Everand Logo

Welcome to Everand!

  • Discover millions of ebooks, audiobooks, and so much more with a free trial

    Only €10,99/month after trial. Cancel anytime.

    On the Origin of Species: By Means of Natural Selection
    On the Origin of Species: By Means of Natural Selection
    On the Origin of Species: By Means of Natural Selection
    Ebook549 pages11 hours

    On the Origin of Species: By Means of Natural Selection

    By Charles Darwin

    4/5

    ()

    Read preview

    About this ebook

    "The Origin is one of the most important books ever published, and a knowledge of it should be a part of the intellectual equipment of every educated person. . . . The book will endure in future ages so long as a knowledge of science persists among mankind." — Nature
    It took Charles Darwin more than twenty years to publish this book, in part because he realized that it would ignite a firestorm of controversy. On the Origin of Species first appeared in 1859, and it remains a continuing source of conflict to this day. Even among those who reject its ideas, however, the work's impact is undeniable. In science, philosophy, and theology, this is a book that changed the world.
    In addition to its status as the focus of a dramatic turning point in scientific thought, On the Origin of Species stands as a remarkably readable study. Carefully reasoned and well-documented in its arguments, the work offers coherent views of natural selection, adaptation, the struggle for existence, survival of the fittest, and other concepts that form the foundation of modern evolutionary theory. This volume is a reprint of the critically acclaimed first edition.
    LanguageEnglish
    PublisherDover Publications
    Release dateMar 12, 2012
    ISBN9780486114828
    On the Origin of Species: By Means of Natural Selection
    Author

    Charles Darwin

    Charles Darwin (1809–1882) was an English naturalist and geologist best known for his contributions to the field of evolutionary biology. After sailing around the world on the HMS Beagle in 1831, Darwin wrote On the Origin of Species, which put forth his theory of natural selection.  

    Read more from Charles Darwin

    Related to On the Origin of Species

    Related ebooks

    Biology For You

    View More
    View More

    Related podcast episodes

    Related articles

    • Article

      Why Science Needs Metaphysics: Science can’t tell us whether science explains everything.

      Oct 1, 2015

      Technology cannot keep pace with theoretical predictions about subatomic reality coming from physics. The same applies to our ability to observe the far reaches of the universe. Theory outstrips data and can become more extravagant with the claims it

      6 min read

    • Article

      What’s Philosophy For?

      Aug 10, 2020

      What’s Philosophy For?
      4 min read

    • Article

      Our Library

      Jan 23, 2018

      The alternative of having versus being does not appeal to common sense. To have, so it would seem, is a normal function of our life: in order to live we must have things. Moreover, we must have things in order to enjoy them. In a culture in which the

      2 min read

    • Article

      Yes, Determinists, There Is Free Will

      May 16, 2019

      It’s not just in politics where otherwise smart people consistently talk past one another. People debating whether humans have free will also have this tendency. Neuroscientist and free-will skeptic Sam Harris has dueled philosopher and free-will def

      10 min read

    • Article

      3 Science Books Compellling Enough to Speak to All Readers

      Aug 30, 2017

      Bob Berman's 'Zapped,' Max Tegmark's 'Life 3.0,' and Richard Dawkins's 'Science in the Soul' succeed in turning science books into good summer reads.

      3 min read

    • Article

      Darwin’s Revolution In Thought

      Jan 4, 2023

      God created the heavens and the Earth some 6000 years ago. He filled the planet with plants and animals, and finally he created man and woman. All existing species descend from the animals that survived God’s flood aboard Noah’s Ark. That is Genesis

      3 min read

    • Article

      Charles Darwin

      Feb 28, 2020

      Charles Darwin
      7 min read

    • Article

      The Past

      Nov 4, 2021

      It was his voyage as naturalist on HMS Beagle from 1832 to 1836 and exploration of the Galapagos Islands that triggered Darwin’s early thinking and formed the foundation of his theories. The variety of species he discovered there that had adapted to

      1 min read

    • Article

      On The Origin Of Species Had Been Banned?

      Nov 4, 2021

      John is a retired science research leader at the Natural History Museum, London in marine biodiversity, ecology and evolution, and regent’s lecturer at the University of California. His book, The Fall Of Roman Britain And Why We Speak English, will b

      5 min read

    • Article

      Great Minds Think Alike

      Dec 15, 2022

      Great Minds Think Alike
      5 min read

    • Article

      Every Creeping Thing

      Mar 1, 2024

      Every Creeping Thing
      18 min read

    • Article

      Discovering The Startling Truth

      Mar 14, 2024

      Discovering The Startling Truth
      2 min read

    • Article

      The Best Panaceas for Heartaches

      Sep 22, 2017

      The Best Panaceas for Heartaches
      17 min read

    • Article

      The Rebel Issue

      Apr 8, 2024

      Greetings, Nautilus readers, and welcome to The Rebel Issue. Starting today through the end of April we’re going to bring you stories that revolve around the meaning of rebel. In our own happy rebellion against the conventions of science writing, we’

      2 min read

    • Article

      Darwin Was a Slacker and You Should Be Too

      Mar 30, 2017

      When you examine the lives of history’s most creative figures, you are immediately confronted with a paradox: They organize their lives around their work, but not their days. Figures as different as Charles Dickens, Henri Poincaré, and Ingmar Bergman

      17 min read

    • Article

      Charles Darwin 1809-1882

      Nov 26, 2020

      Charles Darwin 1809-1882
      2 min read

    • Article

      The Power Of Words

      Nov 11, 2022

      The Power Of Words
      2 min read

    • Article

      Survival Situation

      Jun 3, 2024

      In June 1860, the Oxford Natural History Museum hosted an open plenary session on a new book, The Origin of Species. Two thousand people turned up, a prizefighters’ crowd. The discussion period got seriously out of hand. The aftershocks of that day a

      3 min read

    • Article

      Alfred Russel Wallace 1823-1913

      Apr 11, 2024

      Alfred Russel Wallace 1823-1913
      2 min read

    • Article

      Charles Darwin Naturalist, Geologist, Pioneering Thinker

      Sep 10, 2020

      Charles Darwin (1809–82) was born in Shrewsbury, son of a doctor and grandson of Enlightenment thinker Erasmus Darwin. His interest in natural history having been nurtured during studies at Edinburgh and Cambridge Universities, in 1831 he sailed as n

      1 min read

    • Article

      Next Generation

      Nov 22, 2024

      Next Generation
      3 min read

    • Article

      Big Beasts Versus The Bible

      Apr 25, 2024

      Big Beasts Versus The Bible
      4 min read

    • Article

      A Prescription for Awe: In the debate between religion and science, wonder is what the doctor ordered.

