Evolution & Classification: Darwin, Lamarck, Taxonomy, Five Kingdoms, Binomial Nomenclature

Evolution and biological classification are frequently tested in Kerala PSC Science sections. Questions cover key theories, scientists, taxonomy levels, and kingdom classification. Focus on the comparison tables.

1. Theories of Evolution

Lamarck’s Theory (Lamarckism)

Feature	Detail
Proposed by	Jean-Baptiste Lamarck (1809)
Book	Philosophie Zoologique
Key idea	Inheritance of Acquired Characters
Use and Disuse	Organs used extensively become stronger; unused organs degenerate
Classic example	Giraffe’s long neck — stretching over generations to reach high leaves
Status	Largely rejected; acquired characters are not inherited genetically
Weismann’s experiment	Cut tails of mice for 22 generations — tail length remained same; disproved Lamarck

Darwin’s Theory (Darwinism)

Feature	Detail
Proposed by	Charles Darwin (1859)
Book	On the Origin of Species
Voyage	HMS Beagle (1831-1836); visited Galapagos Islands
Key principles	Overproduction, variation, struggle for existence, survival of the fittest, natural selection
Natural selection	Nature selects organisms best adapted to environment; they survive and reproduce
Alfred Russel Wallace	Independently arrived at similar theory; paper read jointly with Darwin (1858)
Status	Foundation of modern evolutionary biology (with modifications)

Neo-Darwinism (Modern Synthetic Theory)

Feature	Detail
Combines	Darwin’s natural selection + Mendelian genetics + population genetics
Key contributors	Theodosius Dobzhansky, Ernst Mayr, Julian Huxley, G. Ledyard Stebbins
Key additions	Gene mutations, genetic drift, gene flow, reproductive isolation
Unit of evolution	Population (not individual)

Comparison: Lamarck vs. Darwin

Aspect	Lamarck	Darwin
Driving force	Inner vital force; use and disuse	Natural selection
Variation	Acquired during lifetime	Pre-existing in population
Inheritance	Acquired characters inherited	Favourable variations inherited
Direction	Organisms change purposefully	Change is random; environment selects
Example	Giraffe stretched neck (acquired)	Giraffes with naturally longer necks survived better

2. Evidence of Evolution

Type of Evidence	Examples
Fossil evidence	Archaeopteryx (link between reptiles and birds); horse evolution series
Homologous organs	Forelimbs of human, whale, bat, horse — same basic structure, different functions; indicate common ancestry
Analogous organs	Wings of bird and insect — different structure, same function; indicate convergent evolution
Vestigial organs	Appendix in humans, wisdom teeth, body hair — reduced organs with no current function
Embryological evidence	Ernst Haeckel’s “Ontogeny recapitulates Phylogeny” — embryos of vertebrates look similar in early stages
Molecular evidence	DNA/protein sequence similarities across species
Biogeography	Distribution of species on continents and islands supports common ancestry

Important Terms

Term	Meaning
Adaptive radiation	Single species evolves into multiple forms to fill different ecological niches (Darwin’s finches)
Convergent evolution	Unrelated species develop similar features (wings of bat and bird)
Divergent evolution	Related species develop different features (forelimbs of whale and human)
Speciation	Formation of new species from existing ones
Genetic drift	Random changes in gene frequency in small populations

3. Taxonomy — Classification of Organisms

Carolus Linnaeus (Father of Taxonomy)

Fact	Detail
Full name	Carl von Linne (Swedish naturalist)
Title	Father of Taxonomy / Father of Modern Taxonomy
Book	Systema Naturae (1735)
Contribution	Binomial nomenclature system; hierarchical classification
Classification basis	Morphological (structural) similarities

Binomial Nomenclature

Rule	Detail
Two names	Genus name + Species name
Genus	Capitalised (e.g., Homo)
Species	Lower case (e.g., sapiens)
Written in	Latin or Latinised; italicised in print, underlined in handwriting
Example	Homo sapiens (human), Mangifera indica (mango), Oryza sativa (rice)
Author name	Sometimes added after species (e.g., Homo sapiens Linnaeus)

