anthro exam 3

Paleoanthropology

The study of human evolution, deep time, and the fossil record of our ancestors.

Paleontology

The broader scientific study of life of the geologic past through preserved plant and animal fossils.

Subfossils

Remains whose fossilization process is incomplete, often retaining some organic material.

Petrification / Permineralization

A fossilization process where organic tissues are replaced by minerals from surrounding water/soil, turning the remains to stone.

Hard Tissues Bias

The tendency of the fossil record to disproportionately preserve bones and teeth rather than soft tissues like skin or organs.

aDNA (Ancient DNA)

DNA extracted from fossils or ancient remains, used in paleogenetics.

Challenges of Paleogenetics

DNA degrades rapidly over time and is highly susceptible to contamination from modern humans and microbes.

Paleoecology

The study of fossil organisms and their interactions with past environments.

Paleothermometer

Chemical or biological proxies (like oxygen isotopes) used to estimate ancient temperatures.

Paleopluviometer / Hygrometer

Proxies used to estimate ancient rainfall, precipitation, and humidity levels.

Isotope Fractionation

The natural process where different isotopes of an element are separated based on their mass (e.g., lighter isotopes evaporating faster).

Oxygen (O) Isotope Studies

Used primarily to reconstruct past temperatures and global ice volume (paleoclimate).

Carbon (C) Isotope Studies

Used to determine ancient diets, specifically whether organisms ate mostly C3 plants (trees/shrubs) or C4 plants (tropical grasses).

Nitrogen (N) Isotope Studies

Used to determine trophic levels (where an animal sat on the food chain) and marine vs. terrestrial diets.

Relative Dating

Determining the age of an object in relation to other objects (e.g., "older than" or "younger than") without a specific numerical age.

Stratigraphy

The branch of geology concerned with the order and relative position of rock strata (layers).

Law of Superposition

The geological principle stating that in undisturbed rock layers, the oldest layer is at the bottom and the youngest is at the top.

Absolute Dating

Chronometric dating methods that provide a specific numerical age or age range for a fossil or rock.

Radioactive Decay

The predictable, constant rate at which unstable radioactive isotopes degrade into stable isotopes.

Half-life

The time it takes for half of the radioactive isotopes in a sample to decay.

Potassium-Argon Dating (K-Ar)

Used to date ancient volcanic rock and ash layers associated with fossils; effective for items millions of years old.

Radiocarbon Dating (C-14)

Used to date organic remains; effective only for relatively recent materials up to about 50,000 years old.

Calibration (Dating)

Adjusting raw dating measurements (like radiocarbon years) to match true calendar years, often using tree-ring data.

Uncertainty, Precision, and Accuracy

Dating methods are estimates; precision is the tightness of the age range, accuracy is how close it is to the true age, and uncertainty is the statistical margin of error.

Mesozoic Era

"Age of Reptiles" (252 to 66 mya); characterized by Pangea breaking up, dominant dinosaurs, and the first mammals (therapsids).

Therapsids

Extinct "mammal-like reptiles" from the Mesozoic that are the ancestors of modern mammals.

Angiosperms

Flowering plants that emerged in the Mesozoic; their fruit and flowers provided a new food source that drove early primate evolution.

K-T Extinction Event

The mass extinction 66 million years ago (caused by the Chicxulub asteroid impact) that wiped out non-avian dinosaurs and allowed mammals to thrive.

Cenozoic Era

"Age of Mammals" (66 mya to present); marked by significant global cooling and the diversification of mammals and primates.

Plesiadapiforms

Paleocene organisms debated to be the very first primates, though they lacked key primate traits like postorbital bars and grasping toes.

Adapids vs. Omomyids

Two groups of true primates in the Eocene. Adapids are likely ancestral to lemurs, while Omomyids are likely ancestral to tarsiers/anthropoids.

Rafting Hypothesis

The theory that early monkeys reached South America from Africa during the Oligocene by floating across the Atlantic on mats of vegetation.

