week 3 and 4 socy200

Why prehistory matters (Barsky quote)

Bodies and brains evolved over millions of years, but technology became an especially powerful way to survive and adapt. Barsky: "We stopped waiting for our bodies to catch up."

What makes us human (two traits)

We are bipedal and technological

Archaeologists

People who try to reconstruct societies from the bones and artifacts left behind

Hominin

A member of the human evolutionary family

Bipedalism

Regular movement on two legs

Habitual biped vs. facultative biped

Habitual = always walks on two legs. Facultative = sometimes walks on two legs.

Arboreal

Tree-climbing

Robust (hominin term)

Strongly built

Cranial capacity

Skull space; an estimate of brain size

When did hominins split from the great apes?

About 5–6 million years ago

Share of hominin history spent hunting and gathering

More than 99%

Why the emergence of hominins matters

Sociocultural evolution replaced biological evolution as the primary means of human adaptation

"Upright & up trees"

Early hominins were often both bipedal and arboreal: upright-walking traits plus climbing adaptations in the arms and wrists. They weren't just "early versions of us"; they were adapted to their own world of ground and trees.

EARS: early hominin habitats

Many habitats, not just savanna: open floodplains, forests and woodlands, dry shrublands, grasslands, riverbanks and lake edges. This challenges the old "forests vanished, so we walked across the savanna" story; environments were mixed, and so were adaptations.

Meet the biped relatives (main idea)

Several hominin groups lived across millions of years, not one species "improving" into the next. Different hominins lived at different times and sometimes overlapped. Groups mixed, interbred, and exchanged ideas (hybridization).

Graeber & Wengrow on ancestral humans

Ancestral humans differed from each other and coexisted with smaller-brained, more ape-like species like Homo naledi. We are composite products of this original mosaic of populations, which interacted, interbred, drifted apart, and came together.

Graeber & Wengrow on ancestral behavior

Mating and child-rearing practices, dominance hierarchies (or their absence), and forms of language likely varied at least as much as physical types, and probably far more.

Australopithecus anamensis

~4.2–3.8 mya. Walked upright, but arms and wrists were still built for climbing.

Australopithecus afarensis

~3.85–2.95 mya. "Lucy's" species. An effective biped that still climbed; small brain.

Australopithecus africanus

~3.3–2.1 mya. South African; known for the Taung Child fossil.

Kenyanthropus platyops

~3.5 mya. Upright walker in mixed grassland and forest.

Paranthropus

~2.7–1.2 mya. Heavy build, powerful jaws, huge teeth.

Early Homo

~2.8 mya onward. Our own genus; lived alongside Paranthropus.

Misleading labels

Homo habilis as "the first toolmaker," Homo erectus as "the great migrator," Neanderthals as inventors of complexity. Misleading because behaviors likely developed gradually and were shared, not "invented" by one species alone.

Going bipedal (main points)

Humans did not become human all at once; evolution was a long series of changes. The first major change was walking upright on two legs, which set early hominins apart from other apes.

Bipedalism as a whole-body redesign

Not just standing up straighter. It required changes to the pelvis, spine, legs, feet, muscles, and skull position, to balance the upper body and move efficiently on two feet.

Why the Lieberman model matters

Bipedalism may go back ~7 million years and may have evolved more than once in different groups. Change was gradual, not all-or-nothing; natural selection favored more efficient walking over time.

Three stages of bipedalism (Lieberman model)

Stage 1: facultative bipedalism; still regular climbers. Stage 2: regular upright walking (Australopithecus); habitual bipeds who kept some climbing traits. Stage 3: modern-style walking and running (genus Homo).

Four explanations for why we went upright

1) The savanna idea, 2) cooling theory (staying cooler), 3) saving energy, 4) links to bigger brains

Explanation 1: the savanna idea

Upright posture let hominins see over tall grass to spot food, predators, or prey; travel more easily across open areas; free the hands to carry food or children; and use or throw stones and carry simple wooden tools.

Explanation 2: cooling theory

An upright body absorbs less direct overhead sun, sits farther from heat radiating off the ground, and catches more breeze. Linked to the loss of thick body hair and the rise of sweating.

Explanation 3: saving energy

Human walking uses roughly 75% less energy than chimp walking on two or four limbs, so efficient walkers could travel farther on less food and water. But more fossil evidence is needed before calling this the main cause.

Explanation 4: links to bigger brains

Upright posture rearranged the skeleton, may have changed how blood drained and circulated around the brain, and possibly improved brain cooling. Bipedalism came first; larger brains came much later in Homo. Walking didn't instantly create big brains but may have made later expansion possible.

Problems early bipeds faced

Shifting climates, dangerous predators, and an unreliable food supply. Like all species, hominins first adapted physically, but technological solutions for hunting and gathering accelerated adaptation.

"Thus, the tools": what each solved

Sharp stone → butchering, hunting. Fire → warmth, protection, cooked food. Shared knowledge → group survival. Language and culture → skills passed to the next generation.

Cultural selection from 40,000 to 8,000 BCE

The rate of technological innovation increased tenfold. Important innovations first introduced by genetically modern humans: the spear-thrower and the bow and arrow.

Innovations of 40,000–10,000 BCE

Lamps, pins, fish gorgets, cords, needles with eyes, antler hammers, shovels, mattocks, spoons, stone axes with hafted handles, jewelry, pestles and grinding slabs, boats, handles, musical instruments, figurative art

Innovations of 10,000–8,000 BCE

Beer, fishhooks, fish traps, fishnets, sickles, plant cultivation, domestication of sheep, basketry, cloth, grinding equipment, leather-working tools, paving, sledges, ice picks, combs

Best-known innovation of the period (40,000–8,000 BCE)

Art. Example: the prehistoric rock painting of Tassili n'Ajjer, Algeria, which shows spiritual belief in sympathetic magic.

