PSYB30 – Lecture 3 – Chapter 2
Evolutionary Process: 3 Basic Elements
Variation – Idea that we differ in our design features (variation in design)
•We come into our world differently physically and psychologically
Inheritance – Design features are inheritable, some design features are
inheritable
Selection – Design features, to a greater or lesser extent, can influence our
abilities to survive & reproduce
•If design feature is heritable & contributes to survival &
reproductive success, trait will appear in increasing frequency
across generations
•Traits that are inheritable & positively impact survival &
reproduction, get passed on at greater rates, than alternative design
features, and propagate amongst the species
•If pressures/environmental challenges remain same over long
enough period of time, traits that equip organisms to survive &
reproduce best, will become so frequent in the population that trait
will become typical amongst the species as a whole
Evolutionary Processes
Natural Selection – Evolution of adaptive characteristics because of the survival
benefits bestowed on those having them (giraffe Neck)
•Key element is that trait/design feature in question is contributing
to survival of organism
Sexual Selection – Evolution of adaptive characteristics because of the
reproductive benefits bestowed on those having them
•Intrasexual Competition (Same Sex Competition) – Members of
one sex will compete for preferential or priority of access of
members of the opposite sex
oTraits/design features/attributes which enable the
males of a species to compete successfully against
other males, will ensure that the male reproduces
successfully (Deer fighting for Do’s)
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