Lamarck, Jean Baptiste Pierre Antoine de Monet (1744-1829)

French naturalist. His theory of evolution, known as Lamarckism, was based on the idea that acquired characteristics (changes acquired in an individual's lifetime) are inherited by the offspring, and that organisms have an intrinsic urge to evolve into better-adapted forms. Philosophie zoologique/Zoological Philosophy (1809) outlined his ‘transformist’ (evolutionary) ideas.

Zoological Philosophy tried to show that various parts of the body developed because they were necessary, or disappeared because of disuse when variations in the environment caused a change in habit. If these body changes were inherited over many generations, new species would eventually be produced.

Lamarck was the first to distinguish vertebrate from invertebrate animals by the presence of a bony spinal column. He was also the first to establish the crustaceans, arachnids, and annelids among the invertebrates. It was Lamarck who coined the word ‘biology’.

Lamarck was born in Bazentin, Picardy. He studied medicine, meteorology, and botany, and travelled across Europe as botanist to King Louis XVI from 1781. In 1793 he was made professor of zoology at the Museum of Natural History in Paris.

So little was known about invertebrates at this time that some scientists grouped snakes and crocodiles with insects. Lamarck studied both living and fossil invertebrates, and described them in his book Histoire naturelle des animaux sans vertèbres/Natural History of Invertebrate Animals (1815-22).