The Big Five Extinctions and Human Evolution

Cretaceous-Tertiary Extinction

K-T event occurred ~65 million years ago.

Iridium Layer

Layer indicating asteroid impact at K-T boundary.

Chicxulub Crater

120 miles wide, evidence of dinosaur extinction.

Adaptive Radiation

Surviving species diversify into unoccupied niches.

Mass Extinction

Event reducing biodiversity, opening new ecological niches.

Fossil Evidence

Over 250,000 species fossils document evolutionary history.

Stromatolite

Layered sedimentary structure formed by microbial activity.

Tiktaalik

Transitional fossil between fish and tetrapods.

Comparative Anatomy

Study of similarities and differences in organisms.

Homologous Structures

Similar structures in different species from common ancestor.

Analogous Structures

Different structures in species with similar functions.

Molecular Biochemistry

Study of biological molecules and their functions.

Amino Acid Sequences

Differences indicate evolutionary relationships among species.

Phylogenetic Trees

Diagrams showing evolutionary relationships based on traits.

Order Primates

Evolved 80-75 million years ago, includes lemurs and apes.

Grasping Hand

Adaptation aiding in climbing and tool use.

Binocular Vision

Depth perception crucial for arboreal living.

Large Brain

Supports complex behaviors and social interactions.

Parental Care

Increases offspring survival through nurturing.

Australopithecus afarensis

Early hominin, known from Lucy's fossil, 3.2 MYA.

Homo Habilis

Known as 'Handy Man', lived 2.1-1.5 MYA.

Homo Erectus

'Upright Man', existed 1.9 MYA to 143,000 YA.

Homo Neanderthalensis

Neanderthals lived 200,000 to 40,000 years ago.

Out of Africa Hypothesis

Theory suggesting modern humans originated in Africa.

Neanderthal DNA

Shared genetic material with modern humans, ~99.5% similar.

Cro-Magnon Man

Early modern humans in Europe, coexisted with Neanderthals.

Genetic Comparison

Studies show divergence between humans and Neanderthals.

Altruism in Neanderthals

Evidence of care and social behavior in Neanderthals.

Mitochondrial DNA Analysis

Reveals human evolution and migration patterns.

Evolutionary Timeline

Chronological sequence of human evolutionary events.

Adaptive Advantages

Traits that enhance survival and reproduction in primates.