      Dec 15, 2016

      Heads down, we plodded along a coastal path into an almost gale-force wind that came howling straight up the English Channel, driving the rain into our faces and making it hard to steal more than an occasional glance ahead of us to the west. Somewher

      14 min read

    Related categories

    Reviews for On the Origin of Species

    4/5

    1,350 ratings24 reviews

    What did you think?

    Tap to rate

    Review must be at least 10 words

    • 5/5
      This isn't a book you'd read for fun, but for understanding and enrichment. Personally, I found it edifying to understand Darwin's thinking. In his younger days, he had traveled much of the world, and was primarily employed in collecting specimens from each region he visited. Over the years, he connected with farmers to discuss how different plants and animals were bred for certain traits. He catalogued the variations in species he would find in different areas having different "conditions of life". He studied and experimented as to how seeds, eggs, larvae, and adult creatures could travel from one place to another. He looked into the geological record and the fossil remains of creatures now extinct. He studies the embryos of plants and animals, and found that embryos of creatures of the same class had the same appearance and features, regardless of how different these creatures came to appear as adults. From a lifetime's study of all these factors, he came up with a unified theory of natural selection. In brief, that a creature's offspring will vary minutely in each generation, and that these miniscule variations give advantages to some and disadvantages to others. The most successful of these variations are passed on.
    • 5/5
      Important foundation for knowledge. An interesting read for me the summer after 8th grade.
    • 3/5
      I enjoyed reading the book that is the foundation of evolutionary biology, and it's fascinating to see what we used to believe and how far we've come.
    • 4/5
      Example after example for the explanation of life and how it has evolved. From plants to animals and everything in between. How climate and geography plays a role in the evolutionary process. He goes into many details that can be lengthy but overall a good representation of different species and their origin.
    • 4/5
      Facsimile of first edition, with "An Historical Sketch" and "Glossary" from sixth edition.
    • 4/5
      A handsome boxed cover edition by the Heritage Press of one of the landmark works of science. I read the book in college and while now I remember only the broad outlines of Darwin's ideas, I was impressed with the clarity of his presentation of the evidence and the theory that arose from it. I have this book already in an earlier 1906 edition. I just couldn't resist this edition I found at an estate sale, because of the lovely wood engravings throughout the book by Paul Landacre. He is a favorite artist of mine; his "Sultry Day" print hangs in my living room.
    • 5/5
      OK, so maybe the book is a difficult read, as many Victorian books are. The language may strike a modern reader as a bit arcane, and the sheer length and breadth of the work may be staggering to those used to getting their information in short, pithy bits. Still, let's be honest. This is THE ORIGIN OF SPECIES, and it completely revolutionized biology, so I think the least one can do is give it 5 stars (since that is all that's allowable). To anyone who really reads this book, it should be impossible to continue to parrot the popular canard that there is no evidence for evolution. In the days before DNA, and when hominid fossils were still fairly sparse, and we knew very little about the microscopic world, Darwin was able to compile an impressive array of evidence, most of it while sitting in his own library at Down House in England. This book is rightly considered a classic, not just for its style, but for its substance.
    • 5/5
      It's been criticized as unscientific, evil, and dry. I found it quite impressive. Though there are places where the detail might be too much for the casual reader, it is a very solid scientific work. He presents a hypothesis, shows significant supporting evidence, and defends it against the most common criticisms. It is not possible to prove that everything started from something simpler but it is now hard to refute that the natural process of natural selection is working on today's species. He leads his argument by showing the effectiveness that domestic breeders have achieved in altering species and guiding that process. Other highlights either new to me or especially interesting: the uniformity gained by consistent inter-crossing, the underlying ability of genetics to allow breakthrough changes and yet also to maintain uniformity, the complexity of larger areas in producing stronger more adaptable species, the effect of geographic changes (elevation, land forms, glaciers) on migration of living species and archival of fossil record, that fossils tend only to be saved during subsidence so only that direction of change is recorded, the species do not reappear once extinct (this seems to be in refutation of Lamarck), the phrase "grain in balance" to show the impact of small differences in the competition for survival, that it is the other species more than anything that determines a given organisms ability to survive in an area. Imagine his chart demonstrating how branching might work if he had had a PC at the time.
    • 3/5
      evolution has gone through many changes since darwin's original writing, but it is always good to go back to the source. darwin may not have been the first person to conceive of evolution, but he was the first to delineate it in such a complete form.
    • 2/5
      Quite stunning in its way - but surely in need of an update in the light of genetics, DNA and plate techtonics. Not that the conclusions need to be changed, just that te argument becomes easier. That said, in the absence of knowledge on those points: that's what makes for the stunning.
    • 5/5
      I'm super glad to read this book - it was really enjoyable!One of the things I was struck by Darwin's writing was that it was eminently readable and was basically constructed as an essay with a prodigious amount of evidence lined up to back up the arguments made. I am impressed by his clarity in articulation that make his communication and message conveyable despite requisite nuance.The heart of this particular book is that animals and plants vary - that they are mutable over time via human control (i.e. breeding) but also do so naturally, and that selection pressures are the mechanism, and that over time variability, heredity, and selection are the underlying principles of evolution.It was quite clear that he was conscious of possible detractors - on both scientific and creationist grounds. And he readily admits that readers who simply are not already convinced of things like the vast age of the earth etc. are just not going to agree because of things like the imperfection of the geological record (which is still true, though some gaps have since been filled). This is still true today even with the accumulated knowledge of paleontology and geology due to (willful?) ignorance and/or disbelief regarding how fossils and rocks are aged.Aside from the assembly, synthesis, and description of a vast array of fascinating facts and evidence, was the ability to put forth a complicated argument fairly succinctly and then address potential detractions head on. What surprised me was that some of the things that he addressed were *still* being used as arguments against evolution of species via natural selection! For example I heard arguments by some espousing Intelligent Design talking about how the eye was something too complicated to have arisen or be selected for -- but Darwin addressed this fairly well (I thought!), noting several species that either had intermediate forms or uses for eyes and light sensitivity. The point being that for all the recent hubabaloo, we appear to be going around the same merry-go-round back and forth regarding whether or not we buy into this explanation of the natural world, without making much progress over the course of a century and a half.If you feel at all invested in the argument over evolution one way or the other, my feeling is that it's at least worth reading Darwin's original works rather than getting into a lather about bullet points that are only a poor shadow of their context.
    • 5/5
      Fantastic book.

      chapter 13 was probably my favorite chapter. Thats where everything comes to a head and he brings up the similarities between different species as well as vestigial organs and how it could have served previous generations but be rendered useless or redundant now.

      It was impressive that he noticed and brought up several things that would later be fully explained by science.

