<正>Transition from a nocturnal to a diurnal lifestyle represents a major shift in primate evolution,plays a central role in the adaptation of these species to new habitats,and is involved in modifications to their physiological and social behaviors(Heesy and Ross,2001;Shultz et al.,2011).However,two core problems concerning the circadian rhythm transition r
Transition from a nocturnal to a diurnal lifestyle represents a major shift in primate evolution, plays a central role in the adaptation of these species to new habitats, and is involved in modifications to their physiological and social behaviors (Heesy and Ross, 2001; Shultz et al., 2011). However, two core problems concerning the circadian rhythm transition re- mains unresolved. First, there is controversy concerning the activity pattern of the ancestral primate (Heesy and Ross, 2001; Tan et al., 2005). Second, the transition process for circadian rhythm in primate evolutionary history is unre- solved. Although most research suggests that primates trans- formed from a nocturnal to a diurnal circadian rhythm in the lineage leading to the common ancestor of the anthropoids or the haplorrhines (anthropoids and tarsier) (Ross, 2000; Heesy and Ross, 2001), evidence has been insufficient to determine whether this occurred in the lineage leading to the common ancestor of the haplorrhines or the anthroooids.