- 01Title page and epigraph
On the Origin of Species
by Charles Darwin · 1859 · 24 chapters · 24/7 tutor
Natural selection and evolutionary theory.
24Chapters
128Lessons
343Topics
Certificate of completion included
This course was produced by Cavua from a public-domain text.
Skills this course leaves you with.
- Explain the core principles of natural selection and evolutionary theory
- Describe variation under domestication and variation under nature
- Analyze the struggle for existence and its role in species change
- Summarize how natural selection leads to adaptation, divergence, and extinction
- Interpret Darwin's arguments about inheritance, hybridism, and the geological record
- Connect geographical distribution and fossil evidence to evolutionary change
About On the Origin of Species.
On the Origin of Species (1859) is Charles Darwin's case that species are not fixed but descend, with modification, from common ancestors, and that natural selection is the main cause of that change. Darwin called it one long argument: the opening chapters build the mechanism, the middle chapters face the strongest objections, and the later ones show how the theory explains fossils, geography and classification. Read the conclusion first, then follow the argument chapter by chapter, separating what Darwin shows from what he admits he cannot yet explain.
Charles Darwin (1809–1882) was an English naturalist who sailed around the world on HMS Beagle from 1831 to 1836, collecting specimens and studying geology, fossils and island species. Over the next two decades he developed his theory privately, until in 1858 Alfred Russel Wallace sent him an essay outlining a similar idea. Papers by both men were presented to the Linnean Society of London that year, and Darwin hurried out what he called an abstract of a larger planned work. John Murray published On the Origin of Species in London in November 1859.
It is read today for two reasons. It is the founding text of evolutionary biology, and its central claims, that living things share common ancestors and that natural selection shapes them, are the organizing ideas of modern biology. It is also a model of scientific argument written for a general reader: no equations, a single diagram, a mass of concrete examples from pigeons to honeybee cells to island species, and an author who states the strongest objections to his theory and answers them one by one.
What the book is really about.
Five ideas run through the book. For each, know the chapter where Darwin develops it and one example he uses.
Questions to ask as you read.
- 1Why does Darwin begin with domestic pigeons rather than wild animals?
- 2How strong is the analogy between artificial and natural selection, and where does it break down?
- 3What does Darwin mean by struggle, and why does he insist the word is used broadly?
- 4What does the branching diagram claim about extinction?
- 5Which difficulty in chapter 6 does Darwin answer most convincingly, and which least?
- 6How does he account for complex instincts such as the honeybee's cell-building?
- 7Why does the incompleteness of the fossil record matter so much to his case?
- 8What do island species show that a theory of separately created species struggles to explain?
- 9How does the missing theory of heredity weaken the argument, and how does Darwin work around it?
- 10Why does the book say so little about humans?
- 11Does the closing image of the entangled bank answer the charge that natural selection makes nature cruel?
Curriculum
The full table of contents.
Every chapter, every lesson, every topic — laid out before you enroll. Click any chapter to expand it.
