1Her altruism was evident in the way she volunteered at the local animal shelter every weekend.
2Is altruism a natural human trait, or is it something we learn from our environment?
3The charity's mission is based on the principle of altruism, where donors give without expecting anything in return.
4If more people practiced altruism, the world would be a better place.
5The researcher studied the effects of altruism on mental health and found a positive correlation.