Epigenetic marks on DNA or chromatin can sometimes be changed in response to various environmental factors or patterns of behavior, and some of these marks can be transmitted from parents to their offspring, resulting in the "inheritance of acquired characters." For example, the food that animals eat may sometimes influence the phenotypes of their offspring.
Landman (1991) presented several examples that are defined operationally by him as "inheritance of acquired characters" (IAC) systems because they conform to the following experimental pattern:
Although Lamarck invented the term "biology" and made important contributions to the study of invertebrates, his name became linked almost synonymously with the inheritance of acquired characters
. Eventually, Darwin and Lamarck came to represent competing theories of how evolution works: natural selection versus transmission of acquired characters.