History of Prehistory and Evolutionary Thought

• Anthropology has 5 components:
• Cultural anthropology
• Archeology
• Linguistic anthropology
• Paleontology
• Paleontology operates as both a laboratory and historical science
• Historical sciences like archeology, geology, and paleontology focus on the past
• Understanding the past involves reconstructing, inferring, and hypothesizing about processes
• Paleoanthropology seeks to understand evolutionary history, reconstruct change patterns using fossils/artifacts, and determine the age of key events
• Artifacts represent behavior; fossils represent biology and behavior

History of Prehistory and Evolutionary Thought

• The concept of a deep human past is a relatively recent idea
• Paleoanthropology is a young science that is less than 200 years old
• Early studies aimed to prove a past different from the present mostly from European perspectives
• Judeo-Christian traditions shaped initial understandings of human history
• Bishop James Ussher (1648-1654) calculated human history began in 4004 BC
• Islamic scholarship contained pre-Darwinian themes
• Rediscovering Greek and Latin texts, via Arabic translations, spurred natural history as an alternative to religious explanations
• Cabinets of curiosity showcased natural artifacts, but lacked interpretive frameworks
• Uniformitarianism explains past events through present-day processes
• 17th-century Europeans mistook stone tools for magical "thunderstones"

Ordering and Classifying the Natural World

• Scala Naturae, or the Great Chain of Being, has a hierarchical arrangement: Rocks, plants, animals, humans, and angels
• Belief existed in the fixity of species which means the unchangeable forms
• Discovery of great apes complicated human-animal distinctions
• Carolus Linnaeus (1707-1778) developed the binomial classification system and placed humans in Primates
• Fossil discoveries challenged religious views like hippos and rhinos in the UK (where they are not found today)
• Mammoths were identified as extinct species, not drowned elephants
• Georges Cuvier (1769-1832) developed catastrophism, where global disasters shaped Earth's history
• Advances in geology consisted of:
• William Smith (1799) who introduced strata and stratigraphy
• James Hutton (1785) who established uniformitarianism
• Charles Lyell (1830) who argued for gradual changes over deep time
• John Frere (1797) found stone tools with extinct animal bones
• Jacques Boucher de Perthes (1846) linked stone tools with ancient fossils
• Photography validated early findings in the 1860s
• Charles Darwin (1809-1882) was inspired by Malthus on population limits
• Geography allowed for the observation of fossils resembling modern species
• Geographic isolation led to species variation, Galapagos finches
• Evolution includes gradual change (anagenesis) and branching evolution (cladogenesis)
• Early views of history were shaped by biblical interpretations
• Scholars shifted to documenting and organizing the natural world
• Fossils, artifacts, and stratigraphy became pivotal in understanding human evolution

Basic Chronology Methods

• Relative dating determines the age of something in relation to another object
• Chronometric (absolute) dating provides a numerical age
• Stratigraphy studies rock layers (strata) to reconstruct Earth's past
• Important concepts are:
• A stratum consists of a distinct layer of rock or sediment
• Boundaries indicate change over time
• Ma (millions of year ago) and ka (thousands of years ago) are used for dating
• Neogene (Miocene: 23-5.3 Ma, Pliocene: 5.3-2.6 Ma) marked early primate evolution
• Quaternary (Pleistocene: 2.6 Ma, Holocene: 11.5 ka) refers to Ice Ages and recent human history
• Key principles of stratigraphy:
• Superposition: Younger layers are on top of older layers
• Association: Artifacts in the same layer were deposited around the same time
• Original horizontality: Sediments are usually deposited horizontally
• Lateral continuity: Strata extend laterally unless abrupt changes indicate disturbances
• Brixham Cave (England) and Somme River (France) gave early evidence of human antiquity
• Mumba Rockshelter (Tanzania) demonstrated changes in human tool use
• Using fossils for dating occurs with tracking changes in animal and plant life over time
• Biostratigraphic correlation is where fossil similarities help date rock layers
• European vole molars used to date archaeological sites
• Dating techniques are:
• Tephrostratigraphy utilizes layers of volcanic ash
• Paleomagnetism tracks changes in Earth's magnetic field recorded in rocks
• Glacial periods refer to cold, dry climates with lower sea levels
• Interglacial periods refer to warm, wet climates and rising sea levels

