Morality starts young...

The title of this post is the title of an editor's summary in the Nov. 22 issue of Nature:

The key to successful social interactions is the ability to assess others' intentions — be they friend or foe. A new study in 6- and 10-month-old infants shows that humans engage in social evaluations even earlier than was thought, before they can use language. The infants could evaluate actors on the basis of their social acts — they were drawn towards an individual who helps an unrelated third party to achieve his or her goal, and they avoided an individual who hinders a third party's efforts to achieve a goal. The findings support the claim that precursors to adult-like social evaluation are present even in babies. This skill could be a biological adaptation that may also serve as the foundation for moral thought and action later in life.

Here is a figure from the paper by Hamlin et al. showing the actors being evaluated by the children:

Figure legend: a, Helping and hindering habituation events of experiments 1 and 3. On each trial, the climber (red circle) attempts to climb the hill twice, each time falling back to the bottom of the hill. On the third attempt, the climber is either bumped up the hill by the helper (left panel) or bumped down the hill by the hinderer (right panel). Infants in experiment 1 saw these two events in alternating sequence; infants in experiment 3 saw either a helping or hindering event in alternation with the corresponding neutral event depicted in d. b, Looking time test events of experiments 1 and 3. The climber moves from the top of the hill to sit with the character on the right (left panel) or the left (right panel). c, Pushing-up and pushing-down habituation events of experiment 2. An inanimate object (red circle) rests (left panel) at the bottom of the hill and is pushed up, or rests (right panel) at the top of the hill and is pushed down. Infants saw these two events in alternation. d, Neutral habituation events from helper/neutral (left panel) and hinderer/neutral (right panel) conditions of experiment 3. The neutral character, without interacting with the climber, traces a path identical to that of the helper (left panel) or hinderer (right panel). Each infant saw either the helping or hindering event depicted in a, in alternation with the corresponding neutral event.