Human Development: Chapter 2 Textbook

natural selection

the evolutionary process in which individuals best adapted to their environment survive and reproduce

adaptive behavior

behavior that promotes an organism’s survival in its natural habitat

evolutionary psychology

a view emphasizing adaptation, reproduction, and survival‑based behaviors shaped by evolution

reproductive success

the ability to pass one’s genes to the next generation

evolutionary developmental psychology

the idea that humans evolved a long childhood to allow brain growth and learning

domain-specific mechanisms

evolved psychological modules specialized for solving specific ancestral problems

Baltes’ evolution–culture view

evolutionary benefits decrease with age while the need for cultural resources increases

chromosomes

threadlike DNA structures in 23 pairs that carry genetic information

DNA

a double‑helix molecule containing genetic instructions

genes

short DNA segments that direct cell reproduction and protein synthesis

genetic expression

the activation or silencing of genes influenced by internal and external environments

methylation

molecules attach to a gene and alter its activity without changing its structure

genotype

an individual’s genetic heritage

phenotype

observable characteristics resulting from genotype–environment interaction

mutated gene

a permanently altered DNA segment

susceptibility genes

genes that increase vulnerability to diseases or aging

longevity genes

genes that promote resistance to disease and longer life

mitosis

cell division producing two identical cells with 23 chromosome pairs

meiosis

specialized cell division producing gametes with 23 unpaired chromosomes

fertilization

fusion of egg and sperm to form a single cell

zygote

the fertilized egg containing 23 paired chromosomes

dominant–recessive principle

one gene (dominant) overrides another (recessive)

sex-linked genes

genes on the X chromosome; males are more affected because they lack a second X

genetic imprinting

gene expression differs depending on whether the gene is inherited from the mother or father

polygenic inheritance

traits influenced by many genes and environmental factors

down syndrome

extra chromosome 21 causing intellectual disability and characteristic physical features

klinefelter syndrome (XXY)

males with an extra X chromosome; underdeveloped testes and possible language issues

fragile X syndrome

abnormality in the X chromosome causing intellectual disability or learning problems

turner syndrome (XO)

females missing an X chromosome; short stature and possible math difficulties

XYY syndrome

males with an extra Y chromosome; often above‑average height