Final answer:
The correct description of how Darwin’s journey affected science is that he developed the theory of evolution by natural selection, based on his observations and studies during his voyage on the HMS Beagle, which included significant time on the Galápagos Islands.
Step-by-step explanation:
Darwin's contributions to science are encapsulated in his development of the theory of evolution by natural selection. This concept emerged from his extensive observations during his voyage on the HMS Beagle, especially on the Galápagos Islands. Darwin recognized that organisms change over time due to variations that can be inherited and that those with beneficial traits are more likely to survive and reproduce, hence passing on those traits to the next generation.
Darwin’s ideas revolutionized our understanding of biology. His work indicated that species are not static but evolve over time and that natural selection is the mechanism driving these changes. Darwin's observations of artificial selection, fossil records, and various species and their adaptations all contributed to the formulation of his theory. During his journey, he pondered on the ideas of Lamarck, Lyell, and Malthus, and the process of artificial selection, which led him to infer that a similar, natural process could shape the evolution of species in the wild.
It is important to note that Darwin's theory of evolution was not about improving current domesticated animals through artificial selection but rather explaining how species adapt and evolve in natural environments through natural selection. Also, Darwin did not come up with cures for diseases, nor was the theory of evolution by natural selection formed later by different scientists; he was the one who formulated it based on his extensive research and observations.