Published in Biology Letters, the researchers found that bereaved macaque mothers spent less time resting (sleep, restful posture, relaxing) than the non-bereaved females in the first two weeks after their infants’ deaths. Researchers believe this physical restlessness could represent an initial period of ‘protest’ among the bereaved macaque mothers, similar to that observed in studies on mother-infant separation in primates. The ‘protest’ phase, however, was not followed by an extended period