      One such thing was linked genes. When talking about pigeons he mentioned that beak size and foot size would always be correlated. He admits hes not sure why but in all cases with pigeon breeding if you have a small beak you have tiny feet.

      As an interesting note: he never brings up the finches. Ever. He hardly ever mentions the Galapagos. Mostly that he visited it and it had a small highly specialized group of species.

      For the most part he talks about fancy pigeons. So if you want an easier time reading the book go look up fancy pigeons, look at all the different breeds of domestic pigeons, memorize them, then read the book. Trust me he brings them up a lot.
    • 4/5
      It is only fair that I divide my review into two parts: Writing and Content:Writing: Darwin is obviously writing from a different century. With complex syntax and extensive vocabulary, both scientific and non, his writing is dense, convoluted and so very boring. Even if one makes allowances for the difference in writing styles, I still find his writing to drag on and on. Darwin stated he wrote this work for the masses, and I grant that he gave it a valiant effort, however much he failed.Content: Brilliant. From someone who was raised (and remains) a believer in Creationism, I have to say his work is logical, scientific, and well-thought out. He answered well many of the main arguments against his ideas. He mentioned many experiments conducted to further study his findings, and mentioned many works by contemporary naturalist that he drew on to reach his conclusion. As someone trained in the sciences, this does much to improve my thoughts about his ideas. Despite what many people say - Evolutionist and Creationist alike - Darwin's work is factual and logical, and demands serious consideration from anyone claiming to want to know the truth. While I have not reconciled my belief in a creator-God and the evidence of evolution, reading Darwin is a start for me and I recommend it as a start for anyone wishing to find the truth.
    • 2/5
      I marked this as 'Read' which isn't wholly true. If there was a 'Kinda, Sorta, Read' button I would have clicked that. Wow, I'm in awe of anyone who did read this cover to cover. Kudos to you, kudos to you.
    • 5/5
      On the Origin of Species is one of the most influential and fact-proven books of all-time. Unfortunately, some people don't think so and want to discredit Charles Darwin's work. However, facts and reason will prevail.
    • 2/5
      The journey of Charles Darwin on the H.M.S. Beagle and his reports, discoveries and observations relating to natural science and evolution. Fairly interesting for a book on science even though it is rather dated. The stir it caused in the mid 1800s no longer carries the same groundbreaking impact.
    • 2/5
      I'm an enthusiast of evolutionary biology and I appreciate Darwin's enormous contribution to our understanding of the natural world. But somehow the Origin of Species wasn't very interesting to read. Maybe it's because most of what Darwin says has so thoroughly diffused itself into modern science that there's little new to find here.
    • 4/5
      It's amazing to me how much Darwin got right in this book, and also all that he got wrong.
    • 4/5
      I recommend reading of this book because of the importance of it. When Charles Darwin published this in 1859 it rocked the English speaking world. Up to that point the religious idea of creation was unquestionably accepted. Religion held a lot of power over people and their lives. Then this book came out, and it put into question all that the English world held dear about God and creation. I don't know if any piece of literature has had such a profound affect on society and its beliefs. When I read it, I thought that it might be boring because of the scope of the work, but it's actually not boring because it's simply and plainly written. Remember the whole theory of evolution originated from this one work.
    • 1/5
      Boring and stupid.
    • 4/5
      Rating this was not easy. I think this book is a 5 star for importance however this was a tough book to trudge through. I listened to it on audio and I don't think I could have finished it otherwise.
    • 3/5
      What ages would I recommend it too? – Ten and up.

      Length? – Several days to read.

      Characters? – No.

      Setting? – Real World 1858 and previous

      Written approximately? – reprint 1958.

      Does the story leave questions in the readers mind? – Ready to read more.

      Any issues the author (or a more recent publisher) should cover? A little clean up. Wouldn't it be nice to highlight and announce new findings either for, or against, his ideas?

      Short storyline: The original "The Origin of Species" in full detail.

      Notes for the reader: In almost every chapter, he says he doesn't have room to go into detail. And yet, this is thoroughly indepth. Maybe a bit much. Some things he said almost 200 years ago have only recently been proven by science.

      For low vision readers - Not an easy read. Microscopic font on tiny pages.
    • 3/5
      In 1831, naturalist and geologist Charles Darwin joined the Beagle expedition to Tierra del Fuego. What he observed when he got to the new world would eventually lead him to formulate his theory of natural selection. Published in 1859, “On the Origin of the Species” is the controversial classic that revolutionized natural science and altered our understanding of the world.
    • 4/5
      On the Origin of Species by Charles Darwin (free at Project Gutenberg).
      Drawing from my own reading library, this book a little like Adam Smith's Wealth of Nations in that the author is taking personal observations and anecdotes and developing a broader hypothesis as to how things work and how we got to where we are today. Many of the anecdotal observations and hypotheses have since been proven as false or mistaken, and we now know more about what was observed than the author possibly could have at the time, but the broader implications and the core of the central hypothesis remain intact.

      Darwin spends early part of the book discussing the difference between variations and species. Modern biological classification had not been completely developed at the time of publication. Genealogy was basically undeveloped, or is perhaps not Darwin's strong suit. His religious detractors at the time argued that species were immutable and that the geological record was perfect-- everything that could be known about the history of the earth was essentially already evident. I do not know how widespread the belief was at that time, but creation scientists today acknowledge mass migration, extinction, and "macroevolution," that from one species or phylum can come many different varieties.

      In Chapter 5, Darwin opines on why zebras have stripes in a greater context of how unique traits evolve in offspring and how offspring sometimes revert to the characteristics of their predecessors. There was no agreed-upon model of heredity back then. Scientists are still determining why zebras have stripes.

      Chapters 6 and 7 are interesting as Darwin pivots to address possible criticims of his theory of natural selection. development of organs and the imperfections in the fossil record. He admits that it's hard to believe that something as incredibly complex as the eye developed gradually, but contends that it is not impossible. He contends that whale's lungs developed from an organ that was originally a swim bladder. Since vertebrates have lungs, we must have all evolved from organisms that had swim bladders-- ie: sea-dwelling creatures:

      "The illustration of the swim bladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one purpose, namely, flotation, may be converted into one for a widely different purpose, namely, respiration. The swim bladder has, also, been worked in as an accessory to the auditory organs of certain fishes. All physiologists admit that the swimbladder is homologous, or “ideally similar” in position and structure with the lungs of the higher vertebrate animals: hence there is no reason to doubt that the swim bladder has actually been converted into lungs, or an organ used exclusively for respiration. According to this view it may be inferred that all vertebrate animals with true lungs are descended by ordinary generation from an ancient and unknown prototype, which was furnished with a floating apparatus or swim bladder."



