REVIEW Genetics, Evolutionary Psychology, and Behavior

Learning Objectives

Page 77

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the module). Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Question

6-1 What are chromosomes, DNA, genes, and the human genome? How do behavior geneticists explain our individual differences?

ANSWER: Genes are the biochemical units of heredity that make up chromosomes, the threadlike coils of DNA. When genes are “turned on” (expressed), they provide the code for creating the proteins that form our body's building blocks. Most human traits are influenced by many genes acting together. The human genome is the shared genetic profile that distinguishes humans from other species, consisting at an individual level of all the genetic material in an organism's chromosomes. Behavior geneticists study the relative power and limits of genetic (our heredity) and environmental influences on behavior.

Question

6-2 How do twin and adoption studies help us understand the effects and interactions of nature and nurture?

ANSWER: Studies of identical (monozygotic) twins versus fraternal (dizygotic) twins, separated twins, and biological versus adoptive relatives allow researchers to tease apart the influences of heredity and environment. Research studies on separated identical twins maintain the same genes while testing the effects of different home environments. Studies of adoptive families let researchers maintain the same home environment while studying the effects of genetic differences. Heritable individual differences (in traits such as height and weight) do not necessarily explain gender or ethnic group differences. Shared family environments have little effect on personality, though parenting does influence other factors (such as attitudes).

Question

6-3 How do heredity and environment work together?

ANSWER: Our genetic predispositions and our specific environments interact. Environments can trigger or block genetic expression, and genetically influenced traits can evoke responses from others. The field of epigenetics studies the influences on gene expression that occur without changes in DNA.

Question

6-4 How do evolutionary psychologists use natural selection to explain behavior tendencies?

ANSWER: Evolutionary psychologists seek to understand how our traits and behavior tendencies are shaped by natural selection, as genetic variations increasing the odds of reproducing and surviving in their particular environment are most likely to be passed on to future generations. Some variations arise from mutations (random errors in gene replication), others from new gene combinations at conception. Humans share a genetic legacy and are predisposed to behave in ways that promoted our ancestors' surviving and reproducing. Charles Darwin's theory of evolution is an organizing principle in biology. He anticipated today's application of evolutionary principles in psychology.

Terms and Concepts to Remember

Test yourself on these terms.

Question

environment (p. 66)
heredity (p. 66)
behavior genetics (p. 66)
chromosomes (p. 66)
DNA (deoxyribonucleic acid) (p. 66)
genes (p. 66)
genome (p. 66)
identical (monozygotic) twins (p. 67)
fraternal (dizygotic) twins (p. 68)
interaction (p. 71)
epigenetics (p. 72)
evolutionary psychology (p. 73)
natural selection (p. 73)
mutation (p. 74)
the study of the evolution of behavior and the mind, using principles of natural selection.
the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing proteins.
the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.
develop from a single fertilized egg that splits in two, creating two genetically identical organisms.
develop from separate fertilized eggs. They are genetically no closer than ordinary brothers and sisters, but they share a prenatal environment.
every nongenetic influence, from prenatal nutrition to the people and things around us.
the study of environmental influences on gene expression that occur without a DNA change.
a random error in gene replication that leads to a change.
the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).
threadlike structures made of DNA molecules that contain the genes.
a complex molecule containing the genetic information that makes up the chromosomes.
the study of the relative power and limits of genetic and environmental influences on behavior.
the principle that those chance inherited traits that better enable an organism to survive and reproduce in a particular environment will most likely be passed on to succeeding generations.
the genetic transfer of characteristics from parents to offspring.

Experience the Testing Effect

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

Question 2.29

1. The threadlike structures made largely of DNA molecules are called .

Question 2.30

2. A small segment of DNA that codes for particular proteins is referred to as a .

Question 2.31

3. When the mother's egg and the father's sperm unite, each contributes

A.
B.
C.
D.

Question 2.32

4. Fraternal twins result when

A.
B.
C.
D.

Question 2.33

5. twins share the same DNA.

Question 2.34

6. Adoption studies seek to understand genetic influences on personality. They do this mainly by

A.
B.
C.
D.

Question 2.35

7. Epigenetics is the study of the molecular mechanisms by which trigger or block genetic expression.

Question 2.36

8. Behavior geneticists are most interested in exploring (commonalities/differences) in our behaviors. Evolutionary psychologists are most interested in exploring (commonalities/differences).

Question 2.37

9. Evolutionary psychologists are most likely to focus on

A.
B.
C.
D.

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