Topics to be learn

  • Origin of life (Protobiogenesis)
  • Chemical Evolution
  • Organic Evolution
  • Darwinism
  • Mutation Theory of Life (Self-assembly theory of origin of life)
  • Modern synthetic theory of evolution
  • Mechanism of organic evolution
  • Hardy-Weinberg’s principle
  • Adaptive radiation
  • Evidences of organic evolution
  • Speciation
  • Geological time scale
  • Human Evolution

Origin of Life (Protobiogenesis): Living matter exhibits attributes like responsiveness, growth, metabolism, energy transformations, and reproduction.

Theories and Hypotheses on the Origin of Life:

  • Theory of Special Creation:
  • All living organisms are created by a supernatural power.
  • Oldest theory; lacks scientific proof, based on religious beliefs.
  • Cosmozoic Theory/Theory of Panspermia:
  • Suggests life arrived on Earth from other planets as cosmozoa/panspermia.
  • NASA found fossils of bacteria-like organisms on a piece of Martian rock in Antarctica.
  • Theory of Spontaneous Generation (Abiogenesis):
  • Proposes life originated from non-living material.
  • Disproved by Louis Pasteur.
  • Theory of Biogenesis:
  • Asserts living organisms arise from pre-existing living forms through reproduction.
  • Explains the continuity of life.
  1. Chemical Evolution of Life (Self-Assembly Theory of Origin of Life):Theory of Biochemical Origin of Life:
    • Life emerged on Earth through combinations of chemicals via constant chemical reactions over an extended period.
    • Formulated by Haeckel; further developed by Alexander I. Oparin (1924) and J. B. S. Haldane (1929).

Steps in the Process of Chemical Evolution:

  1. Origin of Earth and Primitive Atmosphere.
  2. Formation of Ammonia, Water, and Methane.
  3. Formation of Simple Organic Molecules.
  4. Formation of Complex Organic Molecules.
  5. Formation of Nucleic Acids.
  6. Formation of Protobionts or Procells.
  7. Formation of the First Cell.

Chemical Evolution of Life: Self-Assembly Theory

(i) Origin of Earth and Primitive Atmosphere:

  • Big Bang Theory by Georges Lemaitre (1931).
  • Earth formed about 4.6 billion years ago within the solar system.
  • Initially a rotating cloud of hot gases and cosmic dust, resembling a nebula.
  • Condensation and cooling led to stratification.
  • Heavier elements settled to the core; lighter elements formed the primitive atmosphere.
  • Earth's primitive atmosphere was reducing, lacked free oxygen, and was very hot.

(ii) Formation of Ammonia, Water, and Methane:

  • Early atmosphere rich in hydrogen, carbon, nitrogen, and sulfur.
  • Active hydrogen reacted with other elements, forming CH4, NH3, H2O, and H2S.

(iii) Formation of Simple Organic Molecules:

  • Decreasing temperature led to chemical reactions among lighter elements.
  • Early atmosphere rich in hydrogen, carbon, nitrogen, and sulfur facilitated chemical reactions.
  • Condensation of steam formed water, leading to heavy rainfall and the formation of water bodies and oceans.
  • Reactions like condensation, polymerization, oxidation, and reduction, driven by energy sources like UV rays, lightning, and volcanic activities, formed monosaccharides, amino acids, purines, pyrimidines, fatty acids, glycerol, etc.

(iv) Formation of Complex Organic Molecules:

  • Neutral primitive broth facilitated polymerization.
  • Simple organic molecules aggregated to form complex ones like polysaccharides, fats, proteins, nucleosides, and nucleotides.
  • Protoproteins formed by polymerization of amino acids; later, proteins formed.
  • Formation of protein molecules marked a significant step in the origin of life.

(v) Formation of Nucleic Acids:

  • Formation of nucleotides, leading to nucleic acids like RNA and DNA.
  • Acquisition of self-replicating ability, a fundamental property of living forms.

(vi) Formation of Protobionts or Procells:

  • Protobionts formed from nucleic acids by coacervation.
  • Protobionts: Prebiotic chemical aggregates showing some properties of living systems.
  • Also known as Coacervates (Oparin) and microspheres (Sidney Fox).
  • Showed growth and division, considered the first primitive living system.

