CHAPTER 1: THE SCIENTIFIC MOVEMENTS LEADING TO EVOLUTIONARY PSYCHOLOGY
Chapter Summary
Evolutionary biology has undergone many historical developments. Evolution—change over time in
organisms was suspected to occur long before Charles Darwin came on the scene. Missing before him,
however, was a theory about a causal process that could explain how changes in life forms could occur.
The theory of natural selection was Darwin’s first contribution to evolutionary biology. It has three
essential ingredients: variation, inheritance, and differential reproduction. Natural selection occurs when
some inherited variations lead to greater reproductive success than other inherited variations. In short,
natural selection is defined as changes over time due to the differential reproductive success of inherited
variants.
Natural selection provided a unifying theory for the biological sciences and solved several important
mysteries. First, it provided a causal process by which change, the modification of organic structures,
takes place over time. Second, it proposed a theory to account for the origin of new species. Third, it
united all living forms into one grand tree of descent and simultaneously revealed the place of humans in
the grand scheme of life. The fact that it has now survived more than a century and a half of scientific
scrutiny, despite many attempts to find flaws in it, must surely qualify it as a great scientific theory
(Alexander, 1979; Dennett, 1995).
In addition to natural selection, sometimes referred to as “survival selection,” Darwin devised a second
evolutionary theory: the theory of sexual selection. Sexual selection deals with the evolution of
characteristics due to success in mating rather than to success in survival. Sexual selection operates
through two processes: intrasexual competition and intersexual selection. In intrasexual competition,
victors in same-sex contests are more likely to reproduce due to increased sexual access to mates. In
intersexual selection, individuals with qualities that are preferred by the opposite sex are more likely to
reproduce. Both processes of sexual selection result in evolution—change over time due to differences in
mating success.
Following the Modern Synthesis, two European biologists, Konrad Lorenz and Nikolas Tinbergen, started
and popularized a new movement called ethology, which sought to place animal behavior within an
evolutionary context by focusing on both the origins and functions of behavior.
In 1964, the theory of natural selection itself was reformulated in a revolutionary pair of articles published
by W. D. Hamilton. The process by which selection operates, according to Hamilton, involves not just
classical fitness (the direct production of offspring), but also inclusive fitness, which includes the effects
of an individual’s actions on the reproductive success of genetic relatives, weighted by the appropriate
degree of genetic relatedness. The inclusive fitness reformulation provided a more precise theory of the
process of natural selection by promoting a “gene’s eye” view of selection.
In 1966, George Williams published the now classic Adaptation and Natural Selection, which had three
effects. First, it led to the downfall of group selection. Second, it promoted the inclusive fitness revolution
and helped to marshal in differential gene reproduction that is the central causal process of evolution by
selection. And third, it provided rigorous criteria for identifying adaptations, such as efficiency,
reliability, and precision. In the 1970s, Robert Trivers built on the work of Hamilton and Williams,
offering three seminal theories that remain important today: reciprocal altruism, parental investment, and
parent–offspring conflict.
Evidence from a variety of disciplines permits us to understand some of the critical milestones in the
evolutionary process that led to modern humans. Humans are mammals, which originated more than 200
million years ago. We are part of a primate line that began 85 million years ago. Our ancestors became
bipedal 4.4 million years ago, developed crude stone tools 2.5 million years ago, and might have begun to
cultivate fire 1.6 million years ago. As the brains of our ancestors expanded, we developed more
sophisticated tools and technology and started to colonize many parts of the world.
While changes were taking place within evolutionary biology, the field of psychology followed a
different course. Sigmund Freud drew attention to the importance of survival and sexuality by proposing a
theory of life-preserving and sexual instincts, paralleling Darwin’s distinction between natural selection
and sexual selection. In 1890, William James published Principles of Psychology, which proposed that
humans have a number of specific instincts. In the 1920s, however, U.S. psychology turned away from
evolutionary ideas and embraced a version of radical behaviorism: the idea that a few highly general
principles of learning could account for the complexity of human behavior.
In the 1960s, however, empirical findings suggested important violations of the general laws of learning.
