How did Lamarckism explain how giraffes developed long necks?

Lamarckism is a discredited scientific theory that proposed physical changes acquired during an organism's lifetime could be inherited by its offspring. It is important to clarify that this theory has been abandoned by modern science in favor of natural selection, which explains evolutionary adaptation through genetic variation and differential survival rather than the inheritance of acquired traits.123

According to Jean-Baptiste Lamarck, the long neck of a giraffe developed because individual giraffes repeatedly stretched their necks to reach higher leaves on trees to satisfy a need for food. Lamarck argued that this persistent effort caused the neck to physically lengthen during the animal's life. He proposed that this acquired trait was then transmitted to the next generation, leading to a gradual increase in neck length across the species over time. While this provided a purposeful, or teleological, explanation for adaptation, it lacks a biological mechanism for the inheritance of such somatic changes and is not supported by evidence.34