(vii) Formation of the First Cell:

  • First cell developed through the formation of RNA and DNA system.
  • Anaerobic, heterotrophic, obtained energy via chemoheterotrophic processes.
  • Urey and Miller's Experiment on Chemical Evolution
Purpose: To provide experimental evidence for Oparin's theory of chemical evolution.
Apparatus:
  • Spark discharge apparatus: Closed glass system with tungsten electrodes.
  • Components: Flask for water boiling, side tube connected to a vacuum pump, cooling jacket, U-shaped trap.
  • Procedure:
  • Evacuation and Sterilization: Apparatus evacuated and made sterile; pre-biotic atmosphere created.
  • Gas Mixture Preparation: Flask filled with water; methane, ammonia, and hydrogen mixture (in ratio 1:2:2) passed through stopcock without air.
  • Simulation of Primitive Environment: Heat applied to flask at low temperature, simulating primitive Earth's ocean. Heating mantle and condenser used to simulate evaporation and precipitation.
  • Simulated Lightning: Continuous electric sparks passed through water vapor and other gases for several days, simulating lightning.
  • Condensation and Collection: Mixture of CH4, NH3, and H2 gases condensed to liquid in a condenser and collected in U-shaped trap.
  • Results: Variety of Simple Organic Compounds formed in the apparatus, including urea, amino acids, lactic acid, and sugars.
  • Significance: Provides evidence supporting the idea that simple molecules in Earth's early atmosphere combined to form organic building blocks of life.
  • RNA World Hypothesis
  • Definition: Hypothesis proposing early life based on RNA, attributed to the discovery of catalytic RNA or ribozymes.
  • Proposers: Carl Woese, Francis Crick, and Leslie Orgel (1960). Ribozymes discovered by Sidney Altman and Thomas Cech in 1980.
  • Early Life: Likely based on RNA.
    • Abundant presence of RNA in all living cells.
    • Structural resemblance to DNA.
    • RNA chains can evolve, mutate, replicate, and catalyze reactions.
    • Nucleotide presence in biomolecules like Acetyl-Co-A.
    • Ribosome, acting as a protein assembly unit, contains RNA and catalyzes translation.
  • Evolutionary Process:
    • Primitive molecules undergo replication and mutation, yielding various RNA molecules with diverse sizes and catalytic properties.
    • Development of protein coats and machinery for survival.
    • Transition to DNA: RNA-based life forms develop into DNA, providing a stable, double-stranded structure.
    • Further Evolution: Continuous evolution leads to the emergence of rich biodiversity on Earth.
  • Supporting Factors:
 Organic Evolution:
  • Definition: Slow, gradual, continuous, and irreversible changes leading to the development or evolution of present-day complex life forms from their simple pre-existing forms.
  • Charles Darwin's Definition: "Descent with modification."

  • Lamarck's Theory:

    • Concept: Traits acquired due to internal forces, environmental changes, new needs, and the use/disuse of organs.
    • Result: Gives rise to new species over several generations.
    • Disproved by: August Weismann.
     
    Weismann's Theory of Germplasm:
  • Concept: Variations in somatic cells (somatoplasm) are not inherited; only variations in germ cells (germplasm) are inherited to the next generation.
  1. Darwinism
  • Definition: Theory of origin of species by Natural Selection, proposed by Charles Darwin.
  • Darwin's Work:Darwin's Book: "The Origin of Species by Natural Selection" (1859), based on observations of variations among tortoises and finches on the Galapagos Islands.
Influences:
  • C. Lyell's Viewpoint: Natural forces existing in the past are the same as those present.
  • Alfred Russel Wallace: Made similar observations.
  • R. Malthus: Idea that human population increase leads to competition and struggle for existence.

Five Main Postulates of Darwinism:

1. Overproduction (Prodigality of Nature):

  • Natural tendency to produce more progeny than can survive.
  • Leads to competition for limited resources.

2. Struggle for Existence:

  • Competition among individuals for food, space, and other resources.
  • Adapting to environmental conditions to survive.

3. Organic Variations:

  • Differences in morphology, physiology, behavior among individuals of the same species.
  • Serve as raw material for evolution.

4. Natural Selection:

  • Some organisms possess variations better suited to their environment.
  • Better adapted organisms survive and reproduce, passing on advantageous traits.
  • Principle known as "Natural Selection" or "Survival of the Fittest".

5. Origin of New Species (Speciation):

  • Favorable variations passed on through generations.
  • Gradually, adaptations become fixed in the life cycle, forming new species.

