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Jean-Baptiste Lamarck
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Jean-Baptiste Lamarck

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Jean-Baptiste Lamarck

Jean-Baptiste Lamarck

Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck ( ; French: [ʒɑ̃batist lamaʁk] ),…

Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), commonly referred to as Lamarck (; French: [ʒɑ̃batist lamaʁk]), was a distinguished French naturalist, biologist, academic, and military figure. He is recognized as an early advocate for the concept of biological evolution, proposing that it unfolded according to natural laws, although the specific mechanisms he posited have since been largely discredited.

Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; French: [ʒɑ̃batistlamaʁk]), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biological evolution occurred and proceeded in accordance with natural laws, though the mechanism he suggested has been refuted at large.

Lamarck participated in the Seven Years' War against Prussia, earning a military commission for his battlefield valor. While stationed in Monaco, he developed an interest in natural history and decided to pursue medical studies. Following an injury in 1766, he retired from military service and resumed his medical education. Lamarck cultivated a strong interest in botany, culminating in the publication of his three-volume work, Flore françoise (1778), which led to his election to the French Academy of Sciences in 1779. His involvement with the Jardin des Plantes resulted in his appointment to the Chair of Botany in 1788. Subsequently, with the establishment of the Muséum national d'Histoire naturelle by the French National Assembly in 1793, Lamarck transitioned to a professorship in zoology.

In 1801, Lamarck released Système des animaux sans vertèbres, a seminal publication dedicated to the classification of invertebrates, a term he originated. By 1802, through another publication, he was among the first to employ the term "biology" with its contemporary meaning. Lamarck maintained his position as a leading authority in invertebrate zoology. Within the field of malacology, he is particularly recognized as a taxonomist of significant influence.

In contemporary discourse, Lamarck is primarily recognized for his theory of the inheritance of acquired characteristics, variously termed Lamarckism (a designation accurately reflecting its originator), soft inheritance, or the use/disuse theory, which he elucidated in his 1809 work, Philosophie zoologique. While the concept of soft inheritance predated Lamarck and constituted only a minor component of his broader evolutionary framework, it was widely accepted by natural historians during his era. Lamarck's principle of use and disuse later resonated with Darwin's theory of natural selection and is believed to have partially influenced Darwin, despite his eventual refutation of Lamarckism. Lamarck's seminal contribution to evolutionary thought was the formulation of the first truly coherent theory of biological evolution, positing an inherent "complexifying force" that propelled organisms towards greater complexity, alongside an environmental adaptive force that shaped them to local conditions through the use and disuse of specific traits, thereby distinguishing them from other species. Recent scientific discussions, particularly concerning advancements in transgenerational epigenetics, have prompted debate regarding the potential partial validity of Lamarck's propositions.

Biography

Jean-Baptiste Lamarck was born in Bazentin, Picardy, located in northern France, as the eleventh child into an impoverished aristocratic family. Historically, male members of the Lamarck lineage had served in the French army. During Lamarck's teenage years, his eldest brother perished in combat at the Siege of Bergen op Zoom, while two other brothers remained in active military service. Complying with his father's desires, Lamarck matriculated at a Jesuit college in Amiens during the late 1750s.

Following his father's death in 1760, Lamarck acquired a horse and traveled across the country to enlist in the French army, then deployed in Germany. During the Seven Years' War with Prussia, Lamarck demonstrated exceptional physical courage on the battlefield, leading to his nomination for a lieutenancy. His company, exposed to direct enemy artillery fire, was rapidly decimated to merely fourteen men, with no commanding officers. Despite a suggestion from one of the soldiers that the slight, seventeen-year-old volunteer assume command and order a retreat, Lamarck, upon accepting leadership, steadfastly insisted that they maintain their position until relieved.

Upon the colonel's arrival at the remnants of their company, Lamarck's exhibition of courage and loyalty profoundly impressed him, resulting in an immediate promotion to officer. Nevertheless, a playful incident where a comrade lifted him by the head led to an inflammation of the lymphatic glands in his neck, necessitating his transfer to Paris for medical treatment. Subsequently, he received a commission and was stationed in Monaco. It was there that he discovered Traité des plantes usuelles, a botanical treatise authored by James Francis Chomel.

