Final answer:
Lamarck's theory suggested organisms pass on traits acquired during their lifetime, an idea later discredited but significant in evolutionary thought's development.
Step-by-step explanation:
French naturalist Jean-Baptiste Lamarck was a pioneer in proposing a theory of evolution before Darwin. Lamarck's theory of change, known as the inheritance of acquired characteristics, suggested that organisms could pass on traits acquired in their lifetime to their offspring. For example, he believed that giraffes developed longer necks by stretching to reach higher leaves, and that these longer necks were then passed on to the next generation. Though Lamarck's ideas about inheritance were later discredited in favor of Darwin's theory of natural selection, they were crucial in the early development of evolutionary thought.