Human Development– the scientific study of the changes that occur in people as they age from conception to death. •Nature: the influence of our inherited characteristics on our personality, physical growth, intellectual growth, and social interactions•Nurture: the influence of the environment on personality, physical growth, intellectual growth, and social interactions•Behavioral genetics: focuses on nature vs. nurture
Table 8.1 A Comparison of Three Developmental Research DesignsResearch DesignsObjectiveDescriptionCross-Sectional DesignDifferentparticipants of various ages are compared at one point in time to determine age-related differences.Group One: 20-year-old participantsGroup Two: 40-year-old participantsGroup Three: 60-year-old participants(research done in 2014)Longitudinal DesignThe sameparticipants are studied at various ages to determine age-related changes.Study One: 20-year-old participants (1974)Study Two: Same participants at 40 years old (1994)Study Three: Same participants are now 60 years old (2014)Cross-Sequential DesignDifferentparticipants of various ages are compared at several points in time to determine both age-related differencesand age-related changes.Study One: Group One: 20-year-old participantsGroup Two: 40-year-old participants (2014)Study Two: Group One: Participants will be 25years old; Group Two: Participants will be 45years old (to be done in 2019)
The Basic Building Blocks of Development •Genetics:the science of inherited traits–Behavioral genetics•DNA (deoxyribonucleic acid): special molecule that contains the genetic material of the organism
Figure 8.1 DNA MoleculeIn this model of a DNA molecule, the two strands making up the sides of the “twisted ladder” are composed of sugars and phosphates. The “rungs” of the ladder that link the two strands are amines. Amines contain the genetic codes for building the proteins that make up organic life.
The Basic Building Blocks of Development cont.•Gene: section of DNA having a certain pattern of chemical elements–Dominant: a gene that actively controls the expression of a trait–Recessive: a gene that only influences the expression of a trait when paired with an identical gene
Inherited Disorders•PKU1 in 10,000-20,000 (baby unable to make use of phenylalanine, an essential amino acid present in proteins found in milk/other foods. •Down Syndrome(presence of an extra chromosome on the 21stpair) 1 in 700; mongolism – old term; mental retardation•Fragile X (injury of a particular gene on X) results in mild to moderate mental retardation•Sickle-cell Anemia 1/10thof African American descent carry the gene, 1 out of 400 actually have the disease. Severe cases die in childhood.