Kindness is offered for the sake of the person who receives it, whether or not the giver is attached to that person. Altruism is concern for the well-being of others that does not depend on personal benefit or being paid back. Empathy is sensing and sharing what another person is feeling. Emotional contagion is the spontaneous spread of emotions between people. Cognitive empathy means understanding another's perspective or mental state. Having empathy does not always mean a person will want to help someone in need.

Researchers have tested helping in very young children. Helping behavior is seen in humans from about two years old, when a toddler can understand subtle emotional cues. In one task, an adult hung clothes on a line. He dropped a clothes peg that he could not reach. Toddlers who were 18 months old helped a grown-up they had never met. In the 2006 toddler study, virtually all of the children helped at least once, and the adult never asked them for help. Toddlers rarely helped in control conditions where the grown-up did not need help.

Next come the apes. Young chimpanzees helped a person who was reaching for something. They helped in easy tasks but not in the harder ones. Nobody asked or rewarded the toddlers and chimpanzees for helping. As of November 2026, in 2006 the researcher Warneken said the chimpanzee study was the first experiment to show helping toward goals in a non-human primate. Bonobos share food with others, even unrelated strangers. After a chimpanzee hunt, the meat is shared with all hunting party members and even bystanders.

A free rat will open the door of a trap to let out a rat from its own cage that is stuck inside. The researchers did not train the rats to free their cagemates. A rat was as likely to free its trapped cagemate first as to open a container of chocolate. Rats freed trapped cagemates even when the reward of social contact was prevented, so the contact was not the only reason. Studies report that rodents show empathy for cagemates in pain, but not for strangers. Researchers think that helping a cagemate may itself be rewarding for a rat. A free rat acted more upset when its cagemate was trapped. It was as if it picked up the cagemate's distress.

Vampire bats form strong bonds with their colony mates. Some unrelated bats have traveled together for more than ten years. A vampire bat can share some of its blood meal with another bat in its colony. A bat that misses a few nights of feeding in a row can starve. A bat that found no food can beg another bat for blood, and a small amount lets it live and hunt another day.

Asian elephants comfort other elephants that are upset, using touch and sounds. An elephant may put its trunk in another elephant's mouth to calm it, a gesture a researcher compared to a handshake or hug. As of November 2026, a 2014 study gave the first scientific evidence that elephants console one another. In a study, pet dogs went up to a person who was crying. Dogs in a study went to a crying stranger, not only to their owner.

Doing something kind for another person can make you feel happier. A psychologist's study found that doing kind acts raised people's well-being. Doing a variety of kind acts seems to work better than repeating the same one. In a study of children under two, toddlers seemed happier giving a treat away than getting one. In a bonus study, how workers spent the money, not how big the bonus was, changed their happiness.

Words to know

• kindness: caring acts
• altruism: selfless concern
• contagion: spreading
• bonobos: apes
• empathy: sharing feelings