1. 3
Genes, Evolution, and Environment

2. Unlocking the Secrets of Genes LO3
Unlocking the Secrets of Genes LO3.1 Explain how genes, chromosomes, DNA, genomes, and epigenetics all relate to one another.
Evolutionary psychology
Emphasizes the evolutionary mechanisms that may help explain human commonalities in social practices, perception, emotional responses, and other areas of behavior.
Behavioral genetics
Interdisciplinary field of study concerned with genetic contributions to individual differences in behavior and personality.

3. Unlocking the Secrets of Genes, cont’ LO3
Unlocking the Secrets of Genes, cont’ LO3.1 Explain how genes, chromosomes, DNA, genomes, and epigenetics all relate to one another.
Genes
Functional units of heredity; they are composed of DNA and specify the structure of proteins.
Chromosomes
Within every cell, rod-shaped structures that carry the genes.
DNA (deoxyribonucleic acid)
Chromosomal molecule that transfers genetic characteristics by way of coded instructions for the structure of proteins.

4. Unlocking the Secrets of Genes, cont’ LO3
Unlocking the Secrets of Genes, cont’ LO3.1 Explain how genes, chromosomes, DNA, genomes, and epigenetics all relate to one another.

5. Unlocking the Secrets of Genes, cont’ LO3
Unlocking the Secrets of Genes, cont’ LO3.1 Explain how genes, chromosomes, DNA, genomes, and epigenetics all relate to one another.
Human genome
Linkage studies
Because genes close to each other are likely to be inherited together, researchers can look for genetic markers in families.
Genetic markers
A segment of DNA that varies among individuals, has a known location on a chromosome, and can function as a genetic landmark for a gene involved in a physical or mental condition.

6. Unlocking the Secrets of Genes, cont’ LO3
Unlocking the Secrets of Genes, cont’ LO3.1 Explain how genes, chromosomes, DNA, genomes, and epigenetics all relate to one another.
The link between genes and behavior
Even when researchers locate a gene on a chromosome, they do not automatically know its role in physical or psychological functioning.
Most human traits are influenced by more than one gene pair.
Intelligence
Shyness

7. Genetics of Similarity LO3
Genetics of Similarity LO3.2 Explain how natural selection contributes to changes in gene frequencies in a population.
Evolution
A change in gene frequencies within a population over many generations
A mechanism by which genetically influenced characteristics of a population may change
Changes may occur due to
mutations or errors occurring during copying of a DNA sequence
natural selection

8. Genetics of Similarity, cont’ LO3
Genetics of Similarity, cont’ LO3.2 Explain how natural selection contributes to changes in gene frequencies in a population.
Natural selection
The evolutionary process in which individuals with genetically influenced traits that are adaptive in a particular environment tend to survive and reproduce in greater numbers.
Their traits then become more common in the population.

9. Genetics of Similarity, cont’ LO3
Genetics of Similarity, cont’ LO3.2 Explain how natural selection contributes to changes in gene frequencies in a population.
Traits and preferences
Ask what sorts of challenges human beings might have faced and then infer which behavioral tendencies might have been selected to overcome these challenges
E.g., avoiding poisonous food and an innate dislike for bitter tastes

10. Genetics of Similarity, cont’ LO3
Genetics of Similarity, cont’ LO3.2 Explain how natural selection contributes to changes in gene frequencies in a population.
Mental modules
The human mind developed as a collection of specialized and independent “mental modules” to handle specific survival problems.
Avoid the error of assuming if some behavior or trait exists, it must therefore be adaptive.

11. Genetics of Similarity, cont’ LO3
Genetics of Similarity, cont’ LO3.3 List and describe five innate human characteristics.
Innate human characteristics
Infant reflexes
Interest in novelty
Desire to explore and manipulate objects
Impulse to play and fool around
Basic cognitive abilities

12. Courtship and Mating LO3
Courtship and Mating LO3.4 Compare the sexual strategies of females and males, according to the sociobiological perspective.
Sociobiology
Interdisciplinary field that emphasizes evolutionary explanations of social behavior in animals, including human beings.
We behave in ways that maximize our chances of passing on our genes, and to help our close biological relatives, with whom we share genes, to do the same.

13. Courtship and Mating, cont’ LO3
Courtship and Mating, cont’ LO3.4 Compare the sexual strategies of females and males, according to the sociobiological perspective.
Evolution and sexual strategies
Due to different kinds of survival and mating problems, the sexes have evolved differently with respect to aggressiveness, physical dominance, and sexual strategies.
Males compete with other males for access to females, and try to inseminate as many females as possible.
Females conceive and carry only a limited number of children, so they choose fewer, more dominant males with good resources and high status.

