Primates_1

Primates in Human Biology

• Presented by: A/Prof Cyril C. Grueter, School of Human Sciences, ANHB 1101 Human Biology I (2025)

Learning Outcomes

• Understand the significance of studying primates.

• Describe evolutionary relationships and similarities between humans and other primates.

• Identify and list traits that characterize primates and differentiate them from other mammals.

Recommended Reading

• Background: Chapter 4.

• Primates Lectures: Chapters 5 & 6; Extension: Chapter 9.

• Hominin Lectures: Chapters 10-13.

Primates in Society

• Primates receive significant scientific and public attention despite being one of many mammal types.

• Humans share close anatomical and evolutionary similarities with primates.

Our Closest Relatives

• Linnaeus (1735) identified similarities among monkeys, apes, and humans, placing them in the order Primates.

• Darwin (1871) suggested that if humans had not classified themselves, they would not have formed a separate order.

Genetic Family Tree

• Gorilla, Chimpanzee, Bonobo, Neandertal, Denisovan, Human.

  • Human genome differs more from gorilla than from chimp or bonobo, indicating separate evolutionary paths.

  • About 15% of the human genome is more similar to gorilla's.

• Traditionally, chimpanzees are viewed as our closest relatives, but new research questions this view by showing close similarities with bonobos as well.

Key Evolutionary Concepts

• Homology: Similar traits shared due to common ancestry.

• Phylogenetic Constraints: Evolutionary history limits variations in current species.

• Vestigial Traits: Non-functional traits inherited from ancestors (e.g., appendix, wisdom teeth).

• Convergence: Similar traits appear in unrelated groups due to similar selective pressures (e.g., flightless kiwi).

Reasons to Study Primates

• Reasoning by Homology: Similarities in closely related species provide insight into ancestor anatomy and behavior.

• Reasoning by Analogy: Similar adaptations arise from similar environments, revealing how evolution shapes diversity and responses to selective pressures.

What Makes Us Human?

• Various contributions explore evolution, culture, and chance shaping humanity.

Examples of Parent Species' Attributes

• Warfare: Both chimps and humans exhibit intergroup aggression, though they manifest differently.

• Culture & Traditions: Chimpanzee cultures highlighted; similarities in societal structures.

• Prosocial Behavior: Example of Kakowet, a bonobo, demonstrating awareness and assisting others in need.

Study of Non-Human Primates

• Important for understanding adaptation over 50-60 million years of evolution and lineage diversity.

• Examines geographic distribution and adaptive radiation across four continents.

Classification of Primates

• Hierarchy of Classification:

  • Kingdom: Animalia

  • Phylum: Chordata

  • Class: Mammalia

  • Order: Primates

  • Suborder: Anthropoidea

  • Infraorder: Catarrhini

  • Superfamily: Cercopithecoidea

  • Family: Cercopithecidae

  • Subfamily: Colobinae

  • Genus: Rhinopithecus

  • Species: bieti

Characteristics of Primates

• Suite of derived traits characteristic of arboreal life:

  • Prehensile Hands/Feet: adaptations for grasping.

  • Opposable Big Toe: enhances ability to grasp.

  • Stereoscopic Vision: depth perception from forward-facing eyes.

  • Reduced Olfactory Apparatus: less reliance on smell.

  • Nails instead of Claws: evolutionary adaptation for grasping.

  • Unspecialized Teeth: indicative of dietary versatility.

  • Larger Relative Brain Size: intelligence correlates with body size.

  • Small Litter Size: typically one offspring leads to prolonged dependency.

Visual Adaptation: Stereoscopic Vision

• Binocular Vision: Overlapping fields of view from both eyes.

• Depth Perception: Signals processed for a cohesive visual field.

• Color Vision: Present in diurnal primates; absent in nocturnal.

Comparison: Prosimii vs Anthropoidea

• Distinctions in cranial structure:

  • Anthropoidea has a postorbital plate; Prosimians have a postorbital bar.

  • Variation in the length of rostrum.

Ancestral and Derived Traits

• Primates retain certain ancestral traits from early evolution such as:

  • Arboreal lifestyle

  • Nocturnal habits

  • Primitive dietary traits.

Evolution of Traits in Primates

• Variations in locomotion, dentition, social structures, and brain development noted as evolutionary trends.

Summary of Primate Evolution

• Visuals illustrate modes of locomotion across primates: vertical clinging, quadrupedalism, brachiation, and bipedalism.

Geographic Distribution of Gorillas and Other Primates

• Map visualizations show habitat ranges, highlighting areas of uncertainty regarding species presence.