Replicating a fiction

Editor's Introduction -- The writers of many biology books like to tell about Jean-Baptiste de Lamarck, but their Lamarck is an invention. He has acquired his characteristics from hearsay and wrong guesses, and he has been replicated in successive generations of schoolbooks by successive teams of plagiarists.
from The Textbook Letter, September-October 1994

The Imaginary Lamarck:
A Look at Bogus "History" in Schoolbooks

Michael T. Ghiselin

Jean-Baptiste de Lamarck (1744-1829) takes a prominent place in many biology textbooks and life-science textbooks, which depict him as the author of a "theory" of evolution based upon the inheritance of acquired characteristics. Lamarck's views, these books say, should be rejected in favor of the theory of evolution by natural selection, propounded by Charles Darwin (1809-1882), because only Darwin's theory is compatible with the findings of 20th-century genetics.

The Lamarck presented in schoolbooks, however, is a fiction -- an imaginary figure who has been fashioned from hearsay and wrong guesses, and who has been replicated in countless books by successive teams of plagiarists. This figure shares very little, except his name, with the Lamarck of history. Textbook-writers have imbued the fictitious Lamarck with an importance that the real Lamarck never had, and they have credited him with ideas that the real Lamarck did not hold. They also have invented a myth in which those ideas are compared falsely with Darwin's ideas, to produce a bogus dichotomy.

Textbooks typically introduce Lamarck with a flourish, as in this passage from Prentice Hall's Biology: The Study of Life:

One of the first theories of evolution was presented by the French biologist Jean Baptiste de Lamarck in 1809. From his studies of animals, Lamarck became convinced that species were not constant. Instead, he believed that they evolved from preexisting species. . . . According to Lamarck's theory, evolution involved two principles. He called his first principle the law of use and disuse. . . . The second part of Lamarck's theory was the inheritance of acquired characteristics. Lamarck assumed that the characteristics an organism developed through use and disuse could be passed on to its offspring.

Much the same material appears in Holt's Biology Today:

In 1809 a French biologist named Jean Baptiste de Lamarck presented an explanation of the origin of species in his work Zoological Philosophy. Lamarck developed a theory of evolution based on his belief in two biological processes:

  • The use and disuse of organs. According to Lamarck, organisms respond to changes in their environment by developing new organs or changing the structure and function of old organs. . . .

  • Inheritance of acquired traits. Lamarck believed that acquired characteristics were passed on to the organism's offspring. . . .

Such claims give many false or misleading impressions, starting with the implication that Lamarck's views were original. They were not. Lamarck did not originate the idea of organic evolution (a concept that dates from ancient times), did not originate any ideas to explain why evolution happens, and did not originate the doctrine that acquired characteristics could be inherited. That doctrine, the one with which Lamarck's name is most famously associated, had been widely accepted since antiquity and was taken for granted by most 19th-century biologists.

While schoolbooks suggest that Lamarck was an eminent figure in the history of science, he actually had only a small following among the scientists of his day. Furthermore, this following arose largely by default: For anyone who accepted that organic evolution really went on in nature, the only theoretical framework for explaining it lay in the views that Lamarck absorbed and publicized. And one reason why the concept of evolution was not broadly accepted was that Lamarck's views were implausible. Charles Lyell (1797-1875), in his exceedingly influential book Principles of Geology, used that implausibility to discredit the idea of evolution itself.

Lamarck's notions about evolution appeared in his book Philosophie Zoologique, which presented little (if any) scientific evidence -- either for the hypothesis that evolution had occurred or for the particular explanatory ideas that Lamarck favored. Lamarck's style, left over from an earlier generation, was heavy on speculation but weak on fact. Indeed, what he set forth was generally regarded as philosophy, not science.

Imagining a mysterious "tendency to perfection," Lamarck declared that simple animals arose spontaneously and then became more complex, evolving in the direction of man. They deviated somewhat from this evolutionary path, however, because they had to adapt to their surroundings and their conditions of existence. As the animals strove to satisfy their daily needs, the movement of their internal fluids caused parts of their bodies to swell, Lamarck said, and these changes were passed to the animals' offspring.

