Charles Darwin’s the Foundations of the Origin of Species Informative Summary

Overview: This volume contains two essays written by Charles Darwin in 1842 and 1844, which were the precursors to his famous Origin of Species. These essays reveal Darwin’s early development of his theory of evolution by natural selection Darwin starts by discussing variation under domestication, observing how humans have created a wide array of breeds through selective breeding. He then explores variation in a state of nature, arguing that the same principles of variation and selection apply to wild organisms. He proposes the concept of “natural selection,” where organisms with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits on to their offspring. He explores the difficulties of his theory, particularly in explaining the existence of complex organs and instincts, but argues that gradual changes over long periods of time could account for such complexity.

Key Findings:

  • Variation under Domestication: Darwin observed that domestication, which involves a change from natural conditions, often results in increased variation in organisms. This variation can be further manipulated by humans through selection, leading to the creation of diverse breeds.
  • Natural Selection: Darwin proposed that in nature, a “struggle for existence” occurs, driven by limited resources and the tendency for organisms to reproduce geometrically. This struggle favors individuals with variations that better suit them to the environment, leading to the gradual selection of those traits.
  • Species as Races: Darwin argues that species are not fixed entities, but rather “races” that have been formed naturally by a process of descent with modification through natural selection. This challenges the traditional view of species being created separately.


  • The Mechanism of Evolution: Darwin’s essays demonstrate the two key elements of his theory: variation and selection. Variation refers to the inherent differences among organisms within a species, while selection refers to the process by which some individuals are more likely to survive and reproduce based on their traits.
  • The Struggle for Existence: Darwin emphasized the ongoing struggle for resources and survival that shapes the characteristics of species. This struggle is driven by the tendency for organisms to reproduce more offspring than the environment can sustain.
  • The Imperfection of the Fossil Record: Darwin acknowledged the limitations of the fossil record and its inability to provide a complete picture of the history of life on Earth. He argued that this limitation does not invalidate his theory, but rather highlights the vastness of time and the many gaps in our understanding.

Historical Context: Darwin’s essays were written in a time of great scientific and societal change. Lyell’s theory of uniformitarianism, which proposed that the same geological processes we see today have been operating throughout Earth’s history, was a major influence on Darwin’s thinking. Darwin’s theory of evolution also challenged the prevailing view of creationism, which attributed the diversity of life to divine intervention.