Taxonomic Hierarchy (Highest to Lowest)

Level	Example (Human)	Example (Tiger)
Kingdom	Animalia	Animalia
Phylum	Chordata	Chordata
Class	Mammalia	Mammalia
Order	Primates	Carnivora
Family	Hominidae	Felidae
Genus	Homo	Panthera
Species	sapiens	tigris

Memory aid: King Philip Came Over For Good Spaghetti

4. Five Kingdom Classification (R.H. Whittaker, 1969)

Kingdom	Cell Type	Cell Wall	Nutrition	Organisation	Examples
Monera	Prokaryotic	Present (non-cellulose)	Autotrophic or Heterotrophic	Unicellular	Bacteria, Cyanobacteria (blue-green algae)
Protista	Eukaryotic	Present in some	Autotrophic or Heterotrophic	Mostly unicellular	Amoeba, Paramecium, Euglena, diatoms
Fungi	Eukaryotic	Present (chitin)	Heterotrophic (saprophytic/parasitic)	Multicellular (mostly)	Mushrooms, yeast, moulds, Penicillium
Plantae	Eukaryotic	Present (cellulose)	Autotrophic (photosynthesis)	Multicellular	All plants — algae to flowering plants
Animalia	Eukaryotic	Absent	Heterotrophic (holozoic)	Multicellular	All animals — sponges to mammals

Key Differences to Remember

Feature	Monera	Fungi	Plantae	Animalia
Nucleus	No (prokaryotic)	Yes	Yes	Yes
Cell wall material	Peptidoglycan	Chitin	Cellulose	Absent
Nutrition	Mixed	Saprophytic	Autotrophic	Heterotrophic
Chlorophyll	Some (cyanobacteria)	Absent	Present	Absent

5. Earlier Classification Systems

System	Proposed By	Kingdoms
Two Kingdom	Linnaeus	Plantae and Animalia
Three Kingdom	Ernst Haeckel (1866)	Plantae, Animalia, Protista
Four Kingdom	Copeland (1956)	Monera, Protista, Plantae, Animalia
Five Kingdom	R.H. Whittaker (1969)	Monera, Protista, Fungi, Plantae, Animalia
Six Kingdom	Carl Woese (1977)	Added Archaebacteria; or Three-Domain system (Archaea, Bacteria, Eukarya)

6. Human Evolution — Key Stages

Stage	Period (Approx.)	Key Feature
Dryopithecus	25 million years ago	Ape-like; ancestor of both apes and humans
Ramapithecus	15 million years ago	More human-like jaw
Australopithecus	4-2 million years ago	Bipedal; small brain; found in Africa
Homo habilis	2.5 million years ago	”Handy man”; first tool maker
Homo erectus	1.8 million years ago	”Upright man”; used fire; Java Man, Peking Man
Homo neanderthalensis	400,000-40,000 years ago	Large brain; buried dead; lived in Europe
Homo sapiens	200,000 years ago to present	Modern humans; originated in Africa

7. PSC Quick Revision — One-Liners

• Lamarck: Inheritance of Acquired Characters (rejected)
• Darwin: Natural Selection; book “On the Origin of Species” (1859)
• HMS Beagle voyage to Galapagos inspired Darwin’s theory
• Father of Taxonomy: Carolus Linnaeus; book “Systema Naturae”
• Binomial nomenclature: Genus + species (e.g., Homo sapiens)
• Five Kingdom Classification by R.H. Whittaker (1969)
• Monera = prokaryotic (bacteria); Fungi cell wall = chitin; Plant cell wall = cellulose
• Archaeopteryx = transitional fossil between reptiles and birds
• Homologous organs = same structure, different function (common ancestry)
• Analogous organs = different structure, same function (convergent evolution)
• Vestigial organ in humans: appendix, wisdom teeth
• Homo habilis = first tool maker; Homo erectus = first to use fire