- Chapters
- 24
- Lessons
- 128
- Topics
- 343
- 01Introduction
- 02Variation under domestication
- 01Inheritance and domestic variation
- 02Variation under nature
- 03Struggle for existence
- 04Natural selection and sexual selection
- 01Laws of Variation
- 02Difficulties on Theory
- 01The law of unity of type and conditions of existence
- 02Instinct
- 03Hybridism
- 04Imperfection of the geological record
- 01Geological succession of organic beings
- 02Geographical distribution
- 03Geographical distribution continued
- 04Mutual affinities, morphology, embryology, and rudimentary organs
- 01Recapitulation of natural selection and species change
- 01Origin of Species
- 01Darwin’s motivation and publication context
- 02Limits of the abstract and acknowledgments
- 03Why species are modified
- 04Planned structure of the book
- 05Concluding statement of descent and natural selection
- 01Greater variability under domestication
- 02Reproductive system and confinement
- 03Sports and bud variation
- 04Direct effects of conditions of life
- 01Direct action of conditions and habit
- 02Correlation of growth and inherited variation
- 03Inheritance, reversion, and age of appearance
- 01Reversion under unchanged conditions
- 02Domestic races compared with species
- 03Uncertain ancestry of domestic breeds
- 01Multiple origins of domestic animals
- 02Uncertain ancestry of ancient domesticated species
- 03Probable wild ancestors of dogs, cattle, poultry, ducks, and rabbits
- 01Domestic breeds and crossing limits
- 02Domestic pigeons and breed diversity
- 01Distinctive breeds and inherited variation
- 02Arguments for descent from the rock-pigeon
- 03Evidence for the origin of domestic pigeons
- 04Breeders’ belief in distinct species
- 01Accumulative selection in domestic races
- 02Breeders, horticulturists, and correlated variation
- 01Unconscious selection in breeding
- 01Origin of our Domestic Races
- 01Circumstances favourable to man’s power of selection
- 01Selection, breeding, and the formation of domestic races
- 01Variability and individual differences
- 02Polymorphic genera and doubtful species
- 01Varieties as incipient species
- 02Species, varieties, and individual differences
- 03Species that vary most
- 01Dominant species and wide-ranging varieties
- 02Larger genera and the prevalence of varieties
- 01Analogies between large genera and varieties
- 02Restricted ranges of closely allied species
- 03Consequences for the diversification of life
- 01Preliminary remarks on struggle for existence and natural selection
- 01Universal struggle for life
- 02Metaphorical meanings of struggle for existence
- 03Geometrical increase and inevitable destruction
- 04Evidence from rapid population growth
- 01Checks on population increase
- 02Food, predation, and climate as limiting factors
- 01Checks from epidemics, parasites, and crowding
- 02Interdependence of heath, firs, cattle, and insects
- 03Pollination links among bees, mice, and plants
- 01Checks acting on species numbers
- 02Competition among species and varieties
- 01Competition between allied species
- 02Organic structure and competition
- 03Seed nourishment and seedling survival
- 04Limits to population increase
- 01Competition in new countries
- 01Natural selection as preservation of favourable variations
- 02Natural selection compared with man’s selection
- 03Selection on trifling characters and correlated growth
- 01Sexual selection and male rivalry
- 02Female choice and ornamental traits in birds
- 01Wolf prey and inherited hunting habits
- 02Nectar, insect visits, and cross-fertilisation
- 03Separation of the sexes in plants
- 01Mutual adaptation of bees and flowers
- 02Natural selection as gradual accumulation
- 03Occasional cross-fertilisation in hermaphrodites
- 04Evidence from flowers, hybrids, and trees
- 01Occasional intercrossing in animals and plants
- 02Conditions that favor natural selection
- 03Isolation and large areas in species formation
- 04Large continental areas and island isolation
- 05Fresh-water basins and living fossils
- 06Summary of favourable circumstances for natural selection
- 01Extinction and the struggle for life
- 01Extinction of less competitive forms
- 02Principle of divergence in domestic breeding
- 03Diversification and the struggle for places in nature
- 04Divergent variation from a common species
- 05Extinction of intermediate and parent forms
- 06Formation of new genera and sub-genera
- 07Extinct beings and branching descent
- 08From genera to families and orders
- 09Future dominance of larger groups
- 01Natural selection and sexual selection
