An easy to use reciprocal task elicited high levels of altruism in 1- and 2-y-old young ones, whereas friendly but nonreciprocal activity yielded altruism that is little subsequent. In an extra research, reciprocity with one adult led 1- and 2-y-olds to offer assistance to a person that is new.

An easy to use reciprocal task elicited high levels of altruism in 1- and 2-y-old young ones, whereas friendly but nonreciprocal activity yielded altruism that is little subsequent. In an extra research, reciprocity with one adult led 1- and 2-y-olds to offer...