Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 – December 28, 1829) was a French naturalist and an early proponent of the idea that evolution (descent with modification) occurred and proceeded in accordance with natural laws. Lamarck, however, is remembered today mainly in connection with his now superseded theory of heredity, the "inheritance of acquired traits" (see Lamarckism).
In a wider context, Lamarckism remains of use when examining the evolution of cultures and ideas, is generally held in terms of some religious views on karma and inheritance of sin, and remains applicable to some extent for bacteria and microorganisms. In the case of religion, many traditions accept the view that there is an inheritance of acquired spiritual traits—that actions taken in one's life can be passed down in the form of spiritual merit or demerit to one's lineage. The concept of original sin visits the same issue, with the mistake of the original ancestors (Adam and Eve) being inherited by all humanity. (See Lamarckism and inheritance of acquired cultural and spiritual characteristics below.)
Lamarck was born in Bazentin-le-Petit, Picardie into an impoverished family (hence the title of chevalier, knight).
Lamarck served in the army before becoming interested in natural history and writing a multi-volume flora of France. This caught the attention of Georges-Louis Leclerc, Comte de Buffon who arranged for him to be appointed to the Muséum National d'Histoire Naturelle in Paris, France. After years working on plants, Lamarck was appointed curator of invertebrates. He also began a series of public lectures.
Before 1800, Lamarck was an essentialist who believed species were unchanging; however, after working on the mollusks of the Paris Basin, he grew convinced that transmutation of species, or change in the nature of species, occurred over time. He set out to develop an explanation, which he outlined in his 1809 work, Philosophie Zoologique. Lamarck developed two laws to explain evolution: the law of use and disuse (that use of an organ strengthens and develops it and disuse weakens and deteriorates it), and the law of inheritance of acquired characteristics (that acquisitions or losses fostered by nature on an individual are passed on through reproduction to offspring). (See Lamarckism.)
Lamarck saw spontaneous generation as being ongoing, with the simple organisms thus created being transmuted over time (by his mechanism) becoming more complex and closer to some notional idea of perfection. He thus believed in a teleological (goal-oriented) process where organisms became more perfect as they evolved.
Lamarck founded a school of French Transformationism which included Étienne Geoffroy Saint-Hilaire, and which corresponded with a radical British school of comparative anatomy based at the University of Edinburgh, which included the surgeon Robert Knox and the anatomist Robert Edmund Grant. Professor Robert Jameson wrote an anonymous paper in 1826 praising "Mr. Lamarck" for explaining how the higher animals had "evolved" from the "simplest worms"—this was the first use of the word "evolved" in a modern sense. As a young student Charles Darwin was tutored by Grant, and worked with him on marine creatures.
Lamarck married three, possibly four, times. His first marriage was to his mistress from 1777, Marie Delaporte, the mother of his first six children, whom he married on her deathbed in 1792. He remarried in 1795 to Charlotte, but she died in 1797. Lamarck married his third wife, Julie Mallet, in 1798. She died in 1819. Rumors exist of a fourth wife and widow but no documentary evidence exists of her.
Lamarck died penniless in Paris on December 28, 1829.
Lamarckism or Lamarckian evolution is a theory put forward by Lamarck based on the heritability of acquired characteristics, the once widely accepted idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring.
Lamarck proposed that individual efforts during the lifetime of the organisms were the main mechanism driving species to adaptation, as they supposedly would acquire adaptive changes and pass them on to offspring. While enormously popular during the early nineteenth century as an explanation for the complexity observed in living systems, after publication of Charles Darwin's theory of natural selection, the importance of individual efforts in the generation of adaptation was considerably diminished. Later, Mendelian genetics supplanted the notion of inheritance of acquired traits, eventually leading to the development of the modern evolutionary synthesis, and the general abandonment of the Lamarckian theory of evolution in biology.
Between 1794 and 1796 Erasmus Darwin wrote Zoönomia suggesting "that all warm-blooded animals have arisen from one living filament," and "with the power of acquiring new parts" in response to stimuli, with each round of "improvements" being inherited by successive generations. Subsequently Lamarck proposed in his Philosophie Zoologique of 1809 the theory that characteristics that were "needed" were acquired (or diminished) during the lifetime of an organism were then passed on to the offspring. He saw this resulting in the development of species in a progressive chain of development towards higher forms.
Lamarck based his theory on two observations, in his day considered to be generally true:
With this in mind, Lamarck developed two laws:
Examples of Lamarckism would include:
In essence, a change in the environment brings about change in "needs" (besoins), resulting in change in behavior, bringing change in organ usage and development, bringing change in form over time—and thus the gradual transmutation of the species.