Evidences of Darwinism:

Giraffe's Neck:
  • Long-necked giraffes adapted to reach leaves from tall trees.
  • Short-necked giraffes unable to access food, perished.
Peppered Moths:
  • Example of industrial melanism in the UK.
  • Black-colored moths evolved from white-colored forms due to environmental changes.
DDT Resistance in Mosquitoes:
  • Mosquitoes developed resistance to DDT after intensive spraying.
  • Resistant mosquitoes survived and reproduced.

Drawbacks and Objections to Darwinism:

  • Minute fluctuating variations not always heritable.
  • Failure to distinguish between somatic and germinal variation.
  • "Arrival of the fittest" not explained.
  • Inability to explain cause, origin, and inheritance of variations.
  • Lack of recognition of intermediate forms in species evolution.
  • Unable to explain neutral flowers and hybrid sterility.

Mutation Theory
  • Proposer: Hugo de Vries
  • Basis: Observations on Oenothera lamarckiana.
  • Main Features:Nature of Mutations:Large, sudden, and discontinuous variations in a population.
  • Inheritability: Mutations are inheritable.
  • Role in Evolution: Provide raw material for organic evolution.
  • Usefulness: Mutations can be useful or harmful,Useful mutations selected by nature.
  • Formation of New Species:Accumulation of mutations over time leads to origin and establishment of new species. Harmful mutations may persist or be eliminated.

Objections:

  • Nature of Variations: Large, discontinuous variations attributed to chromosomal aberrations, causing minor changes.
  • Rate of Mutation: Mutation rate considered slow.
  • Stability of Chromosomal Aberrations: Chromosomal aberrations deemed unstable and not significant in evolution.
Speciation (Formation of New Species):
  • Darwinian Variations:Small, directional variations.
  • Mutational Variations:Large, sudden, random mutations.
  • Darwin's Opinion:Gradual, inheritable variations over time lead to speciation.
  • De Vries's Opinion:Mutations cause speciation.
  • Saltation:Single-step large mutation. 
  • Modern Synthetic Theory of Evolution
  • Definition:Result of modification of Darwinism and theory of mutations. Incorporates studies of genetics, ecology, anatomy, geography, and paleontology.

Five Key Factors:

  1. Gene Mutations
  2. Chromosome Structure and Number Mutations
  3. Genetic Recombinations
  4. Natural Selection
  5. Reproductive Isolation
  6. Contribute to the evolution of new species or speciation.

Three Main Concepts:

(i) Genetic Variations:

  • Mutations: Sudden, permanent heritable changes. Point mutations or gene mutations change phenotype, causing variations.
  • Genetic Recombination: Exchange of genetic material during gamete formation. Crossing over produces new genetic combinations.
  • Gene Flow: Movement of genes into or out of a population.Migration of organisms, dispersal of gametes or DNA segments.
  • Genetic Drift: Random fluctuation in allele frequency due to chance.Greater impact in smaller populations.
  • Chromosomal Aberrations: Structural changes in chromosomes.Rearrangement of genes leads to variations.

(ii) Natural Selection:Main driving force in evolution. Selects favorable gene combinations through differential reproduction.

(iii) Isolation:Separation of population into smaller units, preventing interbreeding.Leads to speciation over time.

Isolating Mechanisms
  • Definition: Barrier preventing gene flow between isolated populations, leading to gradual divergence and speciation.

Types of Isolating Mechanisms:

(i) Geographical Isolation:Physical distance or geographical barriers.

  1. Process:
    • Original population divides into groups by barriers like rivers, mountains.
    • Separated groups experience different environments, acquire new traits.
    • Develop distinct gene pools, do not interbreed, evolve differently.
    Examples: Darwin’s Finches, African elephant (Loxodonta) and Indian elephant (Elephas).

(ii) Reproductive Isolation: Prevents interbreeding despite occupying the same area.

  1. Causes:
    • Change in genetic material, gene pool, and genital organ structure.
    • Prevents interbreeding, leading to speciation.

Types of Reproductive Isolations:

(i) Pre-zygotic Isolating Mechanisms:

  • Habitat Isolation:Individuals occupy different habitats, preventing interbreeding.
  • Seasonal Isolation:Different sexual maturity times prevent interbreeding.
  • Ethological Isolation: Different mating behaviors prevent interbreeding.
  • Mechanical Isolation: Differences in reproductive organ structure prevent interbreeding.

(ii) Post-zygotic Isolating Mechanisms:

  • Gamete Mortality: Death of gametes prevents fertilization.
  • Zygote Mortality: Zygote fails to thrive after fertilization.
  • Hybrid Sterility: Formed hybrid is sterile, cannot contribute genetically.
  1. Mechanism of Organic Evolution
  2. Population Evolution:Population evolves, individuals pass genetic variation to offspring.

