anthro 1 final chap 11-18

Hominin

A member of the human tribe defined primarily by bipedal locomotion or "Bipedal Apes"

Hominoid

The broad superfamily including all apes such as gibbons, great apes, and humans

Foramen Magnum

The hole in the base of the skull for the spinal cord whose central position in humans allows the head to sit atop the neck for bipedalism

Lumbar Lordosis

The forward curvature of the lower spine that helps a biped balance the weight of the torso over the hips

S-shaped Spine

The unique human spinal shape that acts as a shock absorber and centers weight over the feet

Bipedal Pelvis

A short, broad, and bowl-shaped structure that supports internal organs and provides leverage for abductor muscles during walking

Valgus Angle

The inward "bicondylar" angle of the femur that ensures the knees are positioned under the body’s center of gravity

Bipedal Foot

Characterized by a developed longitudinal arch for energy return and an adducted or aligned big toe for toe-off leverage

Parabolic Arcade

The rounded "V" or "U" shaped dental arrangement in humans compared to the parallel rows seen in apes

Diastema

A gap between the upper canine and incisor to accommodate a large lower canine which is reduced or lost in hominins

Thick Enamel

A dental trait ideal for crushing hard foods like seeds, tubers, or marrow and a key feature of many hominins

Thin Enamel

A dental trait that creates sharp edges for slicing soft fruits and leaves typical of modern African apes

Miocene Climate Context

A period roughly 7 to 5 million years ago where Africa became drier, tropical forests shrank, and woodlands or savannahs expanded to favor bipedal adaptation

Bipedal Efficiency Theory

The concept that bipedalism saves 75 percent more energy than knuckle-walking, allowing for long-distance travel between food patches

Thermoregulation Theory

The idea that bipedalism reduces the body's surface area exposed to direct sun and increases exposure to cooling winds

Feeding and Carrying Theory

The theory that bipedalism evolved to free the hands for harvesting fruit or carrying resources and offspring

Sahelanthropus tchadensis

Dated to 6 or 7 million years ago in Chad, featuring a 370cc brain, heavy browridge, and a central foramen magnum suggesting early bipedalism

Orrorin tugenensis

Dated to approximately 6 million years ago in Kenya, possessing thick tooth enamel and a femur neck length suggesting bipedal balancing

Ardipithecus ramidus (Ardi)

Dated to 4.4 million years ago in Ethiopia, featuring a 300 to 350cc brain and a mixed anatomy of bipedal walking with a grasping big toe for climbing

Australopithecus anamensis

Dated to 4.2 to 3.9 million years ago and considered the earliest known australopith with a U-shaped dental arcade but a tibia adapted for bipedalism

Australopithecus afarensis (Lucy)

Dated to 3.6 to 3.0 million years ago in East Africa with a 450cc brain and fully bipedal lower body despite retaining long curved fingers for climbing

Laetoli Footprints

Evidence from 3.6 million years ago in Tanzania confirming a fully bipedal gait and the absence of a grasping big toe in Au. afarensis

Dikika Child

A 3.3 million year old Au. afarensis specimen showing the early stages of slower brain maturation and an extended childhood

Australopithecus africanus

Dated to 3.0 to 2.2 million years ago in South Africa including the Taung Child with thicker enamel, smaller canines, and a brain of approximately 485cc

Australopithecus sediba

Dated to 1.98 million years ago in South Africa as the most recent australopith showing a mosaic of australopith-like arms and Homo-like teeth and pelvis

Australopithecus garhi

Dated to 2.5 million years ago in Ethiopia and known for having exceptionally large teeth and long legs

Australopithecus deyiremeda

Dated to 3.5 million years ago in Ethiopia and identified primarily by jaws and teeth that are slightly smaller than those of Lucy

The bipedal spine

Trait: S-shaped curve (vs. C-shaped in apes).

Function: Acts as a shock absorber and centers the weight of the torso over the feet.

The bipedal pelvis

Trait: Short, broad, and bowl-shaped

Function: Supports internal organs and provides leverage for abductor muscles to maintain balance during a stride.

The bipedal foot

Trait: Developed longitudinal arch and adducted (aligned) big toe.

