Primate Biology: Traits and Reproduction

Shared Traits in Mammals

• Mammals are characterized by giving birth to live young.
• Mammals nurse their offspring with mothers milk.
• Mammalian offspring have a long period of dependence on parental care.
• Mammals learn essential skills through play.

Primates: Shared Physical Traits

• Primates have a combination of unique physical traits.
• Primates are adapted for arboreal living.
• Prehensile hands and feet are a shared characteristic.
• Primates have an opposable thumb for grasping.
• Flexible arm movement enhances mobility.
• Specific upper and lower limb bone structures are present.

Primates: Shared physical traits

• Primates consume an omnivorous diet.
• Primates have specific teeth structures adapted for their diet.
• Forward-facing eyes provide improved depth perception.
• Stereoscopic and color vision are well-developed.
• Primates have relatively larger brains compared to body size.

Primates: Reproduction

• Primates typically have one to few offspring per birth.
• Primate infants are born helpless and require extensive care.
• Primates take longer to reach sexual maturity compared to other mammals.
• Slower reproduction rates may come with trade offs like increased parental investment.

Dependency and Play

• Primates exhibit a long period of dependency during development.
• A strong mother-infant bond is crucial for primate development.
• Play is important for developing physical and social skills.
• Learning occurs through various means, including imitation, independent exploration, and deliberate teaching.

Social features: Communication

• Referential communication is a key social feature.
• Primates use sounds associated with objects or events in their environment.
• Semantic communication involves conveying specific meanings.
• Symbolic communication uses arbitrary meanings without direct referents.
• Primate communication operates within a closed system.

Primate Classification

• Primate classification uses a clade approach, which considers derived vs ancestral traits.
• Strepsirrhini is a suborder that includes lemurs like ring-tailed lemurs and aye-ayes.
• The suborder Strepsirrhini also includes mouse lemurs and sportive lemurs
• Lorises, pottos, and galagos are part of the Lorisoidea superfamily.
• Tarsiiformes include tarsiers.
• Platyrrhini includes Capuchin monkeys, Owl monkeys, Spider monkeys, Howler monkeys Marmosets and Tamarins
• Langurs, Proboscis monkeys, Colobus monkeys are species of "Leaf monkeys"
• Cercopithecoidea includes Guenons, nacaques, and Baboons which are "Cheekpouch monkeys"
• Hominoidea contains Gibbons and Siamangs, Orangutans, Gorillas, Chimpanzees and Bonobos, as well as Humans.

Strepsirrhini

• Strepsirrhines retain several mammal-like traits
• Strepsirrhines have longer snouts.
• Strepsirrhines possess a rhinarium (wet nose).
• Olfactory senses are well-developed in Strepsirrhines.
• Mobile ears can be found in Strepsirrhines.
• Strepsirrhini exhibit primate traits such as grasping hands.
• Stereoscopic vision is present in Strepsirrhines.

Strepsirrhini: Lemurs, Lorises, Galagos

• Strepsirrhines include lemurs, lorises, and galagos.
• Females often dominate social groups within this suborder.
• Not sexually dimorphic
• Their diet mainly consists of vegetarian food sources and insects.
• Strepsirrhines are generally quadrupedal.
• Vertical clinging and leaping is a common locomotive behavior.

Haplorrhini: humans, apes, monkeys

• Haplorrhines includes humans, apes, and monkeys.
• Haplorrhines have a rounded braincase.
• Haplorrhines have more fully formed placentas.
• Haplorrhines have better vision and lack a rhinarium (dry nose).
• Haplorrhines possess reduced, non-mobile ears.
• Haplorrhines typically have relatively small, flat faces.
• Highly dexterous hands are typical to suborder.

Tarsiers

• Tarsiers are nocturnal and arboreal.
• Tarsiers primarily feed on insects.
• Tarsiers are classified as Haplorrhines.
• Tarsiers have eyes within bony orbits and lack a tapetum lucidum (no eye shine at night).
• Tarsiers are vertical clinger-leapers, similar to lemurs.

Platyrrhines: New World Monkeys

• Platyrrhines are New World Monkeys, with a dental formula of 2.1.3.3.
• Platyrrhines have three premolars.
• Some platyrrhines have prehensile tails.
• Platyrrhines lead an arboreal lifestyle.
• Marmosets and tamarins are examples of platyrrhines.
• Cebids, such as capuchins, are also New World Monkeys.

