1.6 Evidence For Evolution

The Big Five Extinctions

  • Ordovician (445 Million Years Ago)

    • Die Off: 85%

    • Causes: Rapid Cooling, Falling Seas

  • Devonian (360 Million Years Ago)

    • Die Off: 70%

    • Causes: Asteroid Impacts, Rapid Cooling

  • Permian (250 Million Years Ago)

    • Die Off: 95%

    • Causes: Volcanic Activity, Atmospheric Change, Rapid Global Warming

  • Triassic (200 Million Years Ago)

    • Die Off: 76%

    • Causes: Atmospheric Change, Rapid Global Warming

  • Cretaceous (K-T) (65 Million Years Ago)

    • Die Off: 80%

    • Causes: Asteroid Impacts, Volcanic Activity, Falling Sea Levels

Cretaceous-Tertiary Extinction: K-T

  • Chicxulub Crater

    • Iridium layer found at K-T boundary (~65 MYA) indicates asteroid impact

    • Iridium more common in asteroids than Earth rocks

    • Chicxulub crater is 120 miles in diameter, 8-10 miles deep, confirming impact site.

Mass Extinctions - Last 500 Million Years

  • Major extinctions: Ordovician, Devonian, Permian, Triassic, Cretaceous.

  • Timeline indicates sporadic occurrences of mass extinctions.

Why Adaptive Radiations After Mass Extinctions?

  • Mass extinctions create unoccupied niches, allowing surviving species to thrive and diversify.

  • Increased competition among species (e.g., mammals) drives adaptation and niche specialization.

Evidence for Evolution

  • Types of Evidence:

    • Fossil Evidence

    • Anatomical Evidence

    • Molecular Evidence (DNA)

Discussion Points

  • How would you prove evolution to a skeptic?

  • Types of evidence to use.

Conceptual Diagram: Evidence of Evolution

  • Main Components:

    • Natural Selection

    • Fossils

    • Anatomical Evidence

    • Molecular Evidence

Fossils of > 250,000 Species

  • Includes ancient fossils from various periods:

    • 1.8 billion year-old fossils

    • 2.3 billion year-old fossils

    • Examples include: Bacterium, Tiktaalik, Trilobite, Stromatolite, Archaeopteryx, Charniodiscus, Homo sapiens.

In the News

  • Recent finding of a one-billion-year-old fossil could represent the oldest multicellular animal, shedding light on the evolution of complex life forms.

Anatomical Developmental Patterns: Vertebrate Embryos

  • Comparable morphologies evident in fish, reptiles, birds, and mammals during early development stages.

Comparative Anatomy

  • Homologous Structures vs. Analogous Structures:

    • Structures that share a common ancestry (homologous) and those that do not (analogous).

Molecular Commonalities Among Cells

  • Essential molecules:

    • ATP: Energy molecule

    • DNA: Information storage

    • L-amino acids: Building blocks of proteins.

Molecular Biochemistry: Amino Acid Sequences of Proteins

  • Differences in proteins correlate with the time since organisms last shared a common ancestor.

  • Phylogenetic trees based on molecular data align with other evolutionary criteria.

In-Class Question on Mass Extinctions

  • Examines multiple-choice questions focusing on the role of mass extinctions in evolution.

Order Primates

  • Timeline: Evolved 80-75 MYA

  • Include Lemurs, Lorises, Tarsiers, Monkeys, and Apes.

  • Most modern primates have arboreal adaptations.

Major Primate Traits

  • Traits and Advantages:

    1. Grasping Hand - for tool use and mobility.

    2. Binocular Vision - enhances depth perception.

    3. Large Brain - supports complex social interactions.

    4. Parental Care and Sociality - improves survival rates.

Adaptive Advantages of Grasping Hands

  • Provides enhanced gripping and tool-using abilities for survival and resource gathering.

Adaptive Advantages of Binocular Vision

  • Crucial for navigating tree canopies and assessing distances.

Adaptive Advantages of Large Brain

  • Facilitates advanced sensory processing, learning, and social behavior.

Adaptive Advantages of Parental Care & Sociality

  • Promotes offspring survival and enhanced cooperation within groups.

Ancestor & Evolution of Primates (85-30 Million Years Ago)

  1. Earliest common ancestor (85 MYA)

  2. Early primate evolution (80-75 MYA)

  3. Dinosaur extinction (65 MYA)

  4. Adaptive radiation of primates (65-45 MYA)

After Extinction of Dinosaurs

  • Adaptive radiation of primates in the aftermath of dinosaurs' extinction, leading to diverse primate species.

Early Primates (30 Million Years Ago)

  • Example: Aegyptopithecus zeuxis - reveals traits leading to Old World Monkeys, discovered in Egypt.

Family Tree of Human Evolution

  • Chronological order of key species: Australopithecus, Homo habilis, Homo erectus, Homo neanderthalensis.

Hypotheses of Human Evolution

  • Multiregional hypothesis vs. Out of Africa hypothesis: contrasting theories about human origins and migrations.

Timeline of Human Evolution: A Resource

  • Key human ancestors listed with fluctuating climate changes impacting evolution.

Australopithecus Afarensis - Lucy

  • Discovered in Ethiopia, noted for bipedal traits and anatomical differences from modern humans.

Homo Habilis - Handy Man

  • Tools associated with Homo habilis, showcasing early technological advancements.

Homo Erectus - The Upright Man

  • Significant evolutionary marker with advanced tool usage.

Homo Neanderthalensis

  • Comparative features with modern humans—evidence of significant cognitive and social abilities.

Humans & Neanderthals: Genetic Comparison

  • Analysis of mitochondrial DNA reveals evolutionary pathways and interbreeding events.

Human Evolution: Putting it All Together

  • Emphasizes ongoing research and discoveries impacting our understanding of human evolution.

Reminders

  • Exam is next session—review all materials thoroughly for preparation.

Human Evolution: Ongoing Research

  • Highlight the latest findings in human evolution and genetics, predicting future pathways.