Facing a significantly reduced annual pension of only 400 francs, Lamarck decided to embark on a new career path. He initially pursued medical studies, sustaining himself through employment at a bank. After four years, he discontinued his medical education, influenced by his elder brother's counsel. His interest subsequently shifted to botany, particularly after visiting the Jardin du Roi, leading him to become a student of Bernard de Jussieu, a prominent French naturalist. Under Jussieu's tutelage, Lamarck dedicated a decade to the study of French flora. His inaugural scientific publication, a chemical treatise, appeared in 1776.

Following his academic pursuits, Lamarck published a three-volume compilation of his observations and findings in 1778, titled Flore française. This publication garnered significant scholarly acclaim, establishing his reputation within French scientific circles. On August 8, 1778, Lamarck married Marie Anne Rosalie Delaporte. Georges-Louis Leclerc, Comte de Buffon, a leading French scientist of that era, became Lamarck's mentor, facilitating his admission to the French Academy of Sciences in 1779 and securing his appointment as a royal botanist in 1781. This commission enabled him to travel to various international botanical gardens and museums. His first son, André, was born on April 22, 1781, with his colleague André Thouin serving as the child's godfather.

During his two years of travel, Lamarck amassed a collection of rare plants not present in the Royal Garden, alongside other natural history specimens, including minerals and ores, which were absent from French museums. On January 7, 1786, his second son, Antoine, was born; Lamarck selected Antoine Laurent de Jussieu, nephew of Bernard de Jussieu, as the child's godfather. The following year, on April 21, Lamarck's third son, Charles René, was born. René Louiche Desfontaines, a botany professor at the Royal Garden, served as the boy's godfather, while Lamarck's elder sister, Marie Charlotte Pelagie De Monet, was the godmother. In 1788, Charles-Claude Flahaut de la Billaderie, comte d'Angiviller, who succeeded Buffon as Intendant of the Royal Garden, established a new role for Lamarck: keeper of the Royal Garden's herbarium, with an annual salary of 1,000 francs.

In 1790, amidst the French Revolution, Lamarck renamed the Royal Garden from Jardin du Roi to Jardin des Plantes, thereby dissociating it from King Louis XVI. After serving five years as the herbarium's keeper, he was appointed curator and professor of invertebrate zoology at the Muséum national d'histoire naturelle in 1793. During his tenure at the herbarium, Lamarck's wife bore three additional children before her death on September 27, 1792. Holding the official title "Professeur d'Histoire naturelle des Insectes et des Vers," Lamarck earned an annual salary approaching 2,500 francs. The subsequent year, on October 9, he married Charlotte Reverdy, who was three decades his junior. On September 26, 1794, Lamarck was designated secretary of the museum's assembly of professors for a one-year term. Charlotte died in 1797, and he married Julie Mallet the following year; she passed away in 1819.

During his initial six years as a professor, Lamarck published only a single paper in 1798, which explored the moon's influence on Earth's atmosphere. Initially an essentialist who posited the immutability of species, his perspective shifted after studying molluscs from the Paris Basin. This research led him to believe that species underwent transmutation or fundamental change over extended periods. Consequently, he endeavored to formulate an explanatory framework, presenting his nascent evolutionary concepts for the first time in a lecture at the Muséum national d'histoire naturelle on May 11, 1800 (the 21st day of Floreal, Year VIII, according to the revolutionary calendar then in use in France).

In 1801, Lamarck published Système des Animaux sans Vertèbres, a seminal treatise on invertebrate classification. Within this work, he established definitions for natural groupings of invertebrates. He delineated categories for echinoderms, arachnids, crustaceans, and annelids, distinguishing them from the archaic taxon for worms, Vermes. Notably, Lamarck was the first to taxonomically separate arachnids from insects and to elevate crustaceans to a distinct class apart from insects.