  1. Variation Under Domestication: Domestication, especially when combined with excess food, increases variation in organisms. This is evident in the many breeds of domesticated plants and animals created by humans.
  2. Hereditary Tendency: Most congenital peculiarities, including slight differences in structure, are inheritable. This includes traits both beneficial and detrimental.
  3. Effects of External Conditions: Changes in the environment, such as climate, can influence variation in organisms over generations. These changes can be both direct, as in changes to external coverings, and indirect, as in altering reproductive processes.
  4. Selection is Essential: Selection is crucial for creating new races or breeds. It involves choosing individuals with desired traits and breeding them together, leading to the accumulation of those traits in offspring.
  5. Importance of Selection: Selection, both intentional and unintentional, has been practiced for centuries, leading to the creation of diverse breeds of domesticated plants and animals.
  6. The Power of Crossing: Crossing breeds can lead to the creation of new races, especially when selection is applied to the offspring. This has been particularly effective in horticulture, where cuttings and other methods allow for the rapid propagation of desirable crosses.
  7. Limited Variability: While most species can be domesticated and will vary when placed under new conditions, there are limits to the amount and kind of variation possible. These limits are influenced by factors such as health, longevity, and the laws of growth.
  8. Domestication is a Change in Conditions: Domestication can be understood as a significant shift from the natural conditions of a species. This shift can include an increase in food availability or a change in climate, which can affect both physical characteristics and reproductive processes.
  9. Natural Selection in Nature: In the wild, organisms face a “struggle for existence” due to limited resources and the tendency for populations to increase geometrically. This struggle favors individuals with advantageous variations, which are then passed on to offspring, leading to natural selection.
  10. The Struggle is Recurrent: The struggle for existence is not constant, but recurrent, with periods of intense competition during times of scarcity or environmental change.
  11. The Impact of Change: Changes in environmental conditions, especially if prolonged and in combination with limited resources, can lead to a shift in the relative proportions of species within a region, ultimately driving variation and adaptation.
  12. The Importance of Isolation: Isolation, such as on islands or due to geographic barriers, plays a critical role in the formation of new species. It allows for variations to accumulate and become distinct from the parent population.
  13. Species as True to Their Kind: The characteristic feature of a species, besides its sterility when crossed with other species, is the uniformity of its individuals. This reflects the stability and consistency of traits acquired through natural selection.
  14. Sterility is Not Universal: Sterility is not an absolute indicator of a species, as there are examples of closely related species that can interbreed, while more distantly related species may produce fertile offspring.
  15. Sterility is Linked to Constitutional Differences: The sterility of hybrids is often tied to constitutional differences between species, such as their adaptation to different climates or environments. These differences can affect the entire organism, not just specific traits.
  16. Animals in Captivity: Many animals, when removed from their natural habitats and kept in captivity, become infertile, even when well-fed and seemingly healthy. This suggests that fertility is sensitive to even subtle changes in the environment and lifestyle.
  17. Plant Sterility: Plants also exhibit sterility when removed from their natural conditions. This is not always due to poor health, but rather to specific changes in the environment, such as a change in climate or soil composition.
  18. Double Flowers and Sterility: Double flowers, a common feature in cultivated plants, may result from sterility and an excess of nutrients. This sterility can be inherited, resulting in a common and often desirable trait.
  19. The Importance of the Reproductive System: Darwin argues that the reproductive system is highly sensitive to environmental changes, both direct and indirect. This sensitivity explains why variation, sterility, and other changes often occur in the offspring of domesticated and cross-bred organisms.
  20. The Argument from Analogy: Darwin uses analogies between domesticated races and natural species to support his theory of evolution. He argues that the same processes of variation, selection, and inheritance that operate in domestication are also at play in nature.


  1. The Doubling of the Human Population: Darwin uses the fact that human population has doubled in 25 years to illustrate the immense potential for geometrical growth in organisms.
  2. The Number of Robins: Darwin calculates that a population of 8 pairs of robins, with only 4 pairs successfully raising young each year, would result in a population of 2048 robins after 7 years. This illustrates the rapid growth potential of even slow-breeding species.
  3. The Mice of La Plata: Darwin cites the extraordinary increase in mice during a period of drought in La Plata to highlight the impact of environmental changes on population size.
  4. The Number of Cabbages: Darwin mentions the existence of 1200 different varieties of cabbage to underscore the diversity of races that can be created through human selection.
  5. The “Transandantes” Sheep: Darwin cites the case of sheep in Spain that are forced to migrate annually, highlighting the inheritability of even complex habits.
  6. The Galapagos Mockingbird: Darwin notes the presence of two or three distinct species of mockingbird on different islands of the Galapagos Archipelago. This demonstrates how even in a small, isolated area, natural selection can lead to the formation of new species.
  7. The Galapagos Archipelago: Darwin emphasizes the unique fauna of the Galapagos Archipelago, which is almost entirely composed of species not found elsewhere. This demonstrates the impact of isolation on the evolution of distinct species.
  8. The Number of Extinct Mammifers: Darwin cites the numerous extinct mammifers of South America as evidence for the ongoing process of extinction and evolution.
  9. The Number of Living Species vs. Fossils: Darwin points out that we have only discovered a fraction of the species that have existed on Earth, emphasizing the incompleteness of the fossil record.
  10. The Age of the Earth: Darwin discusses the vastness of geological time, arguing that the periods between major geological formations are much longer than previously thought, making it difficult to find a complete fossil record of the transitions between species.
  11. The Time Elapsed Since the Last Ice Age: Darwin cites evidence for the long period of time that has elapsed since the last ice age, illustrating the potential for gradual change in species over millennia.
  12. The Time Required for Sediment Accumulation: Darwin emphasizes the lengthy time scales needed for sediment to accumulate and form geological formations. This further underscores the difficulty of finding complete fossil records.
  13. The Range of Species: Darwin highlights the correlation between the geographical range of a species and its longevity. Species with wider ranges tend to persist for longer periods.
  14. The Falkland Islands Horse: Darwin notes that the wild horse population in the Falkland Islands is limited by the loss of foals due to harsh conditions. This illustrates the impact of environmental factors on population stability and extinction.
  15. The Bizcacha: Darwin mentions the Bizcacha, a rodent found only on the western side of the Plata River, to demonstrate how barriers can limit the distribution of species.
  16. The Australian Bush-Turkey: Darwin cites the example of the Australian bush-turkey, which hatches its eggs using a pile of fermenting materials, to highlight how complex instincts could have evolved through gradual selection.
  17. The Species of Bees: Darwin compares the simple instincts of humble bees to the complex behavior of hive bees, suggesting a gradual progression of instinct through natural selection.


