Primates can be generally defined as mammals who evolved a post
orbital bar, a shift of the orbital plane leading
     to stereoscopic vision (depth perception), reduction of the olfactory
sense dependence substituted by vision, and
     grasping cheiridia.  These are anatomical diagnostic
characteristics primates share, however, primates are
     classified into subsequent more exclusive groups:  Orders, families,
subfamilies, genera and species.  Prosimians,
     monkeys and apes are the three most inclusive groups.  In our study we
investigate and compare male parental
     care in two primate species: New world Titi monkeys (Callicebus) and
Old world Barbary macaques (Macaca).
     Male New world monkeys are known to highly invest in the care of their
offspring (Primate Societies).
     Callithrichids, a New world monkey genus which includes marmosets and
tamarins, always twin birth.  The male,
     therefore, plays an important role and takes care of the offspring from
after birth to post-weaning period (Dunbar,
     1994) .  However, neither Titi monkeys nor Barbary macaques twin birth,
yet paternal care has been observed
     and is characteristic of these two species (PS).  In order to attempt
an understanding of  this behavior in both
     species, we must first learn about their geographical distribution,
habitat and ecology.  These are vital factors,
     among others, that will help us understand the biology behind the
behavior.  An introduction to primate
     classification and group anatomical and ecological characteristics will
provide a transitional overview to the
     intraspecific comparison of male parental investment in Titi monkeys
and Barbary macaques.