      In Chapter 7 Darwin writes that one discovery that would demolish Darwin's theory is if altruistic behavior were to be found in an organism-- if one species acted simply to benefit another. This would be impossible under natural selection since each species has developed by focusing on adapting solely on its own survival in the "battle for life." Some have purported that the behavior of one type of ant which serves as a slave to another type are an example of this. Darwin maintains that the enslaved variety is smaller and weaker, and kept alive by their masters due to their usefulness, and therefore acceptance of the slavery is necessary to their survival.

      One wonders, however, at the symbiotic relationships of many species. For example, I read an article recently about how botanists researching fungi have changed their belief in their relationship with trees:

      “The new theory pictures a more business-like relationship among multiple buyers and sellers connected in a network,” Franklin said in a press release. Instead of being a cooperative trade of carbon and nitrogen between organisms, trees are forced to export large amounts of carbon in order to unlock nitrogen stores from the fungi."


      The fact that mating behavior-- taking two to create offspring-- has evolved among so many species would seem to be problematic to natural selection. Wouldn't it be more efficient for survival if one could reproduce asexually with a relatively small gestation time? Why haven't the majority of species evolved that way? It seems that there are benefits to mating beyond reproduction. There is strength in symbiotic communal behavior, as Darwin gives the example of ants and hive bees. Since this behavior is so widespread, one can deduce that it is closer to the "perfection" eventually achieved by natural selection relative to the lower-order ancestors' way of producing.

      In Chapter 9 and onward, Darwin deals with the imperfection of the fossil record. We are missing transitional forms at every level to verify his theory. In some layers or time periods, species appear which do not appear in the previous time period. This would seem to suggest creation rather than systematic evolution. Darwin's response to such a criticism is :

      On this doctrine of the extermination of an infinitude of connecting links, between the living and extinct inhabitants of the world, and at each successive period between the extinct and still older species, why is not every geological formation charged with such links? Why does not every collection of fossil remains afford plain evidence of the gradation and mutation of the forms of life? Although geological research has undoubtedly revealed the former existence of many links, bringing numerous forms of life much closer together, it does not yield the infinitely many fine gradations between past and present species required on the theory, and this is the most obvious of the many objections which may be urged against it. Why, again, do whole groups of allied species appear, though this appearance is often false, to have come in suddenly on the successive geological stages? Although we now know that organic beings appeared on this globe, at a period incalculably remote, long before the lowest bed of the Cambrian system was deposited, why do we not find beneath this system great piles of strata stored with the remains of the progenitors of the Cambrian fossils? For on the theory, such strata must somewhere have been deposited at these ancient and utterly unknown epochs of the world's history. I can answer these questions and objections only on the supposition that the geological record is far more imperfect than most geologists believe.


      Much has been undiscovered, much may lay under the oceans, and many layers may be compressed due to constantly having more sediment deposited.


      Darwin concludes:

      "Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited, they seem to me to become ennobled... There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone circling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved."


      Darwin's arguments still did not answer the question for me as to how the eye and other organs developed. How did the original cells know that that there were light and sound waves from which information could be gleaned if a complex structure were developed to capture it?

      Darwin either does not think about or chooses not to write about the ethical implications of his work. If we are not made in the image of God, do we have inalienable rights? Why should there be consequences if one murders another? The natural order is always engaged in a "struggle for life," and the end result is that it is leading us toward evolutionary "perfection." But what aspects of our society and behavior are evolutionary artifacts that will eventually die out and which are essential for our survival?

      I give this book 4 stars out of 5. Everyone should read it as it's a classic, definitely one of the most influential books on the 19th, 20th, and 21st centuries. I plan to read Michael Behe's Darwin's Black Box before the end of the year.

      On another note, I listened to this book on the freely-available audio files on Gutenberg. The text was read by a computer, each chapter alternated between a male and a female voice. This made it hard to listen to at my usual 2X speed as the cadence was a bit...unnatural...and some of the pronunciations were butchered. But I found it definitely doable.

    Book preview

    On the Origin of Species - Charles Darwin

    Introduction to the Dover Edition

    FROM THE point of view of modern intellectual life and culture, On the Origin of Species is one of the most important scientific books of all time. It evoked a storm of controversy when it was first published and initiated a revolution in our thinking that continues to this very day. The book deserves to be more widely read, and better understood. This reprint of the 1859 first edition will help make it more accessible. Although it was originally addressed to the scholarly community and not to the general public, On the Origin of Species was nevertheless a best-seller, partly because it was written in plain English by an author who realized that the subject matter was difficult and who earnestly wanted to be understood. Because of Darwin’s clear, jargon-free style, the modern reader will find the book both accessible and comprehensible. Nevertheless, today’s readers may well benefit from a little background material on Darwin and his great work.

    Charles Darwin was born on February 12, 1809, and died on April 19, 1882. His father was a wealthy physician, and his mother was the daughter of a major industrialist, Josiah Wedgwood. His grandfather, Erasmus Darwin (1731–1802), was one of the very few scientists who argued in favor of evolutionary or proto-evolutionary ideas before the publication of On the Origin of Species. He published views similar to those later put forth by the famous (or infamous) French naturalist Lamarck (1744–1829). When the young Darwin studied medicine at Edinburgh University and later prepared for the ministry at Cambridge, he became familiar with such notions but did not accept them. He considered such ideas subversive, and the arguments unconvincing.

    In 1831, Darwin won a berth as unofficial naturalist and companion to Captain Fitzroy of H.M.S. Beagle during the ship’s five-year voyage around the world. Although he was only in his early twenties, Darwin’s observations in the Galapagos Islands, South America and other places visited by the Beagle enabled him to make major contributions to geology as well as to the understanding of the geographical distribution of plants and animals. His observations of the appearance and behavior of different plant and animal species, notably the finches of the Galapagos, convinced him to consider the possibility of evolution. When he got back to England it became clear to him, from his observations and the study of his specimens, that evolution was a fact. However, there was no plausible mechanism for it, and it was not until 1838 that he discovered one, which he called natural selection. However, he kept his discovery to himself and a few close friends and colleagues for the next twenty years. The reasons for the long delay in publication are not a simple matter to explain. Among other things, Darwin suffered from mysterious ailments that hindered his ability to do research, ailments often exacerbated by stress. In spite of his physical frailties, however, Darwin published major books on geology, and a massive treatise on barnacles. These technical works established him as one of the leading scientists of his day. He was also widely known for his firsthand account of the Beagle’s voyage, a book long prized for its literary, as well as scientific, merit.

