Living Primates

• Lectures cover living primates.

Shared Traits in Mammals

• Mammals are live bearing.
• Mammals provide milk to their young.
• Mammals go through a long period of dependence.
• Mammals learn through play.

Primate Physical Traits

• Primates have a unique combination of physical traits.
• Primates are adapted to arboreal life.
• Primates posses prehensile hands and feet.
• Primates prosses opposable thumbs.
• Primates have flexible arm movement.
• Primates feature specialized upper and lower limb bones.

Primate Physical Traits

• Primates have an omnivorous diet and teeth.
• Primates possess forward-facing eyes.
• Primates have stereoscopic and color vision.
• Primates have larger brains.

Primate Reproduction

• Primates typically have one to few offspring.
• Primate infants are born helpless.
• Primates take a longer time to reach sexual maturity.
• There is a trade-off in primate reproduction.

Dependency and Play

• Primates experience a long period of dependency.
• Primates form a strong mother-infant bond.
• Primates develop physical and social skills through play.
• Primates learn through play, imitation, and independent learning.
• Primates exhibit deliberate teaching.

Social Features: Communication

• Primates use referential communication
• Primates communicate with sounds associated with objects or events.
• Primates use symbolic communication.
• Primates' symbolic communication has meaning without a referent and is arbitrary.
• Primate communication is a closed system.

Primate Classification

• Primate classification utilizes clade approaches to understand derived versus ancestral traits.
• See Etting 2023, Chapter 5 for a discussion of traits.

Strepsirrhini Traits

• Strepsirrhines are mammal-like primates,
• Strepsirrhines have longer snouts, rhinariums, and olfactory senses.
• Strepsirrhines have mobile ears.
• Strepsirrhines possess grasping hands.
• Strepsirrhines have stereoscopic vision.

Strepsirrhini: Lemurs, Lorises, Galagos

• Strepsirrhines include lemurs, lorises, and galagos.
• Female Strepsirrhines often dominate social groups.
• Strepsirrhines are not sexually dimorphic.
• Strepsirrhines generally have a vegetarian diet but also eat insects.
• Strepsirrhines are quadrupeds.
• Strepsirrhines use vertical clinging and leaping.

Haplorrhini Traits

• Haplorrhines include humans, apes, and monkeys.
• Haplorrhines have a rounded braincase, better vision, and no rhinarium (dry nose).
• Haplorrhines have reduced non-mobile ears and relatively small, flat faces.
• Haplorrhines feature a more fully formed placenta.
• Haplorrhines feature highly dexterous hands.

Tarsiers

• Tarsiers are nocturnal and arboreal.
• Tarsiers are insectivores.
• Tarsiers are haplorrhines.
• Tarsiers' eyes are in bony orbits, without a tapetum lucidum.
• Tarsiers are vertical clinger leapers like lemurs.

Platyrrhines: New World Monkeys

• Platyrrhines include New World Monkeys and have three premolars.
• Platyrrhines have a dental formula of 2.1.3.3 / 2.1.3.3.
• Platyrrhines feature a prehensile tail in some species.
• Platyrrhines have an arboreal lifestyle.
• Marmosets and tamarins belong to this group.
• Cebids, like capuchins, are examples of platyrrhines.

Catarrhines: Cercopithecoids

• Catarrhines include Cercopithecoids and have an arboreal or terrestrial lifestyle.
• Arboreal Catarrhines include Colobine monkeys.
• The dental formula for Catarrhines is 2.1.2.3 / 2.1.2.3.
• Catarrhines have a variable group size.
• Catarrhine groups are often male-dominated, and have few offspring, and a complex stomach.
• Baboons are terrestrial Catarrhines.
• Terrestrial Catarrhines are sexually dimorphic and live in female troops.

Hominoids: Apes and Humans

• Hominoids include Hylobates, Pongids, and Hominins.
• Hominoids have larger brains, greater flexibility, and longer limbs.
• Hominoids have a short, broad trunk and no tail.

Hominoid Dentition

• Hominoid dentition is flat and rounded with a Y-5 pattern and canine diastema.

Hominoids: Hylobates

• Hylobates are brachiators.
• Hylobates have a small body size and weight.
• Hylobates are frugivores.
• Hylobates live in small family units.
• Hylobates exhibit little sexual dimorphism.

Pongids: Orangutans

• Orangutans are arboreal frugivores.
• Orangutans are sexually dimorphic.
• Orangutans are socially solitary.

Pongids: Gorillas

• Gorillas are quadrupeds and knuckle-walkers.
• Gorillas eat and sleep in trees.
• Gorilla groups are led by a dominant male protector.
• Gorillas have flexible group membership.

Pongids: Bonobos and Chimpanzees

• Bonobo and chimpanzee groups are stable and female centered
• Bonobos and chimpanzees are quadrupedal and bipedal.
• Bonobos and chimpanzees are frugivores that also eat some meat.
• Bonobos and chimpanzees are highly social and live in large groups.
• Bonobos and chimpanzees live in fluid groups.

Primate Adaptations

• Small body size adaptations include being nocturnal, arboreal and frugivorous

• Fast movement in trees are connected to low body size and weight

• Eating Fruit sugars provide high energy

• Being nocturnal makes it easier to move around at night

• Large body size adaptations include being diurnal, terrestrial and Vegetarian

• Slow moving terrestrial animals generally have a larger body size

• Vegetation is carbohydrate poor which results in large guts to process vegetation

• Being active during the day and living in large groups offers protection

Primate Adaptations

• Primates possess an increased brain size relative to body size.
• Frugivores tend to have larger brains.
• Primates learn to remember where and when fruit is produced.
• Primates feature variable group sizes.
• Group size impacts safety, with smaller numbers when feeding at night and larger numbers when feeding in the day.

Hominins: Homo sapiens

• Hominins (Homo sapiens) are bipedal.
• Hominins (Homo sapiens) have a dish-shaped pelvis and straight lower limbs.
• Hominins (Homo sapiens) have feet that are not prehensile (grasping).
• Hominins (Homo sapiens) have dexterous hands.
• Hominins (Homo sapiens) have no large teeth or claws.

Hominins: Homo sapiens

• Hominins (Homo sapiens) have a large, complex brain.
• Hominins (Homo sapiens) have a large cerebral cortex which enables thinking and spoken language.
• Hominins (Homo sapiens) feature a lowered larynx.
• Hominins (Homo sapiens) dentition reflects an omnivorous diet with incisors and canines that are similar, and no spaces between teeth.

Hominins: Homo sapiens

• Hominins (Homo sapiens) learn through culture.
• Tool use by greater apes may be considered a form of culture.
• Chimpanzees use termite sticks as tools.
• .Chimpanzees exhibit 'planning' and tool use.
• .Chimpanzees crack seeds open with two rocks

Models for Understanding Hominin Behavior

• Models for understanding hominin behavior include analysis of homologous vs. analogous traits.
• Homologous traits are from a common ancestor, while analogous traits are independently derived in two primates.
• Living primate behavior serves as a model for understanding hominin behavior.
• Ethnographic analogy, including studies of non-Western traditional societies, is used.
• All cultural groups have their own qualities, and findings may not always be reflective of a universal pattern (limitations).