- 02Extinction, divergence, and affinities of organic beings
- 01Classification as a branching tree of life
- 01Effects of external conditions on variation
- 01Direct and indirect effects of climate and conditions of life
- 02Effects of use and disuse in domestic and wild animals
- 03Blindness and eye reduction in cave animals
- 01Habit and acclimatisation in plants and animals
- 02Natural selection, habit, and constitutional flexibility
- 01Correlation of growth and homologous variation
- 02Examples of correlated structures in plants and animals
- 03Misleading correlations and compensation of growth
- 01Compensation between organs
- 02Natural selection economising organisation
- 03Variation in repeated parts
- 01Rudimentary parts and variable organs
- 02Extraordinary development and high variability
- 03Domestic selection and fluctuating characters
- 01Specific characters versus generic characters
- 02Secondary sexual characters and sexual selection
- 01Analogous variations in domestic races and plants
- 02Reversion to ancestral characters in pigeons
- 03Inherited tendencies and ancestral reappearance
- 01Reversion and analogous variation in domestic breeds
- 02Striping in horses and horse hybrids
- 01Reappearance of ancient equine and pigeon characters
- 02Summary of the laws of variation
- 01Absence or rarity of transitional varieties
- 01Intermediate varieties and fossil evidence
- 02Transitions to aquatic, gliding, and flying habits
- 03Changed and diversified habits within species
- 01Organs of extreme perfection and complication
- 01Gradations in the eye and natural selection
- 02The eye compared with a telescope
- 01Conversion of organs by natural selection
- 02Neuter insects and electric organs as difficulties
- 01Electric organs as a difficulty for descent
- 02Gradual transitions and the canon of nature
- 03Organs of little apparent importance
- 01Trifling characters and natural selection
- 02Secondary causes and correlated variation
- 03Examples of apparently unimportant adaptations
- 01Structures with no direct use to their possessors
- 02Structures evolved for the good of other species
- 03Limits of perfection under natural selection
- 01Objections to the theory and missing intermediates
- 02Gradual change in habits and organs
- 03Natural selection, competition, and the laws of existence
- 01Instinct compared with habit
- 02Variation and natural selection of instincts
- 03Aphides and ants
- 01Inherited domestic instincts in dogs and other breeds
- 02Habit, selection, and the loss of natural instincts
- 03Examples for instincts in nature: cuckoo, ants, and bees
- 01Cuckoo's parasitic nesting instinct
- 02Ostrich egg-laying and shared nests
- 03Parasitic bees and wasp-like insects
- 01Formica rufescens and dependence on slaves
- 02Observations on Formica sanguinea in England
- 03Slave raids, pupae capture, and species discrimination
- 01Slave-making instinct in Formica sanguinea
- 02Hive-bee comb construction
- 01Gradation from humble-bee to hive-bee cells
- 02Geometric explanation of hive-bee comb construction
- 03Experiments with wax strips and vermilion ridges
- 04Construction of the comb wall
- 05Cooperative cell building by many bees
- 06Rough walls and hexagonal foundations
- 01Economy of wax in hive construction
- 02Natural selection and the perfect hexagonal comb
- 01Sterile females as a difficulty for natural selection
- 02Working ants and correlated differences
- 01Selection acting on the family in social insects
- 02Gradations among ant worker castes
- 01Neuter insects and division of labour
- 02Summary of instinct and natural selection
- 01Sterility of first crosses and hybrids
- 02Effects of close interbreeding on hybrid fertility
- 03Horticultural and animal hybrid experiments
- 01Sterility in first crosses and hybrids
- 02Sterility of first crosses and hybrids
- 03Sterility as an incidental result of reproductive differences
- 01Grafting and hybridisation compared
- 02Causes of sterility in first crosses
- 03Sterility of hybrids under unnatural conditions
- 04Parallel between slight changes and slight crosses
- 01Fertility of varieties under nature and domestication
- 02Cases of partial sterility in varieties
- 01Comparison of hybrids and mongrels
- 02Resemblance to parent forms and reversion
- 01Sterility of first crosses and hybrids
- 02Fertility of varieties and mongrels
- 01Intermediate varieties and the geological record
- 02The lapse of time shown by deposition and denudation
- 01Poorness of palæontological collections
- 01Fragmentary preservation of terrestrial and mammalian remains
- 02Wide time gaps between formations