    Around 1855 Darwin began work on a book intended to explain his evolutionary theory in minute detail, with massive documentation. Then, in 1858, Alfred Russel Wallace, with whom Darwin had been in communication, sent him a manuscript presenting the same basic theory. A joint publication was soon in print. At this point, Darwin gave up on the long book he had planned, and wrote instead a much briefer one, entitled On the Origin of Species. An immediate best-seller, the work appeared in six editions during Darwin’s lifetime. Each edition was extensively revised and in each Darwin took the opportunity to respond to criticisms. However, the first edition is in many ways better for the modern reader, for the arguments with his contemporaries tend to distract the reader’s attention from Darwin’s basic line of reasoning. In addition to On the Origin of Species he also published a series of books on a variety of topics, all of them with evolution as a theme.

    In his work, Darwin endeavored to show both that evolution has in fact occurred and that natural selection has been the main, if not the exclusive, cause of the process. He especially wished to show that descent with modification provided a much better explanation for the facts of biology and geology than the vague creationist notions that were still popular, and he carefully crafted his arguments with that end in mind. The mechanism he proposed was also fully in line with the kind of naturalism that leaves God completely out of the picture, without necessarily denying His existence. Darwin’s scientific colleagues were generally won over to his theory of evolution within ten years, however, alternative explanations to natural selection remained popular until around 1950. These alternative mechanisms were popular largely because they fitted in with political philosophies, though religion had much to do with it as well.

    Although it is a familiar notion now, the very idea of natural selection was so novel that a major task for Darwin in writing On the Origin of Species was just to explain how the mechanism operated. The title of the book ends in a sort of definition of the term (The Preservation of Favoured Races in the Struggle for Life), which is sometimes mistaken for a subtitle, but Darwin’s real task was to show how evolution by natural selection provides legitimate scientific explanations for facts that are otherwise inexplicable. Implicitly or explicitly, much of his argument was directed against the creationism that existed at the time, which left all sorts of phenomena unintelligible in scientific terms.

    Darwin’s reasoning provides a good example of the so-called hypothetico-deductive scientific method in action. His statements toward the front of the book about having patiently collected facts and then having allowed himself to speculate are quite misleading. Actually he used his imagination as well as earlier experience to come up with what seemed plausible conjectures, or hypotheses, and then proceeded to test them by seeing how well they could predict, or explain, the relevant data. He went out of his way to specify the kinds of observations that would refute his hypotheses, and showed that the predictions were often quite unexpected.

    What Darwin called artificial selection provided an analogy that made it easier to explain natural selection to his readers. Domesticated plants and animals were well known to have been considerably modified. These organisms are quite heterogeneous, i.e. they vary. A breeder who wants to create a dwarf breed of chickens selects the smallest individuals in the flock and makes them the parents of the next generation. Thus, Darwin shows that organisms in general are highly variable, and that artificial selection has indeed proven effective in producing useful variants in agriculture. Such artificial selection establishes the plausibility of selection mechanisms in general. It does not, however, suffice to show that selection can produce enough change to give rise to a new species. Indeed, it was generally assumed that such modification is definitely limited. To overcome that difficulty it was important to show that the difference between species and varieties is only a matter of degree.

    In natural selection there is no breeder. Rather, the kind of variant organism that sires the next generation depends upon environmental circumstances. Viewing the natural economy as something fundamentally competitive was a major innovation on Darwin’s part, much of the inspiration for which he owed to early political economists, especially Malthus. In a sense, Darwin thereby invented modern ecology. In the natural world there is reproductive competition between organisms of the same species. Those who have what it takes to outcompete the others are like the ones selected by the breeder in artificial selection. The nature of artificial selection allows for parental care and such alliances as families, but unlike natural selection, the organisms do not evolve adaptations that exist for the good of the species, much less for the welfare of nature as a whole. The lack of such adaptations among artificially selected species, and their presence among naturally selected varieties provided strong confirmation of Darwin’s theory. Furthermore, competitive success means not only surviving, but reproducing. The existence of a third kind of selection, which Darwin called sexual selection, provided him with a compelling argument for the importance of sexual selection as a driving force of evolution. Peacocks succeed reproductively by winning a kind of beauty contest, in which females select the most attractive males. This explanation for the existence of such otherwise useless features undermined the creationist assumption that the world had been intelligently designed.

    Competition on a grander scale explained the phenomena of extinction and diversification through time. The original forms are squeezed out by the modified ones, which occupy an increasing diversity of niches (places in the economy of nature). Darwin provides a tree-like diagram showing how this happens, with lineages repeatedly splitting up and becoming increasingly different. This tree-like view of evolution was quite different from that of Lamarck, who looked upon it as a matter of separate lineages proceeding from simple to complex. Darwin also rejected Lamarck’s vague notion of a law of progress. However, Darwin recognized that progress is a real phenomenon and showed how natural selection can explain it when it does occur.

    Darwin’s chapter on the laws of variation takes the position that the origin of variations (we now call them mutations) is an orderly affair, and that treating variations as a matter of chance is to misconstrue what really goes on. For Darwin, what actually evolves are the developmental processes that give rise to the fully formed organism. Although he owed much to his French predecessors Étienne and Isidore Geoffroy Saint-Hilaire, for this insight, Darwin was the first to study evolution from that developmental point of view, which became fashionable again as evo-devo, beginning in the 1980s.

    In developing and defending his thesis, Darwin considered a number of features that might at first seem difficult to account for by means of gradual transformation through natural selection. One of these difficult features was a complex structure like the vertebrate eye. Through his study of fossils and living specimens, Darwin was able to show that it was possible for even an exquisitely sensitive organ such as the eye to evolve over the course of millions of years of vertebrate evolution. The result of these and other arguments was that Darwin provided evidence that his theory could withstand serious efforts at refutation, but that he stood ready to modify the theory if there were real evidence against it. The chapter on instincts provides further examples. It includes adaptations in sterile castes of colonial insects, which of course do not reproduce. Their relatives do reproduce, however, and the unit that gets selected may be the entire family, rather than the individual organism.

    The imperfection of the fossil record was a serious obstacle to evolution in Darwin’s day, since there was a dearth of fossils detailing ancestral and transitional forms. Darwin not only acknowledged this difficulty, but gave compelling arguments for thinking that the fossil record was even more fragmentary than had been thought. In spite of the lack of fossil evidence in Darwin’s day, however, his theory has been borne out by later experience as paleontologists have continued filling in the gaps. Biogeography, on the other hand, was the most compelling evidence in favor of evolution at the time. Indeed, it still is. According to Darwin’s branching model of evolution, species originated within a limited area, and gradually diversified and moved elsewhere. The organisms’ mobility has been limited by barriers. What constitutes a barrier depends upon the kind of organism. Putting the two together allowed Darwin to predict general patterns of biogeography, and thereby test his hypothesis of common descent. Islands, including the Galapagos and New Zealand, which he had visited during his journey around the world, provided crucial evidence. Insular faunas tend to be relatively rich in birds, which can get there by flying. But they have disproportionately fewer amphibians and terrestrial mammals.

