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Chapter 8

Personality Psychology Chapter 8 .docx

11 pages61 viewsWinter 2012

Department
Psychology
Course Code
PSYC 2600
Professor
Elizabeth Nisbet
Chapter
8

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Chapter 8- Evolutionary perspectives on personality
8.1- Evolution and Natural selection
Evolutionary psychology is a new and rapidly growing scientific perspective, and it offers important
insights into human personality.
We carry with us the genes for the adaptive mechanisms that led for their success. From this
perspective, our human naturethe collection of mechanisms that defines us as humanis the product
of the evolutionary process. Nonetheless, humans are rarely aware of these mechanisms.
***Natural selection a.k.a survival selection: Darwin’s contribution was not in observing change over
time, nor in noticing the adaptive design of mechanisms. Rather, Darwin proposed a theory of the
process by which adaptations are created and a change takes place over time. He called it the theory of
natural selection. Darwin noticed that species seemed to produce many more offspring than could
possibly survive and reproduce. He reasoned that changes, or variants, that better enabled an organism
to survive and reproduce will lead to more descendants. The descendants would inherit the variants
that led to their ancestor’s survival and reproduction. Through this process, the successful variants that
led to their ancestors’ survival and reproduction. Through this process, the successful variants were
selected and unsuccessful weeded out. This process of natural selection, led Darwin to focus on the
events that impede survival, which he called the hostile forces of nature. These hostile forces included
food shortages, diseases, parasites, predators and extreme weather.
Adaptations: Inherited solutions to the survival and reproductive problems posed by hostile forces of
nature. Adaptations are the primary product of the selective process. An adaptation is a “reliably
developing structure in the organism, which, because it meshes with the recurrent structure of the
world, causes the solution to an adaptive problem”.
***Sexual selection: Darwin answer to the mysteries of the peacock’s tail and the stag’s antlers was that
they evolved because they contributed to an individual’s mating success, providing an advantage in the
competition for desirable mates. The evolution of characteristics because of their mating benefits,
rather than because of their survival benefits, is known as sexual selection
According to Darwin it takes two forms. In one form, members of the same sex compete with each other
and the outcome of their contest gives the winner greater sexual access to member of the opposite sex.
It is known as intrasexual competition. The characteristics that lead to success in contests of this kind,
such as greater strength, intelligence, or attractiveness to allies, evolve because the victors are able to
make more often and, hence, pass on more genes.
Intersexual competition is the other form of sexual selection. Members of one sex choose a mate based
on their preferences for particular qualities in a mate. These characteristics evolve because animals that
possess them are chosen more often as mates, and their genes thrive. Animals that lack the desired
characteristics are excluded from mating, and their genes perish.
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***Genes and inclusive fitness: genes are packets of DNA that are inherited by children from their
parents in distinct chunks. Genes are the smallest discrete units that are inherited by offspring intact,
without being broken up. According to modern evolutionary biologists, evolution operates by the
process of differential gene reproduction; define reproductive success relative to others. The genes of
organisms that reproduce more than others get passed down to future generations at a greater
frequency than do the genes of those that reproduce less. Survival is critical for reproductive success, so
characteristics that lead to greater survival get passed along. Success in mating is also critical for
reproductive success, and the qualities that lead to success in the same-sex competition or to success at
being chosen as a mate to get passed along.
The modern evolutionary theory based on differential gene reproduction is called inclusive fitness
theory. The “inclusive” part is the fact that the characteristics that facilitate reproduction need not
affect the personal production of offspring. They can affect the survival and reproduction of genetic
relatives as well.
***Products of the evolutionary process: All living humans are products of the evolutionary process, the
descendants of a long line of ancestors who succeeded in surviving, reproducing, and helping their
genetic relatives. The evolutionary process acts as a series of filters. In each generation, only a small
subset of genes passes through the filter. The recurrent filtering process lets only three things pass
through: adaptations; by-products of adaptations; and noise, or random variations.