Evidence of Climate Change

• Glacial moraines: Deposits left by glaciers
• Ocean sediments: Preserve climate records
• Oxygen isotope ratios: Reveal glacial (cold) vs. interglacial (warm) periods
• Marine Oxygen Isotope Stages (MIS):
• Even numbers = Glacial periods
• Odd numbers = Interglacial periods
• Currently we're in the interglacial period (Holocene)
• The principle of radioactive decay states elements lose electrons over time
• Dating is either relative or uses absolute (radiometric) methods
• Age is determined by comparing parent-to-daughter element ratios
• Half-life is the time for half the parent material to decay
• Dating types include:
• Radiocarbon (C-14) to date organic material
• K-Ar to date volcanic rock
• Other dating methods include:
• 40Ar/39Ar: dates volcanic rock
• TL/OSL/ESR: dates artifacts, sand, teeth
• U-Series: dates flowstones and eggshells
• Methods to reconstruct ancient environments:
• Analyze sediments, fauna, flora, and isotopes
• Analyze fossil evidence like animal remains to indicate climate
• Analyze Deep-sea cores for dust levels indicate vegetation/aridity
• Analyzing carbon isotopes to differentiate forest vs. grassland environments

Early Ideas of Evolution

• Preformationism: Life exists pre-formed; no new organisms arise
• Epigenesis: Organisms develop from formless matter
• Natural History & Historicization of Nature
• Variation within species is heritable and naturally selected.
• Traits vary, are inherited, and can be selected
• Evolution is not progressive or goal-oriented
• Modern Synthesis (1942): Evolution = Change in allele frequencies over generations
• Mutation is the primary source of variation
• Evolution mechanisms:
• Traits that aid survival and reproduction persist through natural selection
• Random fluctuations in gene frequencies
• Gene flow: exchange of genes between populations
• Genetic variation is introduced through mutation

What is a Hominin?

• All species since the last common ancestor with chimpanzees
• Defined by bipedalism and non-honing chewing
• Key Anatomical Features:
• Skull & Teeth: Small canines, no diastema, centralized foramen magnum
• Postcranial Evidence: Curved spine, wide pelvis, angled knee, arched foot
• Key Hominin Species:
• Sahelanthropus tchadensis (~7 Ma), an early hominin with a central foramen magnum (suggesting bipedality)
• Ardipithecus (~5.8-4.4 Ma) exhibiting bipedal traits but also adapted for climbing
• Australopithecus afarensis (~3.9-3 Ma) nicknamed 'Lucy', discovered in ethopia, exhibits habitual bipedality
• Paranthropus (2.7-1.2 Ma): Robust Australopiths, heavy chewing adaptations
• Early Homo (~2 Ma): Larger brains, tool use, more advanced locomotion
• Gracile Australopith (~3-4 million years ago) discovered in Afar Basin, Ethiopia
• Key researchers include: Zeray Alemseged (Dikika Project) and Bill Kimbel (Hadar Project)
• A fairly complete skeleton of Lucy was recovered, that offers insights into body structure and locomotion
• Variation within the species is seen at the AL 333 'First Family' site offering a large fossil sample showing intraspecies differences with information on life history from juvenile specimens
• Evidence of bipedalism is from Laetoli footprints, Tanzania (3.7 Ma)
• Intermediate locomotion between terrestrial and arboreal life can be seen through anatomical features, which includes:
• Long arms, curved fingers
• Small body size
• Sexual dimorphism is significantly larger

Diet & Dental Evidence

• Reduced diastema but still larger teeth for teeth analysis
• Chimpanzees A. afarensis to Homo sapiens demonstrates a comparison
• Dietary adaptations are:
• Robust Australopiths (Paranthropus boisei), massive jaws, sagittal keel, large flat molars for grinding
• Gracile Australopiths: broader diet with less specialization
• Microwear analysis on teeth:
• Scratches equal a Leaf/fruit-based diet
• Pits equal a hard foods diet like seeds
• Isotopic analysis (carbon signatures in teeth):
• C3 (trees/shrubs) vs. C4 (grasses) diet can be differentiated
• The environmental adaptions can be seen with over-time Australopiths increasing their grass based food consumption:
• Gracile Australopiths are generalists that stayed near trees
• Robust Australopiths specialized for open, grassy environments
• Australopithecus garhi (~2.5 Ma, Ethiopia): Associated with cut-marked bones
• A few questions about Taphonomy & Fossil Interpretation :
• Early hominins consist of hunters or scavengers?
• Do stone tools give a greater access to food sources?
• Tools allow for a shift in ecological role with more interaction with other species in the food chain
• Regarding the use of technology: :
• Hominins were technologically dependent, tools expanded dietary ranges
• Earliest tools found are not determined from late astralopiths of Early Homo
• Earliest stone tools:
• Lomekwian industry (~3.3 Ma, Kenya): Large cores predate Homo
• Oldowan industry (~2.5 Ma, Ethiopia/Tanzania): Tool making behavior coincides with Homo
• First fossil evidence (~2.3 Ma, Ethiopia) included Homo sp. maxilla & teeth with Oldowan tools
• Teeth are key for the scrappy fossil record is how to identify said teeth
• Oldowan Sites (~2.6 – 1.6 Ma) were found across Africa with stone tools indicating incresed cognitive abilities
• Hominin Transport Behavior: tools found 10+ km from stone sources leading to wider ranges

