Encyclopedia Britannica explaines the term kin selection
as the following:
selection occurs when an animal engages in self-sacrificial behavior that benefits the
genetic fitness of its relatives
Study.com would define it as:
A type of natural selection where
individuals will sacrifice their own lives in an effort to save closely related
organisms; therefore, ensuring the survival of genes that they both share.
A form of natural selection that favors altruistic
behavior toward close relatives resulting in an increase in the altruistic
individual’s genetic contribution to the next generation.
Before looking deeper into the theory of a kin selection
we should have a brief look into the term Altruism and Darwins theory of
The theory of evolution by natural selection, first
formulated in Darwin’s book “On the Origin of Species” in 1859,
is the process by which organisms change over time as a result of changes
in heritable physical or behavioral traits. Changes that allow an organism
to better adapt to its environment will help it survive and have more
Altruism is the principle or practice of unselfish
concern for or devotion to the welfare of others and plays a major part
when studying kin selection theory.
The theory of kin selection is
one of the foundations of the modern study of social behaviour. British
evolutionary biologist W.D. Hamilton first proposed the theory in 1963 and
noted that it plays a role in the evolution of altruism,
cooperation, and sociality; however, the term kin selection was
coined in 1964 by British evolutionary biologist Maynard Smith.
The theory states that in general animals
tend to cooperate with relatives, even if this brings risk to themselves. This cooperation brings benefit if the
animals are closely related due to related organisms having to some extent
shared genes. This theory is supported by the fact that the
transferring of a gene to a next generation is one of a main function of an
Kin selection also extends beyond the
relationship between parents and their offspring. It provides for the
development of altruistic behavior when the risk or energy invested, by an
individual is compensated in excess by the benefits ensuing to relatives. The
closer the relationship between the helper and the one receiving help and the
greater the number of beneficiaries, the higher the risks and efforts made by
an altruist. Individuals that live together in a herd or troop usually are
related and often behave toward each other in this way.
Such statement can also be expressed in a mathematical equation as per below:
r = the degree of relatedness
c = cost for the helper
b = benefit to the one being helped
In order to better understand the topic it would be a
benefit to look at same examples of kin selection.
One of the popular examples of altruistic behavior are an
alarm calls motivated by kin selection. In some groups of closely related
animals, such as apes, members of the family will call out an alarm signal
when a predator is causing a danger. Such warning provides other members of a
family to save themselves from danger, while potentially drawing dangerous
attention to the caller itself, therefore qualifying as altruistic behavior.
Large colonies of certain ants, bees and wasps are
other popular examples. In many of these colonies, the queen is the only female
that reproduces. Unfertile female workers handle nearly every task in the
colony, from scouting and collecting food, to building the nest or hive, and
raising the young. Since successive generations of these insects are born from
the same mother, they are, in fact, sisters.
To conclude I would like to add that humans also possess
some degree of kin selection, in that humans are inclined to behave more
altruistically toward kin than toward unrelated individuals. Many people choose
to live near relatives, exchange sizeable gifts with relatives, and favour
relatives in wills in proportion to their relatedness