Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 – December 18, 1829), often known simply as Lamarck, is a French naturalist.

He is a soldier, biologist, academic, and an early proponent of the idea that biological evolution occurs and proceeds in accordance with natural laws.

Lamarck fights in the Pomeranian War (1757–62) against Prussia, and is awarded a commission for bravery on the battlefield.

Posted to Monaco, Lamarck becomes interested in natural history and resolves to study medicine.

He retires from the army after being injured in 1766, and returns to his medical studies.

Lamarck developsa particular interest in botany, and later, after he publishes the three-volume work Flore françoise (1778), he gains membership of the French Academy of Sciences in 1779.

Lamarck becomes involved in the Jardin des Plantes and is appointed to the Chair of Botany in 1788.\

When the French National Assembly founds the Muséum national d'Histoire naturelle in 1793, Lamarck becomes a professor of zoology.

In 1801, he publishes Système des animaux sans vertèbres, a major work on the classification of invertebrates, a term he coins.

In an 1802 publication he becomes one of the first to use the term biology in its modern sense.

Lamarck continues his work as a premier authority on invertebrate zoology.

He is remembered, at least in malacology, as a taxonomist of considerable stature.

The modern era generally remembers Lamarck for a theory of inheritance of acquired characteristics, called soft inheritance, Lamarckism or use/disuse theory, which he describes in his 1809 Philosophie Zoologique.

However, his idea of soft inheritance is, perhaps, a reflection of the wisdom of the time accepted by many natural historians.

Lamarck's contribution to evolutionary theory consists of the first truly cohesive theory of biological evolution, in which an alchemical complexifying force drives organisms up a ladder of complexity, and a second environmental force adapts them to local environments through use and disuse of characteristics, differentiating them from other organisms.

Scientists will debate whether advances in the field of transgenerational epigenetics mean that Lamarck was to an extent correct, or not.