While such a theory might explain the observed diversity of species and the first law is generally true, the main argument against Lamarckism is that experiments simply do not support the second law—purely "acquired traits" do not appear in any meaningful sense to be inherited. For example, a human child must learn how to catch a ball even though his or her parents learned the same feat when they were children.
The argument that instinct in animals is evidence for hereditary knowledge is generally regarded within science as false. Such behaviors are more probably passed on through a mechanism called the Baldwin effect. Lamarck’s theories gained initial acceptance because the mechanisms of Mendelian inheritance were not elucidated until later in the nineteenth Century, after Lamarck's death.
The Vestiges of the Natural History of Creation, authored by Robert Chambers and published anonymously in England in 1844, proposed a theory modeled after Lamarckism, causing political controversy for its radicalism and unorthodoxy, but exciting popular interest and paving the way for Darwin.
In the 1920s, experiments by Paul Kammerer on amphibians, particularly the midwife toad, appeared to find evidence supporting Lamarckism, but were discredited as having been falsified. In The Case of the Midwife Toad, Arthur Koestler surmised that the specimens had been faked by a Nazi sympathizer to discredit Kammerer for his political views.
In the 1920s, Harvard University researcher William McDougall studied the abilities of rats to correctly solve mazes. He claimed that offspring of rats that had learned the maze were able to run it faster. The first rats would get it wrong an average of 165 times before being able to run it perfectly each time, but after a few generations it was down to 20. McDougall attributed this to some sort of Lamarckian evolutionary process.
A form of Lamarckism was revived in the Soviet Union of the 1930s when Trofim Lysenko promoted Lysenkoism, which suited the ideological opposition of Joseph Stalin to genetics. This unscientific agricultural policy was later blamed for crop failures and famine.
Steele et al. (1998) produced some indirect evidence for somatic transfer of antibody genes into sex cells via reverse transcription. Homologous DNA sequences from VDJ regions of parent mice were found in germ cells and then their offspring. However, there has been no definitive experiment
Neo-Lamarckism is a theory of inheritance based on a modification and extension of Lamarckism, essentially maintaining the principle that genetic changes can be influenced and directed by environmental factors.
While there is not evidence for Lamarckism with respect to higher organisms—that is, there is no evidence that acquired changes are genetically transmitted—some scientists argue that it can be observed among microorganisms, with induced changes inherited among bacteria and protozoans (Cairns 1998).
In 1988, John Cairns, Julie Overbaugh, and Stefan Miller suggested in a publication in Nature that some E. coli mutations could develop in a Lamarckian manner (Cairns et al. 1988). The group took a mutated strain of E. coli that was unable to consume the sugar lactose and placed it in an environment where lactose was the only food source. They observed over time that mutations occurred within the colony at a rate that suggested the bacteria were overcoming their handicap by altering their own genes. Cairns, among others, dubbed the process adaptive mutagenesis.
If bacteria that had overcome their own inability to consume lactose passed on this "learned" trait to future generations, it could be argued as a form of Lamarckism; though Cairns later chose to distance himself from such a position. More typically, it might be viewed as a form of ontogenic evolution.
There has been some research into Lamarckism and prions. A group of researchers, for example, discovered that in yeast cells containing a specific prion protein Sup35, the yeast were able to gain new genetic material, some of which gave them new abilities such as resistance to a particular herbicide. When the researchers mated the yeast cells with cells not containing the prion, the trait reappeared in some of the resulting offspring, indicating that some information indeed was passed down, though whether or not the information is genetic is debatable: trace prion amounts in the cells may be passed to their offspring, giving the appearance of a new genetic trait where there is none (Cohen 2004).
Finally, there is growing evidence that cells can activate low-fidelity DNA polymerases in times of stress to induce mutations. While this does not directly confer advantage to the organism on the organismal level, it makes sense at the gene-evolution level. While the acquisition of new genetic traits is random, and selection remains Darwinian, the active process of identifying the necessity to mutate is considered to be Lamarckian.
Jean Molino (2000) has proposed that Lamarckian evolution may be accurately applied to cultural evolution. This was also previously suggested by Peter Medawar (1959) and Conrad Waddington (1961).
Likewise, religions generally adhere to the view of the inheritance of acquired spiritual traits. That is, there is a view that actions in one's life affect one's spirit and that such passes down to one's lineage in the form of spiritual merit or demerit. This is the view that the "sins of the fathers, when they have not been properly expiated, are passed on and lead to evil consequences for subsequent generation" (Wilson 1991). The doctrine of karma, common to many Eastern religions, as well as the inheritance of sin in some Western religions, reflect this viewpoint.