Major Events ~2.7 – 2 Ma

• Extinction of Gracile Australopiths
• The emergence of Genus Homo with behavioral shifts and smaller teeth
• Rise of Robust Australopiths adapting a specialized dietary niche
• Regular Use of Stone Tools (Oldowan Industry)
• Experimental elephant butchery indicates used tools for meat
• Cut-marked bones (~2.5 Ma) suggest early Homo accessed meat
• Hominin brains got larger over time through expensive tissue hypothesis

Climate Change & Evolution

• Hominins either hunted or scavenged
• Olduvai Gorge indicates early Homo had access to nutrient-rich parts of carcasses
• Suggested hunting or power scavenging rather than relying on leftovers
• Expansion of Grasslands (Miocene-Pleistocene) • More C4 grasses indicates dietary and habitat shifts
• Adaptions led to:
• Bipedality for moving between food patches
• New resource exploitation
• By 1.5 Ma, Homo became dominant with a Routine bipedalism
• Small, generalized teeth
• Stone tool dependency
• Meat-inclusive diet and a expanded geographic range

Homo erectus Overview

• Key Features of Homo erectus
• Expanded Geographic Range including:
  • Eastern Africa, Indonesia, and Georgia
  • First identified in Asia but fossils suggest and African origin
  • The oldest African fossils date back to ~1.9-1.7 Ma
• Geographic Variability in Skull Morphology between Africa, China, and Indonesia:
  • Inconsistencies include size differences and thick skull bones
  • There's a weak divide between African and Asian specimens
• Postcranial Anatomy Resembling Modern Humans which includes example from the Turkana Boy:
• Nearly complete skeleton from 1.5 Ma
• An efficient walker and runner with
• Narrow pelvis and long legs to suit long range walking
• A faster Growth & Development included the Turkana Boy who was tall but still a child that indicating
• Faster growth rates and a shorter childhood
• Hand axes served as the multi-functional tool during this time period including:
• Butchery, woodworking, and possibly digging
• Cognitive complexity can be seen through imposed form (symmetrical design)
• Control of Fire:
• Suggested that hominids controlled fire a million years ago
• Important for cooking and warmth in new environments
• Reduced Behavioral Variation could be possibly due to dispersed populaitons
• The Hand axe design remained stable for over 1 million years due to limited social connectivity

Key Concepts of Early Human Expansion

• Climate change pushed humans out of africa by shifting environments

• The examples of environmental:

• Biogeography which consists of changes due to shift distribution and environmental change of species

• Deserts or Rainforests Expansion

• Glacial periods lowered sea levels by connecting land masses

• The key fossols in archaeological sties are:

  • Dmanisi, Georgia with oldowan tools and significant variation in H. erectus fossils
  • Ubeidiya, Israel the mix between African and Eurasian species

• Java, Indonesia for Early H. erectus fossols

• The preference in diet and foraging:

  • Game
  • Shift to lower ranked foods

• Acheuleian Handaxes persisted due to efficiency and the disperse populations

• Homo floresiensis (‘The Hobbit’):

• Found Indonesia

• Small stature

• Australopith-like lower limbs and Homo-like skull and teeth

• Homo naledi:

  • Rising Star Cave, South Africa
  • Primitive and modern traits

• Homo

• Homo erectus, was a highly adaptable species • Acheulian technology shows cognitive complexity and adaptability. • Environmental factors in hominin dispersals. • Evidence showed H. floresiensis and H. naledi had complex evolutionary paths with geographic isolation

Key Study Strategies for the Midterm

Understand Fossil Evidence:

• Fossil size
• Gracile vs. robust Australopiths

2. Memorize Key Discoveries: • Lucy ○ Lomekwian tools ○ Oldowan tools • Paranthropus boisei

3. Compare & Contrast Early: • Locomotion: • Diet: • Tool use:

4. Know How that changes in Climate • Environmental changes impacted hominin evolution • Savanna Hypothesis

5. Practice Essay Questions: • How did diet influence hominin evolution?" • "Compare early with Australopithecus