Lamarck explained the long neck of the giraffe by suggesting that
- A. giraffes with longer necks survived and left more offspring
- B. a mutation in a growth gene lengthened the neck
- C. chance alone lengthened necks in a small isolated population
- D. each generation stretched its neck to reach higher leaves and the gain was inherited
Explanation
In Lamarck's account the effort of stretching lengthens the neck within the animal's own lifetime and the longer neck is then handed to the offspring, so the trait grows a little in every generation. Darwin's explanation, offered in the first option, starts from neck length varying at birth and lets the environment select among those variations. The two theories are distinguished by this exact contrast in almost every exam.