BONOBO Chimpanzee "Ai" Crania photos Itani Jun'ichiro archives Guidelines for Care and Use of Nonhuman Primates(pdf) Study material catalogue/database Guideline for field research of non-human primates Primate Genome DB
Primate Research Institute, Kyoto University
Hamada / Poster
Characteristics of the growth of chimpanzee and the implications for its evolution.
Growth pattern reflects the phylogenetic position, ecology,
and social system of a given species. Compared with macaques, great apes and humans,
chimpanzees (Pan troglodytes) have such growth characteristics as follows: relatively
longer infantile period, that is, the period before weaning; shorter juvenile period: and
longer post-adolescent growth period, that is, the period from the end of adolescent rapid
growth to the end of growth. They do not also show the adolescent growth spurt in linear
physical dimensions. Thus the same relationships between somatic growth and reproductive
development found in macaques and humans does not always hold for all catarrhine primates.
I give here an example of the discussion of the evolution of chimpanzee's longer infantile
period. It is true at the comparison with gorilla and orangutan. Ecological and social
factors are considered to have influenced the length of infantile period. First factor is
the care of infant. Infant chimpanzee and orangutan is cared only by its mother. On the
other hand, gorilla infant is also taken care of by adult male gorilla, and human infant
is by grandmother and/or the other member(s) of the society. Second factor is the feeding
habit. Chimpanzees are fruit eater. As they tend to live in a relatively dry forest, the
distribution of fruit trees is patchy and the variation of yield is wide with time.
Although orangutan is fruit eater, it inhabits the dense forest. Gorilla takes fibrous
plant parts more than chimpanzee does. Humans eat variety of food items and shared foods.
The variation of yield with time in the three anthropoids is less than that in chimpanzee.