Giraffes’ towering height is the key to their ability to survive in their often-dry habitat. It allows them to reach the tender leaves at the top of acacia trees. Because these leaves are about three-quarters water, they also provide moisture when there are no watering places nearby. Giraffes didn’t just decide to grow longer necks to reach these leaves! Over hundreds of generations, the tallest giraffes, who could reach more leaves, became healthier, lived longer, and had more offspring. Gradually, the average height increased .3. Paraphrase the first two sentences of the text.

4. Summarize the paragraph.