14. Courtship and Mating, cont’ LO3
Courtship and Mating, cont’ LO3.4 Compare the sexual strategies of females and males, according to the sociobiological perspective.
Preferred age in a mate
Evolutionary psychologists consider such analogies of human and animal behaviors simplistic and misleading.
Focus more on commonalities of human mating and courtship around the world.

15. Courtship and Mating, cont’ LO3
Courtship and Mating, cont’ LO3.5 Discuss four challenges to the evolutionary view of human mating strategies.
The genetic leash
Criticisms of sociobiological and evolutionary explanations for sexual behavior include:
Stereotypes vs. actual behavior
What people say vs. what they do
Convenience vs. representative sample
The Fred Flintstone problem.

16. Courtship and Mating, cont’ LO3
Courtship and Mating, cont’ LO3.5 Discuss four challenges to the evolutionary view of human mating strategies.
Attitudes toward chastity

17. The Genetics of Difference LO3
The Genetics of Difference LO3.6 Explain what heritability refers to, and discuss three important facts about heritability that should be kept in mind when discussing genetic contributions to behavior.
Meaning of heritability
An estimate of heritability applies only to a particular group living in a particular environment.
Heritability estimates do not apply to a specific person, only to variations within a group of people.
Even highly heritable traits can be modified by the environment.

18. Computing Heritability LO3
Computing Heritability LO3.7 Outline the basic design of a heritability study that involves twins and adoptees.
Computing heritability
Studying adopted children allows researchers to compare correlations between the traits of adopted children and those of their biological and adoptive relatives.

19. Computing Heritability, cont’ LO3
Computing Heritability, cont’ LO3.7 Outline the basic design of a heritability study that involves twins and adoptees.
Computing heritability
If identical twins are more alike than fraternal twins, then the increased similarity must be due to genetic differences.

20. Computing Heritability, cont’ LO3
Computing Heritability, cont’ LO3.7 Outline the basic design of a heritability study that involves twins and adoptees.
Computing heritability
Investigators have also studied twins who were separated early in life and reared apart.
Any similarities in traits between them should be primarily genetic.

21. The Case of Intelligence LO3
The Case of Intelligence LO3.8 Discuss the extent to which intelligence may be heritable.
Genes and individual differences
Intelligence Quotient (IQ)
Measure of intelligence originally computed by dividing a person’s mental age by his/her chronological age and multiplying by 100. Now derived from norms provided for standard intelligence tests.
The kind of intelligence that produces high IQ scores is highly heritable.
Two-thirds of all test takers score between 85 and 115.

22. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.8 Discuss the extent to which intelligence may be heritable.
Twins and intelligence
Intelligence scores of identical twins are always correlated more strongly than those of fraternal twins.

23. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.8 Discuss the extent to which intelligence may be heritable.
Adopted children and intelligence
The scores of adopted children are strongly correlated with those of their biological parents.

24. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.9 Explain why both between-groups and within-groups variability are important in arguments about group differences in intelligence.
The question of group differences
Genetics are used to explain differences between groups.
These differences are used to justify differential treatment for these groups.
Differences between average IQ scores for African Americans and European Americans
Genetic explanations have a flaw.
Use heritability estimates based on white samples to estimate the role of heredity in group differences.

25. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.9 Explain why both between-groups and within-groups variability are important in arguments about group differences in intelligence.
The question of group differences

26. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.9 Explain why both between-groups and within-groups variability are important in arguments about group differences in intelligence.
Those studies overcoming past methodological problems fail to reveal genetic differences between blacks and whites on IQ.
Example:
Children fathered by black and white American soldiers in Germany after WWII and reared in similar German communities did not differ significantly in IQ.

27. The Case of Intelligence, cont’ LO3
The Case of Intelligence, cont’ LO3.10 List four ways that the environment nurtures or thwarts mental ability, and give an example of each.
Environment and intelligence
Experiences that hinder:
Poor prenatal care
Malnutrition
Exposure to toxins
Stressful family circumstances
Experiences that help:
Good health care and nutrition
Mental enrichment in home and child care or school

28. Beyond Nature vs. Nurture LO3
Beyond Nature vs. Nurture LO3.11 Explain how both nurture and nature play an interactive role in shaping behavior.
Beyond nature versus nurture
Heredity and environment always interact to produce the unique mixture of qualities that make a human.
Psychological diversity is adaptive.