Summary
Natural selection favouring behaviours that help relatives, explained by Hamilton's rule rb greater than c.
In depth
Alleles for helping relatives can spread because relatives share copies. Hamilton's rule: help if r times b is greater than c, where r is relatedness, b the benefit and c the cost. Siblings share r = 0.5.
J.B.S. Haldane joked he would lay down his life for two brothers or eight cousins.
Haldane quipped that he would lay down his life for two brothers or eight cousins. Hamilton's 1964 rule explains eusociality in haplodiploid insects: sisters share 75 percent of genes in Hymenoptera, favouring workers helping their mother raise sisters, though this does not explain all cases (termites are diploid). Examples include alarm calls in ground squirrels, helpers at the nest in birds and naked mole rats.
Kin recognition mechanisms include location, association and chemical or genetic cues. Reciprocal altruism (Trivers) explains help among non-relatives, as in vampire bats sharing blood meals with those that shared before. Group selection models offer another perspective, and inclusive fitness is mathematically related to them.
Example: a worker bee gives up reproduction because helping the queen spread many copies of shared genes is worth more.
Frequently asked questions
What is Kin Selection?
Natural selection favouring behaviours that help relatives, explained by Hamilton's rule rb greater than c.
Which area of biology covers Kin Selection, and how advanced is it?
Kin Selection is one of the 53 topics in Evolution. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Evolutionary Trade-offs, Evolution of Sex, Reproductive Isolation.
Can you give an example of Kin Selection?
Worker bees help the queen, who is their mother, and sisters share 75 percent of genes due to haplodiploidy.
What should I learn before Kin Selection?
Work through the Beginner topics in Evolution first, such as Evolution, Natural Selection, Charles Darwin, then return to Kin Selection. Advanced topics assume the Intermediate vocabulary.
What topics are related to Kin Selection?
The closest topics to Kin Selection are Evolutionary Trade-offs, Evolution of Sex, Reproductive Isolation, Evolutionary Developmental Biology. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Kin Selection?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Kin Selection. To practise the whole of Evolution, use the Evolution quiz.
How is Kin Selection different from Evolutionary Trade-offs?
Kin Selection: Natural selection favouring behaviours that help relatives, explained by Hamilton's rule rb greater than c. Evolutionary Trade-offs: Improving one trait often costs another, constraining which adaptations can evolve. Read both side by side and note what each one explains.
How should I study Kin Selection step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Evolutionary Trade-offs and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.