Human Behavioral Genetics

Define human behavioral genetics.

study of the interaction of genetic & environmental factors

Describe three ways in which the complexity of behavior, as described in class, complicates our analyses of human behavioral genetics.

phenotypic variance

observable variability in a trait w/in a population

broad-sense heritability

proportion of total phenotypic variance in a population

narrow-sense heritability

(h²); a proportion of variation of a trait that is due to variation of only additive genetic factors

Outline an example which explains the concept of heritability as a relative measure, as discussed in class.

Why does heritability not apply to the relative role of genetics for individuals?

because it measures the proportion of variation in a trait across a population due to genetic differences

Why does heritability not apply to the relative role of genetics between groups?

it can’t separate genes from differing environments

Describe different ways in which intelligence may be defined.

• accumulated knowledge

• innate quality of info.

• problem-solving ability

Outline some of the various ways in which intelligence has been measured throughout history.

• Stanford-Binet test: IQ = (mental age/chronological age) x 100

• Galton: early anthropometric measures

Describe two different views regarding the relationship of IQ tests to intelligence.

• hereditarian view: IQ differences reflect inherent genetic group disparities

• environmentalist view: intelligence molded by culture/environment

What is g?

general intelligence factor

Describe potential evidence of genetic influences on intelligence.

• heritability is high & increases over lifespan

• higher concordance in twins

• impact of shared environments

Heritability increases gradually over a lifetime. Why might this be so?

individuals increasing select and shape experiences that align w/their genetic predispositions

What do genome-wide association studies suggest about IQ?

IQ is highly heritable and polygenic

Outline some of the environmental influences on intelligence.

• family life

• socio-economic status

• physical environment

• maternal environment

What is the Flynn effect?

IQ test scores have increased

What are some of the implications of the Flynn effect?

• better at test-taking

• better nutrition

• more parental education

• changes in early childhood experiences

The results of several IQ studies suggest that group difference in average IQ scores exist. Debate the four contemporary positions by which these data are interpreted. Be sure to include examples used to support each position and explanations for such supportive evidence.

1. real differences, caused be genetics?

   1. EX: reaction time test is a culture-free cognitive measure

2. real differences, product of environment?

   1. black children raised by white families score higher than black children raised by black families

3. no real difference

   1. test bias, culture bias

4. meaningless comparisons

   1. difficult to define & measure intelligence