*Adaptations: are the primary products of the selective process. An adaptation can be define as a
“reliably developing structure in the organism, which, because it meshes with the recurrent structure of
the world, causes the solution to an adaptive problem. Adaptations might include a taste for sweet and
fatty foods, the drive to defend one’s close relatives, and preferences for specific mates, such as those
that are healthy. Let’s examine the components of the definition of adaptation. The focus on reliably
developing structure means that an adaptation. The focus on reliably developing structure means that
and adaptation tends to emerge with regularity during the course of a person’s life. The mechanisms
that allow humans to see, for example, develop reliably. But this does not mean that vision develops
invariantly. The development of the eye can be perturbed by genetic anomalies or by environmental
trauma. The emphasis on reliable development suggests that evolutionary approaches are not forms of
“genetic determinism”. Environments are always needed for the development of an adaption, and
environmental events can always interfere with or enhance such development.
The emphasis on meshing with recurrent structures of the world means that adaptations emerge from,
and are structured by, the selective environment. Features of the environment must be recurrent over
time for an adaption to evolve. The venomous snakes must be recurrently dangerous, ripe fruit must be
recurrently nutritive before adaptations to then can emerge.
Finally, an adaptation must facilitate the solution to an adaptive problem. An adaptive problem is
anything that impedes survival or reproduction. Stated more precisely, all adaptations must contribute
to fitness during the period of time in which they evolve by helping an organism survive, reproduce, or
facilitate the reproductive success of genetic relatives.
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The hallmark of adaptation is special design. Special design: features of an adaptation are recognized as
components of specialized problem-solving machinery. Factors such as efficiency in solving a specific
adaptive problem, precision in solving the adaptive problem, and reliability in solving the adaptive
problem are key criteria in recognizing the special design of an adaptation. Adaptations are like keys that
fit only specific locks.
*By-products of adaptations: The evolutionary process also produces things that are not adaptations
such as by-products of adaptations. Consider the design of a light bulb. A light bulb is designed to
produce lightthat is its function. But it may also produce heat, not because it is designed to produce
heat but, rather, because heat is an incidental by-product, which occurs as a consequence of design for
light. In the same way, human adaptation can also have evolutionary by-products, or incidental effects
that are not properly considered to be adaptations. The human nose, for example is clearly an
adaptation designed for smelling.
*Noise, or Random variations: the third product of the evolutionary process is evolutionary noise, or
random variations that are neutral with respect to selection. In the design of a light bulb, for example,
there are minor variations in the surface texture of the bulb that do not affect the functioning of the
design elements. Neutral variations introduced into the gene pool through mutation, for example, are
perpetuated over generations if they do not hinder the functioning of adaptations.
In sum, there are three products of the evolutionary process: adaptations, by-products, and noise.
Adaptations are the primary product of the selective process, so evolutionary psychology is primarily
focused on identifying and describing human psychology adaptations. The hypothesis that something is
a by-product requires specifying the adaptation of which it is a by-product. The analysis of by-products,
therefore, leads back to the need to describe adaptations. And noise is the residue of non-functional
variation that is selectively neutral.
8.2-Evolutionary Psychology
***Premises of evolutionary psychology:
Evolutionary psychology involves three key premises: domain specificity, numerousness, and
functionality.
*Domain specificity: adaptations are presumed to be domain-specific in the sense that they are
designed by the evolutionary process to solve a particular adaptive problem. Consider the problem of
food selectionchoosing the right foods to eat from among a large array of possible objects in the
world. A general decision rule, such as “eat the first thing you encounter” , would be highly maladaptive,
because it would fail to guide you to choose the small subset of objects that are edible and nutritious.
Such a general rule would result in the consumption of poisonous plants, twigs, dirt, or feces, which
would interfere with successful survival. The mechanisms favored by the evolutionary process are more
specialized. In the area of food selection, domain specificity is seen in our preferences for calorically rich
fat and in our evolved sweet tooth, which leads us to objects rich in sugar, such as ripe fruits and berries.
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