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Module 1.1

Does the same process work with naturally occurring selection? Does natural selection
explain our human tendencies? Nature has indeed selected advantageous variations from
the new gene combinations produced at each human conception plus occasional mutations
(random errors in gene replication that become nature’s preliminary tests of alternative pos- PRACTICE
sibilities). But the tight genetic leash that predisposes a dog’s retrieving, a cat’s pouncing, or
a bird’s nesting is looser on humans. The genes selected during our ancestral history provide Research Methods &
more than a long leash; they give us a great capacity to learn and therefore to adapt to life
in varied environments, from the tundra to the jungle. Genes and experience together wire Design (SP 2)
the brain. Our adaptive flexibility in responding to different environments contributes to our (10 minutes) Notice the AP ®
fitness — our ability to survive and reproduce.
Science Practices included
Evolutionary Success Helps Explain Similarities throughout the text. Take advantage
Human differences grab our attention. The Guinness World Records, for example, entertain of these features by discussing
us by highlighting the tallest, oldest, longest-haired, and most-tattooed humans. But our the research terms with your
deep similarities also demand explanation. At the Amsterdam Airport’s international arriv- students in the context of each
als area, one sees the same delighted joy on the faces of Indonesian grandmothers, Chinese ®
®
children, and homecoming Dutch. In our genes and our behaviors, we humans are more AP Science Practice module. The AP exam will require
alike than different. “Your DNA and mine are 99.9 percent the same,” observed Francis Research that students evaluate research
Collins (2007), who led the human genome’s decoding. “At the DNA level, we are clearly In research terminology, a popu- within a psychological context.
all part of one big worldwide family.” lation refers to all those in a group
being studied, say in a survey or Take a moment here to review the
experiment, from which a sample
Our Genetic Legacy can be drawn. You can review difference between samples and
this and other terms related to
Our similarities reflect our shared human genome — our common set of genes. No more than research methods in Unit 0. populations as well as the various
5 percent of the genetic differences among humans arise from population group differences. measures of central tendency.
Worth Publishers.
Some 95 percent of genetic variation exists within populations (Rosenberg et al., 2002). Thus,
the typical genetic difference between two South Africans or between two Singaporeans is
much greater than the average difference between the two groups (Lewontin, 1982).
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And how did we develop this shared human genome? At the dawn of human history, AP Science Practice
our ancestors faced certain questions: Who is my ally, who is my foe? With whom should Research TEACH 1.1-1
I mate? What food should I eat? Some individuals answered those questions more suc- The text refers to average differ-
cessfully than others. For example, women who experienced nausea in the critical first ences here. Recall from Unit 0 Discussion Prompt
3 months of pregnancy were genetically predisposed to avoid certain bitter, strongly fla- & Worth Publishers. Not for redistribution.
that the average is determined by
The textbook describes how prehis-
vored, and novel foods. Avoiding such foods had survival value, since they are the very calculating the mean, which is a
measure of central tendency.
foods most often toxic to prenatal development (Profet, 1992; Schmitt & Pilcher, 2004). Early toric women who were genetically pre-
humans disposed to eat nourishing rather than poisonous foods survived to contribute their disposed to avoid bitter foods might
Bedford, Freeman &
genes to later generations. Those who deemed leopards “nice to pet” often did not. have had more successful pregnan-
Similarly successful were those whose mating helped them produce and nurture
offspring. Over generations, the genes of individuals not disposed to mate or nurture cies, thus passing down this gene. In
tended to be lost from the human gene pool. As success-enhancing genes continued to be small groups, have students discuss
selected, behavioral tendencies and learning capacities emerged that prepared our Stone why they eat and what they eat. How
Age ancestors to survive, reproduce, and send their genes into the future, and into you.
For all such universal human tendencies, from our intense need to give parental care can the evolutionary perspective
to our shared fears and lusts, evolutionary theory proposes a single, all-encompassing explain their current eating habits?
Distributed by Bedford, Freeman
explanation (Schloss, 2009).
As heirs to this prehistoric legacy, we were not born as unprogrammed “blank slates.”
Instead, we are genetically predisposed to think and act in ways that promoted our biologi- TEACH 1.1-1
Copyright ©
cal ancestors’ survival and reproduction. But in some ways, we are biologically prepared for
a world that no longer exists. We love the taste of sweets and fats, nutrients that prepared mutation a random error in Teaching Tip
our physically active ancestors to survive food shortages. Few of us now hunt and gather gene replication that leads to a Students may not appreciate the
for our food; instead, we too readily find sweets and fats in fast-food outlets and vending change.
machines. Our deeply rooted natural dispositions are mismatched with today’s proliferation importance of predisposition. Explain
that whereas a person’s genetic code
will determine many physical and
Interaction of Heredity and Environment Module 1.1 7
hair color, height, weight, and extra-
version/introversion, these qualities
03_myersAPpsychology4e_28116_ch01_002_163.indd 7 15/12/23 9:20 AM personal qualities such as eye color,
ENGAGE 1.1-1 forefingers are determined by a recessive interact with the environment to influ-
(5 minutes) Use these quick demonstrations trait in females, whereas in males it is ence things like popularity, interests,
dominant.)
to show that many traits and behaviors are and dating choices. Even identical
inherited. • When interlocking their fingers, do twins, who share 100 percent of the
students place the left or right thumb on same genes, can differ in many ways
• Have students draw a straight horizontal top? (Some characteristics are genetically depending on even slightly different
line on a sheet of paper. When the tip controlled. Practice or experience has environments.
of their ring finger is placed on the line, no effect on which thumb you place
does the tip of the forefinger also reach on top.)
the line? (Research indicates that short

Interaction of Heredity and Environment Module 1.1 7

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