Certain foods, such as meat, appear to harbour toxic bacteria - known as endotoxins - that can trigger inflammation in your arteries, even when food is fully cooked.
Biology will relate every human gene to the genes of other animals and bacteria, to this great chain of being.
For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.
Every time someone uses a bathroom and they flush, all the bacteria is shot into the air.