Fayum Depression

A crucial fossil site in Egypt yielding the most comprehensive evidence of Oligocene primates, which were arboreal quadrupeds with early monkey-like traits.

Miocene Ape Trends

A massive boom in ape biodiversity globally, followed by a sharp decline as climates cooled and monkey populations outcompeted them.

Gigantopithecus

The largest primate to ever live; a massive Asian ape from the Miocene/Pleistocene known primarily from giant jawbones and teeth.

Hominin Definition

Any species more closely related to modern humans than to chimpanzees, primarily defined by evidence of obligate bipedalism.

Human-Chimpanzee LCA

The Last Common Ancestor of humans and chimps, estimated to have lived between 6 to 8 million years ago.

Anatomical Changes for Bipedalism

Foramen magnum at the bottom of the skull, S-shaped spine, bowl-shaped pelvis, angled femurs, and non-divergent big toe.

Evolutionary Cause of Bipedalism

Likely evolved as a highly efficient way to travel across expanding savanna grasslands, freeing hands to carry food or tools.

Non-Honing Chewing

The loss of the sharp, slicing canine teeth seen in apes, indicating a diet change and a decrease in male-to-male aggression in hominins.

Diastema

The gap next to the canine teeth in apes that allows the upper and lower jaws to close; hominins lost this as canines shrank.

Mosaic Evolution

The pattern in which different traits evolve at different rates; e.g., hominins evolved bipedalism millions of years before large brains.

East African Rift

A geologically active area that created volcanic ash layers perfect for K-Ar dating and burying hominin fossils (e.g., Olduvai Gorge).

Mary & Louis Leakey

Pioneering paleoanthropologists whose work in Olduvai Gorge proved that early human evolution centered in Africa.

Taung Child

The first Australopithecus africanus fossil discovered; its small brain but bipedal placement of the foramen magnum proved bipedalism preceded large brains.

Sahelanthropus tchadensis

7 mya (Pre-Australopithecine); one of the oldest debated hominin species, found in Chad, displaying a mix of ape-like brain size and hominin-like face/canines.

Orrorin tugenensis

6 mya (Pre-Australopithecine); found in Kenya, its femur structure strongly suggests early bipedalism.

Ardipithecus ramidus ("Ardi")

4.4 mya (Pre-Australopithecine); a highly informative fossil showing a mosaic of tree-climbing hands/feet but bipedal pelvis adaptations.

Gracile vs. Robust Australopithecines

Gracile species had lighter, more generalized dietary traits. Robust species (Paranthropus) had massive jaws and sagittal crests for heavy chewing.

Australopithecus afarensis

3.9 - 2.9 mya; famous species including "Lucy" and the "Dikika Child" (Selam); highly successful, habitual bipeds with small brains.

Laetoli Footprints

Fossilized footprints in volcanic ash proving A. afarensis walked fully upright with a non-grasping big toe 3.6 million years ago.

Pleistocene Glaciation

Often called the "Ice Age"; characterized by fluctuating cycles of massive glacial advance and warmer interglacial retreat.

Megadonty

Enlarged teeth (especially molars and premolars) seen in Genus Paranthropus, adapted for grinding tough, fibrous plant foods.

The Black Skull

Paranthropus aethiopicus; famous for its dark mineral staining and massive sagittal crest, showing early extreme robust features.

Defining Genus Homo

Difficult due to fragmented fossils and debated transition points; generally defined by brain expansion, smaller faces, and reliance on material culture.

Homo habilis vs. Homo rudolfensis

H. habilis had a smaller brain and generalized face; H. rudolfensis had a larger brain but robust face. Debated whether they are one sexually dimorphic species or two.

Knapping

The process of striking stones together to create tools.

Flake, Core, Hammerstone

The hammerstone strikes the core rock to knock off a sharp piece, known as the flake.

Lithics / Lithicist

Lithics refers to stone tools; a lithicist is an archaeologist who specializes in studying them.

