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. Mimicry is thought to be one foundation of how emotion moves between people. Having empathy does not always mean a person will want to help someone in need.

Kindness is most often taught by parents to children and is learned through observation and some direct teaching; 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 and 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. Warneken argued that people have a biological predisposition to be helpful, so not much moral instruction is needed to develop helping.

Young chimpanzees helped a person who was reaching for something. Young chimpanzees helped in easy tasks but not in the harder ones. 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. In a study of chimpanzees, females were more consoling than males overall, and bystanders seemed sensitive to the neglected victims' need for comfort.

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; a free rat acted more upset when its cagemate was trapped, as if it picked up the cagemate's distress. Alarm calls were rare in the rat study, so the authors judged that the free rat was unlikely to be opening the door just to end the alarm calls; 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.

Wilkinson first reported in 1984 that vampire bats may share regurgitated blood with non-relatives; vampire bats form strong bonds with their colony mates, and 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 vampire bat that found no food can beg another bat for blood, and a small amount lets it live and hunt another day. A vampire bat that misses a few nights of feeding in a row can starve; in captive bats, those that were more generous were fed more when they failed to feed.

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. Scientists often debate how much emotion elephants feel. In a study, pet dogs went up to a person who was crying. The dog study used a method first used with human infants, and most dogs responded to the crying person in a submissive way.

Mirror neurons were first found in macaque monkeys: some cells fired when a monkey grasped food and when it watched a person do the same. In macaques, mirror neurons are found in the inferior frontal gyrus (area F5) and the inferior parietal lobule. Scientists still argue about what mirror neurons do in people, including how much they explain reading other minds.

Oxytocin is a peptide hormone and neuropeptide normally made in the hypothalamus and released by the posterior pituitary. Oxytocin has a role in social behaviors in many species, so it likely also does in humans, and it may play a part in bonding between humans and dogs. Studies of nasal oxytocin have been criticized: evidence suggests nasal sprays may not produce behavioral effects, and results may reflect publication bias.

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; in one experiment, people were handed a $5 or $20 bill and told to spend it by 5 p.m. that day; those who spent it on others reported more happiness. Regular volunteering has been linked to a lower risk of dying and better physical functioning into old age.

In a cooperation experiment, a small number of generous people changed how other people in the group behaved. A science writer noted that Fowler and Christakis report that both cooperative and selfish acts spread, so it is unclear how the ripples affect real networks. Christakis compared a social network to a matching grant: one person's giving in the first round was ultimately tripled by others. Cooperative behavior in the experiments spread up to three degrees of separation.

Words to know

• empathy: sharing feelings
• mimicry: copying
• oxytocin: a hormone
• bystanders: onlookers