifestation of the genotype • Both can be impacted by the environment • Toxins • Disease • Mutations • Etc…

  4. Gene—Segment of DNA that synthesizes a particular protein; contains the key to any inherited characteristic • Chromosome—Carrier of genes in a particular patter; 23 pairs; • 22 pairs are linked to non-sex specific attributes • 1 pair linked to sex-specific attributes • Female—2 X chromosomes • Male—1 X and 1 Y chromosome

  5. Diversity and Reproduction • Zygote: following initial cell division of the fertilized egg • Mitosis—Exact replication of 22 non-sex linked chromosomes (autosomes) • Meiosis—When sex cells (egg & sperm) replicate, genetic material is shuffled and each chromosome has 23 single stranded chromosomes; when sperm and egg unite, there is a unique pairing of chromosomes, thus genetic diversity is accomplished

  6. Exception to the rule: • Monozygotic Twins • Initial zygote divides with two identical replications • All genetic material is the same • Monozygotic twins have been objects of much research on heritability of human characteristics • Dizygotic Twins • Same process as siblings except for simultaneous pregnancy

  7. Dominant & Recessive Genes • Dominant genes—expressed in the presence of another Dominant or a Recessive gene • Recessive genes—only expressed in the presence of another recessive gene • Dominant-Recessive patterns determine the likelihood of a given characteristic being expressed

  8. Inherited Anomalies • Dominant Gene Anomalies • Huntington Disease (progressive neurological damage • Progeria Disease (premature aging) • Recessive Gene Anomalies • Cycle cell anemia (defective hemoglobin) • Cystic fibrosis (affects lungs, gastrointestinal tracks)

  9. Inherited Anomalies • Sex-Linked (genetic anomalies) • Congenital deafness • Hemophilia • Chromosomal anomalies • Down’s Syndrome (trisomy 2) • Likelihood associated with maternal age (note this is correlational)

  10. Inherited Anomalies • Pre-conception genetic testing • Couples contemplating conception are screened for likelihood of passing on anomalous traits • Prenatal Screening • Ultrasound—can be unreliable • Amniocentesis—potential damage to fetus • Chorionic villus sampling—risk of inducing miscarriage • Ethics, values, and who decides

  11. Genetic—Environment Interaction • Range of Reactions: Genes place limits on range of reactions of phenotypic responses • Canalization: genotype provides a series of likely pathways and the environment nudges the individual into one or more

  12. Genetic—Environment Interaction • Niche-Picking: individuals are more or less suited for particular environmental niches; • Passive: infant’s environment typically determined by those who contributed genetic make-up • Evocative: child’s phenotypic expressions of genotype evoke particular responses from caregivers and others • Active/Niche-Picking: offspring actively select environments that fit the phenotypic expression of genotype (Scarr, 1992)

  13. Genetic—Environment Interaction • Probabilistic Epigenesis • As organism develops, environmental stimuli are necessary to turn on genes • Presence and magnitude of stimulation impact the nature of the genetic expression • Similar to ethological concept of sign stimulus and action potential (see Gotlieb, 1997)

  14. Behavioral Genetics • Heritability of traits • Estimation (0.0-1.0) of genetic influence • Related to • Prevalence of trait in biological parentage • Shared and non-shared environment • Based on comparison of monozygotic and dizygotic twin studies with shared and non-shared environments • Estimates average about .5 across traits (Table 2.4, pg 73 & 74) • Niche-Picking and Probabilistic Epigenesis likely explanations

  15. What we know: • Nature and nurture play a role • Genotypes are expressed as phenotypes • Environmental and cultural factors impact the effect of phenotypic differences • Genetics and shared/non-shared environments are likely responsible for significant variance in individuals

More Related