The primary reason that the human population has grown rapidly over the past one hundred years is that there has been

significant advancements in medical technology and healthcare. This has resulted in lower mortality rates, longer life expectancy, and reduced infant mortality, leading to a population increase. Additionally, improved sanitation, access to clean water, and increased food production have also played a role in the population growth. There has also been a decrease in fertility rates in some regions, which has contributed to population growth. However, overall, advancements in medical care and technology have been the most significant factor in the rapid population growth.