Examples are found in the Bible (Exodus 20:5-6, "For I the Lord your God am a jealous God, visiting the iniquity of the fathers upon the children to the third and fourth generation"), the Talmud of Judaism (Yoma 87a, "Not alone that they render themselves guilty but they bestow guilt upon their children and children's children until the end of all generation. Many sons did Cannan have, who were worthy to be ordained like Tabi, ... but the guilt of their ancestor caused them to lose their chance"), the Taoist Treatise on Response and Retribution (4-5, "If any guilt remains unpunished at death, the judgement extends to the individuals posterity"), the Hindu Laws of Manu (4.173, "if the punishment falls not on the offender himself, it falls on his sons; if not on the sons, at least on his grandsons"), among other sacred scripture. The concept of original sin is also based on this understanding, for all humanity inherited the spiritual mistake of the original ancestors.
Removal of the disharmony caused in the universe through wrong actions, or the paying of karmic debt, requires restitution for the past actions, such as reflected in the Buddhist Diamond Sutra (16, "By virtue of their present misfortunes, the reacting effects of their past will be thereby worked out"). This can be seen as being paid by future generations who have inherited the repercussions of the wrong actions.
Several historians have argued that Lamarck's name is linked somewhat unfairly to the theory that has come to bear his name, and that Lamarck deserves credit for being an influential early proponent of the concept of biological evolution, far more than for the mechanism of evolution, in which he simply followed the accepted wisdom of his time. Lamarck believed in organic evolution at a time when there was no theoretical framework to explain evolution. He also argued that function precedes form, an issue of some contention among evolutionary theorists at the time.
Lamarck died 30 years before the first publication of Charles Darwin's Origin of Species. As science historian, evolutionist, and paleontologist Stephen Jay Gould has noted, if Lamarck had been aware of Darwin's proposed mechanism of natural selection, there is no reason to assume he would not have accepted it as a more likely alternative to his "own" mechanism. It is also notable that Darwin, like Lamarck, lacked a plausible alternative mechanism of inheritance—the particulate nature of inheritance was only to be observed by Gregor Mendel somewhat later, published in 1866. Its importance, although Darwin cited Mendel's paper, was not recognized until the modern evolutionary synthesis in the early 1900s. An important point in Lamarck's favor at the time was that his theory contained a mechanism describing how variation is maintained, which Darwin’s own theory lacked.
Furthermore, while Darwin proposed natural selection as the main mechanism for development of species, in the Origin of Species Darwin did not rule out a variant of Lamarckism as a supplementary mechanism. Indeed, Darwin not only praised Lamarck in the third edition of The Origin of Species for supporting the concept of evolution and bringing it to the attention of others, but also accepted the idea of use and disuse, and developed his theory of pangenesis partially to explain its apparent occurrence. Darwin and many contemporaries also believed in the inheritance of acquired characteristics, an idea that was much more plausible before the discovery of the cellular mechanisms for genetic transmission.
On the other hand, Lamarck's preeminent theory, the inheritance of acquired characteristics (also called the theory of adaptation), is now widely rejected. For example, August Weismann claimed to disprove the theory by cutting the tails off mice, demonstrating that the injury was not passed on to the offspring. (However, Lamarck did not count injury or mutilation as a true acquired characteristic, only those which were initiated by the animal's own needs were deemed to be passed on.)
Epigenetic inheritance is thought to be Lamarckian, by some, but this is not widely accepted by evolutionary biologists. Epigenetics itself is the study of various gene functions arising from the same gene in different environments. The same gene is passed on to offspring, and the environment determines its expression, so this process still fails to be Lamarckian.
The memetic theory of cultural evolution could be considered a form of Lamarckian inheritance of non-genetic traits. However, this is a point against memetics as a true parallel to genetics, not a point for Lamarckian inheritance.
|Basic topics in evolutionary biology||(edit)|
|Processes of evolution: evidence - macroevolution - microevolution - speciation|
|Mechanisms: natural selection - genetic drift - gene flow - mutation - phenotypic plasticity|
|Modes: anagenesis - catagenesis - cladogenesis|
|History: History of evolutionary thought - Charles Darwin - The Origin of Species - modern evolutionary synthesis|
|Subfields: population genetics - ecological genetics - human evolution - molecular evolution - phylogenetics - systematics|
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