How did neo-Lamarckism differ from Darwin’s explanation of adaptation?

Neo-Lamarckism emerged in the late 19th century as an alternative to Charles Darwin’s theory of natural selection. While Darwin’s explanation of adaptation relied on the preservation of favorable variations through natural selection, neo-Lamarckism fundamentally differed by rejecting this mechanism.12

Instead, neo-Lamarckism emphasized the following concepts:

• Direct Environmental Influence: It proposed that the environment acts directly on organic structures, causing changes that explain an organism's adaptation to its way of life.1
• Use and Disuse: It retained the core Lamarckian principle that the use or disuse of organs leads to their development or obliteration, with these resulting material alterations being passed to offspring.31
• Inheritance of Acquired Characteristics: The theory maintained that traits acquired by an individual during its lifetime—such as physical changes resulting from environmental interaction or behavioral habits—are inherited by subsequent generations.431

In contrast, Darwin’s theory of natural selection focused on the survival and reproduction of individuals possessing advantageous variations, rather than the inheritance of characteristics acquired through an organism's own efforts or environmental responses.21