Bird's alarm calls to warn others about approaching predators
Emperor penguins taking turns to block wind for others during
storm
Vampire bat's sharing food (blood).
A gene of altruism can increase, if the individual who receive the benefit also carries the same gene (e.g. relatives).
Example:
A subpopulation with many cooperative altruists may have higher overall productivity than a subpopulation with selfish individuals.
Example:
Let's consider a haploid model, where there are two alleles: A for altruist, and S for selfish allele.
p | frequency of Altruists in the group |
c | cost, the reduction in individual fitness of altruist to help others |
b | benefit to the group due to altruistic behavior. |
The problem is that altruist help out everyone including the selfish bastards.