Lamarck's notion of organisms changing progressively from simple to complex suggested the sort of goal-seeking that might have appealed to a person who had a theological bent. Lamarck, however, tried to explain everything in strictly materialistic terms, with body fluids acting in ways that were vaguely analogous to the movement of air in the atmosphere or the movement of water within the earth.

Even this short summary of the ideas in Philosophie Zoologique suffices to show that Lamarck's approach to evolution was that of a metaphysician rather than a natural scientist. It invoked a mystical assumption (the notion that organisms sought "perfection" and tended to become increasingly complex and man-like) which could not be treated scientifically and could not be supported or contravened by evidence. For that very reason, Lamarck's construct was not a proper theory and was not at all comparable to the theory that Darwin would later present in On the Origin of Species. Darwin's concept was a well articulated body of scientific thought that could be, and was, tested by recourse to facts. Lamarck's was not.

Lamarck's idea about giraffes -- that their necks grew longer as they stretched for distant leaves, and that their elongated necks were inherited by their offspring -- has been cited and illustrated in one schoolbook after another, to the point of utter tedium. A passage about giraffes really does occur in Lamarck's writings, but the schoolbook-writers obviously have not looked at it. Instead they have seized upon an addled version of the giraffe scenario, and they have been recycling that version for decades. They present it in a highly misleading way, and they don't tell that the giraffe scenario is merely a hypothetical example of how a Lamarckian "mechanism" might work -- not an example of something that has actually been studied scientifically. They also fail to tell that Lamarck's notion about giraffes, like all his evolutionary speculations, involved the mystical principle of progress toward "perfection."

All of these misrepresentations of Lamarck form part of a bigger folly: Textbooks pit Lamarck against Darwin in a mythical contest from which Darwin emerges victorious. To perpetuate that myth, the textbook-writers lead students to believe that Lamarck embraced the inheritance of acquired characteristics, that Darwin rejected it, and that this was the crucial difference between the two men's ideas about evolution.

None of that is true. First, Lamarck adopted the inheritance of acquired characteristics as an assumption; he needed that assumption to make some of his imagined mechanisms work, but it was an assumption about heredity, not about evolution. Second, Darwin accepted the inheritance of acquired characteristics, just as Lamarck did, and Darwin even thought that there was some experimental evidence to support it. In a book published in 1868, The Variation of Animals and Plants Under Domestication, Darwin presented the "pangenesis" hypothesis to explain how the inheritance of acquired characteristics might operate: All the parts of an organism's body threw off little corpuscles that were collected in the organism's reproductive system and then were passed on to the organism's offspring. (This idea did not originate with Darwin; similar concepts had been published before.)

The tale told in most schoolbooks is all the more misleading because it isolates Darwin from Lamarck, as if there were no historical or intellectual connection between them. That too is false. Darwin was thoroughly familiar with Lamarck's views and writings, and Darwin explicitly acknowledged them when he composed an outline of the development of ideas about evolution. The outline was added to the third edition of On the Origin of Species (published in 1861) and was titled "An Historical Sketch of the Progress of Opinion on the Origin of Species." Here is what it said of Lamarck:

Lamarck was the first man whose conclusions [concerning the origin of species] excited much attention. This justly-celebrated naturalist first published his views in 1801, and he much enlarged them in 1809 in his "Philosophie Zoologique," and subsequently, in 1815, in his Introduction to his "Hist. Nat. des Animaux sans Vertébres." In these works he upholds the doctrine that species, including man, are descended from other species. He first did the eminent service of arousing attention to the probability of all change in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition. Lamarck seems to have been chiefly led to his conclusion on the gradual change of species, by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain organic groups, and by the analogy of domestic productions. With respect to the means of modification, he attributed something to the direct action of the physical conditions of life, something to the crossing of already existing forms, and much to use and disuse, that is, to the effects of habit. To this latter agency he seemed to attribute all the beautiful adaptations in nature; -- such as the long neck of the giraffe for browsing on the branches of trees. But he likewise believed in a law of progressive development; and as all the forms of life thus tend to progress, in order to account for the existence at the present day of very simple productions, he maintains that such forms were now spontaneously generated.