Function: The arch acts as a spring for energy return; the aligned toe provides a "toe-off" lever for walking.

what was happening 6-7 MYA

Appearance of the earliest potential hominins (Sahelanthropus). very end of the miocene as the pleiocene begins

what was happening about 4.4 MYA

Ardipithecus ramidus ("Ardi") lives in Ethiopia, pliocene

what was happening 4.2-2 MYA

Expansion of the Australopithecines across Africa.

what happened in 3.6 MYA

The Laetoli Footprints are made (confirming bipedalism in Au. afarensis).

Why Bipedalism?

1. Efficiency: Better for long-distance travel in expanding grasslands.

2. Thermoregulation: Keeps the body cooler by reducing sun exposure and catching breezes.

3. Feeding/Carrying: Frees the hands to harvest fruit or carry resources/offspring.

Sahelanthropus tchadensis

• Date: 6–7 Ma (The oldest candidate).

• Location: Chad (Central Africa).

• Traits: Chimp-sized brain (370cc), heavy browridge, but a central foramen magnum.

• Takeaway: Potential biped, but still retained climbing abilities (ulna evidence).

Ardipithecus ramidus ("Ardi")

• Date: 4.4 Ma.

• Location: Middle Awash, Ethiopia.

• Skull/Teeth: Small brain (300-350cc); small, non-honed canines (suggests low male-male aggression).

• Locomotion: Bipedal on the ground but had a grasping big toe for life in the trees. Not a knuckle-walker.

Australopithecus afarensis ("Lucy")

• Date: 3.6–3.0 Ma.

• Location: East Africa (Ethiopia, Tanzania).

• Traits: Fully bipedal lower body (valgus knee, arched foot); long, curved fingers and small brain (~450cc).

• Key Evidence: Laetoli Footprints and the "Dikika Child" (showing slower brain growth).

Australopithecus africanus

• Date: 3.0–2.2 Ma.

• Location: South Africa.

• Traits: "Taung Child" specimen; thicker tooth enamel and smaller canines than afarensis; slightly larger brain (approx 480cc).

Australopithecus sediba

• Date: 1.98 Ma.

• Location: South Africa.

Traits: Shows a "mosaic" of traits; australopith-like brain and long arms, but with more Homo-like teeth and a modern-shaped pelvis.

How does the femur of a biped differ from that of a knuckle-walking ape?

The bipedal femur has a longer neck and a valgus angle (slants inward) to keep the knees under the center of gravity, whereas an ape's femur is straighter.

Why is the discovery of Ardipithecus ramidus significant for our understanding of the "Last Common Ancestor" (LCA) of humans and chimps?

It shows that the LCA was likely not a knuckle-walker, as Ardi was a palmigrade climber and a biped, suggesting knuckle-walking evolved later specifically in the Pan (chimp) lineage.

Which physical trait in the A. afarensis hands and feet suggests they still spent significant time in trees?

Long, curved phalanges (fingers and toes).

Based on dental enamel, how would you distinguish a hominin that eats soft fruits from one that eats hard seeds and tubers?

Fruit eaters have thin enamel for sharp slicing edges; seed/tuber/marrow eaters have thick enamel for heavy crushing.

Where was the "Taung Child" discovered, and why was it a revolutionary find?

South Africa (1924); it was the first Australopithecus ever discovered, proving that early human ancestors were in Africa and were bipedal before they had large brains.

Describe why the earliest members of the human lineage can be thought of as bipedal apes

The earliest human ancestors are called bipedal apes because they combined ape-sized brains and climbing adaptations with the defining human trait of walking on two legs

Assess how the evolution of bipedal locomotion altered the skeleton in many important ways

Bipedalism required a centered foramen magnum, an S-shaped spine, a bowl-shaped pelvis, a valgus femur angle, and an arched foot to support and balance upright weight

Discuss why natural selection may have favored bipedal locomotion in early hominins

Natural selection favored bipedalism because it was significantly more energy efficient for traveling long distances, improved body cooling in the sun, and freed hands for carrying resources ;

Late Miocene Epoch

Spanning roughly 23 to 5.3 million years ago, this period saw a cooling climate and the expansion of African woodlands and savannahs which prompted the divergence of the hominin lineage ;

Pliocene Epoch

Spanning roughly 5.3 to 2.6 million years ago, this era was marked by the successful diversification and expansion of Australopithecines across Africa ;

Gracile vs. Robust

Refers to the "sturdiness" of the skull and teeth; Gracile forms (Australopithecus) have smaller teeth and smoother skulls, while Robust forms (Paranthropus) have massive grinding teeth, flared cheekbones, and sagittal crests for heavy chewing.