In 1802, Lamarck published Hydrogéologie, pioneering the use of the term "biology" in its contemporary context. Within Hydrogéologie, Lamarck proposed a steady-state geological model grounded in rigorous uniformitarian principles. He posited that global currents predominantly flowed from east to west, causing continental erosion on eastern margins and subsequent deposition of material on western borders. Consequently, he theorized a continuous westward migration of the Earth's continents.

Concurrently, he released Recherches sur l'Organisation des Corps Vivants, in which he delineated his evolutionary theory. Lamarck contended that all life was structured hierarchically, forming a vertical chain with continuous gradations from the simplest to the most complex organisms, thereby illustrating a trajectory of progressive natural development.

Lamarck's own scientific endeavors initially aligned with the prevailing traditional theory rooted in the classical four elements. Throughout his career, Lamarck generated controversy by critiquing Lavoisier's more advanced chemical theories. Furthermore, he clashed with the esteemed palaeontologist Georges Cuvier, an opponent of evolutionary concepts. Peter J. Bowler notes that Cuvier "ridiculed Lamarck's theory of transformation and defended the fixity of species." Martin J. S. Rudwick further observes:

Cuvier was clearly hostile to the materialistic overtones of current transformist theorizing, but it does not necessarily follow that he regarded species origin as supernatural; certainly he was careful to use neutral language to refer to the causes of the origins of new forms of life, and even of man.

Lamarck progressively lost his sight, ultimately passing away in Paris on December 18, 1829. Upon his death, his family's impoverished state necessitated an appeal to the Académie for financial aid. Lamarck was interred in a communal grave at Montparnasse cemetery for a mere five years, a duration stipulated by the grant secured by his relatives. Subsequently, his remains were exhumed alongside others and became irretrievable. His personal library and household effects were liquidated at auction, and his body was temporarily deposited in a lime pit. Following Lamarck's demise, Cuvier employed the format of a eulogy to disparage his legacy:

[Cuvier's] éloge of Lamarck is one of the most deprecatory and chillingly partisan biographies I have ever read—though he was supposedly writing respectful comments in the old tradition of de mortuis nil nisi bonum.

Lamarckian evolution

During the composition of Hydrogéologie (1802), Lamarck conceived the notion of applying the principle of erosion to biological phenomena. This conceptual leap culminated in his fundamental evolutionary principle, positing that organic fluids within organs acquired increasingly complex forms and functions, subsequently transmitting these characteristics to an organism's progeny. This marked a significant departure from Lamarck's earlier perspective, articulated in his Memoirs of Physics and Natural History (1797), where he briefly alluded to the immutability of species.

Lamarck emphasized two primary tenets in his biological research, neither of which pertained to soft inheritance. The initial tenet asserted that environmental factors induce alterations in animal organisms. He substantiated this principle with examples such as blindness in moles, the dentition of mammals, and the edentulous nature of birds. The second principle maintained that life exhibited an ordered structure, and that the diverse components of all organisms facilitated their organic movements.

While not the inaugural proponent of organic evolution, Lamarck was the first to formulate a genuinely coherent evolutionary theory. He initially presented his evolutionary concepts in his Floreal lecture of 1800, subsequently elaborating them in three published works:

Lamarck posited several evolutionary mechanisms, deriving them from the prevailing scientific understanding of his era and his adherence to pre-Lavoisier chemistry. He utilized these mechanisms to elucidate the two fundamental forces he identified as integral to evolution: one impelling organisms from simpler to more complex configurations, and another facilitating their adaptation to local environments and promoting their differentiation. Lamarck contended that these forces were explicable as inherent outcomes of fundamental physical principles, thereby advocating a materialistic perspective on biology.

Le pouvoir de la vie: The Force of Increasing Complexity

Lamarck posited an inherent tendency for organisms to increase in complexity, progressing along a hierarchical scale. He designated this phenomenon as Le pouvoir de la vie or la force qui tend sans cesse à composer l'organisation (the force that perpetually tends to organize). Lamarck also held the belief in the continuous spontaneous generation of rudimentary living organisms, arising from the interaction of a material life force with physical matter.

