The key difference between reciprocal altruism and kin selection is that reciprocal altruism occurs between two unrelated individuals, while kin selection occurs between closely related organisms.
Altruism refers to any behaviour that reduces an individual’s fitness, but in return, it increases the fitness of other individuals. In altruism, other individuals benefit at the expense of the one that performs the action. Reciprocal altruism is the altruism that occurs between two unrelated individuals. Kin selection is an evolutionary strategy which favours the reproductive success of relatives even at a cost to the organism’s own survival and reproduction. Both processes temporarily reduce the fitness of the organism that performs the action.
1. Overview and Key Difference
2. What is Reciprocal Altruism
3. What is Kin Selection
4. Similarities Between Reciprocal Altruism and Kin Selection
5. Side by Side Comparison – Reciprocal Altruism vs Kin Selection in Tabular Form
What is Reciprocal Altruism?
Reciprocal altruism is the altruism that happens between two unrelated individuals. This term was coined by Robert Trivers. Reciprocal altruism describes a process that favours costly cooperation among reciprocating individuals. Past behaviour is a cue that provides the basis for reciprocal altruism. In reciprocal altruism, altruism occurs when there will be a repayment (or at least the promise of repayment) of the altruistic behaviour in the future. Individuals should be able to recognize each other at a future time for reciprocity to work. Normally, animals are capable of recognizing each other.
One example for reciprocal altruism is the mutual grooming among many birds and mammals. Another example is the vampire bats that share their food with hungry social companions if they have received food from them in the past.
What is Kin Selection?
Kin selection is a type of natural selection. It is an evolutionary strategy which favours the reproductive success of relatives even at a cost to the organism’s own survival and reproduction. Kin selection favours altruism. Charles Darwin was the first person to discuss the concept of kin selection. However, the term “kin selection” was coined by British evolutionary biologist Maynard Smith. Generally, animals engage in self-sacrificial behaviours that benefit the genetic fitness of their relatives. Therefore, kin selection is responsible for the changes in gene frequency across generations. Since the members of the same family or social group share genes, kin selection ensures the passing of their genes to the next generation.
Kin selection can be explained using the following examples.
- Adult zebras turn toward an attacking predator to guard the youngsters in the herd.
- Belding’sground squirrels give alarm calls to warn other group members regarding a predator’s approach, putting their life at risk by drawing dangerous attention to the caller itself. Alarm calls allow other members to flee from the danger.
- Worker honeybees defend their colony by performing suicidal attacks on intruders.
- The Florida scrub-jay is a bird species which helps the members of the social group to reproduce, gathering foods and protecting the nests from predators.
What are the Similarities Between Reciprocal Altruism and Kin Selection?
- Both involve indirect increments to inclusive fitness.
- They temporarily reduce the fitness of the organism that performs the action.
What is the Difference Between Reciprocal Altruism and Kin Selection?
Reciprocal altruism is altruism that occurs between unrelated individuals when there will be repayment of the altruistic act in the future while the kin selection is the natural selection that favours the altruism between closely related organisms. Thus, this is the key difference between reciprocal altruism and kin selection. The term reciprocal altruism was coined by Robert Trivers while the term kin selection was coined by Maynard Smith.
Moreover, in reciprocal altruism, one individual makes sacrifices for another unrelated individual with the promise of future aid while in the kin selection, one individual making sacrifices for relatives/closely related organisms without the promise in future aid.
Below infographic provides more details of the differences between reciprocal altruism and kin selection.
Summary – Reciprocal Altruism vs Kin Selection
In reciprocal altruisms, there is no need for two individuals to be relatives. But kin selection involves closely related organisms. So, this is the key difference between reciprocal altruism and kin selection. Moreover, reciprocal altruism occurs with the promise of future aid, unlike kin selection. Thus, this summarizes the difference between reciprocal altruism and kin selection.
1. “Kin Selection.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
2. “Reciprocal Altruism.” Wikipedia, Wikimedia Foundation, 22 Sept. 2020, Available here.