Early vs. Late Traits

Bipedalism and thick dental enamel emerged very early in the lineage (~6–7 Ma); significantly larger brain sizes and more refined "Homo-like" dental and pelvic shapes emerged much later (~2 Ma).

3 Pliocene Genera

The three main genera that diversified during the Pliocene epoch are Ardipithecus, Australopithecus, and Paranthropus.

Paranthropus vs. Australopithecus

While both were bipedal, Australopithecus had more generalized diets and "gracile" skulls; Paranthropus was a specialized "chewing machine" with huge molars and crests for attaching powerful jaw muscles.

Origin of True Mammals

Evolved from cynodonts during the Triassic period (250–200 mya).

Pliocene & Pleistocene Epochs

Pliocene (5–1.8 mya); Pleistocene (1.8 mya–10,000 years ago). Hominin evolution accelerated during these periods.

The "Chewing Machine" Adaptation

Specialized traits of Paranthropus for processing tough plant foods: Sagittal crest, flared zygomatic arches (cheekbones), and megadontia (huge molars).

Paranthropus aethiopicus

"The Black Skull" (2.5 mya). Found in Kenya; small brain (~410 cc) but massive teeth and tray-like face.

Paranthropus boisei

"Nutcracker Man" (2.2–1.3 mya). East Africa; hyper-robust, brain ~500 cc. Lived alongside early Homo.

Paranthropus robustus

(1.8–1.0 mya) South Africa. High sexual dimorphism; diet of seeds and hard nuts.

Boundary between Australopithecus and Homo

Marked by a transition around 2.8 mya. Homo features larger brains (550–800 cc), flatter faces (less prognathism), and smaller teeth.

Homo habilis

"Handy Man." Smaller brain (~510 cc) and smaller face (e.g., KNM-ER 1813).

Homo rudolfensis

Larger brain (~750–775 cc) and flatter, broader face (e.g., KNM-ER 1470).

Morphology of earliest Homo

Brain size 500–800 cc; reduced molar size; thicker enamel than apes but thinner than Paranthropus; more rounded cranium.

Morphology of Homo erectus/ergaster

Shelf-like occipital torus, prominent brow ridge, receding forehead, no chin, and brain size averaging ~1,000 cc.

Nariokotome Boy (KNM-WT 15000)

Nearly complete H. erectus skeleton (1.6 mya). Modern body proportions: long legs, narrow hips, and barrel-shaped chest for endurance running.

How/When hominins left Africa

H. erectus was the first to leave (~1.8 mya). Evidence found in Dmanisi (Georgia), Java (Indonesia), and China.

The First Stone Tools (Lomekwian)

3.3 mya (Turkana, Kenya). Large, simple tools (33 lbs) made by smashing stones. Possibly made by Au. afarensis.

Oldowan Tool Industry (Mode 1)

Begins 2.6 mya. Uses "flakes" (cutting) and "cores" (chopping). Used for butchery and marrow extraction.

Acheulean Tool Industry (Mode 2)

Associated with H. erectus (1.7 mya). Characterized by the Biface or Hand Axe; required a mental template to create.

Foraging: Humans vs. Primates

Primates mostly eat "collected" foods (fruit/leaves). Humans rely on extracted (tubers/honey) and hunted (meat) foods which are harder to get.

Complex Foraging & Life History

High-skill foraging requires a long learning period, leading to a longer juvenile period, larger brains, and longer lifespans.

Oldowan Strategies: Hunt vs. Scavenge

Scavenging: Cut marks on top of tooth marks (carnivore killed first). Hunting: Cut marks on meatiest bones/prime age prey. Evidence suggests both occurred.

Division of Labor & Sharing

Because high-skill foraging is risky, humans share food. Men often hunt and women often collect/extract, with resources pooled.

Unique Human Life History

Characterized by: Early weaning, long juvenile dependency, high paternal investment, and post-menopausal longevity.

Control of Fire for early homo

Evidence is sparse for early Homo, but consistent fire use is associated with H. erectus for cooking (softening food) and warmth.

Describe the morphology of the earliest members of the human genus, Homo.

They possessed brains significantly larger than Australopiths (550–800 cc). Their faces were less projecting (prognathic), and their teeth were smaller, though they still retained thick enamel. The cranium was more rounded.

Describe the morphology, life history, and lifeways of Homo erectus.

Morphology: Tall, thin frame (Nariokotome Boy) suited for heat; brain ~1,000 cc; thick skull bones with an occipital torus.