Basic Processes Bringing Evolution:

  • Mutations: Permanent heritable changes in genetic material, Adds new alleles to gene pool.
  • Gene Recombination: Alleles combine during sexual reproduction, producing variations. Random union of gametes, chromosome separation, crossing over.
  • Gene Flow: Emigration and immigration transfer genes between genetically different populations. Alters allele frequency.
  • Genetic Drift: Alteration in allelic frequency by chance, significant in small populations. Random drifts create 'founder' populations.
  • Natural Selection:Types: Stabilizing, Directional, Disruptive. Selects better-adapted individuals, leaving more offspring.Leads to adaptation, speciation.
  • Isolation: Separation of single interbreeding population into subunits.Restricts gene flow between discrete populations.
  • Speciation: Subunits of single interbreeding population break down into species.
  • Prevents interbreeding, forms new species.

Types of Natural Selection:

  1. 1. Stabilizing Selection:

     

    • Balances population, favors intermediate forms.
    • Reduces variations, maintains phenotypic stability.
    • Well-adapted to environment.


  2. 2. Directional Selection:

     

    • Brings directional change without disrupting balance.
    • Eliminates one extreme, favors other.
    • Results in evolutionary trend within population.

  3.  

    3. Disruptive Natural Selection:

     

    • More individuals acquire peripheral character values.
    • Nature selects extreme phenotypes, eliminates intermediate.
    • Rare, affects entire gene pool of population.
Example of Disruptive Selection:African seed cracker finches:
  • Different sizes of beaks, feed on different seed sizes.
  • Large and small beak sizes thrive, intermediate sizes starve.
  • Natural selection eliminates intermediate, population appears disrupted.
Hardy-Weinberg Principle
  • Definition:Gene, allele, or genotype frequencies remain constant across generations unless disturbed by factors like mutation, non-random mating, genetic drift, etc.
  • Assumptions:
  • Two alleles at a single locus (A and a).
  • Respective frequencies: p and q.
  • Frequency of genotype AA = p, 2Aa = 2pq, aa = q.
  • Equilibrium Equation:
  • p² + 2pq + q² = 1
  • Sum total of gene frequencies = 1, so is the sum total of genotype frequencies.
  • Explanation:
    • States that unless equilibrium is disturbed, evolution doesn't occur.
    • Factors disrupting equilibrium: mutation, non-random mating, genetic drift, etc.

  1. Adaptive Radiation

  2. Definition:Process of evolution transforming original species into many different varieties.

  3. Examples:

    (i) Darwin’s Finches:
    • Observed by Charles Darwin in Galapagos Islands.
    • Original mainland species migrated to different islands.
    • Adapted to differing environmental conditions.
    • Altered beak shapes due to changed feeding patterns.
    (ii) Australian Marsupials:
    • Many marsupial mammals evolved from common ancestor.
    • Adapted to various ecological niches.

  4. Characteristics:

    • Leads to divergent evolution.
    • Results in the proliferation of diverse species from a common ancestor.

    Evidences of Organic Evolution:

  5. Theory of Organic Evolution: Complex organisms today originated from simpler forms. Supported by evidence from: Palaeontology, Comparative Anatomy, Embryology, Molecular Biology.

(i) Palaeontology:

  • Study of ancient life through fossils.
  • Provides convincing evidence of evolution.
  • Fossils found in sedimentary rocks, amber, ice, peat bogs, etc.
  • Primitive forms in lower, older layers; advanced forms in upper, recent layers.

Types of Fossils:

  • Actual remains: Bodies preserved in permafrost (e.g., Woolly Mammoth in Siberia), or in amber.
  • Moulds: Cavities or impressions left by decayed organisms (e.g., footprints).
  • Casts: Mineral matter deposited in mould cavities.
  • Compressions: Thin carbon film showing outline of ancient organism.

Significance of Palaeontology:

  • Reconstruction of phylogeny
  • Studying extinct animals
  • Record of missing links
  • Understanding habits of extinct organisms
  1. (ii) A Connecting Link (Missing Link):
    • Intermediate state between two systematic groups of organisms.
    • Bears common characters of both groups.
    • Also known as a missing link.
  1. Examples:
    • Archaeopteryx: Between Reptiles and Aves (birds).
    • Seymouria: Between Amphibia and Reptilia.
    • Ichthyostega: Between Pisces (fish) and Amphibia.
     

