Chapter summary imageHow do biology and natural selection shape our lives?

WHAT ARE THE GENETIC MECHANISMS OF TRAIT INHERITANCE?

  • Made up of DNA, chromosomes inside cell nuclei contain all the genetic information needed to make an organism.
  • Human cells contain 23 pairs of chromosomes, including an XX or XY pair that determines whether an individual is male or female.
  • Egg and sperm cells contain half the genetic information of other cells. They combine during fertilization, passing on parents’ genetic information in a new permutation.

IN WHAT WAY DO GENES AND ENVIRONMENT INTERACT TO MAKE US WHO WE ARE?

  • Traits are carried on genes. Genes can be recessive or dominant.
  • Dominant genes suppress the expression of the other gene in a pair of alleles.
  • Recessive genes are suppressed by the dominant gene in a pair of alleles.
  • Some traits, such as eye colour, depend entirely on genetics. Others, such as height and weight, can be influenced by the environment.
  • While genetics might predispose an individual to a certain trait, how that trait is expressed can depend on environmental factors.
  • An environment may be external or chemical.
  • Behavioural genetics examines the relative contributions of genetics and the environment on who we are, through the use of twin and adoption studies.
  • The study of genetics has led to many advancements in our understanding of illness, diseases, and disorders. These advancements continue to have a great impact on the diagnosis, classification, and treatment of autism, cancers, diabetes, and so on.

HOW HAS THE IDEA OF EVOLUTION BY NATURAL SELECTION INFLUENCED THE STUDY OF HUMAN BEHAVIOUR?

  • According to the theory of natural selection, organisms with features that best adapted to their environment are more likely to survive and reproduce.
  • Some genes are dominant or recessive, affecting the likelihood that a particular trait will be passed on.
  • Research in behaviour genetics, molecular genetics, and evolutionary psychology has developed from the idea of natural selection.

WHAT ARE THE TYPICAL MATING PATTERNS OF DIFFERENT SPECIES?

  • Mating patterns depend on gender differences in parental investment.
  • There are four types of mating patterns: polygyny, polyandry, monogamy, and polygynandry.