Final answer:
The population of the world has increased dramatically over time due to factors such as decreased death rates and high birth rates in developing countries.
Step-by-step explanation:
The population of the world has changed significantly over time. At the beginning of the 20th century, the world population was about 1.6 billion. After 100 years, it had increased to roughly 6 billion, and as of 2018, the population is approximately 7.6 billion. This rapid growth can be attributed to factors such as decreased death rates due to disease and malnutrition, as well as high birth rates in developing countries. These trends have led to a significant increase in global population.