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Chapter 1

PSYC 3420 Chapter Notes - Chapter 1: Classical Conditioning, Sociobiology, Homo Erectus

Course Code
PSYC 3420
Irwin Silverman

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Chapter 1: The scientific movements leading to evolutionary psychology
Landmarks in the history of evolutionary thinking
- Evolution refers to change over time
- Lamarck was one of the first scientists to use the work biologie, thus recognizing the study of life as a
distinct science
- He believed in two major causes of species change: first, a natural tendency for each species to
progress toward a higher form and, scond, the inheritance of acquired characteristics
- Cuvier proposed a theory called catastrophism, according to which species are extinguished
periodically by sudden catastrophes, such as meteorites, and then replaced by different species
- Darwin’s answer to all these puzzles of life was the theory of natural selection (survival selection)
and its three essential ingredients: variation, inheritance, and selection
- Variations is essential for the process of evolution to operate, it provides the raw materials for
evolution. Variations are inherited, passed down reliably from parents to their offspring and down to
the generations
- Selection, organisms with some heritable variants leave more offspring because those attributes help
with the tasks of survival or reproduction
- Sexual selection focused on the adaption’s that have arisen as a consequence of successful mating
- Two primary means by which sexual selection could operate are;
- 1. Intrasexual competition, competition between members of one sex, the outcomes of which
contributed to mating access to the other sex. Qualities lead to success in the same sex contests, such as
greater size, strength, or athletic ability, will be passed on to the next generation by virtue of mating
success of the victors
- 2. Intersexual selection, evolutionary changes occurs simply because the qualities that are desired in a
mate increase in frequency with the passing of each generation. Darwin called this female choice
because females of many species we discriminating or choosy about whom they mated with
- Genetic drift, which is defined as random changes in the genetic makeup of a population
- Random changes come about through several processes, including mutation (a random heredity change
in DNA), founder effects, and genetic bottlenecks
- Founder effect occurs when a small portion of a population establishes a new colony and the founders
of the new colony are not entirely genetically representative of the original population
- Genetic bottlenecks, which happen when a population shrinks, perhaps owing to a random
catastrophe such as an earthquake
- Evolution by natural selection is not forward-looking and it not intentional
- Another critical feature of selection is that it is gradual
- One objection was that Darwinian evolution lacked a coherent theory of inheritance. Darwin himself
preferred a blending theory of inheritance, in which offspring are mixtures of their parents
- Another objection was that some biologists could not imagine how the early stages of the evolution of
an adaption could be useful to an organism
- A third objection came from religious creationists, many whom viewed species as immutable
(unchanging) and created by a deity rather than by the gradual process of evolution by selection
- The qualities of the parents are not blended with each other, but rather are passed on intact to their
offspring in distinct packets called genes. Genes must be passed on, not acquired
- Mendel’s discovery that inheritance is particulate, which he demonstrated by crossbreeding different
strains of pea plants
- A gene is defined as the smallest discrete unit that is inherited by offspring intact, without being
broken up or blended
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