Competitive altruism is a hypothesis that attempts to explain the presence of cooperative behaviors (like helping and sharing) in organisms that don't have a direct benefit to the organism performing the the behavior.
What's the biological and evolutionary advantage to altruistic behavior?
Research by Hardy and Van Vugt has shown that altruistic behaviors occur more when they're public than when an individual is alone. Their research has also shown that the most altruistic individuals reached the highest status in their group and were viewed most positively by their peers. This suggests that altruistic behaviors occur because individuals who perform altruistic acts get a higher status within their group and a better reputation amongst their peers.