Life History: Faster growth than modern humans but slower than apes; first evidence of "childhood" dependency.

Lifeways: First endurance runners; used Acheulean hand axes; first to migrate out of Africa into diverse climates.

Explain why some experts think that Oldowan toolmakers hunted game, whereas others think they mostly scavenged meat.

The "Scavenging" view points to cut marks appearing on top of carnivore tooth marks on low-quality bone scraps. The "Hunting" view points to the presence of entire carcasses of large animals at sites and cut marks on "meaty" bones, suggesting hominins had first access.

Lomekwi Tools

Definition: The oldest possible stone tools, dating to approximately 3.3 Ma. Context: Found in Lomekwi, age and function are uncertain, but they were likely made by throwing and smashing rocks together. Potential Maker: A. afarensis is the only hominin known in that area at that time.

Oldowan Tool Industry (Mode 1)

A stone tool technology that began 2.6 mya and became more abundant around 2 mya. Production: Made by knocking a hammerstone against a core to produce sharp flakes. Both flakes and cores were used as tools. Associated Species: Homo habilis and Homo erectus.

Acheulean Industry (Mode 2)

A more standardized stone tool technology appearing around 1.75 Ma. Key Tools: The hand axe and the cleaver. Associated Species: Primarily Homo erectus and later Homo heidelbergensis. Geographic Note: Rarely found in East Asia, where H. erectus continued to use Mode 1 (Oldowan) tools.

Anatomy of a Stone Tool

Cortex: The outer weathered surface of the rock.

Bulb of Percussion: A swelling on the interior (ventral) surface of a flake just below the point of impact.

Striking Platform: The flat surface where the hammerstone hit the core to detach a flake.

Flake Scar: The mark left on a core after a flake has been removed.;

Categories of Human Food

Collected Foods: Immobile foods that can be gathered and eaten directly (e.g., leaves, fruit).
Extracted Foods: Immobile foods protected by shells, skins, or underground that require processing (e.g., tubers, termites, nuts).
Hunted Foods: Mobile resources that must be caught and often require extraction

Sexual Division of Labor

Concept: A human universal in foraging societies where men and women specialize in different tasks to maximize efficiency. Typical Split: Women focus on collected men focus on hunted foods. This specialization is only possible because they share the food they acquire.

Slow Life History

Concept: The evolution of a longer juvenile period, larger brains, and increased longevity.
Drivers: Extractive foraging and hunting require high intelligence and many years of learning.

Paternal Investment & Reduced Dimorphism

Concept: Because human children are dependent for so long, selection favors males who contribute resources to their offspring.
Outcome: This shift away from direct physical male-male competition led to reduced sexual dimorphism in the genus Homo.

Control of Fire

Timeline: Regular use of fire began around 300 kya.
Evidence: Stone hearths and burnt flints (notably at Tabun Cave, Israel).
Note: Homo erectus likely did not control fire for most of its existence.

How did early Homo differ from australopiths?

Answer: Early Homo had larger brains.

Which statement is true regarding Homo erectus tools?

Answer: Homo erectus used both Mode 1 (Oldowan) and Mode 2 (Acheulean) technology.

Contemporary experiments show Acheulean hand axes are more efficient than Oldowan flakes for what specific task?

Answer: Butchering animals.

If you find an antelope bone where stone tool cut marks are ON TOP of carnivore tooth marks, what can you conclude?

Answer: A hominin likely scavenged the meat after a carnivore had already killed the animal.

What is unique about human life history compared to other primates like chimpanzees?

Answer: Humans have higher fertility rates, shorter inter-birth intervals (IBI), and overlapping dependent offspring because mothers receive help from fathers and grandmothers.

At which site is there evidence of hominin occupation for 200,000 years, showing the transition to regular fire use?

Answer: Tabun Cave, Israel (415 kya to 215 kya).

Pleistocene:

The geological epoch from 2.6 million to 11,700 years ago, characterized by repeated glaciations.

Interglacial:

A warm, wet period between glacial stages characterized by forests and grasslands.

Glacial:

A cold, dry period characterized by ice, deserts, and steppe-tundra.

Steppe-Tundra:

The most widespread biome during glacial periods; a cold, dry grassland.

Occipital Bun:

A prominent bulge or projection on the back of the skull, a characteristic feature of Neanderthals.

Taurodontism:

Teeth with enlarged pulp cavities and reduced roots, common in Neanderthals.