    Darwin then proceeded to make evolutionary sense out of the systems of classification that existed at the time. Animals and plants had been arranged in systems of groups within groups. But why was this possible? Darwin proposed that each group was descended from a common ancestor, and the larger groups had a remoter common ancestry than the smaller ones of which they were composed. Classification was, or at least could be, a genealogy. Groups of animals and plants had often been characterized by saying that there was a unity of type or a common plan for their anatomy, with variations upon a common theme. Some of Darwin’s predecessors had maintained that there really is a plan—a kind of idea in the mind of God. This was Platonism and Darwin rejected such philosophy, maintaining instead that the groups share a common ancestor. Comparative embryologists had observed that during the course of development animals start out very much alike, and become increasingly divergent as they get older. Darwin argued that development itself has evolved, under the influence of natural selection. Likewise rudimentary organs, or ones that are imperfect and useless, although once quite useful, are on the way out.

    After recapitulating his main arguments, Darwin made some predictions about the future of science. It was an appeal to his fellow scientists, for whom there were splendid opportunities for new research. But the prospects for innovation and discovery went far beyond the limits of biology and geology. He provided a single sentence about the human species: Light will be thrown on the origin of man and his history. This magnificent understatement did not pass unnoticed by his readers. At the very end of the book Darwin waxes poetic. He suggests a grand vision of the living world, and implicitly compares his accomplishment with that of Newton. The comparison seems apt, for thanks to Darwin, life could now be explained by a combination of the laws of nature and historical circumstances, and without recourse to the supernatural.

    Michael T. Ghiselin

    Introduction

    WHEN ON board H.M.S. ‘Beagle,’ as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years’ work I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions, which then seemed to me probable: from that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.

    My work is now nearly finished; but as it will take me two or three more years to complete it, and as my health is far from strong, I have been urged to publish this Abstract. I have more especially been induced to do this, as Mr. Wallace, who is now studying the natural history of the Malay archipelago, has arrived at almost exactly the same general conclusions that I have on the origin of species. Last year he sent to me a memoir on this subject, with a request that I would forward it to Sir Charles Lyell, who sent it to the Linnean Society, and it is published in the third volume of the Journal of that Society. Sir C. Lyell and Dr. Hooker, who both knew of my work—the latter having read my sketch of 1844—honoured me by thinking it advisable to publish, with Mr. Wallace’s excellent memoir, some brief extracts from my manuscripts.

    This Abstract, which I now publish, must necessarily be imperfect. I cannot here give references and authorities for my several statements; and I must trust to the reader reposing some confidence in my accuracy. No doubt errors will have crept in, though I hope I have always been cautious in trusting to good authorities alone. I can here give only the general conclusions at which I have arrived, with a few facts in illustration, but which, I hope, in most cases will suffice. No one can feel more sensible than I do of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded; and I hope in a future work to do this. For I am well aware that scarcely a single point is discussed in this volume on which facts cannot be adduced, often apparently leading to conclusions directly opposite to those at which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question; and this cannot possibly be here done.

    I much regret that want of space prevents my having the satisfaction of acknowledging the generous assistance which I have received from very many naturalists, some of them personally unknown to me. I cannot, however, let this opportunity pass without expressing my deep obligations to Dr. Hooker, who for the last fifteen years has aided me in every possible way by his large stores of knowledge and his excellent judgment.

    In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which most justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, etc., as the only possible cause of variation. In one very limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the misseltoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself.

    The author of the ‘Vestiges of Creation’ would, I presume, say that, after a certain unknown number of generations, some bird had given birth to a woodpecker, and some plant to the misseltoe, and that these had been produced perfect as we now see them; but this assumption seems to me to be no explanation, for it leaves the case of the coadapta-tions of organic beings to each other and to their physical conditions of life, untouched and unexplained.

    It is, therefore, of the highest importance to gain a clear insight into the means of modification and coadaptation. At the commencement of my observations it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, although they have been very commonly neglected by naturalists.

    From these considerations, I shall devote the first chapter of this Abstract to Variation under Domestication. We shall thus see that a large amount of hereditary modification is at least possible; and, what is equally or more important, we shall see how great is the power of man in accumulating by his Selection successive slight variations. I will then pass on to the variability of species in a state of nature; but I shall, unfortunately, be compelled to treat this subject far too briefly, as it can be treated properly only by giving long catalogues of facts. We shall, however, be enabled to discuss what circumstances are most favourable to variation. In the next chapter the Struggle for Existence amongst all organic beings throughout the world, which inevitably follows from their high geometrical powers of increase, will be treated of. This is the doctrine of Malthus, applied to the whole animal and vegetable kingdoms. As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.

    This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character. In the next chapter I shall discuss the complex and little known laws of variation and of correlation of growth. In the four succeeding chapters, the most apparent and gravest difficulties on the theory will be given: namely, first, the difficulties of transitions, or in understanding how a simple being or a simple organ can be changed and perfected into a highly developed being or elaborately constructed organ; secondly, the subject of Instinct, or the mental powers of animals; thirdly, Hybridism, or the infertility of species and the fertility of varieties when intercrossed; and fourthly, the imperfection of the Geological Record. In the next chapter I shall consider the geological succession of organic beings throughout time; in the eleventh and twelfth, their geographical distribution throughout space; in the thirteenth, their classification or mutual affinities, both when mature and in an embryonic condition. In the last chapter I shall give a brief recapitulation of the whole work, and a few concluding remarks.

    No one ought to feel surprise at much remaining as yet unexplained in regard to the origin of species and varieties, if he makes due allowance for our profound ignorance in regard to the mutual relations of all the beings which live around us. Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare, and, as I believe, the future success and modification of every inhabitant of this world. Still less do we know of the mutual relations of the innumerable inhabitants of the world during the many past geological epochs in its history. Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained—namely, that each species has been independently created—is erroneous. I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that Natural Selection has been the main but not exclusive means of modification.

    CHAPTER I.

    VARIATION UNDER DOMESTICATION.

    Causes of Variability—Effects of Habit—Correlation of Growth—Inheritance—Character of Domestic Varieties—Difficulty of distinguishing between Varieties and Species—Origin of Domestic Varieties from one or more Species—Domestic Pigeons, their Differences and Origin—Principle of Selection anciently followed, its Effects—Methodical and Unconscious Selection—Unknown Origin of our Domestic Productions—Circumstances favourable to Man’s power of Selection.

    WHEN WE look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ much more from each other, than do the individuals of any one species or variety in a state of nature. When we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, I think we are driven to conclude that this greater variability is simply due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have been exposed under nature. There is, also, I think, some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organisation has once begun to vary, it generally continues to vary for many generations. No case is on record of a variable being ceasing to be variable under cultivation. Our oldest cultivated plants, such as wheat, still often yield new varieties: our oldest domesticated animals are still capable of rapid improvement or modification.

