Altruism is when an individual engages in a behavior that decreases their own fitness, but increases the fitness of another individual [1]. Altruistic behaviors are seen throughout the world in a variety of different species. Acting individuals of altruism can experience a permanent loss of direct fitness with the chance of indirect fitness gain or a temporary loss of direct fitness with the chance of regaining direct fitness in the future depending on the situation [2]. One example of altruism is how some prairie dogs will give a warning call when a predator is nearby. The prairie dog that gives out that warning call increases its chance of death by attracting the predator, but allows other prairie dogs that hear the call to escape [1].
Another example is how some ant species have sterile worker ants that will help care for the offspring of the closely related queen [3]. There have been a lot of questions around why altruism occurs instead of all individuals trying to increase their own fitness. Scientists believe that this behavior occurs in ants and other social insects because the closely related queen having offspring is a way that the sterile workers can indirectly pass off their genes [1]. Individuals in various species that lower their own fitness to help increase the fitness of relatives evolve through kin selection [1].
References:
- Boundless. Innate Behaviors: Altruism. Boundless Biology. 03 Jul. 2014. Retrieved 20 Mar. 2015 from: https://www.boundless.com/biology/textbooks/boundless-biology-textbook/population-and-community-ecology-45/behavioral-biology-proximate-and-ultimate-255/innate-behaviors-altruism-942-12201/
- Kerr, B., Godfrey-Smith, P., and Feldman, M. W. 2004. What is altruism? TRENDS in Ecology and Evolution. Retrieved from: http://www.petergodfreysmith.com/KerrGSFeldmanAltruismTREE.pdf
- Gilbert, N. 2010. Altruism can be explained by natural selection. Nature. doi:10.1038/news.2010.427. Retrieved from: http://www.nature.com/news/2010/100825/full/news.2010.427.html