05 Genetics Evolution

Skin pigmentation is one example of a continuous trait. Which of your other traits are continuous?

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?

• Some traits, such as eye color, 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.

How has the idea of evolution by natural selection influenced the study of human behavior?

• 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 behavior 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.