Chevalier de Lamarck was a French naturalist and invertebrate zoologist who lived from 1844-1829. He is best known for a theory of evolution developed in his book, Philosophie Zoologique, published in 1809. This theory, known today as Lamarckism, is based on the so-called "inheritance of acquired traits," meaning that characteristics that an organism may develop during its lifetime are heritable, and can be passed on to its progeny.

The anatomical, biochemical, and behavioral characteristics that an individual organism displays as its develops through life is known as its phenotype. However, the phenotype that an individual actually develops is somewhat conditional, and is based on two key factors: (1) the fixed genetic potential of the organism (or its genotype; this refers to the specific qualities of its genetic material, or DNA [deoxyribonucleic acid]); and (2) the environmental conditions which an organism experiences as it grows. For example, an individual plant (with a...