Lamarck - Jean-Baptiste de Monet, Chevalier de Lamarck

French naturalist and evolutionist. Born to a minor noble family in Basentin-le-Petit, Picardie, northern France. After a seminary and military career, he studied medicine in Paris and attended botany lectures at the Royal Botanical Gardens. In 1778 he published a kind of guidebook, the Flora de France, which he became famous for. However, the classification used in the book was artificial, and it seems unlikely that he gained anything about evolution from his study of botany. After the Revolution, he became a professor of "entomopathology and wormology" at the Natural History Museum, which was reorganized from the botanical gardens. He went on to study zoology, especially invertebrate zoology, and coined the words "invertebrates" and "biology." He published major works such as "Systema invertebrata" (1801), "Philosophia zoologiae" (2 volumes, 1809), and "History of Invertebrate Zoology" (7 volumes, 1815-1822). He was also interested in geology and meteorology, and founded the Annales Meteorologie in 1799, but it was later discontinued due to the interference of Napoleon I. After Cuvier took up the post of head of the museum, Lamarck and Cuvier were always in conflict with each other, and while Cuvier was at the forefront of academia, Lamarck received a lot of criticism, and in his later years he suffered from poverty and blindness, but continued to write with the help of his two daughters.

In zoology, he first classified invertebrates into five classes and later into ten classes, which is closer to the modern classification system, and he classified lower animals as insensory animals, those above insects as sensory animals, and vertebrates as intelligent animals, and explained the development of psychological abilities.

Regarding evolution, Lamarck said that living things arise spontaneously and that biological systems have a tendency to develop (progressive development). He also said that, as a secondary factor of evolution, traits acquired by individuals during their lifetime through external influences and the use or disuse of their organs can be passed on to the next generation. Generally, the term Lamarckism refers to the inheritance of acquired traits, but the idea of ​​progressive development is also central to Lamarck's theory.

[Sadao Yasugi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

フランスの博物学者、進化学者。北フランス、ピカルディー県のバザンタン・ル・プチの小貴族の出身。神学生、軍人を経て、パリで医学を学び、王立植物園で植物学の講義を聴講した。1778年には一種のガイドブックである『フランス植物誌』を出版して著名になった。しかしここで用いられた分類法は人為分類で、彼は植物学の研究からは進化論について得るところはなかったと思われる。大革命ののちに植物園を母体に改組された自然史博物館で、「昆虫および蠕虫(ぜんちゅう)学」教授の位置につき、動物学、とくに無脊椎(むせきつい)動物学の研究に進み、「無脊椎動物」「生物学」などの語をつくり、『無脊椎動物の体系』（1801）、『動物哲学』（2巻、1809）、『無脊椎動物誌』（7巻、1815～1822）などの主要著作を出版した。また地質学や気象学にも関心を抱き、『気象学年報』を1799年に創刊したが、のちにナポレオン1世の干渉によって廃刊した。キュビエが博物館に就任して以後、ラマルクとキュビエはつねに対立関係にあり、キュビエが学界の主流を歩んだのに対してラマルクは多くの批判を受け、晩年は貧困と失明に苦しみ、二人の娘の助力で著述を続けた。

　動物学においては、無脊椎動物を最初は5綱、のちに10綱に分類して現在の分類体系に近づけ、また下等なものを無感覚動物、昆虫類以上のものを感覚動物、さらに脊椎動物を知能動物として、心理能力の発達を説いた。

　進化に関しては、生物が自然発生をし、生物体制が発達の傾向をもつ（前進的発達）とした。さらに進化の副次的要因として、個体が一生の間に外界の影響や器官の使用、不使用によって獲得した形質が、次世代に遺伝することがある、と説いた。一般にラマルキズムの語はこの獲得形質の遺伝を意味することが多いが、前進的発達の思想もラマルク学説の中心となっている。

［八杉貞雄］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例