  1. Domestication: The process by which animals and plants are adapted to live with humans and be controlled by them, often involving selective breeding.
  2. Variation: Differences in traits between individuals within a species, whether caused by genetic inheritance, environmental factors, or a combination of both.
  3. Selection: The process by which certain organisms are more likely to survive and reproduce due to having advantageous traits.
  4. Natural Selection: The process of selection in nature, where the environment determines which traits are most beneficial for survival and reproduction.
  5. Race: A distinct group within a species that shares specific characteristics, often resulting from human selection.
  6. Species: A group of organisms that can interbreed and produce fertile offspring, typically considered a distinct unit in nature.
  7. Sterility: The inability to reproduce, often applied to hybrids, the offspring of different species.
  8. Hybrid: The offspring of two different species.
  9. Mongrel: The offspring of two different breeds within the same species.
  10. Instinct: A complex, unlearned behavior that is typically inherited and performed without conscious thought.


  1. The “Ancon” Sheep: A breed of sheep with a short, crooked leg, selected for its inability to jump over fences. This illustrates the power of human selection to create new breeds.
  2. The Turnspit Dog: A breed of dog specifically bred for its ability to turn a spit for roasting meat. This highlights the specialized roles that breeds can fill.
  3. Lord Western’s Sheep: The remarkable transformation of a sheep breed in a short time through careful selection, showing the effectiveness of selective breeding.
  4. The Wild-Duck: Domesticated wild-ducks often lose their natural plumage due to changes in diet and lifestyle, demonstrating the influence of environmental factors on traits.
  5. The Potato, Dahlia, and Scotch Rose: These are examples of plants that have varied significantly without any known cross-breeding, demonstrating that variation can occur within a single species.
  6. The Greyhounds: The diverse breeds of greyhounds, from the rough deerhound to the smooth Persian, illustrate the range of variation that can occur within a single species through selection.
  7. The “Transandantes” Sheep: These sheep, bred for centuries to migrate across Spain, highlight the inheritability of even complex habits and instincts.
  8. The Tailor-Bird: This bird uses threads to sew together leaves for its nest, and will use artificial threads when available. This demonstrates the adaptability and complexity of instinctive behaviors.
  9. The Australian Bush-Turkey: This bird builds a large nest of fermenting materials to incubate its eggs, showing how complex instincts can evolve through gradual selection.
  10. The Hive-Bee: The remarkable architecture and complex social structure of the hive bee exemplify the intricate and often unfathomable nature of instinctive behavior.


Darwin’s Foundations of the Origin of Species provides a fascinating glimpse into his early development of his theory of evolution by natural selection. These essays highlight the importance of variation and selection, both in domestication and in nature, and challenge the traditional view of species as fixed entities. Darwin explores the difficulties of his theory, particularly in explaining the origin of complex organs and instincts, but argues that gradual changes over long periods of time could account for such complexity. These essays, written long before the publication of his more famous Origin of Species, demonstrate the depth of Darwin’s thinking and the foundational nature of his ideas.

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