We're a nation of confused germophobes.
microbes
Bacteria are everywhere, surviving in even the most extreme environments like hot springs and ice cubes.
Ancient documents decay over time. Understanding the underlying cause of the deterioration is obviously necessary to prevent or reverse it.
What happens when we die? This question is both existential and biological. While scientists cannot address the first, they certainly can address the second. What happens to your body after you die is not pretty.