    It has been disputed at what period of life the causes of variability, whatever they may be, generally act; whether during the early or late period of development of the embryo, or at the instant of conception. Geoffroy St. Hilaire’s experiments show that unnatural treatment of the embryo causes monstrosities; and monstrosities cannot be separated by any clear line of distinction from mere variations. But I am strongly inclined to suspect that the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception. Several reasons make me believe in this; but the chief one is the remarkable effect which confinement or cultivation has on the functions of the reproductive system; this system appearing to be far more susceptible than any other part of the organisation, to the action of any change in the conditions of life. Nothing is more easy than to tame an animal, and few things more difficult than to get it to breed freely under confinement, even in the many cases when the male and female unite. How many animals there are which will not breed, though living long under not very close confinement in their native country! This is generally attributed to vitiated instincts; but how many cultivated plants display the utmost vigour, and yet rarely or never seed! In some few such cases it has been found out that very trifling changes, such as a little more or less water at some particular period of growth, will determine whether or not the plant sets a seed. I cannot here enter on the copious details which I have collected on this curious subject; but to show how singular the laws are which determine the reproduction of animals under confinement, I may just mention that carnivorous animals, even from the tropics, breed in this country pretty freely under confinement, with the exception of the plantigrades or bear family; whereas, carnivorous birds, with the rarest exceptions, hardly ever lay fertile eggs. Many exotic plants have pollen utterly worthless, in the same exact condition as in the most sterile hybrids. When, on the one hand, we see domesticated animals and plants, though often weak and sickly, yet breeding quite freely under confinement; and when, on the other hand, we see individuals, though taken young from a state of nature, perfectly tamed, long-lived, and healthy (of which I could give numerous instances), yet having their reproductive system so seriously affected by unperceived causes as to fail in acting, we need not be surprised at this system, when it does act under confinement, acting not quite regularly, and producing offspring not perfectly like their parents or variable.

    Sterility has been said to be the bane of horticulture; but on this view we owe variability to the same cause which produces sterility; and variability is the source of all the choicest productions of the garden. I may add, that as some organisms will breed most freely under the most unnatural conditions (for instance, the rabbit and ferret kept in hutches), showing that their reproductive system has not been thus affected; so will some animals and plants withstand domestication or cultivation, and vary very slightly—perhaps hardly more than in a state of nature.

    A long list could easily be given of sporting plants; by this term gardeners mean a single bud or offset, which suddenly assumes a new and sometimes very different character from that of the rest of the plant. Such buds can be propagated by grafting, etc., and sometimes by seed. These sports are extremely rare under nature, but far from rare under cultivation; and in this case we see that the treatment of the parent has affected a bud or offset, and not the ovules or pollen. But it is the opinion of most physiologists that there is no essential difference between a bud and an ovule in their earliest stages of formation; so that, in fact, sports support my view, that variability may be largely attributed to the ovules or pollen, or to both, having been affected by the treatment of the parent prior to the act of conception. These cases anyhow show that variation is not necessarily connected, as some authors have supposed, with the act of generation.

    Seedlings from the same fruit, and the young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life; and this shows how unimportant the direct effects of the conditions of life are in comparison with the laws of reproduction, and of growth, and of inheritance; for had the action of the conditions been direct, if any of the young had varied, all would probably have varied in the same manner. To judge how much, in the case of any variation, we should attribute to the direct action of heat, moisture, light, food, etc., is most difficult: my impression is, that with animals such agencies have produced very little direct effect, though apparently more in the case of plants. Under this point of view, Mr. Buckman’s recent experiments on plants seem extremely valuable. When all or nearly all the individuals exposed to certain conditions are affected in the same way, the change at first appears to be directly due to such conditions; but in some cases it can be shown that quite opposite conditions produce similar changes of structure. Nevertheless some slight amount of change may, I think, be attributed to the direct action of the conditions of life—as, in some cases, increased size from amount of food, colour from particular kinds of food and from light, and perhaps the thickness of fur from climate.

    Habit also has a decided influence, as in the period of flowering with plants when transported from one climate to another. In animals it has a more marked effect; for instance, I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild-duck; and I presume that this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parent. The great and inherited development of the udders in cows and goats in countries where they are habitually milked, in comparison with the state of these organs in other countries, is another instance of the effect of use. Not a single domestic animal can be named which has not in some country drooping ears; and the view suggested by some authors, that the drooping is due to the disuse of the muscles of the ear, from the animals not being much alarmed by danger, seems probable.

    There are many laws regulating variation, some few of which can be dimly seen, and will be hereafter briefly mentioned. I will here only allude to what may be called correlation of growth. Any change in the embryo or larva will almost certainly entail changes in the mature animal. In monstrosities, the correlations between quite distinct parts are very curious; and many instances are given in Isidore Geoffroy St. Hilaire’s great work on this subject. Breeders believe that long limbs are almost always accompanied by an elongated head. Some instances of correlation are quite whimsical; thus cats with blue eyes are invariably deaf; colour and constitutional peculiarities go together, of which many remarkable cases could be given amongst animals and plants. From the facts collected by Heusinger, it appears that white sheep and pigs are differently affected from coloured individuals by certain vegetable poisons. Hairless dogs have imperfect teeth; long-haired and coarse-haired animals are apt to have, as is asserted, long or many horns; pigeons with feathered feet have skin between their outer toes; pigeons with short beaks have small feet, and those with long beaks large feet. Hence, if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly unconsciously modify other parts of the structure, owing to the mysterious laws of the correlation of growth.

    The result of the various, quite unknown, or dimly seen laws of variation is infinitely complex and diversified. It is well worth while carefully to study the several treatises published on some of our old cultivated plants, as on the hyacinth, potato, even the dahlia, etc.; and it is really surprising to note the endless points in structure and constitution in which the varieties and sub-varieties differ slightly from each other. The whole organisation seems to have become plastic, and tends to depart in some small degree from that of the parental type.

    Any variation which is not inherited is unimportant for us. But the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, is endless. Dr. Prosper Lucas’s treatise, in two large volumes, is the fullest and the best on this subject. No breeder doubts how strong is the tendency to inheritance: like produces like is his fundamental belief: doubts have been thrown on this principle by theoretical writers alone. When a deviation appears not unfrequently, and we see it in the father and child, we cannot tell whether it may not be due to the same original cause acting on both; but when amongst individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent—say, once amongst several million individuals—and it reappears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance. Every one must have heard of cases of albinism, prickly skin, hairy bodies, etc., appearing in several members of the same family. If strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable. Perhaps the correct way of viewing the whole subject, would be, to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly.

