BIO1022 Week 2 – Fossils & Human Evolution

Vocabulary flashcards covering key terms from Week 2 on fossils, phylogeny, and human evolution.

Fossil

Any preserved remains, impression, or trace of once-living organisms that provide direct evidence of past life.

Phylogeny

The evolutionary history and relationships among species or groups, usually depicted as a tree.

Carbon-14

A radioactive isotope used in radiometric dating of once-living material up to ~50,000 years old.

Half-life

The time required for half of the atoms of a radioactive isotope to decay; used to calculate the age of fossils.

Radiometric Dating

Technique that determines the absolute age of rocks or fossils by measuring the decay of radioactive isotopes.

Sedimentary Rock Layers

Strata that accumulate over time and place fossils in relative chronological order (older layers below younger ones).

Mass Extinction

A rapid, widespread decrease in biodiversity that reshapes evolutionary trajectories of surviving lineages.

Great Apes

A family of large primates—including humans, chimpanzees, gorillas, and orangutans—sharing common ancestry.

Anatomic Evidence

Comparative structural features (e.g., skeletal traits) that reveal evolutionary relationships among species.

Genetic Evidence

DNA sequence similarities and differences used to infer relatedness and evolutionary divergence times.

Fossil Evidence

Physical remains showing transitional forms and geographic/temporal distribution of ancestral species.

Hominin

Any species on the human branch of the evolutionary tree after the split from the last common ancestor with chimpanzees.

Bipedalism

Habitual upright walking on two legs, a hallmark of hominin evolution.

Cranium

The skull portion enclosing the brain; its size and shape track brain expansion in hominins.

Foramen Magnum

The hole at the skull base where the spinal cord enters; its forward position is associated with bipedal posture.

FOXP2

A gene linked to speech and language capability; shows human-specific modifications.

Mandible

The lower jawbone; changes in size and shape reflect diet and speech evolution in hominins.

Sagittal Crest

A ridge of bone atop the skull for jaw-muscle attachment; prominent in robust australopiths, absent in Homo.

Pan troglodytes

Common chimpanzee; our closest living relative, sharing ~98.8 % of DNA with humans.

Ardipithecus ramidus (Ardi)

Early hominin (~4.4 Ma) showing a mix of bipedal traits and tree-climbing adaptations.

Australopithecus afarensis (Lucy)

Hominin species (~3.2 Ma) with clear bipedal locomotion but chimp-sized brain.

Paranthropus boisei

‘Nutcracker Man’; robust australopith with massive jaws and sagittal crest for heavy chewing.

Homo erectus

Extinct human ancestor (~1.9 Ma–143 ka) first to use fire and leave Africa widely.

Homo neanderthalensis

Archaic human living in Europe/Asia (~400-40 ka) with large brains and robust builds.

Homo sapiens

Modern humans, originating in Africa ~300 ka and globally dispersed by ~50 ka.

Multiregional Hypothesis

Model proposing that modern humans evolved concurrently in multiple regions from local Homo erectus populations with gene flow between them.

Out-of-Africa Hypothesis

Model stating that modern humans evolved in Africa and then spread globally, replacing archaic populations with limited interbreeding.

Mitochondrial DNA (mtDNA)

Maternal-inherited DNA useful for tracing maternal lineages and recent human migrations.

Y-chromosome DNA

Paternal-inherited DNA used to trace male lineage and population history.

Neanderthal Introgression

Genetic contribution from Neanderthals to non-African modern humans through interbreeding events.

Natural Selection

Differential survival and reproduction leading to adaptive traits, explaining regional human variations (e.g., skin color).

Calibrating Molecular Clocks

Using fossil ages to assign absolute dates to genetic divergence times in phylogenies.

Synapomorphy

A shared derived trait indicating common ancestry, used in cladistic analyses.

Culture

Learned, shared behaviors and knowledge transmitted across generations in humans (e.g., tool traditions).

Language

Complex symbolic communication with grammar and syntax, facilitated by neural and vocal tract adaptations.

Consciousness

Self-awareness and subjective experience; debatably more developed in humans than in other animals.

Adaptive Radiation

Rapid lineage diversification following ecological opportunity, often after mass extinctions.

Calibration Point

A fossil or geologic event of known age used to anchor nodes in a phylogenetic tree.