Harry Harlow demonstrated that monkeys do not prefer wiremesh “mothers,” even when they receive
their primary food reinforcement from those mothers. John Garcia showed that organisms could learn
some things readily and rapidly. Something was going on inside the brains of organisms that could not be
accounted for solely by the external contingencies of reinforcement.
Suggested Readings
Buss, D. M. (2009). The great struggles of life: Darwin and the emergence of evolutionary psychology.
American Psychologist, 64, 140–148.
Confer, J. C., Easton, J. E., Fleischman, D. S., Goetz, C., Lewis, D. M., Perilloux, C., & Buss, D. M.
(2010). Evolutionary psychology: Controversies, questions, prospects, and limitations. American
Psychologist, 65, 110–126.
Darwin, C. (1859). The origin of the species. London: Murray.
Davies, N. B., Krebs, J. R., & West, S. A. (2012). An introduction to behavioural ecology
(4th ed.). Wiley-Blackwell.
Multiple Choice Questions
(a) Why is the mind designed the way that it is?
(b) How do the components of the mind interact with the environment?
(c) What is the relationship between the human mind and the Big Bang?
(d) What are the functions of the components of the human mind?
(a) changes over time in organic structure
(b) differences between species
(c) changes over time in the shape of the human skull
(d) differences between men and women
(a) first by Darwin
(b) well before Darwin’s time
(c) well after Darwin’s time
(d) first by George Williams
(a) Species originate from microscopic algae.
(b) Species progress toward a lower form.
(c) acquisition of inherited characteristics
(d) inheritance of acquired characteristics
(a) extinguished by sudden catastrophes and replaced by different species
(b) irradiated by sudden catastrophes, thereafter replacing other species
(c) extinguished by gradual elimination due to disease, leaving room for new species
(d) irradiated and extinguished, and replaced by the same species
6. Which of the following clues to change in organic structure over time were not known or noted prior to
(a) cross-species structural similarities
(b) cross-species embryological similarities
(c) apparent function of traits
(d) mechanism to explain change in organic structure over time
(a) natural selection
(b) founder effect
(c) genetic bottleneck
(d) mutation
8. Which of the following is NOT one of the three essential processes identified by Darwin’s theory of
(a) variation
(b) particulation
(c) selection
(d) inheritance
(a) Variation
(b) Particulation
(c) Selection
(d) Inheritance
10. For evolution to work, successful variations must be _________, or passed down reliably from parent
(a) variated
(b) particulated
(c) selected
(d) inherited
11. The process of _________ refers to the component of Darwin’s theory of evolution that states that
organisms with some heritable attributes leave more offspring because those attributes help with the tasks
(a) variation
(b) particulation
(c) selection
(d) inheritance
12. In contrast to the theory of natural selection, which focused on adaptations that have arisen as a
consequence of successful survival, the theory of ______________ focused on adaptations that have
(a) sexual selection
(b) internal selection
(c) external selection
(d) social selection
(a) evolution is unlikely to have occurred in pea plants
(b) evolution is unlikely to have occurred in pea genes
(c) inheritance is particulate, not blended
(d) inheritance is blended, not particulate
14. A _______ is the smallest discrete unit that is inherited by offspring intact, without being broken up
(a) genotype
(b) phenotype
(c) meme
(d) gene
15. Ethologists are interested in four key issues, which became known as the four “whys” of behavior
advanced by Niko Tinbergen, a founder of ethology. Which of the following is not one of the four “whys”
(a) imprinted influences of behavior
(b) immediate influences of behavior
(c) developmental influences of behavior
(d) function of behavior
16. According to Hamilton (1954), _________ is the sum of classical fitness plus the effects the
individual’s actions have on the reproductive success of his or her genetic relatives, weighted by the
(a) direct fitness
(b) indirect fitness
(c) inclusive fitness
(d) exclusive fitness
(a) grandmother
(b) niece
(c) half-brother
(d) first cousin
18. Williams’s (1966) book clarified the concept of _________, an evolved solution to a specific problem
(a) genetic drift
(b) byproduct
(c) adaptation
(d) exaptation
(a) theory of parental investment
(b) theory of gene selection
(c) theory of reciprocal altruism
(d) theory of parent-offspring conflict
20. Edward O. Wilson’s 1975 book ignited controversy for the assertion that much of human behavior
(a) socialization
(b) evolutionary biology
(c) inclusive fitness theory
(d) ethology
(a) based on research documenting the importance of cognition in human behavior
(b) based on little empirical work
(c) controversial because it portrayed humans as being subject to different evolutionary forces than
other animals
(d) controversial because it did not account for the role of culture in shaping behavior
(a) genetic determinism
(b) Behavior is impervious to change.
