Bacteria have been on the planet for more than 3 billion years, yet early man only appeared 250 thousand years ago! So there's a good probability we'll never be able to eradicate them, and we certainly wouldn't want to. Despite the fact that germs have been a scourge of humanity since the dawn of time, we require them. Natural bacteria on our skin, the lining of our intestines, and our mucous membranes, for example, contribute to protect us against diseases caused by harmful bacteria. Furthermore, the presence of bacteria in our gut aids in the digestion of food.