Lamarck opposed the contemporary chemistry advocated by Lavoisier, whose concepts he viewed with contempt, instead favoring a more archaic alchemical perspective on elements, which he believed were primarily influenced by earth, air, fire, and water. He contended that following their initial formation, the circulation of fluids within living organisms inherently propelled their evolution towards progressively higher degrees of complexity:

The rapid motion of fluids will etch canals between delicate tissues. Soon their flow will begin to vary, leading to the emergence of distinct organs. The fluids themselves, now more elaborate, will become more complex, engendering a greater variety of secretions and substances composing the organs.

He contended that organisms progressed from rudimentary to intricate forms in a consistent, foreseeable manner, grounded in the foundational physical tenets of alchemy. Within this framework, simple organisms persisted indefinitely because they were continually generated through spontaneous generation, a concept characterized as a "steady-state biology." Lamarck perceived spontaneous generation as an unceasing process, with the newly formed simple organisms undergoing transmutation over time to achieve greater complexity. While occasionally attributed with a belief in a teleological (goal-oriented) evolutionary process leading to organismal perfection, as a materialist, he underscored that these forces inherently stemmed from fundamental physical principles. Paleontologist Henry Fairfield Osborn stated, "Lamarck denied, absolutely, the existence of any 'perfecting tendency' in nature, and regarded evolution as the final necessary effect of surrounding conditions on life." Similarly, science historian Charles Coulston Gillispie observed that "life is a purely physical phenomenon in Lamarck," asserting that Lamarck's perspectives should not be conflated with vitalist doctrines.

L'influence des circonstances: The Force of Adaptation

The second constituent of Lamarck's evolutionary theory involved the adaptation of organisms to their specific environments. This mechanism could propel organisms beyond the general progression, leading to novel and distinct forms characterized by localized adaptations. Conversely, it could also guide organisms into evolutionary cul-de-sacs, where an organism's extreme specialization precluded further morphological alteration. Lamarck posited that this adaptive impetus was fueled by the reciprocal interaction between organisms and their surroundings, specifically through the utilization or non-utilization of particular traits.

First Law: Principles of Use and Disuse

First Law: In any animal that has not reached the culmination of its development, the more frequent and sustained use of an organ progressively strengthens, develops, and enlarges it, conferring a power commensurate with its duration of use; conversely, the permanent disuse of an organ imperceptibly weakens and deteriorates it, gradually diminishing its functional capacity or expected performance, until its eventual disappearance.

Second Law: Inheritance of Acquired Characteristics

Second Law: All acquisitions or losses imposed upon individuals by nature, resulting from the environmental conditions to which their lineage has long been exposed, and consequently from the predominant use or permanent disuse of any organ, are preserved through reproduction in the new individuals that emerge, provided that these acquired modifications are shared by both sexes, or at minimum, by the individuals responsible for procreation.

The final provision of this statute introduces the concept now termed soft inheritance, which refers to the transmission of acquired characteristics, or "Lamarckism," despite constituting only a segment of Lamarck's broader theoretical framework. Nevertheless, within the domain of epigenetics, accumulating evidence suggests that soft inheritance influences phenotypic alterations in certain organisms. This process does not modify the genetic material (DNA), thereby upholding the central dogma of biology, but rather inhibits gene expression, for instance, through methylation that alters DNA transcription. Such modifications can arise from behavioral and environmental shifts, although no documented instance currently links this to the use or disuse of an organ or function. Numerous epigenetic changes exhibit a degree of heritability, albeit frequently for only a limited number of generations. Consequently, while DNA itself is not directly modified by environmental factors and behavior, apart from selective pressures, the genotype-phenotype relationship can be altered, even across several generations, by an individual's lifetime environment. This has prompted biologists to advocate for a reevaluation of the potential for Lamarckian-like evolutionary mechanisms, considering contemporary advancements in molecular biology.

Religious Perspectives

In his seminal work, Philosophie zoologique, Lamarck characterized God as the "sublime author of nature." Alpheus Packard's 1901 book, Lamarck, the Founder of Evolution, delves into Lamarck's religious convictions, concluding, based on Lamarck's writings, that he can be classified as a deist.