- 03Why geological formations are intermittent
- 04Subsidence and fossil-rich deposits
- 05Elevation, subsidence, and missing transitional forms
- 01Why intermediate varieties are rarely preserved
- 02Species, varieties, and the difficulty of recognition
- 03Preservation of transitional gradations
- 04Malay Archipelago as an imperfect record
- 01Why transitional forms are rarely preserved
- 02Sudden appearance of allied species in formations
- 03Examples from mammals, monkeys, whales, and cirripedes
- 01Sudden appearance of allied species in the lowest fossiliferous strata
- 01Slow appearance and differing rates of species change
- 02Extinction and the nonreappearance of lost species
- 03Natural selection and uneven geological succession
- 01Gradual appearance and disappearance of groups
- 02Extinction as a gradual process
- 03Competition, rarity, and replacement of species
- 01Extinction and natural selection
- 02Parallel succession of marine life worldwide
- 03Dominant species, diffusion, and extinction
- 04Blank intervals and contemporaneous formations
- 01Parallel succession in separate regions
- 02Extinct species and living forms in one natural system
- 03Intermediate character of ancient genera and faunas
- 04Intermediate character of successive faunas
- 05Closely related fossils in consecutive formations
- 01Development of ancient forms and natural selection
- 01Succession of the same types within the same areas
- 01Extinction and modified descendants
- 02Summary of the geological record and succession
- 01Objections from the fossil record
- 02Descent with modification explains paleontology
- 01Geological succession and inheritance
- 01Physical conditions and species distribution
- 02Barriers and migration
- 01Barriers separating continents and seas
- 02Inheritance with modification across regions
- 01Single birthplace and migration of species
- 02Related species in neighboring regions
- 03Individuals descended from one pair or many
- 01Means of dispersal
- 01Occasional means of distribution
- 02Seed flotation and seawater experiments
- 01Sea currents and floating driftwood
- 02Birds, fish, and icebergs as seed carriers
- 03Limits of accidental transport
- 01Glacial-period dispersal of alpine and arctic species
- 02Earlier warm-period continuity of circumpolar land
- 03Southern migration and modification of temperate species
- + 2 more topics inside the course.
- + 2 more topics inside the course.
- + 2 more topics inside the course.
- + 2 more topics inside the course.
- + 2 more topics inside the course.
- + 3 more topics inside the course.
- + 8 more topics inside the course.
- + 3 more topics inside the course.
- + 1 more topic inside the course.
- + 2 more topics inside the course.
- + 3 more topics inside the course.
- + 1 more topic inside the course.
- + 1 more topic inside the course.
- + 2 more topics inside the course.
- + 1 more topic inside the course.
- + 3 more topics inside the course.
- + 8 more topics inside the course.
- + 3 more topics inside the course.
- + 3 more topics inside the course.
- + 5 more topics inside the course.
- + 1 more topic inside the course.
- + 2 more topics inside the course.
- + 3 more topics inside the course.
- + 2 more topics inside the course.
- + 3 more topics inside the course.
- + 4 more topics inside the course.
- + 2 more topics inside the course.
- + 3 more topics inside the course.
- + 3 more topics inside the course.
- + 3 more topics inside the course.
- + 1 more topic inside the course.
- + 9 more topics inside the course.
01How many chapters are in the On the Origin of Species course?
The On the Origin of Species course has 24 chapters, each with its own lessons and topics.
02How many lessons are in the On the Origin of Species course?
There are 128 lessons across the course, and you can ask your 24/7 tutor about any of them.
03Can I see what the On the Origin of Species course covers before I start?
Yes. The full curriculum is listed on this page, beginning with "BY MEANS OF NATURAL SELECTION, OR THE · LONDON: JOHN MURRAY, ALBEMARLE STREET.".
04Do I get a certificate for the On the Origin of Species course?
Yes. Finishing the course earns a personal Cavua certificate of completion.
Keep exploring
View all BiologyMore in Biology.
Cavua Seed Library
Experiments on Plant Hybridization
BiologyAll levels
12chapters4h 18m
This course was produced by Cavua from a public-domain text.
With membership
Or preview chapter 1 free
Updated Oct 2026
Learn with AI
Ready to start this course?
Create your account to enroll, talk to your 24/7 tutor, and track your progress — across every device.