Lomekwi Tools

Discovered in Kenya (3.3 mya), pre-dating Genus Homo; suggests Australopithecus or Kenyanthropus made the first stone tools.

Oldowan Tools

Simple, early stone tools (choppers and flakes) associated with Homo habilis, used primarily for scavenging and marrow extraction.

Homo erectus

The first hominin to leave Africa; known for modern body proportions, larger brains, and running endurance.

Turkana Boy / Nariokotome Boy

A nearly complete juvenile Homo erectus skeleton showing tall stature and loss of tree-climbing adaptations.

Acheulean Stone Tools

Hand axes and cleavers associated with H. erectus; distinctly bi-faced and teardrop-shaped, requiring mental templates to create.

Homo erectus and Fire

First disputed evidence of controlled fire use, which allowed for cooking (easier digestion/brain growth), warmth, and predator protection.

The Muddle in the Middle

The Middle Pleistocene period characterized by an array of hominin fossils with confusing mixes of H. erectus and modern human traits.

Kabwe Cranium

An important fossil from Zambia representing Homo heidelbergensis, showing massive brow ridges but a larger braincase.

Homo heidelbergensis vs Archaic H. sapiens

A major debate: some view H. heidelbergensis as a distinct species ancestral to both Neanderthals and AMHS, while others group them all as "Archaic Homo sapiens."

Homo naledi

Found in the Rising Star Cave; incredibly surprising because they had tiny brains and primitive shoulders but lived recently (approx. 250kya).

Funerary Caching

The controversial theory that Homo naledi deliberately disposed of their dead in deep, hard-to-reach cave chambers.

Homo floresiensis

"The Hobbit"; found in Liang Bua cave in Indonesia. Tiny hominins (approx. 3.5 feet tall) with small brains but associated with stone tools.

Foster’s Rule (Island Dwarfism)

The ecological rule that large mammals trapped on islands shrink over time due to limited resources (explains H. floresiensis).

Neanderthals

Cold-adapted hominins living in Europe and the Middle East, possessing large brains, stocky bodies, and complex Mousterian tools.

Neanderthal Cultural Evidence

Evidence includes purposeful burials, jewelry, clothing, and mutual care (healing of severe injuries like in the Shanidar fossils).

Paleogenomics & Interbreeding

DNA proves Neanderthals interbred with early modern humans; modern non-African populations carry 1-2% Neanderthal DNA.

Denisovans

An extinct, sister group to Neanderthals discovered via aDNA in a Siberian cave finger bone.

Harbin Cranium

"Dragon Man" found in China; potentially represents the physical appearance of the mysterious Denisovans.

Ghost-Lineage

An ancient, undiscovered hominin population whose existence is only known because their genetic signatures are found in the DNA of modern species.

Anatomically Modern Homo sapiens (AMHS)

Characterized by tall/rounded braincases, a distinct chin, lack of prominent brow ridges, and a vertical forehead.

Jebel Irhoud

Fossil site in Morocco dating to 300,000 years ago, representing the oldest known evidence of AMHS.

Herto & Omo Kibish

Fossil sites in East Africa providing critical, early evidence of AMHS evolving in Africa.

Migration to Australia (Lake Mungo)

Required sophisticated watercraft to cross Wallace's Line; Lake Mungo yields evidence of early human cremation and settlement by ~50,000 years ago.

Beringia vs Coastal Route

The two main theories for migrating to the Americas: walking across the Bering Land Bridge ice-free corridor vs. navigating the Pacific coastline by boat.

Assimilation Model

The best-supported model of human origins: AMHS evolved first in Africa, migrated out, and heavily assimilated/interbred with regional archaic populations (Neanderthals/Denisovans).

Holocene Trends

The current geological epoch (beginning 11,700 years ago) defined by a stable, warm climate and the independent invention of agriculture globally.

Biocultural Impacts of Agriculture

Farming led to massive population growth and settled cities, but also caused a decline in health (dental cavities, bone lesions from malnutrition, and zoonotic diseases).