Catarrhines: Cercopithecoids

• Catarrhines encompasses Cercopithecoids, or Old World monkeys.
• Colobine monkeys are arboreal catarrhines, digesting food with complex stomachs.
• The ditition of Catarrhines is 2.1.2.3
• Group size is variable.
• Male Dominated groups
• They only give birth to few offspring
• Baboons are terrestrial catarrhines.
• Baboons are sexually dimorphic and have female troops.

Hominoids: Apes and Humans

• Hominoids include hylobates, pongids, and hominins.
• Hominoids have larger brains compared to other primates.
• Hominoids have greater flexibility in their limbs and body.
• Hominoids have longer limbs.
• Hominoids have a short, broad trunk with no tail.

Hominoid: Dentition

• Hominoids have flat and rounded teeth
• Hominoids teeth have a Y-5 pattern.
• Canine diastema (gap) is also present.

Hominoids: Hylobates

• Hylobates are brachiators, swinging from tree limb to tree limb.
• Hylobates have a small body size and weight.
• Hylobates primarily eat fruits (frugivores).
• Hylobates live in small family units.
• Hylobates exhibit little sexual dimorphism.

Pongids: Orangutans

• Orangutans are arboreal creatures
• Orangutans are primarily frugivores.
• Orangutans are sexually dimorphic
• Orangutans are typically socially solitary.
• the diet and predation among orangutans is still being investigated

Pongids: Gorillas

• Gorillas are quadrupeds.
• Gorillas move using knuckle-walking.
• Gorillas will eat and sleep in trees.
• Gorillas have a dominant male protector within social groups.
• Gorilla social groups also have flexible troop memberships.

Pongids: Bonobos and Chimpanzees

• Bonobo and Chimpanzee groups are stable and female-centered.
• Bonobos and Chimpanzees can walk using quadrupedal and bipedal locomotion.
• Bonobos and Chimpanzees are typically frugivores, but supplement their diet with some meat.
• Bonobos and Chimpanzees are highly social and live in large groups.
• Bonobos groups tend to be fluid in nature

Primate adaptations

• Nocturnal and smaller primates live in arboreal environments.
• Diurnal and larger primates live in terrestrial environments.
• Frugivores are often of smaller body size.
• Vegetarian primates are often of larger body size.
• Fast moving in trees helps low body size and weight
• High fruit sugar, gives small body primates high energy
• Easier to move around at night for small primates.
• Larger primates move slow due to terrestrial environment
• Large guts need to get through vegetation
• Primates benefit from groups

Primate adaptations

• Primates have an increased brain size relative to body size.
• Frugivorous primates tend to have larger brains.
• Primates remember where fruit production occurs.
• Group size is variable among different species
• Increased individual Safety when in groups
• Smaller groups occur when feeding at night.
• Larger groups occur when feeding in the day due to increased individual safety

Hominins: Homo sapiens

• Homo sapiens are bipedal.
• Homo sapiens have a dish-shaped pelvis.
• Homo sapiens have straight lower limbs.
• Homo sapiens have feet that are not prehensile.
• Homo sapiens exhibit dexterous hands.
• Homo sapiens do not have large teeth or claws.

Hominins: Homo sapiens

• Homo sapiens have a large and complex brain.
• Homo sapiens possess a large cerebral cortex.
• Homo sapiens have the capacity for thinking and spoken language.
• Homo sapiens have a lowered larynx
• Homo sapiens have dentition that reflects omnivorous diets.
• Homo sapiens have canines and incisors of similar size.
• Homo sapiens dentition displays no spaces between teeth.

Hominins: Homo sapiens

• Homo sapiens exhibit learning through culture.
• The role of tool use by greater apes is still being investigated
• Chimpanzees are observed using termite sticks.
• Chimpanzees demonstrate 'planning' and tool use.
• Chimpanzees crack seeds open with two rocks.

Models for understanding hominin behaviour

• Homologous traits: traits from common ancestor
• Analogous traits: traits independently derived in two primates
• Analogous traits are found using studies of living primate behavior
• Ethnographic analogy is a model for understanding hominin behavior
• Analogous traits are found in non-western traditional societies
• **Limitations exist in ethnographic analogy since all cultural groups have their own qualities
• Not always reflective of a universal pattern of behavior of primates