Tails of Mice, Ears of Dogs

More confusion is sown when schoolbooks purport to explain why the mythical contest between Lamarck and Darwin was decided in Darwin's favor. Here the textbook-writers tell fictitious stories about "tests" that supposedly have refuted Lamarck's "theory." In reality, those "tests" have been directed not at Lamarck's particular claims but at the idea of the inheritance of acquired characteristics -- an idea that, as I have said, was held by Lamarck and Darwin alike, and by most of their scientific contemporaries.

One such "test" that has been mindlessly cited in many textbooks is an exercise carried out by the biologist August Weismann (1834-1914). Here is how it is described in the high-school book Addison-Wesley Biology, under the headline "Lamarck Disproven":

In 1889, German biologist August Weismann showed that Lamarck's [explanation of evolution] was incorrect. Weismann cut off the tails of hundreds of mice for 22 generations. Lamarck's hypothesis [sic] would predict that eventually mice would be born with shorter tails or no tails at all. However, Weismann's mice continued to produce baby mice with normal tails. Weismann concluded that changes in the body during an individual's lifetime do not affect the reproductive cells or the offspring.

That story combines false "history" with a fundamental misconception. The acquired characteristics that figured in Lamarck's thinking were changes that resulted from an individual's own drives and actions, not from the actions of external agents. Lamarck was not concerned with wounds, injuries or mutilations, and nothing that Lamarck had set forth was tested or "disproven" by the Weismann tail-chopping experiment.

The truth about Weismann's work is much more interesting than the story told in schoolbooks. Weismann questioned whether the inheritance of acquired characteristics could take place at all, and he devised many ingenious arguments against it. These arguments, however, did not involve the negative results of his tail-chopping experiment. Weismann himself didn't consider such results to have much weight, and he knew that the experiment had not disclosed anything new: Experience with circumcision in humans (and with other kinds of ceremonial or cosmetic mutilation) had already shown that repeated surgery, through many successive generations, did not cause an inherited change in an organ's form.

Despite this, textbook-writers continue to promote the notion that Lamarck's view of evolution can be refuted by experiments involving mutilation. As an alternative to the bogus story about mice, some books tell a bogus story about dogs, complete with pictures to suggest that something important is being taught. Heath's Biological Science: A Molecular Approach, for example, shows pictures of an adult Doberman pinscher and a Doberman pup, with this caption:

Acquired characteristics are not inherited as Lamarck thought. Even though this adult Doberman has had its tail and ears cropped, you can see that its offspring still was born with long ears and tail.

The same pictures, with a similarly misconceived caption, appear in Kendall/Hunt's Biological Science: An Ecological Approach.

In Prentice Hall's Biology, the two dogs are in a single picture, but the false lesson is the same. The caption says:

The ears of this adult Doberman pinscher have been clipped so that they stand up on her head. But the ears of her puppy still hang down by the side of its head. This is proof that traits acquired during a lifetime are not passed on to the next generation.

Like the story of Weismann's mice, these notions about dogs have nothing to do with Lamarck, with Lamarck's thoughts about evolution, or with Lamarck's conception of the inheritance of acquired characteristics. As I already have explained, Lamarck was not concerned with features arising from wounds.

Though one schoolbook after another recites irrelevant stories about the tails of mice or the ears of dogs, what really led scientists to reject the inheritance of acquired characteristics was the expanding body of knowledge about cell biology. Given all that we now know about cells and chromosomes, it is very hard to imagine how the hereditary material can be affected by changes in other components of an organism's body.

