Final answer:
Charles Darwin's theory of natural selection is often credited with explaining why giraffes have long necks, as it provided an advantage in reaching food and being more likely to survive and reproduce. Lamarck also posed a theory, suggesting that physical changes during a giraffe's life led to longer necks in the next generation, but this was proven incorrect. Instead, natural selection favored giraffes with long necks, as demonstrated by Darwin and subsequent scientific experiments.
Step-by-step explanation:
Evolution of Giraffes' Long Necks
The concept that giraffes with longer necks survived better due to competition for food is largely attributed to Charles Darwin and his theory of natural selection. According to this theory, individual giraffes with slightly longer necks could reach higher leaves and therefore had more food resources than those with shorter necks. This increased their chance of survival and the likelihood of passing on their genes to the next generation. Over time, as these long-necked giraffes continued to reproduce, the trait became more common in the population, leading to the modern-day giraffe with its characteristic long neck.
While Jean-Baptiste Lamarck also proposed a theory where giraffes developed longer necks, his hypothesis was different. Lamarck suggested that the stretching of the neck to reach higher food sources physically increased neck length, which was then inherited by offspring. This idea of the inheritance of acquired characteristics, known as Lamarckian inheritance, has since been scientifically disproven in favor of Darwin's natural selection.
Scientist B's experiments showed that muscle stretching did not lead to bone growth or DNA changes necessary for the inheritance of such traits. This reinforced the concept of natural selection, where environmental pressures select for certain traits, like long necks, that provide a survival advantage.