(iii) Morphology (Comparative Anatomy):

  • Morphology: Study of external structures.
  • Anatomy: Study of internal structures.
  • Comparative study reveals: Homologous organs, Analogous organs & Vestigial organs

(a) Homologous Organs:

  • Structurally similar but functionally dissimilar.
  • Indicates common ancestry.
  • Different homologous organs indicate divergent evolution or adaptive radiation.
  • Helps trace phylogenetic relationships.
Examples:
  • Forelimbs of frog, lizard, bird, bat, whale, and man.
  • Vertebrate heart and brain.
  • In plants, thorns of Bougainvillea and tendrils of Cucurbita.
 
  1. (b) Analogous Organs:
  • Similar in function but dissimilar in structural details.
  • Do not trace evolutionary relationships but help understand convergent evolution.
  • Structural modifications due to similar habitat.

Examples:
  • Insect wing and bird wing: Both for flight, structurally different (exoskeleton vs. modified forelimb).
  • Octopus eye and mammal eye: Different structures, same function (vision).
  • Penguin flippers and dolphin flippers.
  • Sweet potato (root modification) and potato (stem modification): Both store starchy food.

(c) Vestigial Organs:

  • Rudimentary, imperfectly developed, non-functional organs.
  • Become functionless in animals, but still present due to evolutionary descent.
  • Indicate evolutionary line.
Examples in humans:
  • Caecum and vermiform appendix: Functional in herbivores for cellulose digestion, functionless in humans.
  • Nictitating membrane: Remnant of third eyelid.
  • Coccyx (tail vertebrae), wisdom teeth.

  • Indicate human descent from ape-like ancestors.

  1. (iv) Embryological Evidences: Similar development pattern in different vertebrates.

     

Molecular Biological Evidences:

  • Basic similarities in molecular constituents.
  • All organisms have the same basic structural and functional unit: the cell.
  • Cell organelles (endoplasmic reticulum, Golgi bodies, mitochondria) present in different organisms.
  • Proteins and genes performing different functions show a common ancestry.
  • Similar catabolic activities (liberating energy, synthesis of macromolecules) in different organisms.
  • ATP is the common energy currency.
  • These are called molecular evidences in favor of evolution.
Speciation:Speciation is the process by which new species arise from existing ones. A species is defined as a group of similar organisms capable of interbreeding and producing fertile offspring in nature.

Types of Speciation

  1. Intraspecific Speciation: (i) Allopatric Speciation: Occurs when a segment of a population becomes geographically isolated from the rest of the population.

    • Geographical barriers separate populations, leading to genetic divergence.
    • Migration of individuals may aid in allopatric speciation.
    • Example: African elephant and Indian elephant.

     

    (ii) Sympatric Speciation: New species arise within a single population without geographical isolation.

    • No geographical barrier is present during sympatric speciation.
    • Speciation is driven by physiological or reproductive isolating barriers.
    • Mutations play a role in sympatric speciation.
    • Example: Cichlid fishes in Lake Victoria.

  2. Interspecific Speciation:

    (i) Hybridization: 
    • Occurs when individuals from different species interbreed, giving rise to a new species.
    • Example: Mule (cross between a male donkey and a female horse) and Hinny (cross between a male horse and a female donkey).
  1. Geological Time Scale:
    • Arrangement of major divisions of geological time: eras, periods, and epochs.
    • Based on study of fossilized organisms from different earth strata.
    • Characteristic events in organism organization aid understanding.
    • Eras are major divisions, divided into periods, and periods into epochs.
    • Fossils help trace evolutionary changes in organisms.
Human Evolution

Human evolution traces the evolutionary development of the Homo sapiens species from earlier hominids or primates. Key changes in human evolution include:

  • Increase in Brain Size and Complexity: Humans evolved larger and more complex brains, leading to enhanced intelligence and increased cranial capacity.
  • Bipedal Locomotion and Erect Posture: The transition to walking on two legs (bipedalism) and an upright posture distinguish humans from their primate ancestors.
  • Opposable Thumb: The development of an opposable thumb allowed for fine motor skills and tool use, facilitating manipulation and dexterity.
  • Changes in Limb Proportions: Forelimbs shortened, while hind limbs lengthened, aiding in bipedal locomotion and upright posture.
  • Development of Facial Features: Humans developed a protruding chin and orthognathous face, distinguishing them from other primates.
  • Pelvic Girdle Changes: The pelvic girdle broadened, and a lumbar curvature developed, supporting bipedalism and childbirth.
  • Cultural and Behavioral Advancements: Humans developed articulated speech, art, tool-making abilities, and complex social structures, leading to cultural and technological advancements.
Classification of mammals :
 