Michael Ruse, a prominent philosopher of biology, characterized Lamarck as adhering to a belief in God as an unmoved mover, the creator of the world and its inherent laws, who refrained from miraculous intervention in creation. Similarly, biographer James Moore identified Lamarck as a "thoroughgoing deist."

Historian Jacques Roger asserted that Lamarck exhibited materialistic tendencies, inasmuch as he deemed it unnecessary to invoke any spiritual principles. Roger further noted that Lamarck's deism remained imprecise, and his concept of creation did not preclude his conviction that all phenomena in nature, including the most complex life forms, arose solely from natural processes.

Legacy

Lamarck is predominantly recognized for his evolutionary theories, which were largely superseded by advancements in Darwinism. Paradoxically, his theory of evolution gained significant attention only subsequent to the 1859 publication of Charles Darwin's On the Origin of Species, as critics of Darwin's novel propositions often reverted to Lamarckian evolution as a seemingly more established alternative.

Lamarck is primarily recalled for his adherence to the then-prevalent theory of the inheritance of acquired characteristics and the use and disuse model, which posited how organisms developed their traits. He integrated this concept into his evolutionary theory, alongside other contemporary notions like spontaneous generation. The inheritance of acquired characteristics, also known as the theory of adaptation or soft inheritance, was decisively refuted by August Weismann in the 1880s. Weismann formulated an inheritance theory asserting that germ plasm (sex cells, subsequently identified as DNA) remained distinct and separate from the soma (the somatic body cells). Consequently, no changes occurring in the soma could be transmitted via the germ plasm. This model is widely considered to form the foundation of contemporary inheritance understanding.

Lamarck established one of the earliest comprehensive theoretical frameworks for organic evolution. Although his theory faced widespread rejection during his lifetime, Stephen Jay Gould contended that Lamarck served as the "primary evolutionary theorist." Gould argued that Lamarck's concepts and the structural organization of his theory significantly influenced subsequent thought in evolutionary biology, extending to the present era. Recent advancements in epigenetics, which investigates heritable cellular and physiological traits not attributable to DNA sequence alterations, have ignited discussions regarding the potential validity of a "neolamarckist" perspective on inheritance. It is important to note that Lamarck lacked the scientific context to provide a molecular explanation for his theory. Prominent researchers such as Eva Jablonka and Marion Lamb identify as neolamarckists. However, David Haig, upon reviewing the available evidence, posited that any such epigenetic mechanisms must themselves have originated through natural selection.

Darwin acknowledged the influence of use and disuse as an evolutionary mechanism, primarily concerning disuse, though he considered it secondary to natural selection. He commended Lamarck for his significant contribution in highlighting "the probability of all change in the organic... world, being the result of law, not miraculous interposition." Furthermore, the term Lamarckism is occasionally applied to quasi-evolutionary concepts within societal frameworks, despite not originating from Lamarck himself. For instance, the memetic theory of cultural evolution is sometimes characterized as a form of Lamarckian inheritance involving non-genetic traits.

Taxa Identified by Lamarck

Throughout his career, Lamarck designated numerous species, many of which are now considered synonyms. The World Register of Marine Species documents no fewer than 1,634 of his records, while the Indo-Pacific Molluscan Database lists 1,781. These include prominent families such as the ark clams (Arcidae), sea hares (Aplysiidae), and cockles (Cardiidae). The International Plant Names Index further attributes 58 records to him, encompassing several recognized genera like the mosquito fern (Azolla).

Species Honoring Lamarck

The honeybee subspecies Apis mellifera lamarckii and the bluefire jellyfish (Cyanea lamarckii) are both named in Lamarck's honor. Additionally, several plant species bear his name, such as Amelanchier lamarckii (juneberry), Digitalis lamarckii, the palm tree Dictyocaryum lamarckinum, and Aconitum lamarckii, alongside the grass genus Lamarckia.

The International Plant Names Index documents 116 plant species named in tribute to Lamarck.

Within marine taxonomy, at least 103 species or genera incorporate the epithets "lamarcki", "lamarckii", or "lamarckiana"; however, a significant portion of these are now considered synonyms. Valid marine species names include:

Principal Publications