Hunter-gatherer population: size and density

Average group size of about 40 people, because of prolonged nursing of infants, high maternal mobility, and high death rates

Hunter-gatherers as extraordinarily nomadic

They moved sometimes every week, migrating for a big kill, bad omens, and more. This requires and encourages restricted accumulation of possessions.

Hunter-gatherer kinship

The foundation of obligations and responsibilities between people. Sharing is a major reason the extended family matters. Polygyny and exogamy exist, and "divorce" is permitted and very common.

Polygyny (as defined in lecture)

Marriage of one partner to two or three partners

Exogamy

Marrying outside the group; it establishes a web of kinship ties with neighboring groups

Hunter-gatherer economy

Everything is free for members to use. The quest for food is paramount but well accomplished (one anthropologist called them "the most leisured people"). Little division of labor: mostly by age-grade (and, the authors claim, by sex).

Anatomically modern humans (AMH)

Homo sapiens: slim skeletons, longer legs, smaller teeth, a chin, no heavy brow ridge. Signature feature: a bulging forehead and a bigger frontal brain region, which powers planning, memory, abstract thought, and social skills.

Herto Man

Found in Ethiopia; dated in 2003 to ~160,000 years ago

Jebel Irhoud

Find in Morocco dated to ~300,000 years ago, nearly doubling the age of our species

Misliya and Apidima fossils

Fossils in Israel (Misliya) and Greece (Apidima) show modern humans left Africa by ~200,000 years ago

Out of Africa: key dates

Rapid spread after leaving Africa: Australia by ~65,000 years ago; the Americas by ~15,000–20,000 years ago

Homo sapiens and other human species

Overlapped and interbred with Neanderthals, Denisovans, and others. The other species eventually disappeared, leaving us as the only humans.

The real game-changer for Homo sapiens

Symbolic thinking. Symbols (art, jewelry, ritual, language) let people share meaning, created group identity ("us" vs. "them"), enforced social rules, passed knowledge across generations, and let technology and culture snowball as populations grew.

Culture speeding up: tool traditions

Oldowan tools were used for ~1.7 million years and Acheulian tools for ~1.4 million years. The Upper Paleolithic lasted only ~30,000 years but was packed with innovation.

New tools, bigger reach

Bow and arrow: accurate, long-range hunting. Atlatl (spear-thrower): more force, greater distance. Result: modern humans could hunt safer, farther, and smarter than any earlier hominin.

Atlatl

A spear-thrower; gives more force and greater distance

The explosion of art (~40,000 years ago)

Cave paintings (e.g., Chauvet, France), sculptures, engravings, body decoration. Art moved inner thoughts and feelings into the outside world; not just decoration but a way to share meaning across a community.

Art as a "secret language" of the group

Symbols only mean something to insiders who share the culture. Early art favored animals and geometric signs, rarely people or landscapes. Some works were hidden deep in caves (ritual or personal), and handprints and signs may have been social signals, even at a distance.

Why symbols won: cooperation at scale

Bigger groups mean more people to coordinate with, and it's impossible to read every individual's intentions personally. Shared symbols, gestures, and language let large groups cooperate. Group-level "survival of the fittest": societies that cooperated better survived better.

The brain caught up

Symbolic behaviors reshaped our biology. Modern humans show high cephalization (large brain for body size) and big expansion of the neocortex (gray matter) and frontal lobe, the regions behind abstract thought, planning, and language.

Cephalization

Having a large brain for body size

Culture goes local

As modern humans spread across Eurasia and Africa, they split into regional groups with their own tools, art styles, and traditions. Archaeologists name these "cultures" after the sites where they were first found. The Upper Paleolithic is best documented in Western Europe.

Divisions of the Upper Paleolithic (in order)

Châtelperronian (~45–40 Ka), Aurignacian (~40 Ka), Gravettian (~32–26 Ka), Solutrean (~26–20 Ka), Magdalenian (~20–12 Ka)

Châtelperronian (~45–40 Ka)

Transition from Middle to Upper Paleolithic. Likely made by late Neanderthals (still debated). Small blade tools, bone pendants, perforated teeth; post holes show they built circular huts.

Aurignacian (~40 Ka)

First widely recognized modern-human culture in Europe. Refined flint blades, carved bone and ivory, cave paintings including Chauvet, France (discovered 1994). A clean break from Neanderthal (Mousterian) traditions.

Gravettian (~32–26 Ka)

Signature tool: the Gravette point, a hafted hunting blade. Expert hunters of reindeer and mammoths. Famous for "Venus" figurines (possibly fertility symbols). In Ukraine, huts built from mammoth bones and tusks.

Solutrean (~26–20 Ka)

Beautifully crafted leaf-shaped flint points made with a fine, flat "retouch" technique, a peak of stone craftsmanship. Tools resemble later ones in Siberia and North America's Clovis culture. Rich art: cave paintings, sculptures, ornaments, jewelry.

Magdalenian (~20–12 Ka)

The peak of the Upper Paleolithic. Fine backed blades, harpoons, sewing needles, chisels. Extensive reindeer hunting ("the age of reindeer"). Art and spirituality at their most sophisticated.

Mousterian

The earlier Neanderthal tool tradition that the Aurignacian broke away from

A global pattern of cultural leaps

Similar leaps happened in Africa, Asia, the Levant, the Americas, and Australia. ~20,000 years ago, humans crossed into the Americas via the Bering land bridge. Innovation likely snowballed everywhere, not just in Europe.

A turning point with nature

Earlier hominins lived roughly in balance with nature. By the end of the Upper Paleolithic, humans began reshaping environments; hunting and gathering began to affect animal and cereal populations.