Factions and Fantasies

Textbooks perpetuate all these follies so that they can perpetuate a bogus dichotomy between Lamarck's views and Darwin's. But why? And where did the notion of a dichotomy come from in the first place? It seems that schoolbook-writers have perceived the history of evolutionary thought in a badly muddled way and have been confused by terminology. To understand this, we have to look at what happened after Darwin published On the Origin of Species.

When Darwin's theory of evolution became widely known, it made evolution a matter for serious scientific discourse. It also focused attention on the principle of natural selection, which a lot of people did not like. Some of the people were French, and their attitudes were colored by chauvinism. They wanted an explanatory principle devised by a Frenchman. Others rejected natural selection because they did not like the relentlessly competitive world that selection implied and that Darwin envisioned. They wanted something that would be more in keeping with their personal, beneficent political values. For these and other reasons, people espoused various alternatives to natural selection, and a number of factions were formed.

By the beginning of the 1900s, two of the factions had gained major importance and were dominating the debate about evolution. One faction comprised people who favored natural selection as the chief mechanism of evolution, and who rejected the inheritance of acquired characteristics; these people came to be called "Neo-Darwinians." The other group advocated a wide variety of evolutionary mechanisms (known or unknown), and they also accepted the premise that acquired traits could pass from one generation to the next; these people were called "Neo-Lamarckians."

The controversy between the two groups endured for several decades, but by 1940 biologists had learned so much about genetics and related subjects that the ideas of the "Neo-Lamarckians" were generally abandoned. They play no role in our modern theory of evolution, which emerged during the 1940s and the early 1950s.

These historical developments -- and especially the names of the two factions that disputed with each other during the early 1900s -- probably explain why textbooks have got things so wrong. It is easy to see how mere terminology could have led an uninformed textbook-writer into error: Upon hearing that there was a controversy between "Neo-Lamarckians" and "Neo-Darwinians," the writer evidently inferred that Lamarck and Darwin themselves must have been opponents, and that their ideas about evolution must have been utterly different; the writer then invented a tale based on his false inferences, and he put his tale into a schoolbook many years ago. Ever since then, textbook-company plagiarists have been copying and recopying it, so students and teachers have been stuck with it.

Worse still, the tale has acquired fictitious embellishments and "improvements" that render it even more misleading. For example, Addison-Wesley Biology says this:

While studying fossils of extinct invertebrates, Lamarck found some that looked like primitive forms of modern animals. He reasoned that these could be the ancestors of some of the invertebrates alive today.

That may sound like a plausible explanation of why Lamarck was interested in evolution, but it is really a guess. It is not an accurate description of what happened. According to Lamarck's own writings, his research into fossils led him to the idea that each group of animals seemed to blend into another, so that all groups could presumably be arranged in a great, continuous series -- with no abrupt breaks -- if enough specimens could be collected. Schoolbook-writers may find it pleasing to imagine that Lamarck viewed a series of fossils as a series of ancestors and descendants, but he did not.

Darwin is abused in much the same way. Darwin's recognition of evolution was based on evidence supplied by biogeography, not by the fossil record; in other words, it was based on the distribution of organisms in space, not on their distribution in time. The peculiar organisms of islands and of isolated places like Australia provided the crucial evidence, and it was Darwin's brilliant analysis of biogeographic phenomena that convinced his fellow scientists that he was right. All of that is straightforward history, but some textbook-writers prefer to tell a story in which Darwin acquires his understanding of evolution while he is contemplating fossils; in this story, biogeography and Darwin's biogeographic observations are not even mentioned.

From such misinformation -- about Lamarck, Darwin and all the rest of it -- is fabricated the bogus scientific "history" found in our schoolbooks.

Michael T. Ghiselin is a biologist, a senior research fellow at the California Academy of Sciences, and chairman of the Academy's Center for the History and Philosophy of Science. His research has emphasized comparative anatomy and the evolution of modes of reproduction. His books include The Triumph of the Darwinian Method and The Economy of Nature and the Evolution of Sex.


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