Veri interesting study! In the article they were given the example of a person hanging clothes and dropping a clothes pin (accidentally), most of these 18 months old toddlers retrieved the pin without expecting anything in return but when the pin was dropped on purpose, they did not retrieve it, so they perfectly knew when it was needed or when it was not without being instructed to do.
Altruism is a concern for the welfare of others without thought of any gain for self and often with great self-sacrifice. While many people do altruistic acts on occasion throughout their lives I think there have been few bona fide altruists. Among them I would list Jesus Christ, Mahatma Ghandi, Mother Theresa, Martin Luther King, Jr.
Studying altruism through virtual reality
A computer-based environment has been developed with the aim to shed light on the origins of altruism. This new study immersed participants in a virtual environment that reproduced a building on fire which they had to evacuate in a hurry, deciding whether to save their lives or interrupt their escape and help rescue an injured person. The results showed that altruistic individuals self-reported to have greater concern for others’ wellbeing and had larger right anterior insula (A brain area involved in processing social emotions) compared to non-altruists. Ref. Source 3i.
Chatter in the deep brain spurs empathy in rats. By combining electrical monitoring of neural activity with machine learning, a team of neuroscientists has tuned into the brain chatter of rats engaged in helping other rats. The results clarify earlier conflicting findings on the role of specific brain regions, such as the insula, in guiding antisocial and psychopathic behavior, and may shed light on how to encourage altruistic behavior in humans. Source 8u.
For the first time, a neural link between altruism and empathy toward strangers. Using fMRI scans of a brain region called the anterior insula, researchers have discovered that people who donated a kidney to an anonymous recipient were more sensitive to a stranger's fear and pain. Source 3i.