    The laws governing inheritance are quite unknown; no one can say why the same peculiarity in different individuals of the same species, and in individuals of different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characters to its grandfather or grandmother or other much more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex. It is a fact of some little importance to us, that peculiarities appearing in the males of our domestic breeds are often transmitted either exclusively, or in a much greater degree, to males alone. A much more important rule, which I think may be trusted, is that, at whatever period of life a peculiarity first appears, it tends to appear in the offspring at a corresponding age, though sometimes earlier. In many cases this could not be otherwise: thus the inherited peculiarities in the horns of cattle could appear only in the offspring when nearly mature; peculiarities in the silkworm are known to appear at the corresponding caterpillar or cocoon stage. But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that when there is no apparent reason why a peculiarity should appear at any particular age, yet that it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology. These remarks are of course confined to the first appearance of the peculiarity, and not to its primary cause, which may have acted on the ovules or male element; in nearly the same manner as in the crossed offspring from a short-horned cow by a long-horned bull, the greater length of horn, though appearing late in life, is clearly due to the male element.

    Having alluded to the subject of reversion, I may here refer to a statement often made by naturalists—namely, that our domestic varieties, when run wild, gradually but certainly revert in character to their aboriginal stocks. Hence it has been argued that no deductions can be drawn from domestic races to species in a state of nature. I have in vain endeavoured to discover on what decisive facts the above statement has so often and so boldly been made. There would be great difficulty in proving its truth: we may safely conclude that very many of the most strongly-marked domestic varieties could not possibly live in a wild state. In many cases we do not know what the aboriginal stock was, and so could not tell whether or not nearly perfect reversion had ensued. It would be quite necessary, in order to prevent the effects of intercrossing, that only a single variety should be turned loose in its new home. Nevertheless, as our varieties certainly do occasionally revert in some of their characters to ancestral forms, it seems to me not improbable, that if we could succeed in naturalising, or were to cultivate, during many generations, the several races, for instance, of the cabbage, in very poor soil (in which case, however, some effect would have to be attributed to the direct action of the poor soil), that they would to a large extent, or even wholly, revert to the wild aboriginal stock. Whether or not the experiment would succeed, is not of great importance for our line of argument; for by the experiment itself the conditions of life are changed. If it could be shown that our domestic varieties manifested a strong tendency to reversion,—that is, to lose their acquired characters, whilst kept under unchanged conditions, and whilst kept in a considerable body, so that free intercrossing might check, by blending together, any slight deviations of structure, in such case, I grant that we could deduce nothing from domestic varieties in regard to species. But there is not a shadow of evidence in favour of this view: to assert that we could not breed our cart and race-horses, long and short-horned cattle, and poultry of various breeds, and esculent vegetables, for an almost infinite number of generations, would be opposed to all experience. I may add, that when under nature the conditions of life do change, variations and reversions of character probably do occur; but natural selection, as will hereafter be explained, will determine how far the new characters thus arising shall be preserved.

    When we look to the hereditary varieties or races of our domestic animals and plants, and compare them with species closely allied together, we generally perceive in each domestic race, as already remarked, less uniformity of character than in true species. Domestic races of the same species, also, often have a somewhat monstrous character; by which I mean, that, although differing from each other, and from the other species of the same genus, in several trifling respects, they often differ in an extreme degree in some one part, both when compared one with another, and more especially when compared with all the species in nature to which they are nearest allied. With these exceptions (and with that of the perfect fertility of varieties when crossed,—a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as, only in most cases in a lesser degree than, do closely-allied species of the same genus in a state of nature. I think this must be admitted, when we find that there are hardly any domestic races, either amongst animals or plants, which have not been ranked by some competent judges as mere varieties, and by other competent judges as the descendants of aboriginally distinct species. If any marked distinction existed between domestic races and species, this source of doubt could not so perpetually recur. It has often been stated that domestic races do not differ from each other in characters of generic value. I think it could be shown that this statement is hardly correct; but naturalists differ most widely in determining what characters are of generic value; all such valuations being at present empirical. Moreover, on the view of the origin of genera which I shall presently give, we have no right to expect often to meet with generic differences in our domesticated productions.

    When we attempt to estimate the amount of structural difference between the domestic races of the same species, we are soon involved in doubt, from not knowing whether they have descended from one or several parent-species. This point, if it could be cleared up, would be interesting; if, for instance, it could be shown that the greyhound, bloodhound, terrier, spaniel, and bull-dog, which we all know propagate their kind so truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many very closely allied and natural species—for instance, of the many foxes—inhabiting different quarters of the world. I do not believe, as we shall presently see, that all our dogs have descended from any one wild species; but, in the case of some other domestic races, there is presumptive, or even strong, evidence in favour of this view.

    It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would endure other climates? Has the little variability of the ass or guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold by the common camel, prevented their domestication? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would vary on an average as largely as the parent species of our existing domesticated productions have varied.

    In the case of most of our anciently domesticated animals and plants, I do not think it is possible to come to any definite conclusion, whether they have descended from one or several species. The argument mainly relied on by those who believe in the multiple origin of our domestic animals is, that we find in the most ancient records, more especially on the monuments of Egypt, much diversity in the breeds; and that some of the breeds closely resemble, perhaps are identical with, those still existing. Even if this latter fact were found more strictly and generally true than seems to me to be the case, what does it show, but that some of our breeds originated there, four or five thousand years ago? But Mr. Horner’s researches have rendered it in some degree probable that man sufficiently civilized to have manufactured pottery existed in the valley of the Nile thirteen or fourteen thousand years ago; and who will pretend to say how long before these ancient periods, savages, like those of Tierra del Fuego or Australia, who possess a semi-domestic dog, may not have existed in Egypt?

    The whole subject must, I think, remain vague; nevertheless, I may, without here entering on any details, state that, from geographical and other considerations, I think it highly probable that our domestic dogs have descended from several wild species. In regard to sheep and goats I can form no opinion. I should think, from facts communicated to me by Mr. Blyth, on the habits, voice, and constitution, etc., of the humped Indian cattle, that these had descended from a different aboriginal stock from our European cattle; and several competent judges believe that these latter have had more than one wild parent. With respect to horses, from reasons which I cannot give here, I am doubtfully inclined to believe, in opposition to several authors, that all the races have descended from one wild stock. Mr. Blyth, whose opinion, from his large and varied stores of knowledge, I should value more than that of almost any one, thinks that all the breeds of poultry have proceeded from the common wild Indian fowl (Gallus bankiva). In regard to ducks and rabbits, the breeds of which differ considerably from each other in structure,

    Enjoying the preview?
    Page 1 of 1