The Five Primates

     As there are a number of environmental and physiological variables within the principles of behavioral evolution, studying primates whose behavior is unaffected by human activities will help discover fundamental behavioral principles (184). Therefore, comparing the social and mating patterns of lemurs, spider monkeys, baboons, gibbons, and chimpanzees will gain one an evolutionary perspective by using the behavioral ecology approach. First, a thorough description of the environment in which the primates live is essential to understand behavior: social and mating patterns. Take the lemurs for instance, found in the suborder as Strepsirhini. They have an extremely restricted range of habitual life, exclusively to the island of Madagascar and the Comoro Islands; lemurs do not have competition from the more advanced non-human primates. Next are the spider monkeys (New World monkeys) in the Ceboidea superfamily, which are limited to tropical forest environments of southern Mexico, Central and South America. They are predominantly arboreal (meaning they live in trees), and they are herbivores that love the minimally fluctuating tropical temperature .  Baboons (Old World monkeys) belong to the Cercopithecoidea superfamily within the Haplorhini suborder of the primate order, and they live in Africa and Asia. They inhabit a range of environments: tropical rain forest, savanna, shrub land, mountainous terrain. They are also found surviving in Gibraltar, south of Spain. By tending to live in trees, they are also known to be terrestrial quadrupeds. Fourth, the gibbon (lesser ape) from the Hylobatidae family inhabit the tropical and subtropical rainforest from northeast India to Indonesia, as well as northern and southern China, Sumatra, Borneo, and Java. Gibbons have mastered brachiation (swinging from tree limb to tree limb), in which they are known as the fastest non-flying mammals that live in the trees. Lastly, chimpanzees (Great ape) are considered to be within the Hominidae family; they are colloquially referred to as “chimps.” Under the genus Pan, they live in tropical forests and wet savannas of Western and Central Africa and in the forests of the Democratic Republic of the Congo (DRC).

Lemur (Prosimians/Strepsirhini)

     Each of these environments influence the primates’ behaviors, respectively. For instance, lemurs are known to be extremely sociable. The ring-tailed lemurs, for example, are found in groups of up to 25, and they spend most of the day on the ground, than in the trees. Also unlike the other primates to follow, females generally dominate males in lemur social interactions. They are arboreal and omnivorous as they are also nocturnal as opposed to monkeys and apes, which allows them to develop a niche when hunting for insects, eggs, and baby birds. Lemurs have a breeding season instead of an individual cycle. When the annual mating season occurs, which consists of several days, males fight with each other for access to the groups of promiscuous females as the females each are sexually receptive for only one day.  

Spider Monkey (New World Monkey/Platyrrhini)

     Next, the male spider monkeys have stronger bonds when compared to their female relationships; therefore, when females go through puberty, they disperse to join new groups. Yet, the strongest social bonds form between females and young offspring. Groups are led by a female in the daily routine of feeding activities. Spider monkeys are diurnal, and they don’t view grooming as an important social interaction. This may be due to a lack of thumbs. Spider monkeys mate year-round. Female monkeys choose a male from her group to mate with. Once a possible mate is picked, they each sniff their mates to check their readiness for copulation, known as anogential sniffing. Mothers are extremely protective of their young, and the males have part in raising of offspring. 

Baboon (Old World Monkey/Cercopithecidae)

     Baboons are very social. The smallest size group has about 50 members, and they can easily reach up to 250 members. They are complex in the way they form subgroups to help keep things from becoming chaotic. The organization of groups allows for subcultures to arise amongst them, and they have a lot of social activity. They spend time chattering among themselves, which can sound very loud and chaotic when in their environment. This brings comfort and safety to the group. Baboon males tend to be plentiful and extremely dominant to which they have several females in their harems. When the females are in esterus, their sexual skins or swellings are hairless and large swollen patches of skin around the genital that entices male baboons. Males are often fighting over the females that they want to be part of their harems. 

Gibbon (Lesser ape/Hylobatidae)

     Gibbons live in similar nuclear families, compared to humans. Gibbons are monogamous, and their communities consist of adults and their offspring. They rarely go down to the forest floor as they live in the tree tops. They are always defending their territory against other species with loud whooping and hooting vocalizations, much like howler monkeys. As they are very social animals, their vocal capabilities aid them in gaining their mate. Males tend to sing solos to attracts mates and advertise their territories. If a male and female like each other’s song, they’ll find each other. They’ll start their mating ritual of a short mating dance that leads to a vigorous mating ritual for about three days, in which they’ll mate about five-hundred times in this period. 

Chimpanzee (Great ape/Hominidae)

     Chimpanzees typically live in communities of about 20 to more than 150 members although they spend most of their travel time with a small parties or a few individuals. The Common Chimpanzee lives in a fission-fusion society: mating is promiscuous. The male is the core of the societies in which they roam around, protect, and search for food. There is a dominance hierarchy among males, yet the fission-fusion social structure allows for an intermixing of smaller groups on a daily basis. These smaller groups allow for different purposes. A male group is used to hunt for meat; a bisexual group (one male and one female) copulate; an individual may also be left to forage alone: the structure of their societies are highly complicated. There is no mating season, so when female chimpanzees go off in separate directions to forage for fruit, they may often mate with other subordinate males, whether by choice or not.

     Nevertheless, these five primates’ social and mating patterns have been influenced by their environments; these traits can be viewed as an adaptation to the primates’ habitat. Take the lemurs, for instance, since they are secluded on Madagascar, their competition for their environmental niche has evolved them to become diurnal. This allows them to avoid competition and predation as they forage freely for food. Their mating rituals, as well, show that males fighting males has allowed them a development of testosterone to compete for the limited resource of females, thus allowing them to reproduce/evolve. The spider monkeys spend their lives in the tropical trees defending their territory from threats by twisting and breaking of large and heavy branches close to their threats. This evolutionary adaptation has allowed them to remain in the trees as well as create a dynamic environment for the trees to continue to grow and evolve, as well. The baboons have developed large sexual skin, thus allowing them to reproduce dominant traits within the dominant baboon genetics that tend to favor bigger and smellier sexual skins from females, thus allowing the species to evolve as a dominant species. Gibbons have developed and the brachiating masters, thus their arms have evolved to assist this need as they live high up in the trees. Lastly, chimpanzees have develop subgroup organization because of the large environment that they occupy. In order for them to survive and thrive, working together in their environment is an example of their evolutionary adaptation.