CHAPTER 3: BIOLOGICAL BEGINNINGS THE EVEOLUTIONARY PERSPECTIVE

Natural Selection and Adaptive Behavior Natural Selection – The evolutionary process that favors individuals of a species that are best adapted to survive and reproduce – Darwin’s On the Origin of Species. Adaptive Behavior – That which promotes an organism’s survival in its habitat (e.g, eagle’s claws), attachment in humans. Evolutionary psychology – Emphasis on the importance of adaptation, reproduction, and survival of the fittest in explaining behavior. Evolution favors behaviors that promote survival.

GENETIC FOUNDATIONS : What are Genes? Chromosomes – Threadlike structures of 23 pairs, one member of each pair from each parent, containing DNA. Each gene is a short segment composed of DNA acting as a blueprint for cells to reproduce themselves. Mitosis is the process where each chromosome in the cell’s nucleus duplicates itself. Meiosis is where each pair of chromosomes separates – one member going to each gamete.

Genetic Principles Dominant-recessive genes principle – The explanation of gene dominance relative to hair color, eyesight, and freckles. Sex-linked genes – An explanation of the XY chromosomal makeup that determines gender. Genetic imprinting – The dominance of imprinted genes and its effect on some genetic diseases. Polygenic inheritance – The interaction of genes, forming the organism’s genotype and phenotype. Reaction range – Demonstrates the importance of an environment’s positive and negative effects. Canalization – Nature’s pathway to development thought to be a protective measure from environmental extremes.

Methods Used by Behavior Genetics – genetic influence on behavior. Identical twins – monozygotic – single fertilized egg Fraternal twins – dizygotic – separate eggs Twin studies help establish heredity’s effect on behavior. Adoption studies reveal more strength for the inherited- behavior theory. Molecular genetics – and the categorization of the human gene through the Genome Project. There is great potential here for the control of some diseases.

Chromosome and Gene-Linked Abnormalities Down syndrome – The presence of a 47 th chromosome, leading to a child with specific physical characteristics and mental limitations. Klinefelter syndrome – A sex-linked abnormality found in males who have an extra X chromosome affecting sexual traits. Fragile X syndrome – An abnormality in the X chromosome, causing mental retardation and learning disabilities. Turner syndrome – Females missing an X chromosome, leading to possible infertility and some learning disabilities. XYY syndrome – An extra Y chromosome in males, causing above- average height. Phenylketonuria – Organism cannot metabolize an amino acid – could cause mental retardation and hyperactivity. Sickle-cell anemia – Most often found in African Americans, affecting red blood cells, causing anemia and possibly early death.

Reproductive Challenges and Choices Amniocentesis – A test by which amniotic fluid is withdrawn and tested for chromosomal or metabolic disorders. Ultrasound sonography – Soundwaves that are transformed into visual representations of the fetus. Chorionic villi sampling – Where a sample of the placenta is removed and tested for birth defects; considered to be more dangerous than amniocentesis. Maternal blood test – Used to assess blood alpha protein level to identify possible defects to the brain and spinal cord formation. Infertility – Occurring in approximately 10 to 15 percent of couples in the United States who cannot conceive a child through regular intercourse. Causes and results are studied. Adoption – The effects of adoption on children and the challenges to adoptive parents are discussed.

HEREDITY-ENVIRONMENT INTERACTION Intelligence – What is the heredity and environmental influence on intelligence? Jensen contended that environment is minimal to heredity – a view that sparked controversy. The Bell Curve – A book by Herrrnstein and Murray (1994) statistically supporting Jensen’s contention also provided controversy. The argument centers on the belief that IQ can or cannot be quantified. Environment – Scientists believe that rich environments can raise intelligence, as is evidence by some studies that focused on children born of low socioeconomic status parents and raised in high socioeconomic status environments.

HEREDITY-ENVIRONMENT CORRELATIOINS Passive genotype-environment correlations –Biological parents provide rearing environment for child. Evocative genotype-environment correlations – Genetic foundation s elicit social and physical influences from the environment. (Agreeable children get more positive attention.) Active (niche-picking) genotype-environment correlations – seeking environments that are found compatible to the individual. Shared and nonshared environmental experiences – Children’s common genetic inheritances versus their unique experiences in and outside the family. Conclusions about heredity-environment interaction – Heredity and environment operate together. Both environment and heredity are complex in their own way and both are influenced by the other.