altruism

• Altruistic behaviour definition

  Altruism is when one organism sacrifices its own well-being for the benefit of others in its group.
• Kin selection

  organism helps relatives, like siblings or offspring, because it increases the chances of its own genes being passed on

  Hamilton’s rule: Genes will increase in frequency when:

  rB > C

  • r: How closely related the recipient is to the one performing the altruistic act.
  • B: The extra reproductive benefit gained by the recipient.
  • C: The reproductive cost to the individual performing the act.
• Eusocial insects 


  animals live in highly organized groups

  1. Overlapping Generations: Parents and offspring live together
  2. Cooperative Care: Everyone pitches in to take care of the babies, helps the group survive.
  3. Specialized Roles: Some members, focus on tasks like gathering food or taking care of the young.

  • The relatedness coefficient r among worker sisters is high due to haplodiploidy
  • ratedness among sisters high, explain why they help each other instead of having their own babies.
• Reciprocal altruism

  • In reciprocal altruism, animals help each other out without expecting an immediate return favor.
  • To prevent being taken advantage of by others who don't return the favor, there needs to be a way to recognize and punish "cheaters."
  • An example of this is seen in vampire bats. They share blood with others who haven't eaten much, and later, those bats return the favor. Bats that don't reciprocate are remembered by the group and kicked out of the sharing arrangement.