(c) Adaptations are optimally designed.
(d) Adaptations are designed to confront environmental problems.
(a) genes determine behavior
(b) behavior is caused by the interaction of genes and environment
(c) culture determines all behavior
(d) if a trait is natural, it is “good”
(a) culture and socialization
(b) psychological machinery and natural selection
(c) adaptations and environmental input
(d) environmental input and developmental activation
(a) provides evidence that genes play the most important role in shaping behavior
(b) suggests that humans are different from all other animals
(c) suggests that behavior is not modifiable
(d) gives us power to change targeted behaviors
(a) Evolved psychological mechanisms are optimally designed.
(b) Evolved psychological mechanisms are not optimally designed because of evolutionary time lags.
(c) Evolved psychological mechanisms are associated with costs.
(d) Adaptations work reasonably well at solving adaptive problems.
(a) descent from mammals
(b) bipedal locomotion
(c) development of agriculture
(d) brain expansion
(a) 35–40 thousand
(b) 120–150 thousand
(c) 27 million
(d) 30 million
29. William James was one of the first to posit that humans have _________ instincts than/from other
(a) fewer
(b) equal but different
(c) more
(d) different
(a) Darwin’s theory of natural selection
(b) the cognitive revolution
(c) classical conditioning
(d) James’s psychology of instincts
31. Classical conditioning differed from operant conditioning in the role given to _________ in human
(a) reinforcement
(b) radical behaviorism
(c) culture
(d) instincts
(a) all behavior is instinctual, but can be modified by learning
(b) reflexes are the only instincts
(c) a general ability to learn is the only instinct
(d) there are no instincts
(a) her fieldwork studying Antarctic cultures
(b) claiming to have found cultures with reversed sex roles, and with no fighting, murder, or sexual
jealousy
(c) debunking findings of cultures with reversed sex roles
(d) her writings on the thoughts, behaviors, and rituals on which learning could operate
(a) monkeys would prefer a wire mesh mother that dispensed food
(b) monkeys would prefer a wire mesh mother with a soft cloth cover that did not dispense food
(c) monkeys would withdraw from, and be frightened by, both wire mesh mothers
(d) monkeys would prefer both wire mesh mothers equally
(a) the ability to condition humans to fear things such as snakes and electrical outlets
(b) taking into account the role of learning in conditioning fears
(c) the fact that humans are wired to learn all things equally well
(d) the ability to learn some things more easily than others
(a) violations of the fundamental laws of learning
(b) underlying structures for language that are invariable across cultures
(c) technology such as magnetic resonance imaging (MRI) that allowed psychologists to “peer” into
the minds of humans
(d) the rise of computers
(a) neurobiology
(b) information processing
(c) computers
(d) domain-general learning
(a) the number of behaviors possible in any one situation caused by combining two or more
sequential possibilities
(b) the explosion of life on the planet about 4 billion years ago
(c) the problem of not having enough domain-specific programming to account for the entire range of
possible human behavior
(d) general-purpose learning mechanisms capable of an infinite range of behaviors
39. Scientists have brought three fundamental sources of evidence to bear on testing theories about origins
(a) anatomical evidence
(b) archeological evidence
(c) anthropological evidence
(d) genetic evidence
40. Which of the following is the theory of human origins which has received much support from
archeological evidence, though recent genetic evidence has refuted its exclusivity as a full explanation?
(b) multiregional continuity
(c) North American bottleneck
(d) creative explosion
(a) result in more muscular animals
(b) promote the good of the species
(c) increase the intelligence of the species
(d) promote inclusive fitness