Fundamental Concepts in
Sociobiology
Anthropology 1
Honors Transfer Level
Kin Selection
 Concept formalized by W.D. Hamilton in 1963-4.
Reconciles altruism with Darwinian selection by
pointing to the fact that close relatives share large
numbers of genes in common. The theory
predicts therefore that you would more likely try
to pull a full sibling from a hungry polar bear than
a second cousin or mother-in-law.
Kin Recognition
 A necessary prerequisite of kin selection. For kin
recognition to exist, animals must possess the
means to distinguish kin from non-kin.
Mechanisms include imprinting and phenotype
matching.
Reciprocal Altruism
 Proposed by Robert Trivers in 1971. Explains
that cooperative behavior may have evolved from
an organism realizing that if it temporarly lowers
its fitness by helping another organism, its fitness
will be raised when that organism reciprocates.
Preconditions for Reciprocal Altruism
For reciprocal altruism to have come into
existence, there are two necessary preconditions:
 1. There has to be way of identifying
cheaters/deception.
 2. Opportunities for altruistic behavior must be
frequent.
Inclusive Fitness
 Another mechanism proposed by W.D. Hamilton
to explain altruism. He predicted that organisms
would behave in ways that would maximize their
inclusive fitness.
If an organism displays an altruistic behavior,
one that causes the organism to be protective of
close relatives and their offspring, then the gene
underlying this behavior will increase in the
population as it would be shared with these
relatives.
 The theory of inclusive fitness also proposes that
there will be ways for one organism to recognize
the altruistic acts of another non-related
organism, and to support that behavior.