Origin and Evolution of Humans:

The evolution of humans is traced through various stages, beginning with the divergence of the Homo lineage from other primates. The stages include:

  • Dryopithecus: An ape-like primate that lived in the Miocene epoch and is considered an early ancestor of humans.
  • Ramapithecus: An ape-like primate that existed during the late Miocene and early Pliocene epochs and is considered an early hominid.
  • Australopithecus: An early hominid species that lived during the late Pliocene and early Pleistocene epochs, exhibiting bipedal locomotion and primitive features.
  • Homo habilis: An early member of the Homo genus that lived during the late Pliocene and early Pleistocene epochs, known as the "handy man" for its tool-making abilities.
  • Homo erectus: An extinct species of human that lived during the middle Pleistocene epoch and exhibited advanced tool use and bipedal locomotion.
  • Neanderthal Man: An extinct species of human that lived during the late Pleistocene epoch and is known for its robust physical features, advanced tool use, and cultural practices.

  1.  

    Origin and Evolution of Human Beings:

    Order Primates: Divided into two sub-orders:
    • a) Prosimii: Includes lemurs, lorises, and tarsiers.
    • b) Anthropoidea: Includes New World monkeys (Ceboidea), Old World monkeys (Cercopithecoidea), apes, and humans (Hominoidea).

Evolution of Hominoidea:

  • Evolved in the Miocene in three separate lines:
    • Hyalobatidae: Gibbons.
    • Pongidae: Gorilla, Chimpanzee, and Orangutan.
    • Hominidae: Primates with human characteristics.

Paleontological Evidences of Human Evolution: Fossils include skulls, mandibles, teeth, bones (humerus, femur), and stone implements.

Important Stages in Human Origin:

  • Ape-like stage: Dryopithecus
  • Man-like stage: Ramapithecus
  • Connecting link between ape and man: Australopithecus
  • Handy man: Homo habilis
  • Ape man: Homo erectus
  • Advanced prehistoric man: Homo neanderthalensis (Neanderthal man)
  • Modern man: Homo sapiens
Dryopithecus:
  • Fossils discovered by Leakey in Lake Victoria, Africa, and in Haritalyanga, Bilaspur, Himachal Pradesh.
  • Lived in Miocene epoch (20-25 million years ago).
  • Close similarity to chimpanzee.
  • Walked like modern chimpanzee, but less knuckle walking.
  • Used flat of hands like a monkey.
  • Arms and legs of same length, semi-erect posture.
Ramapithecus:
  • Considered on direct line of human evolution.
  • Fossils found in Siwalik Hills (India) and Kenya.
  • Lived in late Miocene to early Pliocene (14-12 million years ago).
  • Walked erect on hind limbs.
  • Close similarity to chimpanzee.
  • Some believe Dryopithecus evolved into Ramapithecus.

Australopithecus:

  • Connecting link between ape and man.
  • Fossils found in Toung Valley (South Africa), Ethiopia, and Tanzania.
  • Lived in late Pliocene to early Pleistocene (4-1.8 million years ago).
  • About 4 feet tall, prognathous face without chin.
  • Lumbar curvature present, walked upright.
  • Cranial capacity: 450-600 CC.

Homo habilis:

  • Described as Handy man.
  • Fossils found in Olduvai Gorge, Tanzania, Africa.
  • Lived in late Pliocene to early Pleistocene (2.5-1.4 million years ago).
  • Lightly built, small molars.
  • Walked erect, cranial capacity: 640-800 cc.
  • Did not eat meat, made stone tools.

Homo erectus:

  • Also known as Java man or Peking Man.
  • Lived in middle Pleistocene (1.5 million years ago).
  • 5 feet tall, prognathous face, no chin.
  • Cranial capacity: 900 cc.
  • Omnivorous, probably used fire and ate meat.

Neanderthal Man:

  • Heavily built, short, outwardly curved thigh bones.
  • Prominent brow ridges, thick skull bones, low forehead, deep jaw without chin.
  • Lived in late Pleistocene (100,000-40,000 years ago).
  • Widely spread in Europe, Asia, and North America, extinct 25,000 years ago.
  • Cranial capacity: 1400 cc.
  • Used hide for dressing, constructed and used flint tools and fire.
  • Buried dead with tools, performed ceremonies.
Human Evolution Table