There is very little sexual dimorphism between the sexes for the common chimpanzee, however the males overall do weigh more than the females. Males weigh between 45 to 60kg and females are usually between 21 to 45 kgs. Both sexes are generally black in colour with some variation between individuals. Males are also easily distinguished by their large testicles and the females by genital swellings that occur every month when they ovulate. Considered to be our closest living relative, it is estimated that the genomes of humans and chimpanzees are around 98.8 percent the same.
Habitat and Distribution
Occupying wide variety ecological niches, the Chimpanzee can be found right across Africa. Types of habitats include; humid evergreen forests, deciduous forests to dry, open savannah. They are the most adaptable and wide spread of the great apes: found in various elevations from sea level in West Africa to 2 600m in elevation in East Africa. They are also the most comfortable on any level of most habitats being found to move comfortably along the ground as well as high up in the forest canopy.
Considered endangered, the chimpanzee is under threat due to loss of habitat, disease brought about through contact with humans and the ever expanding bush meat trade. This species was once found in high numbers across many African countries; however isolated groups of chimpanzees make it difficult for genetic material to be exchanged, placing this species under serious threat of extinction. One of the many strategies undertaken by conservationists is the replanting of forest corridors between pockets of chimp groups to help encourage the exchange of genetic material.
Chimpanzees are incredibly flexible in their dietary composition, consuming a variety of fruit, flowers, seeds, leaves, mushrooms and small mammals. In fact as many as 330 different food items have been eaten in one year (Caldecott, 2005).Wild studies have shown that chimpanzees are also good hunters, consuming at least 32 species of mammal, in particular the red colobus monkey.
Breeding and Lifecycle
The chimpanzee has a reproductive cycle that is similar to humans; females have a monthly oestrus cycle, which is slightly longer at 36 days. Like many social primates that live in large groups, the females develop a large perineal or genital swelling that indicates that the female is ovulating. This lets the males know that the female is ready for breeding. Gestation or length of pregnancy is estimated at 8.5 months and usually only single infants are born although twins do occur. Chimpanzees are relatively long lived, with the potential for chimps living in zoos living to well into their sixties or more.
Great ape evolution is a diverse and interesting topic of study with 1.2 percent currently estimated to be the genetic difference between humans and chimpanzees. One of the initial beliefs is that enzymes used for breaking down amino acids or complex proteins, have been found to be linked to human lineage due to a meat eating/carnivorous diet. It is also speculated that this contributed to the development of a larger brain and subsequent higher intelligence in human beings.
Caldecott, J., Miles, L., (2005) World Atlas of Great Apes and their Conservation, UNEP World Conservation Monitoring Centre. University of California Press, Berkeley, USA.
Groves C, 2001, Primate Taxonomy ,Library of Congress Cataloging-in-Publication Data, USA.